Dissertations / Theses on the topic 'Sheep Fertility'

Includes bibliographical references (leaves 274-316) Examines several aspects of male reproduction in the sheep, and how these are related to fertility in the female when semen is introduced by natural mating or artificial insemination.

Reproductive and productive performance of a composite sheep population, containing 50% Dorset, 25% Rambouillet and 25% Finn sheep breeding and under selection for ability to lamb in the fall, was evaluated. Traits considered were spring fertility, faIl litter size, live weights at birth, weaning, and at about 90 and 120 d of age, and scrotal circumference at weaning and at about 90 and 120 d of age. Fertility was defined as 1 or 0 depending upon whether a ewe lambed or failed to lamb, respectively, in fall. Litter size was defined as the number of lambs born per ewe lambing. A total of 1,102 exposures were used. Fertility averaged .59 for adult ewes (3 years and older), .45 for second-lambing ewes and .11 for yearling ewes (12 months old). Mean litter size averaged 1.89 across seasons and ages. Scrotal circumferences (SC) and body weights (WT) were measured at means of65, 96 and 128 d. Data were collected on 1878 lambs over 5 years; 63 sires and 420 dams were represented. Genetic parameters were estimated by restricted maximum likelihood (REML) using various animal models. Heritability estimates for spring fertility ranged from .07 to .11. Litter size heritability was .05 for fall lambing and .10 for all lambings. Heritability estimates for weights from birth to 120 d ranged from .04 to . 19. Heritabilities for SC ranged from .02 to .25. Estimated genetic correlations among weights were large, and ranged from. 77 to unity. The genetic correlations of litter size with birth weight (BWT), 90-d weight (90WT) and 90-d scrotal circumference (90SC) were .17, .33 and .36, respectively. Genetic correlations of spring fertility with BWT, 90WT and 90SC were .22, -.31 and .29, respectively. Mixed model methodology was applied to estimate genetic trends for fertility, litter size, BWT, weaning weight (WWT), 90WT and 90SC resulting from selection for fall lambing. Positive genetic gains in both spring fertility and fall litter size were observed. Rate of increase was higher for fertility than litter size, which was due to direct selection for fertility. Selection for spring fertility did not cause significant correlated changes in BWT, WWT, 90WT or 90SC. Thus, no genetic antagonisms resulted from the selection for fall lambing.<br>Ph. D.

Bibliography: leaves 281-316. Presents investigations on pubertal development in South Australian merino ram lambs and examines the effect of active and passive immunizations against oestradiol-17ℓ or oestrone on testicular maturation.

This dissertation research contained three studies. The first two studies were conducted to investigate the ability of ewes to rebreed while lactating during seasonal anestrus. Breeds studied included the Virginia Tech Out-of-season (OOS) Line, which is a wool line genetically selected to lamb in the fall, and the St. Croix, a hair breed of tropical origin thought to be lowly seasonal. When January-lambing ewes were exposed to rams while lactating in April, significantly more OOS than St. Croix ewes were marked by rams in the first 21 d and total 39 d of ram exposure (58.3 vs. 8.7%, P = 0.0003 and 95.8 vs. 43.5%, P < 0.0001). Percentages of ewes diagnosed pregnant (53.2%) and percentages of ewes lambing (41.3%) were not different between breeds. When March-lambing OOS ewes were exposed to rams while lactating in May, 52.9% of ewes were marked though only 20% of ewes exposed to rams gave birth to viable lambs. Both OOS and St. Croix ewes appear to be well suited to accelerated production systems involving 7 to 8 mo lambing intervals. However, reduction of lambing intervals to 6 to 7 mo appeared to have detrimental effects on fetal survival in OOS ewes. In a third study, alterations in endocrine profiles associated with differing degrees of hypothalamic sensitivity to estradiol-negative feedback and changing daylength in OOS, St. Croix, and Suffolk ewes in the absence of rams were investigated for 1 yr. The results show for the first time that based on progesterone profiles from intact ewes, St. Croix ewes do not have shorter anestrous periods than ewes of wool breeds, as previously thought. Based on luteinizing hormone profiles from ovariectomized ewes treated with estradiol implants, the duration of luteinizing hormone inhibition was shorter in OOS than Suffolk ewes (68 vs. 170.2 d, P = 0.02), but was not different from that found in St. Croix ewes (124.8 d). Specific roles for thyroxine and prolactin in timing the breeding season could not be assigned. This study was the first known use of the ovariectomized, estradiol-implanted ewe model to compare degree of reproductive seasonality in different breeds.<br>Ph. D.

The objectives of this dissertation were to evaluate genetic influences on ewe productivity, its growth and reproductive components, and measures indicative of accelerated lambing performance. Genetic parameters were estimated for total weight of litter weaned per ewe lambing (TW) and its components, number of lambs born (NB), number of lambs weaned (NW) and average weight of lambs weaned (AW), measured as traits of the ewe, and lamb survival (LS) and weaning weight (WW), measured as traits of the lamb, in Katahdin sheep. Heritabilities of TW, NB, NW, and AW, were 0.12, 0.12, 0.09, and 0.13, respectively. Heritability of WW was 0.15 to 0.20. Genetic effects on LS were negligible. Genetic correlation of TW with NB, NW, and AW averaged 0.30, 0.90, and 0.74, respectively, those of NB with NW and AW averaged 0.72 and 0.01, respectively, and that between NW and AW averaged 0.50. Direct genetic effects on WW were independent of NB and NW, but correlation between maternal genetic effects on WW and animal genetic effects on NW averaged 0.35. Ewe fertility, NB, LS, and WW were modeled using stochastic simulation and used to derive NW, AW, and TW to test alternative predictors of genetic merit for TW. A random 8% of WW observations were set to missing values and AW and TW were recalculated to evaluate the effects of data reporting inconsistencies on efficacy of different prediction strategies. Four alternative predictors of estimated breeding values (EBV) for TW involved direct univariate prediction (TW1), an index of EBV for NW and AW (TW2), indirect prediction using data for NW and AW and genetic correlations among NW, AW and TW (TW3), and indirect prediction augmenting TW3 with data and genetic correlations involving NB (TW4). To validate efficacy of predictors, daughter data sets were generated from the original ewes and their realized TW were regressed on alternative predictors. Regression coefficients from TW1, TW3, and TW4 were close to the expected value of 0.50 whereas those from TW2 were less than 0.50. Model Rsquare statistics were similar among predictors when there were no missing WW data but regressions involving TW1 had lowest model R-square when some WW data was missing. Ewe lamb fertility (ELF), ages at first, second, and third lambings (AGE1 to AGE3), first and second lambing intervals (INT1 and INT2), and number of lambings by 38 mo of age (LAMB3) were evaluated for an accelerated lambing Polypay flock. Relationships among these traits and NB and WW were estimated. Heritability of ELF, AGE1, AGE2, AGE3, INT1, INT2, and LAMB3 were 0.14, 0.39, 0.28, 0.36, 0.00, 0.09, and 0.27, respectively. Heritability of AGE2 and AGE3 were negligible after accounting for variation in AGE1. Genetic correlations of ELF with AGE1 and AGE2 were -0.89, -0.91, respectively, and that with LAMB3 was 0.89. Genetic correlations of LAMB3 with AGE1 and AGE2 were -0.49 and -1.00, respectively. Genetic correlations of ELF and LAMB3 with direct genetic effects on WW were close to -0.70, but correlations with maternal genetic effects on WW were 0.88 and 0.58, respectively. Prolificacy was independent of ELF and LAMB3.<br>Ph. D.

Despite the major reproductive advances in the livestock industry, prenatal embryonic loss is still one of the major issues that causes substantial economic loss. While there are many tests available to determine pregnancy soon after maternal recognition of pregnancy, most of the prenatal losses are undetectable because it occurs before then. Based on previous research we hypothesized that increased plasma volume around the time of estrus will increase the survivability of the embryo at early stages of gestation. However, our findings indicate that hematocrit levels are not a consistent measurement in determining successful pregnancies.

The present studies were conducted to check the effects of acute ram introduction into a flock of anestrus ewes in Virginia. Ewes were bled via jugular venipuncture twice weekly and serum samples were radioimmunoassayed for progesterone (P4) content as an indicator of estrous activity. All rams were fitted with crayon equipped marking harnesses for use as an indicator of mating behavior in ewes. The first study tested the effects of introduction of vasectomized rams into a flock: of' 50 Dorset (D) and 50 Hampshire (H) purebred ewes in either May or June. More D ewes ovulated (96% vs 72% for H ewes) and mated (80% vs 20% for H ewes) in May. Of ewes which mated in May 65% D but no H ewes continued to cycle in June after removal of rams. Of ewes exposed to rams in June no difference among breeds was observed in percentage of ewes ovulating but more D ewes (72%) mated than H ewes (44%). Twenty-four percent of D but no H ewes cycled continuously throughout the 68 d or the study. Lambing date significantly affected mating behavior in H but not D ewes. The second study tested the effects of ram breed on incidence of mating and subsequent lambing in Rambouillet x Q Suffollk ewes In June and July of 1984 and 1985. Ewes were Q pre-exposed to either confined Suffolk (S) or Dorset (D) Q yearling rams or no (N) ram for 2 wk prior to breeding by Q either S or D rams. Lambing date was significantly affected by breeding treatment in 1984 and by pre-exposure treatment in 1985. Sixty-three percent of the ewes lambed in 1984 while 65% lambed in 1985.<br>Master of Science

