Dissertations / Theses on the topic 'Calving interval'

Mestrado em Engenharia Zootécnica - Produção Animal - Instituto Superior de Agronomia / Faculdade de Medicina Veterinária
It is well accepted that one of the biggest concerns of the beef producers is reducing the calving interval, because of the great impact it has on the productivity of the herd, as well as the productive parameters of their calves. All these factors are influenced by environmental conditions in which the environment and management, namely reproductive and feeding management can be highlighted. The aim of this work was to study the effect of farm, calving number, sex of the calf, year and season of births in the calving interval of the Alentejano cows in two farms (Paço and Pinheiros) belonging to Eugénio de Almeida Foundation. Also, the effects of farm, year and season of birth on the various productive parameters of steers produced were studied. The results obtained indicate the existence of a strong effect of year of birth, probably related to annual rainfall, as well as calving number on the calving interval. Also, the season of birth influenced the lenght of calving interval, revealing that the best seasons are spring and autumn. Also the year and season of birth had influences on the productive characteristics of animals, noting that the summer was clearly the season of births which showed worse results.

Dissertação de Mestrado Integrado em Medicina Veterinária
Este estudo teve como objetivos analisar a distribuição de partos na raça Mertolenga e a influência dos principais efeitos ambientais no intervalo entre partos (IEP) em bovinos da mesma raça. Foram utilizados os registos de 8 explorações de criadores, inscritas no livro genealógico da Associação de Criadores de Bovinos Mertolengos (ACBM), correspondendo a 17 090 partos e 13 510 IEP de 2 655 fêmeas, ocorridos entre 1990 e 2019. Os registos foram submetidos a várias análises preliminares com o programa SAS®, utilizando-se o PROC UNIVARIATE, o PROC MEANS e o PROC FREQ. Com um modelo misto, através do PROC MIXED do mesmo programa, analisou-se o IEP com um modelo que incluiu os efeitos fixos da exploração, ano e mês de parto, sexo e raça do vitelo e como covariável o efeito linear e quadrático da idade ao parto; a fêmea (vaca) foi considerada como efeito aleatório no modelo misto. A idade média ao primeiro parto (IPP) foi de 34,3 meses, a idade média de morte foi de 13,76 anos e o número médio de partos por vaca ao longo da vida foi de 5,3±3,4 partos/vaca. Neste estudo observou-se um IEP médio de 436,9 ±116,2 dias e as variáveis “exploração”, “mês do parto”, “ano do parto”, “raça do vitelo” e “idade da vaca ao parto” influenciaram significativamente o IEP (p<0,0001) enquanto que a variável “sexo do vitelo” não se revelou significativa (p=0,1127). Observou-se que a maior concentração de partos ocorre nos meses de verão, principalmente entre meados de julho e setembro e que existem grandes diferenças nos valores de IEP médios entre as distintas explorações e anos avaliados. Vacas paridas em abril tiveram o IEP médio mais curto (418,9±4,6 dias) e vacas paridas em janeiro e fevereiro apresentaram valores médios de IEP mais longos (451,9±3,5 dias versus 450,315±3,755 dias). Vacas que parem vitelos Mertolengos puros têm, em média, IEP inferiores (421,9) que vacas que parem vitelos cruzados (440,1). Apesar de não existirem diferenças significativas, observou-se que vacas que parem vitelas, em média, têm IEP cerca de 3 dias mais curtos que vacas que parem machos (432,5±1,9 dias versus 429,5±1,9 dias). Em relação à idade ao parto, verificou-se que se trata de uma variável com um efeito quadrático neste parâmetro reprodutivo, sendo que fêmeas mais novas apresentam IEP superiores e que este intervalo vai diminuindo com o avançar da idade das vacas até aos 9,3 anos (112 meses), idade em que se verificou o menor IEP médio (404 dias) e a partir da qual este valor volta a aumentar. Tendo em conta a influência significativa do maneio realizado na vacada no seu IEP médio, é fundamental a sensibilização dos produtores para o papel que o médico veterinário representa para a melhoria da eficiência reprodutiva dos seus efetivos.
ABSTRACT - The role of the veterinarian in the reproductive maximization in beef cattle: calving to calving interval of Mertolenga breed as a case study - This study aimed to analyse the distribution of Mertolenga calving and the influence of the main environmental effects on the calving-to-calving interval (CCI) in cattle of the same breed. The records of 8 farms of breeders, registered in the genealogical book of the Association of Mertolengo Bovine Breeders (ACBM) were used, corresponding to 17 090 births and 13 510 CCI of 2 655 females, which occurred between 1990 and 2019. The records were submitted to several preliminary analyses with the SAS® program, using PROC, PROC MEANS and PROC FREQ. With a mixed model, through the PROC MIXED of the same program, the CCI was analysed with a model that included the fixed effects of the herd, year and month of calving, sex and breed of the calf and as covariable the linear and quadratic effect of age to delivery; the female (cow) was considered as a random effect in the mixed model. The average age at first calving (AFC) observed was 34.3 months, the average age of death was 13.8 years and the average number of births per cow throughout life was 5.3 ± 3,9 calves per cow. In this study, an average IEP of 436.9 ± 116.2 days was observed and the variables “herd”, “month of calving”, “year of calving”, “calf breed” and “cow age at calving” influenced significantly the CCI (p <0.0001) while the variable “calf sex” was not significant (p = 0.1127). It was observed that the highest concentration of births occurs in the summer months, mainly between mid-July and September, and that there are large differences in the mean CCI values between the different farms and years evaluated. Cows calved in April had the shortest CCI average (418.9 ± 4.6 days), and cows calved in January and February had longer CCI values (451,9 ± 3,5 days / 450,3 ± 3,8 days). Cows that calve pure Mertolengos calves have, on average, lower CCI (421,9) that cows that calve crossed calves (440,1). Although there were no significant differences, it was observed that cows that calved female calves, on average, had CCI about 3 days shorter than cows that calved males (432.5 ± 1.9 days / 429.5 ± 1.9 days). Regarding the age at calving, it was found that this is a variable with a quadratic effect on this reproductive parameter and that younger females have higher CCI and that this interval decreases with the advancing age of the cows up to 9.3 years (112 months), age at which the lowest mean CCI (404 days) was observed and after which this value increases again. Bearing in mind the significant influence of the management carried out on the cow in its average CCI, it is essential to raise awareness among producers about the advantages that may arise from improving the reproductive efficiency of their herds and the role that the veterinarian plays to successfully achieve this goal.
N/A

The objectives of this research were to evaluate breed differences for heat-stress resistance using age at first calving and first calving interval, and to assess breed by region interactions for seven regions of the United States for survival-related traits up to five years of age in Brown Swiss, Holstein, and Jersey cows. Age at first calving and first calving interval were studied in farms with two breeds, with Holstein and Brown Swiss or Holstein and Jersey cows. The survival-related traits were analyzed in farms with one or two breeds. Seven regions within the United States were defined: Northeast, Northwest, Central north, Central, Central south, Southwest and Southeast. The fertility traits were also analyzed in seven individual states: Wisconsin, Ohio, Oregon, California, Arizona, Florida, and Texas. Brown Swiss were older than Holsteins at first calving (833 ± 2.4 d vs. 806 ± 2.0 d in regions, and 830 ± 3.1 d vs. 803 ± 2.4 d in states), but Holsteins and Brown Swiss did not differ for first calving interval. Jerseys were younger than Holsteins at first calving and had shorter first calving intervals (P < 0.01). In data from individual states, Holsteins housed with Brown Swiss were older at first calving than Holsteins housed with Jerseys (800 ± 2.7 d vs. 780 ± 2.5 d). Holsteins housed with Jerseys had slightly shorter first calving intervals than Holsteins housed with Brown Swiss, and the interaction of "type of Holstein: with season of the first calving was highly significant (P < 0.01). Region and season effects were smaller for Jerseys than for Holsteins, thus, Jerseys showed evidence of heat-stress resistance with respect to Holsteins. Management modified age at first calving in Holsteins, depending on the type of herd they were located in. Longer calving intervals might have been partly due to voluntary waiting period to breed the cows. The survival-related traits were evaluated up to five years of age. They consisted of stayability, number of completed lactations, days lived, herd-life, and total days in milk. For herds with one breed, the order for stayability to five years of age, from longer to shorter-lived breed was: Brown Swiss, Jersey and Holstein, but for the ratio of days in milk to herd-life the order was: Holstein, Jersey and Brown Swiss, and for the ratio of days in milk to days lived, it was: Jersey, and Holstein and Brown Swiss tied. This last ordering was the same for number of lactations completed by five years of age. The results for two-breed herds were similar since Brown Swiss and Jerseys had larger (Chi-square P < 0.01) probabilities of living past five years of age than Holsteins, and for days in milk and number of lactations completed, Jerseys had higher values than Holsteins (P < 0.01), but Holsteins and Brown Swiss tied in some analyses. Breed by region interaction was always significant. If all other conditions were assumed equal, Jerseys would give fastest returns by five years of age. The overall conclusion is that Jerseys performed better for the traits analyzed, all of them highly influenced by environmental conditions.