A significant proportion of potential lambs are lost (commonly 15-20%) between ovulation and day 30 of gestation. Moreover, little is known about factors associated with multiple birth capacity of the uterus which would be necessary to convert gains in ovulation rate to the birth of live lambs. This project has investigated the relationship between maternal uterine and hormonal environment as well as the heritability of embryonic survival (ES) in prolific ewes. Litter size (LS) from known ovulation rate (OR) records (n=6393) collected over 16 years were analysed for heritability. ASReml analysis reported ES to be a trait of low repeatability (r� = 0.103) and heritability (h� = 0.04) which is consistent with earlier studies of this trait. However, pedigrees of outlier animals indicated a segregation pattern consistent with a single autosomal gene with a major affect on enhanced ES. From this flock, closely related high ovulation rate ewes with significantly different litter sizes (High ES; OR2.6/LS2.4 versus Low ES; OR2.9/LS1.6) were selected for further study. The anatomy and gene expression of the uterus collected at day 14 of the oestrous cycle (n=5 High and n=5 Low ES ewes) and day 16 of gestation (n=14 high and n=10 Low ES ewes) as well as systemic concentrations of hormones indicative of uterine (activin-A, follistatin) and ovarian (inhibin-α, progesterone) function during the oestrous cycle and early gestation were compared. Progesterone concentrations were found to rise earlier in high ES ewes with a difference in number of ewes with detectable levels of progesterone apparent by day 4 of gestation. The peak concentration and slope of progesterone increase as well as plasma profiles of oestradiol and inhibin-α were not different between groups. A number of pathways worthy of closer investigation were implicated by microarray analysis with Ingenuity Pathway Analysis, Pubmatrix, and candidate gene approaches. In particular, the altered expression of many immune cell factors suggests that high ES ewes have maternal gene expression of the inflammatory pathways favourable to embryo implantation. The plasma concentration of activin, but not follistatin, was found to be significantly higher in low ES ewes, a difference that remained apparent when the concentration of follistatin was corrected for individual samples. Furthermore, the concentration of activin, but not follistatin, was significantly elevated on day 16 of gestation in the uterine fluid of low ES ewes. Further investigation of the pattern of gene expression during the oestrous cycle and early gestation (day10-16 oestrus and days10-20 gestation) revealed that a significant increase in follistatin mRNA in the luminal epithelia and interacting trophoblast cells of the embryo occurs on day 18 and 20 of gestation. It is likely the appropriate balance between activin and follistatin during the time of implantation enhances embryonic survival in this line of ewes. This may be secondary to or concomitant with the observed earlier rise in progesterone concentration. The implication that embryo survival may be positively influenced by a single autosomal gene has important implications for New Zealand's agricultural industry.

A successful business needs to generate enough cash to cover expenses, current debt, and family living expenses, pay interest on owned and borrowed capital, maintain productivity, and earn a reasonable return for the operator. Income from sheep production is generally only part of a total farm and nonfarm income. Thus options, opportunity costs, and decisions regarding the sheep production enterprise are not isolated; they affect other agricultural enterprises. Sheep production consistently returns profits to producers, which makes it an enticing agricultural enterprise. There are advantages in raising sheep in Virginia, such as abundant, high-quality forage, moderate climate, pasture improvement, and good access to markets with high demand for lamb. The disadvantages to sheep production are unavailable and inexperienced labor and operators, predators, and inconsistent market demand and supply. Sheep producers have the opportunity to choose which lambing system fits their existing operations and lifestyle. The use of economic analysis enables operator to make sound business management decisions. To compare different lambing systems (spring, fall with winter clean-up, and high-fertility fall) in a systematic way, a simulation model was constructed with a fixed forage resource of 50 acres of pasture including typical Virginia mountain pasture plus various amounts of fescue for stockpiling. The simulation included a production calendar; nutritional requirements for ewes, lambs, and artificially reared triplets; growth rates for lambs; lambing distributions; forage growth; and enterprise budgets including income, costs, and returns. A economic analysis was performed for each lambing system with average prices or with plus or minus one standard deviation for prices of corn, SBOM, and market lambs, and price differentials for market lambs across lambing seasons. Comparisons of each lambing systems produced various results. In spring lambing, only 78 ewes could be maintained on the fixed forage resource, while the fall with winter clean-up and high-fertility fall lambing system each had 115 ewes. This result occurred because of limited forage in July and August and higher nutrient requirements for spring lambing in those months. The overall nutrient requirements were higher in the fall with winter clean-up and high-fertility fall lambing than in spring lambing as a result of the increased ewe and lamb numbers. Concentrate consumption by lambs was also greater for fall with winter clean-up and high-fertility fall lambing than for spring lambing because of the increased numbers of lambs. Because of the low number of ewes and lambs, spring system produced the most hay. Labor costs were highest in fall with winter clean-up lambing because of the two lambing seasons. In the economic analysis system, each lambing was compared. With 10-year average prices for market lambs, corn, and SBOM, high-fertility fall lambing had the greatest income ($17,467), followed by fall with winter clean-up lambing ($14,695), and spring lambing ($10,358). This result occurred because high-fertility fall and fall with winter clean-up lambing had more lambs sold at higher market lambs prices than spring lambing. With 10-year average prices for market lambs, corn, and SBOM, high-fertility fall lambing had the highest cost ($7,935), followed by fall with winter clean-up lambing ($7,360), and spring lambing ($6,084). This was the result of increased ewe and lamb numbers in high-fertility fall and fall with winter clean-up lambing than spring lambing. High-fertility fall lambing had the greatest returns ($6,210), followed by fall with winter clean-up lambing ($4,025), and spring lambing ($2,028). On a fixed forage resource, increasing fertility in fall lambing clearly results in increased returns. In this model, forage availability controlled the number of ewes that a lambing system can have because of limited summer growth and had a major impact on profits. Conclusions of Tolman (1993) differed from those found within this thesis. On a per ewe basis, she found that spring lambing to yielded the highest returns whereas this thesis found that high-fertility fall lambing yielded the highest returns. A key difference between this study and that of Tolman (1993) was after weaning this thesis feed fall lambs stockpiled fescue and she feed fall lambs feed in dry lot.<br>Master of Science

Temos aktualumas. Avininkystė Lietuvoje yra svarbi žemės ūkio sritis. Šio sektoriaus plėtrai šalyje yra palankios gamtinės sąlygos, susiformavusios gyvulių auginimo tradicijos, sukaupta patirtis. Gyvulininkystės sektorius yra daugiašakė ir įvairiapuse produkcija pasižyminti veikla, reikšminga Lietuvos gyventojams daugeliu ekonominių ir socialinių aspektų. Šis sektorius yra reikšmingas, aprūpinant Lietuvos vartotojus įvairiais maisto produktais bei svarbus Lietuvos eksporto šaltinis. Gyvūninės kilmės produktai yra svarbi subalansuotos mitybos dalis. Juose yra daug žmogaus organizmui reikalingų maisto medžiagų, vitaminų ir mineralų. Lietuvos Respublikos žemės ūkis atlieka svarbią ekonominę, socialinę, gamtosauginę ir etnokultūrinę funkciją, todėl laikomas prioritetine ūkio šaka. Jis pajėgus aprūpinti šalies gyventojus visais kokybiškais maisto produktais ir dalį jų eksportuoti. Nors ir lėtai, avininkystės sektorius plečiasi. Auga mėsos paklausa, atsigauna ir vilnos bei kailių perdirbėjai. Vidutinis avių ūkis Lietuvoje, palyginti su vakarų šalimis, dar yra labai mažas. Dauguma augintojų laiko nedaug avių. O tų žmonių, kuriems avininkystė yra verslas, tėra vos kelios dešimtys. Tačiau mažieji augintojai pamažu didina savo bandas. Įdiegus pažangias intensyvaus avių auginimo technologijas, auginant perspektyvias krypties avių veisles, galima tikėtis šio verslo sėkmės. Darbo objektas: skirtingą skaičių avių turintys ūkiai. Darbo tikslas: išanalizuoti ūkio dydžio įtaką avių... [toliau žr. visą tekstą]<br>Relevance of the thesis. Shepherding has an important place in Lithuania‘s agriculture. There are suitable enviromental conditions, established cattle herding traditions and accumulated experience needed for this sector‘s further development in the country. The area of animal husbandry is activity known for its multisectoral and multifaceted production, many aspects of which has great economical and social significance for Lithuanians. This area is also very significant when providing Lithuanian consumer with eatables, furthermore it is very important branch of Lithuania‘s export. Products of animal origin takes big part in a balanced diet. They contain many components, vitamins and minerals which human body requires daily. Husbandry has important economical, social, enviromental and ethnocultural function in the Republic of Lithuania, thus it has priority in Lithuania‘s economy. It has capability not only to provide quality eatables for citizens, but also to export some. Sheepherding sector is growing, even though the growth rate is not very pronounced. The demand for meat grows; wool and fur processors are recovering. In Lithuania average sheep farm is very small when comparing with farms in other western countries. Most livestock owners don‘t have a lot of sheep. Furthermore, there are only few who make business out of it. However the small farmers seem to be increasing their flocks. If this business were introduced to advanced sheep herding technologies as well as... [to full text]

Neste relatório são descritas as atividades desenvolvidas durante o estágio curricular em clínica e reprodução de espécies pecuárias. Contempla ainda uma revisão bibliografia e um estudo de caso sobre os fatores que afetam a fertilidade e a avaliação da eficiência reprodutiva em ovinos. No estudo de caso procurou avaliar-se a influência da idade, da raça e da condição corporal na fertilidade de um rebanho leiteiro, em duas épocas de cobrição (estudo 1) e na sincronização de estros (estudo 2). A fertilidade do efetivo variou segundo a época de cobrição (58,2% e 55,9%, na cobrição de junho-outubro e dezembro respetivamente). A existência de animais muito jovens teve um impacto negativo na fertilidade, sendo que fertilidade apenas no efetivo adulto foi de 71,6% e 66,7%, na cobrição de junho-outubro e dezembro respetivamente. Na cobrição de junho-outubro a fertilidade foi influenciada significativamente pela idade e raça (p<0,01). A taxa de gestação após sincronização de estros não foi influenciada pela raça ou a idade (p>0,05), contudo a condição corporal teve um efeito significativo, com taxas de gestação mais elevadas nas ovelhas com melhor condição corporal; Clinical and reproduction of livestock species Abstract: This report describes the activities developed during the traineeship in clinical and reproduction of livestock species. It also includes a literature review and a case study about the factors that affect fertility and the evaluation of reproductive efficiency in sheep. This study aims to determine the influence of age, breed and body condition on fertility of a dairy herd, in two periods of mating (Study 1) and estrus synchronization (Study 2). The herd fertility varied according to the period of mating (58.2% and 55.9% in mating from June to October and December respectively) The existence of very young animals had a negative impact on fertility, wherein the fertility only in adult was 71.6% and 66.7%, in the mating from June to October and December respectively. In mating from June-October, the fertility was significantly influenced by age and breed (p <0.01). The pregnancy rate after synchronization of estrus was not influenced by breed or age (p> 0.05), however the body condition had a significant effect with higher pregnancy rates in ewes with better body condition.

Bibliography : leaves 120-133. Defines the sources of reproductive wastage in FecB FecÊ Booroola Merino x South Australian Merino ewes and examines factors associated with the survival of embryos, fetuses and lambs with the aim of improving net reproduction efficiency. Experiments were conducted to define the problem; to examine factors affecting embryonic and fetal loss; and, to investigate factors influencing wastage at lambing.

Resumo: A demanda por produtos de origem animal, tem aumentado, paralelamente a este crescimento, observam-se esforços para promover melhorias na produtividade de carne dos rebanhos ovinos. Com o objetivo de estudar o desempenho produtivo e reprodutivo de cruzas de ovinos lanados, foram utilizados os dados da escrituração zootécnica do rebanho, pertencente ao Setor de Ovinocultura do Departamento de Zootecnia da Faculdade de Ciências Agrárias e Veterinárias (FCAV/Unesp), Jaboticabal, SP. Os dados da escrituração foram oriundos de 312 ovelhas, sendo 129 da raça Ideal, 44 1/2 Ile de France 1/2 Ideal, 98 3/4 Ile de France 1/4 Ideal e 41 7/8 Ile de France 1/8 Ideal, submetidas ao cruzamento absorvente para a raça Ile de France. As ovelhas foram mantidas em sistema de criação semi-extensivo, levadas ao pasto pela manhã e recolhidas ao aprisco no final da tarde. A estação de monta aconteceu nos meses de novembro a janeiro. Após o nascimento, as crias eram pesadas e marcadas com número de identificação e as informações registradas em fichas individuais, que posteriormente foram transcritas para planilhas do Microsoft ExcelÒ. As análises das características produtivas: peso ao nascer (PN), peso ao desmame (PD), peso aos 180 dias (P180), ganho médio diário (GMD) e tempo para o animal atingir 32 kg de peso corporal (D32), foram realizadas no SAS, (1996) baseadas no método dos quadrados mínimos, utlizando o procedimento GLM e o teste Tukey para comparação das médias. Para as curvas de crescimento foi utilizado o modelo não-linear Von Bertalanffy, sendo o ajuste realizado pelo procedimento NLIN, utilizandose o método de DUD. Para as características reprodutivas foram utilizados o procedimento GLM e o teste Tukey, basedo no método dos quadrados mínimos para idade ao primeiro parto (IPP) e o teste de qui-quadrado para fertilidade, taxa de desmame, e prolificidade... (Resumo completo, clicar acesso eletrônico abaixo)<br>Abstract: The demand for products originated from animals, mainly meat, has been increasing and it is clear that efforts are being made to improve the productivity in ovine cattle. Aiming to study productive and reproductive performance of crossbred sheep, data from the sheep recording of the ovine cattle from Paulista State University, FCAV/Unesp, Jaboticabal, SP, Brazil were used. The record data came from 312 sheep (129 of Polwarth breed, 44 1/2 Ile de France 1/2 Polwarth, 98 3/4 Ile de France 1/4 Polwarth e 41 7/8 Ile de France 1/8 Polwarth) submitted to absorber crossbreeding for Ile de France. The sheep were kept in semi-extensive raising system; they were taken to the field in the morning and returned to the shelter late in the afternoon. The breeding season happened from November until January. After birth, the sheep were weighted and marked with the identification number and the information registered in individual forms that were later transcripted to Microsoft ExcelÒ. Productive characteristic analysis: body weight at birth (BWB), body weight at weaning (BWW), body weight with 180 days (BW180), daily weight gain average (DWGA) and necessary period for animals to get 32 kg of body weight (BW32) were carried out at SAS statistical analysis (1996), based on the Chi-square method, using the GLM procedure and the Tukey test for average comparisons. The non linear model of Van Bertalanffy was used to analyse growth pattern and the adjustment was accomplished by the NLIN procedure using the DUD method. It was used the GLM procedure for the reproductive characteristics, the Tukey test to analyse age at the first birth (AFB) and the Chi-square test to analyse fertility, weaning rate and prolificacy. None significant alterations were observed for the following productive characteristics, BWB, BWW, and BW32 (p>0.05), with composition genetic averages... (Complete abstract click electronic access below)<br>Orientador: Américo Garcia da Silva Sobrinho<br>Coorientadora: Sandra Aidar de Queiroz<br>Banca: Humberto Tonhati<br>Banca: Cledson Augusto Garcia<br>Mestre

Made available in DSpace on 2014-06-11T19:28:22Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-07-18Bitstream added on 2014-06-13T20:57:57Z : No. of bitstreams: 1 perez_hl_me_jabo.pdf: 253936 bytes, checksum: b4207e189c180a854872829f47586958 (MD5)<br>Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)<br>A demanda por produtos de origem animal, tem aumentado, paralelamente a este crescimento, observam-se esforços para promover melhorias na produtividade de carne dos rebanhos ovinos. Com o objetivo de estudar o desempenho produtivo e reprodutivo de cruzas de ovinos lanados, foram utilizados os dados da escrituração zootécnica do rebanho, pertencente ao Setor de Ovinocultura do Departamento de Zootecnia da Faculdade de Ciências Agrárias e Veterinárias (FCAV/Unesp), Jaboticabal, SP. Os dados da escrituração foram oriundos de 312 ovelhas, sendo 129 da raça Ideal, 44 1/2 Ile de France 1/2 Ideal, 98 3/4 Ile de France 1/4 Ideal e 41 7/8 Ile de France 1/8 Ideal, submetidas ao cruzamento absorvente para a raça Ile de France. As ovelhas foram mantidas em sistema de criação semi-extensivo, levadas ao pasto pela manhã e recolhidas ao aprisco no final da tarde. A estação de monta aconteceu nos meses de novembro a janeiro. Após o nascimento, as crias eram pesadas e marcadas com número de identificação e as informações registradas em fichas individuais, que posteriormente foram transcritas para planilhas do Microsoft ExcelÒ. As análises das características produtivas: peso ao nascer (PN), peso ao desmame (PD), peso aos 180 dias (P180), ganho médio diário (GMD) e tempo para o animal atingir 32 kg de peso corporal (D32), foram realizadas no SAS, (1996) baseadas no método dos quadrados mínimos, utlizando o procedimento GLM e o teste Tukey para comparação das médias. Para as curvas de crescimento foi utilizado o modelo não-linear Von Bertalanffy, sendo o ajuste realizado pelo procedimento NLIN, utilizandose o método de DUD. Para as características reprodutivas foram utilizados o procedimento GLM e o teste Tukey, basedo no método dos quadrados mínimos para idade ao primeiro parto (IPP) e o teste de qui-quadrado para fertilidade, taxa de desmame, e prolificidade...<br>The demand for products originated from animals, mainly meat, has been increasing and it is clear that efforts are being made to improve the productivity in ovine cattle. Aiming to study productive and reproductive performance of crossbred sheep, data from the sheep recording of the ovine cattle from Paulista State University, FCAV/Unesp, Jaboticabal, SP, Brazil were used. The record data came from 312 sheep (129 of Polwarth breed, 44 1/2 Ile de France 1/2 Polwarth, 98 3/4 Ile de France 1/4 Polwarth e 41 7/8 Ile de France 1/8 Polwarth) submitted to absorber crossbreeding for Ile de France. The sheep were kept in semi-extensive raising system; they were taken to the field in the morning and returned to the shelter late in the afternoon. The breeding season happened from November until January. After birth, the sheep were weighted and marked with the identification number and the information registered in individual forms that were later transcripted to Microsoft ExcelÒ. Productive characteristic analysis: body weight at birth (BWB), body weight at weaning (BWW), body weight with 180 days (BW180), daily weight gain average (DWGA) and necessary period for animals to get 32 kg of body weight (BW32) were carried out at SAS statistical analysis (1996), based on the Chi-square method, using the GLM procedure and the Tukey test for average comparisons. The non linear model of Van Bertalanffy was used to analyse growth pattern and the adjustment was accomplished by the NLIN procedure using the DUD method. It was used the GLM procedure for the reproductive characteristics, the Tukey test to analyse age at the first birth (AFB) and the Chi-square test to analyse fertility, weaning rate and prolificacy. None significant alterations were observed for the following productive characteristics, BWB, BWW, and BW32 (p>0.05), with composition genetic averages... (Complete abstract click electronic access below)

L'érosion de la biodiversité prairiale est devenue une préoccupation majeure à l'échelle Européenne. Le pâturage ovin est supposé avoir un impact négatif sur la diversité prairiale, en raison de leur forte sélectivité pour les dicotylédones, indispensables aux insectes pollinisateurs. Comparés aux bovins, les ovins structurent peu les couverts et créent également moins de niches écologiques contrastées. L'objectif de cette thèse était de tester la faisabilité, et les bénéfices en pâturage ovin, d'une conduite en rotation dans laquelle une sous-parcelle est temporairement exclue du pâturage au moment du pic de floraison. Les effets de cette conduite ont été comparés à ceux d'un pâturage continu au même chargement. Au delà des indicateurs directs de performances zootechniques et de biodiversité (plantes, papillons, bourdons et carabes), nous avons analysé la sélection alimentaire des brebis dans les deux modes de conduite. Nous avons aussi cherché à appréhender comment la race et la fertilité du milieu pouvaient moduler la faisabilité d'un tel pâturage tournant et son intérêt vis-à-vis de la préservation de la biodiversité. Indépendamment de leur race, les brebis ont présenté une sélection alimentaire accrue vis-à-vis des dicotylédones dans les parcelles pâturées en rotation, qui a rapidement entraîné une diminution de leur richesse floristique en comparaison des parcelles pâturées en continu. L'augmentation de l'intensité de floraison des sous parcelles temporairement exclues de la rotation a favorisé les bourdons, probablement en raison de l'augmentation de la ressource en pollen et en nectar. En revanche, ce mode de gestion n'a pas permis d'augmenter la densité ni la richesse spécifique des papillons et des carabes. Le bénéfice d'une mise en défens temporaire d'une partie des parcelles semble donc moindre qu'en pâturage bovin. Définir les dates de mises en défens par rapport à la floraison d'espèces indicatrices, moduler la durée de la mise en défens en fonction de la pousse de printemps, et prolonger l'exclusion de certaines parcelles en automne et en hiver sont autant de pistes qu'il nous reste à explorer, afin de déterminer les conditions d'application optimale d'une telle conduite.

Os objetivos deste trabalho foram estimar parâmetros genéticos, com os modelos mistos reprodutor e animal, para características reprodutivas contínuas e discretas, bem como, predizer os valores genéticos dos reprodutores para características reprodutivas contínuas e discretas em ovinos da raça Santa Inês. Foram analisadas as características reprodutivas intervalo de partos (IDP, N=1.066), fertilidade ao parto (FP, N=1.006) e número de cordeiros ao parto (NCP, N=3.593) de ovinos com partos ocorridos entre os anos de 1998 a 2005. A característica FP foi expressa na forma de fêmeas paridas em relação às fêmeas cobertas, sendo codificada como \"1\" se pariu e \"0\", caso contrário e NCP, representou o número de crias nascidas por ovelha parida, codificada como \"1\" (simples) e 2 (múltiplos). O modelo reprodutor apresentou a característica de superestimar as herdabilidades para as características reprodutivas em relação ao modelo animal. As estimativas de herdabilidades, obtidas por modelo animal linear, foram 0,12, 0,23 e 0,16 para NCP, FP e IDP, respectivamente. As estimativas de herdabilidades, obtidas por modelo animal de limiar, foram 0,16, 0,15 e 0,10 para NCP, FP e IDP, respectivamente. As estimativas das correlações genéticas pelo uso de modelo animal linear, foram 0,13 (entre NCP e FP) e -0,21 (entre NCP e IDP). Já as estimativas das correlações genéticas, quando utilizado modelo animal de limiar, foram 0,81 (entre NCP e FP) e -0,52 (entre NCP e IDP). As correlações entre os valores genéticos preditos para 258 reprodutores avaliados variaram de 0,4835 a 0,8561 entre os modelos reprodutor e animal obtidos por metodologia linear e de limiar. Este fato sugere a existência de alterações significativas nas classificações dos valores genéticos preditos dos reprodutores em função do tipo de modelo e da metodologia utilizada na avaliação genética.<br>The aims of this study were evaluated genetic parameters with sire and animal mixed models, to continuous and discreet reproductive traits, as well as predict sires breeding values to continuous and discreet reproductive traits in Santa Inês ewes breed. The traits analyzed in this study were lambing interval (LI, N = 1,066), fertility (FR, N = 1,006) and number of lambs born (NLB, N = 3,593) of ewes with birth occurred among 1998 to 2005. The FR trait was expressed in form of delivered females in respect to sheltered females, been codified as \"1\" delivered and \"0\" otherwise. The NLB trait represented the number of fully formed lambs born per ewe lambing, codified as \"1\" (simple) and \"2\" (multiples). The sire model showed super estimate comportment in respect to animal model for reproductive traits heritabilities. The estimates of heritability obtained by linear animal model were 0.12, 0.23 and 0.16 for NLB, FR and LI, respectively. The estimates of heritability obtained by threshold animal model were 0.16, 0.15 and 0.10 for NLB, FR and LI, respectively. The estimates of genetic correlations using linear animal model were 0.13 (between NLB and FR) and -0,21 (between NLB and LI). However, the estimates of genetics correlations using threshold animal model were 0.81 (between NLB and FR) and -0,52 (between NLB and LI). The Pearson correlations between predicted breeding values for 258 sires varying by 0.4835 to 0.8561 between sire and animal models obtained by linear and threshold methodology. This fact suggest the existence of significative changes on sires predicted breeding values classifications by virtue of model type and used methodology on genetic evaluation.

This thesis describes a series of four experiments designed to evaluate the role of the supply of protein in livestock grazing high quality pasture during mating and during pregnancy. The first two studies investigated the effects of high crude protein content of spring or autumn re-growth pasture on the reproductive performance of dairy cows and of ewes at mating. The last two studies investigated how the dietary supply of protein, body condition and their interactions contribute to the breakdown of immunity during the peri-parturient period in ewes and investigated underlying endocrine mechanisms. In the first study (Chapter 3) cows were blood sampled via the tail vein during the breeding period in spring. Plasma was then analysed for urea concentration. Cows with high plasma urea (HPU) or low plasma urea (LPU) were defined as those with plasma urea concentrations of ≥ or < 44.9 mg/dl respectively. Lactating cows (n = 200) were also categorized into high milk producers (HMP) or low milk producers (LPM) relative to an average daily yield of 26.6 l/d. Pasture clipping showed an average pasture CP (crude protein) content of 223 g/kg DM. Concentrations of plasma urea ranged from 26.6 to 64.4 mg/dl. No correlation was observed between plasma urea concentration and either reproductive indicators or milk parameters. Mean blood urea concentration of HPU cows was 50.8 compared to 38.5 mg/dl in LPU cows. There was a trend for more animals (P = 0.09) in the HPU group than in the LPU group not to return to oestrus. Cumulative pregnancy rate in HPU and LPU was similar except at week 6 after the start of mating when more (P < 0.01) HPU than LPU cows were pregnant. Calving to conception interval, calving interval and interval between conception and first service were similar (P > 0.05) between HPU and LPU cows. Gestation length, calving rate, milk yield and milk components were also similar (P > 0.05) between LPU and HPU cows. There was no difference (P > 0.05) in plasma urea concentrations between HMP and LMP milk producers. However, calving to conception interval, interval between calving and first service and calving interval were longer (P < 0.001), submission rate higher (P < 0.001) and NRR (Non-return rate) higher (P < 0.05) in LMP than HMP. The number of services, the interval between first and second service, gestation length and CR (calving rate) were similar (P > 0.05) between HMP and LMP cows. HMP had lower (P < 0.001) milk protein and fat concentrations than LMP cows. This information indicates that, despite the fact that plasma urea was consistently higher than levels in the literature which have been associated with reduced fertility in dairy cows; no impairment of reproductive performance was observed. In the second experiment (Chapter 4) mature and dry Coopworth ewes were blocked by weight, body condition and previous prolificacy (high, HP vs low twinning frequency, LP) into two groups and thereafter randomly allocated to diet which were designed to provided either 1) high protein (163 g/kg DM, ryegrass/red clover pasture, HPP) or low protein (119 g/kg DM, hay and barley grain, HB) supply at joining. These were designed to provide high and low plasma urea concentration. Over a period of 17 days, ewes recorded as mated were examined by laparoscopy, at which time there was no difference in blood urea concentration (58.6 vs 56.1 mg/dl) between HPP and HB groups. Fifty days after the start of joining the number of foetuses present was counted using ultrasonography. As a consequence of lack of difference in the plasma urea concentration, irrespective of treatment group, individual animals were categorized into high (HU) and low plasma urea (LU) status based on whether plasma urea concentration was higher or lower than the sample mean of 51.5 mg urea/dl. Lambs which weighed greater than the mean plus one standard deviation for their litter size were classified as oversize. Ovulation rate and conception rate were similar (P > 0.05) between HPP and BH and between HU and LU ewes. Ewes with previous high reproductive performance (HP) as would be expected had higher ovulation rate (P < 0.001) and conception rate (P < 0.01) than LP ewes. Embryo losses was not (P = 0.06) different between HB and HPP ewes. Urea category (HU vs LU) did not (P > 0.05) influence embryo mortality. Foetal loss, neonatal loss, total reproductive loss and mean lamb birth weight was were not affected by diet, nor urea category (P > 0.05). Single ovulations had tended (P = 0.08) to contribute to higher embryo loss compared to multiple ovulations, and, single foetuses suffered higher (P<0.001) losses compared to multiples. While the study did not achieve large differences in plasma urea concentrations between diets, the levels of plasma urea operating were high yet reproductive wastage rates were similar to those recorded in the literature. Together with similar apparent lack of effect on a high plasma urea environment, the data suggest either that previous findings from controlled studies have a more complex aetiology or that pastoral animals can adapt to high tissue ammonia/urea status. The third trial (Chapter 5) was designed to provide information on the supply of amino acids to the abomasum from protein supplementation which have previously been found to overcome dietary scarcity associated with limitation of peri-parturient increase in FEC. Twin-suckling ewes were fitted with rumen and abomasal cannulae and grazed a ryegrass/clover sward (C) or the same sward but with a 500 g/h/d protein supplement (S). The trial was designed as a cross-over with two 14 day adaptation periods followed by two five-day digesta-sampling periods. All ewes were treated with anthelmintic 14 days after lambing. Weekly analysis of blood glucose was carried on whole blood and analysis of amino acids in plasma. The flows of amino acids (AA) and dry matter (DM) at the abomasum were measured during both sampling periods using intra-ruminally infused markers. Live weight and faecal egg count (FEC) were recorded weekly. Diurnal variation in AA flow at the abomasum peaked between 12:00 and 15:00 h and was greatest in S ewes. Flows of AA, including DAPA, were increased by supplementation by 16%, while sulphur amino acids (SAA) were the most enhanced (by 21%) and flows of leucine, lysine, glutamine and aspartate were increased by about 20%. There were significant time effects in rumen and abomasal pH (P < 0.01; in both cases in both periods) reflecting increase in pH after 09.00 h. During Period II, rumen pH in digesta of C ewes was significantly higher (P < 0.001) than that of S ewes (6.7 ± 0.05 vs 6.4 ± 0.05 for C and S ewes, respectively). Plasma AA concentrations (P < 0.01) were lower in S ewes 21 days after parturition, but similar (P > 0.05) to those of C ewes at other times. Forty-three days after lambing (after cross over), the order was reversed as plasma methionine and cysteine concentrations of C ewes became low (P < 0.05). These changes in plasma AA were accompanied by changes in body condition score between day 23 and 70 post-partum whereby C ewes lost more body condition than S ewes. There was evidence for a lower FEC in S ewes, being 46 vs. 670 epg, respectively for S and C groups (P = 0.08) 21 days after anthelmintic treatment. There were higher (P < 0.05) blood glucose levels in C compared to S ewes at day +35 relative to lambing which was reversed and significantly higher (P < 0.01) for S ewes by day +56 from lambing (after treatments were reversed). There was no significant effect of treatment on live weight and lamb performance. There are limited data in amino acid supply on lactating ewes on pasture and the present study contributes additional information on the supply of amino acids at the abomasum. The prediction that flow rates that sulphur amino acids may have been enhanced to the greatest degree could be significant since sulphur amino acids are needed for the synthesis of glutathione for immune response. It can be calculated that supplementation to supply the quantities of S-amino acid at pasture would be needed, since it would not be possible for sheep to increase pasture intake to achieve similar S-amino acid flow. Increase in bypass amino acids in S ewes at certain times in the day probably suggests influence by protein supplementation at certain times of the grazing cycle. Reduced plasma free amino acids at day +21 relative to lambing, may indicate sparing of body protein breakdown by protein supplementation. However, the difference in blood glucose on day 35 and day 56 may indicate re-adjustment of hormonal settings, responsible for nutrient partitioning. The last study (Chapter 6) used ewes during the peri-parturient period on pasture. Eighty pregnant ewes were allocated into four groups balanced for anticipated number of lambs. Group 1 had a high body condition score (BCS) of 4.0 which was maintained throughout pregnancy by pasture allowance (HM; n = 20). Group 2 (n= 40) had medium body condition (BCS 3.0) and were split into two subgroups; one was offered pasture to allow gain of condition (MH; n = 20) and the second allowed to lose condition by offering a low grazing allowance (ML; n = 20). Group 3 were thin ewes (BCS 2.4) and pasture allowance was designed to maintain this condition (LM; n = 20). These feeding regimes were maintained for 3 weeks from week -8 of pregnancy. During week -5 to -4 all ewes were acclimatized to a protein supplement (60 g/d). A glucose tolerance test (GTT) was conducted during week -4 after which half of the ewes in each group were offered a protein supplement at the rate of 500 g/d, creating –S and –NS groups. During wk -2, a second GTT was carried out. Animals were treated with an anthelmintic 3 wks before lambing, and were then challenged with a dose of 10 000 Teladorsagia circumcincta larvae on weeks -2 and -1 relative to lambing. Weekly recording of FEC, live weight and body condition was carried out. Lambs were weighed within 24 h of birth and again at 44 and 65 d of age. Computed tomography body scanning was carried out on ewes at weeks -8, -3 and +8 relative to lambing. There were no differences (P > 0.05) in lamb performance due to body condition or protein supplementation. FEC of all groups was low (≈ 9 peg) and there was no (P > 0.05) significant difference between ewes of different body condition or due to effects of protein supplementation. Ewes bearing/bearing multiple lambs had the highest FEC at day -32 and +12 relative to lambing, which was significant (P < 0.05) on the latter date. There were no significant effects of supplementation on parasite status. There were differences in basal plasma glucose concentration between groups (P < 0.001), being highest in HM/S and least in ML/NS ewes and was generally higher (P <0.001) during GTT 2 than GTT 1. Ewes carrying a single foetus had higher (P <0.001) basal glucose than those carrying multiple lambs (2.2 vs. 1.7 mmol/L, respectively). Other plasma glucose response indexes were similar (P <0.05) between groups. There were differences in insulin responsiveness between groups (P < 0.001), being highest in MH/S and least in ML/S ewes. Insulin responsiveness tended (P = 0.06) to be lower during GTT 1 than GTT 2, but was higher (P < 0.01) in ewes carrying singles than multiples. There was tendency for higher though non-significant, basal insulin concentrations in HM ewes. Insulin trends over time after glucose infusion suggest greater insulin response at GTT 1. Basal insulin was not correlated with CT muscle weight. Despite differences in body muscle mass at the start of the trial and differences induced by nutrition during late pregnancy, positive gains in muscle mass occurred during early pregnancy and muscle mass was similar in all groups by day 56 of lactation. Animals with greatest fat content at parturition (HM) mobilised the greatest amount and those with least fat (LM) deposited fat during lactation. Further experimentation may consider the use of the hyperinsulinemic-euglycemic clamp approach to more precisely estimate whether hormonal re-setting through insulin resistance may be involved in relaxation of immunity during the peri-parturient period.

Two trials were conducted over consecutive years to examine the effects of ewe body condition and post-mating nutrition on ovulation rates and embryo survival. Trial 1 used 146 Polypay ewes ranging in age from 5 to 8 years in a 3 x 2 factorial array of pre-mating (high-H, low flushed-LF and low unflushed-L) and post-mating nutrition (high and low) treatments. Trial 2 was a 2 x 2 x 2 factorial array of 60 Polypay and 60 Coopworth x Polypay (C x P) three year old ewes, two pre-mating (H and LF) and two post-mating (high and low) treatments. To estimate timing and extent of embryo loss, two methods of embryo detection were employed during Trial 2. Real-time ultrasound was performed on all ewes at 21, 28, 34 and 45 days post-mating. Blood samples were also collected on these days for analysis of Pregnancy-specific Protein B (PSPB) levels. There was no effect of pre-mating treatment or ewe age on ovulation or conception rates for Trial 1. Pre-mating treatment was significant in Trial 2, with H ewes having higher ovulation rates than LF ewes. Pre-mating treatment, post-mating treatment, ewe age (for Trial 1) and genotype (for Trial 2) had no effect on mean litter size in either trial. Analysis of litter size among ewes with twin and triple ovulations showed pre-mating treatment to be significant among triple ovulators in Trial 1, where L ewes had much lower litter size (1.86) than LF (2.37) or H (2.60) ewes. In Trial 2, post-mating treatment was significant among the ewes with triple ovulations, with ewes on low nutrition having lower litter size (2.01) than ewes on high nutrition (2.59). Two-way interactions were significant among twin and triple ovulators in Trial 2. Breed x pre-mating interaction among twin ovulating ewes showed C x P LF ewes to have lower litter size (1.43) than the H ewes (1.87), while the opposite was true for Polypay ewes. Pre- x post-mating treatment interaction among triple ovulators showed LF ewes on low post-mating nutrition had lower mean litter size. This effect is largely due to lower litter size in the C x P triple ovulators on low post-mating nutrition. Data available from the ultrasound diagnosis showed little indication of treatment effects on amount or time of embryo loss. Ewes bearing single or multiple embryos differed in PSPB level at day 45, but not at earlier times. However, there were no differences in PSPB levels in ewes with twin or triple embryos at any of the trial days. Assay for PSPB failed to facilitate detection of the amount or time of embryo loss, as determined by ultrasound.<br>Graduation date: 1991

The aim of the diploma thesis was to evaluate reproduction indicators (percentage of pregnancy, fertility, intensity, total rearing, reactivity, rearing of lambs born and total lamb mortality), their comparison over the years and the average in the Czech Republic. The influence of the age of the mother on fertility and the proportion of sheep according to the frequency of litters was also evaluated. Monitoring was carried out in breeding sheep clun forest (at 30 ewes) at Studnice farm from 2015 - 2018. In the monitored reproduction indicators, there was a statistically significant effect (P 0,01) only in the fertility of the herd in question for the period 2015 - 2018. This was caused by higher fertility differences in the first two years on average by 10% between selected breeding and average in the Czech Republic . For the past two years, fertility was on average 25% lower than the national average. When assessing the effect of maternal age on fertility, the highest fertility rates were in three-year-old (174%) and four-year-old sheep (168%). The effect on the highest fertility rates was the highest number of lambs born (about 2 lambs per sheep). Since the third year of age fertility has fallen until the fifth year. Then there was a slight increase (the number of born lambs in the sheep (1.5 lambs) increased) and the lowest fertility (133%) was found in seven-year-old and older sheep, when the number of lambs was also decreasing. Based on the above data on the effect of age on fertility, a statistically highly significant effect (P 0,01) was observed in the observed breeding for the years 2015 - 2018.

It has been observed the breed herd of Texel sheep in the foothills area of Orlické mountains in the year 2005-2008. The base of herd was consisted of 374 ewes, 575 lambs and 6 rams in total. These parametres of reproduction {--} conception, fertility, rearing, empty ewes, abortions, lambing, stillborn, death after born, were monitored at ewes. For the parametres of reproduction at ewes were found significant effects of ewe´s age and ram´s line.

The goal of this Diploma thesis was an analysis of the chosen factors and their influence on sheep fertility in the herd of sumava sheep. This factors were presented through the age of sheep, sheep nutrition and stress influence on the sheep fertility. For this purpose it was chosen the sumava sheep farming in herd Michlova Hut. At first this herd was introduced, than statistically described in terms of sheep fertility and in the next part there was analysis of the chosen factors. Based on these results the conclusions and the basic breeder recommendation to breeder community were deduced. The main reason for choice this topic was a growing breeder´s interest in breeder´s economy and various possibilities of the increasing sheep fertility.

The aim of this thesis was to evaluate the level of reproductive performance of the Wallachian sheep in the flock of sheep bred by Jan Vejčík. At first the following parameters were evaluated in 457 ewes during the period 2007 - 2011: fertilization, fertility, reproduction intensity, total rearing, infertility, rearing of lambs born and total mortality of lambs. Then, using statistical methods, frequency of litters and effect of age on fertility of ewes were evaluated and the identified parametres were compared with the flocks originating from the Union of sheep and goats of the Czech Republic. Finally, the economy sales for slaughter lambs depending on fertility was assessed. The mean fertility of the flock of sheep reached 171, 77 % and the percentage of fertilization was 92, 54 %. Total breeding flock was 143, 19 %. Seven percent of the sheep was infertile, which is directly influenced by the intensity of reproduction (158,93 %). Mortality of lambs was 10, 03 % and thus survival rate of lambs was 89,97 %. The study shows that the longer the period of existence of a farm is, the higher the fertility of ewes is (almost 179 % in 2011). Also an increasing tendency of the number of sheep twins was recorded during the study (59 twins in 2011). This indicates good welfare of the animals and generally good health of the flock. Ewes reached the highest fertility at the age of 5 to 7 years. The indicators of fertility, reproduction and total intensity of rearing showed significant differences when compared with the flocks originating from the Union of sheep and goats of the Czech Republic. Significantly higher fertility, reproduction and overall intensity was achieved in the monitored flock The difference was not statistically significant (p > 0,05) except for the fertilization parameter. Sales for slaughter lambs per ewe were affected by the share of reactive sheep and total lamb mortality, this effect was, however, only about 20 % of the total dependency. Disregarding the overall mortality of lambs and reactive sheep, it would be true that higher fertility is in direct proportion with sales for slaughter lambs.

The aim of this work is to evaluate the levels of production traits in sheep breed Merinolandschaf. Evaluation of the effect of selected factors on commercial properties in the herd of the breed. This thesis mainly focuses on the effect of age ewes, rams line at impact, influence the frequency of newborn lambs on production indicators. The evaluation of these properties were used data from performance tests and evidence from past years. The thesis should clarify some advantages in breeding should point out shortcomings and problems that occur in the breed while providing solutions to improve the situation in the selected breed. In 2009, the percentage of fertilization to the lowest value of 77.1. The performance tests from 2006 to 2012, we can see that the percentage of fertility by 2010 rising, thanks to the experience breeder. Average intensity of the years 2006 - 2012 was 120.9%. Thanks to the year 2009, the average number of weaned lambs from ewes low number of 107%. Minimum number of weaned lambs in 2009 and to 77.1% and the maximum number was reached in 2010 - 123,4%. Average weight of lambs at birth breed Merinolandschaf for the period was 3.41 kg and 100 days of age 22.55 kg. When comparing fertility ewes depending on their age were detected statistically significant differences at the level p < 0.001 yen sheep aged 5 and 7 year olds. When evaluating the impact of fertility ewes depending on the line of ram, a statistically significant difference at moderate level of p < 0.001 > 0.01 MACEK between lines and between the lines and MESTEK MAGOR and MESTEK. Highest percentage of sheep with singleton was achieved in 2010 and the lowest percent in 2009, while in 2009 it achieved the highest percentage of sheep with twins and multiple litters. Based on the results it can be stated average level of breeding. About this fact testifies above all to achieve reproduction indicators, which were compared with countrywide results.

The thesis was focused on the reproductive traits of zwartbles breed level evaluation in Novosedly nad Nežárkou, evaluation data were compared with the average values of reproductive traits of zwartbles flocks, included in the performance monitoring of sheep in the Czech Republic, using statistical methods. Simultaneously, there was the effect of factors that might affect reproductive traits of the breed evaluated. 111 ewes were evaluated during the period 2012-2015. The average fertility in the sheeps during the monitoring period amounted to 175,7 % and an average rearing amounted to 88,5 %. There was a significant difference in fertility (p < 0,05) and even highly significant difference in rearing (p < 0,01) among the monitored flock and the flocks in the performance monitoring. The percentage of fertilization and intensity in breeding didn´t achieve satisfactory values, primarily due to the high percentage of futility in sheep in average of 25,5 %. All the reproduction indicators are below the breed average. Lambing number on litter size was evaluated as highly significant (p < 0,01). Ewe age at lambing was assessed as a highly significant influence exerted on fertility (p < 0,01). Influence paternal lines of ewes on their fertility was not statistically demonstrated (p 0,05).

The aim of this thesis was evaluate fertlility of the Zwartbles sheep in zhe flock of sheep breed by Mrs. Marie Schickerová. In the reporting period of 5 years (2013 2015) were a total of 429 ewes evaluated by the followinf parameters: fertlization, reproduction intensity, total rearing. Basic reproductive parameters were compared with the flocks originating from the Union sheep and goats of the Czech Republic. They were monitored factors that have or may have an impact on fertility. The first factor was the impact of age on fertility, selected second order lambing and the last was the influence line. The average fertility of the herd reached 197,13%. The average share of fertilization was assessed at 94,01%. Sterility reached the level of 5,99 %. The amount of the total breeding herd stood at 164,67%. Intensity of production reached 185,24 %.. Based on calculations, it was found a hightly significant effect of age and rank lambing fertility. Influence line was not clearly demonstrated. Statistical evaluation of indicators of fertility, the intensity of reproduction, fertilization and overal breeding showed differences in the average monitored herds compared with herds in the performance tests. In the observed herd these values were significantly higher.

Includes bibliographical references (leaves 232-257).<br>xv, 257 leaves : ill. ; 30 cm.<br>Title page, contents and abstract only. The complete thesis in print form is available from the University Library.<br>Aims to determine if the compatible solutes (proline, glycine betaine, and trehalose), the epididymal compounds (taurine, hypotaurine and inositol) or the antioxidants (carnosine and ascorbic acid) in tris-citrate based diluents could improve the post-thaw survival and/or fertility of ram spermatazoa.<br>Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Science, 1996?

The aim of this diploma work is to evaluate levels of reproduction and production indicators, the economics of selected stocks of Suffolk sheep and make recommendations to the owner towards improving current practices.

The aim of this thesis was to evaluate the reproductive performance over the period from 2007 to 2010 in selected Suffolk sheep. The evaluation was carried out on the basis of records kept in the selected breeding sheep at Agris Markvarec s r.o. and on own observations. During the reporting period was evaluated 1115 ewes, which were monitored the following parameters such as fertilization, fertility, intensity, rearing of lambs, infertility, ewes lambing, percentage of sheep abortions, stillborn lambs, mortality, percentage of breeding lambs and percentages of sheep by percent occurrence of the cast. There was also observed age structure of the ewes, the dependence of age on fertility of ewes and the effect of father mother on her fertility. In the observed breeding was found the following results, which are presented as an average over the reporting period, so the percentage of fertilization is 91.2%, fertility 145.2% and rearing 81.3%. The percentage of idleness of sheep is 8.8%, which directly affected the percentage of the intensity, which is 118.3% and the lambing percentage, which ranks lower value 81.2%. A relatively high percentage was achieved in postnatal mortality, which is 11.4%. Percentage of sheep abortions in the average is 5.4% and the percentage of stillborn lambs is 4.9%. Breeding lambs 92.3%. The effect of age of ewes on fertility was confirmed by F - test for the significance level of p ? 0,05. Subsequent testing has been demonstrated median significant differences between groups of ewes aged 2 and 3 years and between age groups 3 and 5 years. On the same level of significance was also demonstrated effects of father mother on fertility of mother and on the basis of the results was found that the lowest average fertility rates in the ewes, their father is out of line Yog (110%) and conversely the highest fertility rate (170,8%) is achieved for mothers whose father is out of line Harald. Further testing, which was focused on the effect of age of breeding ewes and breeding year in terms of the father´s line on the mother's fertility wasn´t demonstrated.

Orientação: Sofia Van Harten<br>Atualmente, não existe muita informação sobre a exploração da raça Suffolk em Portugal e, não sendo autóctone, há uma tentativa dos produtores de adaptação do animal ao nosso clima, condições e métodos de exploração. Neste estudo comparou-se a eficácia reprodutiva, com sincronização ou não de cios, com recurso a dois métodos, a monta natural versus a inseminação por laparoscopia, em ovinos da raça Suffolk. Este estudo foi feito observando as práticas de 13 explorações, uma vez que não houve grupos experimentais feitos de propósito para esta dissertação. Tendo em conta o procedimento é de notar que neste estudo o método com taxas de fertilidade mais altas é a monta natural, sendo também economicamente o mais viável. Adicionalmente, verificou-se que as taxas de fertilidade com sincronização atingem aos 100% e as sem sincronização os 94%. Ainda assim, não é possível assumir que a laparoscopia tem resultados inferiores à monta natural pois a amostragem não é igual em ambos os métodos e a sua finalidade reprodutiva pode passar por melhoramento do núcleo genético do seu rebanho. Desta forma, os índices zootécnicos obtidos são satisfatórios para a realidade local mas a raça pode, sem dúvida, beneficiar de mais estudos de campo, com observação de grupos experimentais com metodologia científica para sedimentar conhecimentos.<br>Nowadays, there is not much information about the development of the Suffolk breed in Portugal and, with it not being a native breed, there has been an attempt from the farmers to adapt these animals to the climate, conditions and management of the farm. In this study, the reproductive effectiveness, with or without heat synchronization, was compared using two methods: natural mount versus the insemination through laparoscopy on Suffolk sheep. This study was based on the observation of practices of 13 farms, since there were no purpose-made experimental groups for this dissertation. Having in mind the procedure, it stands out that, in this study, the method with highest fertility rates is the natural mount, also being the most economically viable option. Additionally, it was found that the fertility rates with synchronization have reached 100%, and the ones with no sync 94% Nervertheless, it is not possible to assume that the laparoscopy has lower results when comparing to the natural mount, because the sampling quantities are not equal on both methods and the reproductive purpose could go through the improving of the genetic core of the herd. In this way, the zootechnical indexes obtained are satisfying for the local reality, but the breed can, without a doubt, benefit from more case studies, with experimental group observations with scientific methods, in order to fortify the knowledge.

The primary objective of the thesis will be to evaluate the reproductive performance (the percentage of pregnancy, fertility, the number of lambs reared) in a particular breed of sheep. Another aim will be to assess the impact of certain factors on reproductive performance

The Suffolk is the most well-known of the English lowland sheep breeds. A black-faced sheep with short-stapled wool, the breed is used primarily for meat production. The Suffolk is classified as one of the breeds with the best ability to fatten and its meat yield is approximately 60%. The breed is characterised by its good adaptability to different climate and breeding conditions and overall good health. The ewes are known for their high fertility rate, shorter oestrus cycle, excellent maternal instincts, and high milk production. As a result of these characteristics, the Suffolk has become a very popular breed around the world. This thesis focuses on the breeding of Suffolk sheep as one of the best breeds for the production of slaughter lambs. The thesis also looks at reproduction as a part of sheep breeding, as well as at the factors that have an effect on pregnancy, the birthing process, and the newborn lamb. The main objective of this thesis was to process the lambing data for a specific herd of Suffolk sheep, including performing an evaluation of the basic reproductive indicators, calculating the birth weight of lambs, and determining the ideal age for including ewes in the breeding herd. The basic reproductive indicators include fertility, fertilisation, breeding intensity, and weaned lamb production. In the studied herd of sheep, these indicators were calculated as follows: fertility 182%; fertilisation 91%; breeding intensity 155%; and weaned lamb production 159%. The average birth weight of the lambs was 3.9 kg and the average optimal age for inclusion in the breeding herd was determined to be 17.5 months.

Orientação : João António Martins Cannas da Silva ; co-orientação : Maria do Carmo Feliciano<br>Neste estudo avaliou-se a eficácia reprodutiva da aplicação de dois sistemas de maneio, na época de cobrição, em ovinos. Avaliou-se também a variação sazonal de parâmetros reprodutivos. Na exploração A houve primeiro a pré-exposição a carneiros férteis (45 dias), onde se efectuaram cobrições naturais. O diagnóstico de gestação foi feito aos 90 dias, com nova introdução de machos. Posteriormente foram retirados os carneiros, realizando-se novo diagnóstico aos 180 dias. Efetuaram-se ainda dois grupos de sincronização, sendo aplicado tratamento com progestagéneos (FGA) através de esponjas e injecção de PMSG/eCG no dia da retirada, com posterior cobrição. Na exploração B, os carneiros estiveram presentes durante toda a época reprodutiva, que decorreu entre Fevereiro e Agosto, existindo apenas cobrição natural. Nesta exploração ocorreu um parto por ovelha/ano, ao contrário da A, que teve como objectivo três partos em dois anos. A fertilidade global na exploração A foi de 92,4% e não foi afectada significativamente pelo sistema de maneio aplicado, ao contrário da B que foi de 64%. Os resultados indicaram que o sucesso da exploração A deveu-se à aplicação de tratamentos hormonais ou a técnicas como o efeito macho. Estes induzem a sincronização dos cios permitindo a obtenção de taxas de fertilidade elevadas.<br>In this study we evaluated the reproductive efficiency of the implementation of two systems of management at the time of mating in ovines. We also assessed the seasonal variations of reproductive parameters. In the farm A there was first the pre - exposure to fertile rams (45 days), which made natural mating. Pregnancy diagnosis was made at 90 days, with new introduction of males. Subsequently the males were removed and new pregnancy diagnosis was performed at 180 days. We carried out two further synchronization groups treated with with progestagens (FGA). It was applied using sponges and injection of PMSG / eCG on the day of withdrawal, with subsequent mating. In farm B, the sheep were present throughout the breeding season, which took place between February and August, with only natural mating. On this farm there was a birth per sheep / year, unlike A, which aimed three deliveries in two years. The overall fertility in the farm A was 92.4 % and was not significantly affected by the management system applied, unlike B that was 64 %. The results indicated that the success of the farm A was due to the application of hormonal treatments or techniques as the male effect. These induce synchronization of estrous cycle capable of producing high fertility rates.

Orientação: Carlos Varela Bettencourt ; co-orientação: Maria Cristina Bressan<br>O objetivo neste trabalho foi determinar os efeitos de protocolos de sincronização de estro administrados no período, maioritariamente, anéstrico de ovinos (Merino Branco e Merino Preto) e caprinos (raça Serpentina) criados em condições de Alentejo (nomeadamente no Sistema Agro-pastoril Montado). Os dados avaliados foram a evolução da fertilidade, fecundidade, prolificidade em função da idade, número de animais nascidos dividido pelo total de animais inseminados, e número de animais nascidos dividido pelo total de fêmeas paridas. Os protocolos para as duas espécies foram propostos com base no respetivo ciclo éstrico: a) em ovelhas, como o ciclo estral médio dura 17 dias e a fase lútea dura 12 dias, os tratamentos de indução de estro foram denominados protocolo longo (12 dias) e protocolo curto (8 dias); e b) em cabras, como o ciclo éstrico medio dura 21 dias e a fase lútea dura 15 dias, os tratamentos de indução de estro foram de 11 e 7 dias, ambos considerados protocolos de curta duração. A avaliação do efeito dos tratamentos de indução de estro foi conduzida em pequenos ruminantes em dois estudos distintos: estudo I, com ovinos, e estudo II, com caprinos. As ovelhas e cabras adultas, usadas no trabalho, apresentavam idade entre 2 e 11 anos. No estudo I em todos os tratamentos foram administrados os medicamentos progesterona (por meio de esponjas intravaginais - EI) e gonadotrofina coriónica equina - eCG (via intramuscular). No Protocolo Longo (tradicional), a administração de progesterona foi de 12 dias, seguida da aplicação de eCG. No Protocolo Curto, a administração de progesterona foi de 8 dias, sendo a aplicação eCG e prostaglandina F2a - PG, via intramuscular, 48 horas antes da remoção do dispositivo de progesterona. No estudo I, 141 ovelhas das raças Merino Brancas e Merino Preto foram divididas aleatoriamente em dois grupos com números similares de animais de cada raça. Neste estudo, os resultados mostraram que ovelhas submetidas a indução de estro pelo Protocolo Longo (12 dias), comparativamente aos animais que receberam o Protocolo Curto (8 dias), apresentaram maior taxa de fertilidade ao parto (p<0,05) com medias de 55 % e 35,6 %, respetivamente. As demais respostas analisadas (taxa de fertilidade ao diagnóstico de gestação, número de borregos pelo total de ovelhas inseminadas e número de borregos pelo total de ovelhas paridas) mostraram resultados similares entre tratamentos. No estudo II todas as cabras receberam progesterona (por meio de esponjas intravaginais - EI), gonadotrofina coriónica equina - eCG (via intramuscular), e prostaglandina F2a - PG, aplicado por via intramuscular). No protocolo curto de 11 dias, as cabras foram submetidas ao tratamento com progesterona (EI) por 11 dias, de forma que ao 9.º dia, receberam eCG mais prostaglandina F2aa - PGe no 11.º dia foi removida a EI. No protocolo Curto de 7 dias, a progesterona foi administrada por 7 dias, sendo que ao 5.º dia os animais receberam eCG mais PG, e no 7.º dia a EI foi removida. Neste estudo, as cabras que receberam o protocolo de 7 dias, relativamente ao protocolode 11 dias, mostraram médias mais elevadas (p<0,05)para as taxas de fertilidade ao diagnóstico de gestação (57 % e 16,1 %, respetivamente), taxa de fertilidade ao parto (46,1 % e 5,1 %, respetivamente) e número de cabritos pelo total de cabras inseminadas (0,87 e 0,05, respetivamente). Assim, concluindo, o efeito de indução de estro por meio de protocolo longo e curto nas ovelhas e protocolo de 11 e 7 dias em cabras, sobre os parâmetros reprodutivos, mostraram resultados mais robustos em cabras, do que em ovelhas. Em cabras, o protocolo de 7 dias mostrou ser superior em 30,9 %, 31 % e 0,82 % para taxa de fertilidade ao diagnóstico de gestação, taxa de fertilidade ao parto e número de cabritos pelo total de cabras inseminadas, respetivamente, comparativamente ao protocolo de 11 dias. Ao contrário, em ovelhas, o Protocolo Longo mostrou média superior em 19,4 % para a taxa de fertilidade ao parto, comparativamente ao Protocolo Curto.<br>The main goal of this essay was determine the effects of estrus synchronization protocols administered in the period, mainly, of anestrus of the sheep species (Merino Branco and Merino Preto) and goats (Serpentina breed) raised under Alentejo conditions (in particular the Agro-pastoril Montado system). The data evaluated were the evolution of fertility, fecundity, prolificacy according to age, number of animals born divided by the total of inseminated animals, and number of animals born divided by the total number of females that delivered. The protocols for the two species were proposed based on the respective cycle: a) in sheep, as the average estrous cycle lasts 17 days and the luteal phase lasts for 12 days, the estrus induction treatments were denominated long protocol (12 days ) and short protocol (8 days); and b) in goats, as the average cycle lasts for 21 days and the luteal phase lasts for 15 days, the estrus induction treatments were 11 and 7 days, both considered short-term protocols. The evaluation of the effect of the treatments of estrus induction on small ruminants was conducted in two different studies: study I, with sheep, and study II, with goats. Adult ewes and goats used at work were aged between 2 and 11 years. In study I, progesterone (intravaginal sponges - EI) and equine chorionic gonadotrophin - eCG (intramuscular) were administered in all treatments. In the Long (traditional) Protocol, the administration of progesterone lasted 12 days, followed by the application of eCG. In the Short Protocol, the administration of progesterone lasted 8 days, with the application of eCG and prostaglandin F2α - PG, intramuscularly, 48 hours before the removal of the progesterone device. In study I, 141 Merino White and Black Merino sheep were randomly divided into two groups with similar numbers of animals of each breed. In this study, the results showed that sheep submitted to estrus induction by the Long Protocol (12 days), compared to the animals that received the Short Protocol (8 days), had a higher fertility rate at delivery (p <0.05) with averages of 55% and 35.6%, respectively. The other data analyzed (fertility rate at the gestation diagnosis, number of lambs by total inseminated sheep, and number of lambs by total females that delivered) showed similar results.In study II, all goats received progesterone (intravaginal sponges - EI), equine chorionic gonadotrophin - eCG (intramuscular), and intramuscularly applied prostaglandin F2α - PG). In the short protocol of 11 days, the goats were treated with progesterone (EI) for 11 days, so that on the 9th day, they received eCG plus PG, and on the 11th day the EI was removed. In the short 7 day protocol, progesterone was administered for 7 days, and at the 5th day the animals received eCG plus PG, and on the 7th day the IE was removed. In this study, goats that received the 7-day protocol compared to the 11-day protocol showed higher averages (p <0.05) for the fertility rate at the gestation diagnosis (57% and 16.1%, respectively ), fertility rate at delivery (46.1% and 5.1%, respectively), and number of kids by total inseminated goats (0.87 and 0.05, respectively). In conclusion, the effect of estrus induction by long and short protocol in sheep and protocol of 11 and 7 days in goats, on reproductive parameters, showed more robust results in goats than in sheep. In goats, the 7-day protocol was superior in 30.9%, 31%, and 0.82% for fertility rate at gestation diagnosis, fertility rate at delivery, and number of goats for the total number of inseminated goats, respectively, compared to the 11-day protocol. On the other hand, in sheep, the Long Protocol showed a higher average of 19.4% for the fertility rate at birth, compared to the Short Protocol.

Orientação: Carlos Manuel Varela Bettencourt<br>Este estudo pretendeu: I- Descrever o procedimento do exame andrológico em carneiros e relaciona-lo com a qualidade do sémen; II- Demonstrar as alterações induzidas pela criopreservação e descongelação no sémen de carneiro; III- Comparar a eficácia de dois extensores de sémen (OVIXCellÒ e Glucose-Citrato-Gema de ovo); IV– Determinar os Índices de Fertilidade, Natalidade e número médio de borregos por parto resultantes da inseminação artificial com sémen refrigerado e descongelado. Através da estatística de Pearson, determinou-se uma correlação positiva entre os vários parâmetros do exame andrológico e a qualidade do sémen. A concentração apresentou uma correlação forte (r=0,8), A circunferência escrotal (r=0,59), motilidade (r=0,59), volume (r=0,58) e morfologia (r=0,46) apresentaram correlações médias. Os resultados permitem afirmar com alguma segurança que um carneiro “Apto para Reprodução” produzirá um ejaculado de boa qualidade. Foram feitas 13 sessões de colheitas de sémen. O sémen obtido foi submetido a um protocolo de congelação com dois extensores diferentes; OVIXCellÒ e Glucose- Citrato-Gema de ovo. Todas as amostras de sémen foram avaliadas antes da criopreservação e após a descongelação, quanto á motilidade, vitalidade e morfologia. A criopreservação e descongelação têm um impacto bastante negativo na viabilidade do sémen, independentemente do extensor utilizado. Registou-se um decréscimo de 50% na motilidade progressiva; de 40% na vitalidade espermática e um aumento de 20% de espermatozoides com morfologia anormal. A utilização de Glucose- Citrato-Gema de ovo mostrou-se vantajosa relativamente à utilização de OVIXCellÒ por apresentar um perfil de alterações menos significativo à descongelação. O sémen diluído com OVIXCellÒ teve uma perda de motilidade 10% superior, de vitalidade 7% superior e uma contagem de espermatozoides com morfologia anormal 23% superior quando comparado com o sémen diluído com Glucose-Citrato-Gema de ovo. Relativamente ao índice de Fertilidade e Natalidade, a preparação de doses de inseminação artificial com 50x106spz viáveis/dose poderá compensar a fraca viabilidade do sémen descongelado aplicado por laparoscopia. A utilização desta concentração permitiu obter índices de fertilidade de 34% e de natalidade de 42%, ambos satisfatórios relativamente aos índices descritos na bibliografia. Os resultados não foram conclusivos quanto á média de borregos por parto.<br>This study aimed to: I- Describe the procedure of the breeding soundness evaluation in rams and relate it to the quality of semen; II– Demonstrate the changes induced by cryopreservation and thawing in ram semen; III - Compare the change profile induced by freezing and thawing in semen extended with OVIXCellÒ and with Glucose- Citrate-Egg yolk); IV– Determine the Fertility and Birth rates and average of lambs per lambing resulting from artificial insemination with refrigerated and thawed semen. Using Pearson’s statistics, determined a positive correlation between the various parameters of the breeding soundness evaluation and the quality of semen. Concentration had a strong correlation (r = 0.8); scrotal circumference (r = 0.59), motility (r = 0.59), volume (r = 0.58) and morphology (r = 0.46) had medium correlations. This analysis allows us to assert, that a "Suitable for Reproduction" ram will produce a good quality ejaculate. Thirteen semen collection sessions were carried out. Collected semen was submitted to a freezing protocol with two different extenders; OVIXCellÒ and Glucose- Citrate-Egg Yolk. All semen samples were evaluated before freezing and after thawing for motility, vitality and morphology. Cryopreservation and thawing had a very negative impact on semen viability, regardless of the used extender. It was noted, a 50% decrease in progressive motility, a 40% decrease in sperm vitality and a 20% increase in abnormal morphology count. The use of the Glucose-Citrate-Egg Yolk Extender was advantageous over the use of OVIXCell® because it presented a less significant change profile after thawing. Semen extended with OVIXCellÒ had 10% higher motility loss, 7% higher vitality loss and a 23% higher abnormal sperm morphology count when compared to semen diluted with Glucose-Citrate-egg yolk. Regarding the Fertility and Birth rates, artificial insemination with a concentration of 50x106 viable spz/dose may compensate for the poor viability of thawed semen when applied by intrauterine laparoscopy. Insemination of sheep with these concentrations resulted on a fertility rate of 34% and a 42% birth rate. These rates are satisfactory relative to those described in literature. Results were not conclusive regarding the average number of lambs per lambing.