Ph. D.

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Improvement of animal nutrition and management, together with genetic selection for milk yeld, increased the productivity of the herds, especially Holstein cows. On the other hand, characteristics related to fertility, health and longevity were disadvantaged The aim was to compare the development, milk yeld and composition, the health of the mammary gland, the body condition score (BCS), reproductive performance and longevity of crossbred Holstein x Simmental cows with Holstein cows. To obtain the data set two farms were used, one in Bom Retiro in SC and another in Carambeí in PR. For growth evaluation, weight gain of the animals were evaluated monthly. For production and udder health data from the official Dairy Herds Improvement Programs of the farm were used. BCS and body weight estimation were made on the farm with an interval between 60 and 90 days within one year. Information concerning the date of birth, parity date, date and number of inseminations, were obtained from the management software of the farms, generating information regarding the calving interval, days between calving to first service, conception rate, age at first calving. In one of the farms, calving were monitoring to quantify the calving difficulty, in the same farm, information of culling were obtained to determine the survival rate of cows. Data were analyzed by statistical package of SAS, using the MIXED and GENMOD procedures. For growth curve, production and composition of milk, (BCS) and body weight nonlinear regression was used, using the NLIN procedure of SAS and the curves of Gompertz (growth) and Wood (production and composition) were used because of having the lowest mean square. Holstein x Simmental crossbred cows produced more milk 31,8 x 30,4 kg/day (P < 0,05), with higher content of lactose and protein, with no difference for fat content. Holstein cows had higher somatic cell score (SCS) 4.49 x 2.93 (P <0.0001) compared to crossbreed cows. Holstein x Simmental crossbred cows had better BCS during lactation 3.65 x 2.94 (P <0.0001) with no difference in body weight in relation to Holstein cows. For growth of calves and heifers there was no difference between the genetic groups. Crossbred cows Holstein x Simmental had better reproductive performance than the Holstein cows, characterized by lower calving interval (381 x 445 days), higher conception rate (37.31 x 33, 64%) and shorter interval calving to first service (65.6 x 89.3 days). Crossbred cows Holstein x Simmental had higher survival rate than Holstein cows (83 x 92 In conclusion, crossbred cows Holstein x Simmental produce more milk with higher content of lactose and protein, have less ECS and greater BCS without difference for growing of heifers and body weight in adult age. Crossbred cows still have better reproductive performance and have a higher survival rate than the Holstein cows
Melhorias na nutrição e no manejo dos rebanhos bem como a seleção genética para a produção de leite aumentaram a produtividade dos animais. Em contrapartida, características relacionadas a fertilidade, sanidade e longevidade foram prejudicadas. O objetivo foi comparar o desenvolvimento, a produção e composição do leite, a sanidade da glândula mamária, o escore de condição corporal o desempenho reprodutivo e a longevidade de vacas mestiças Holandês x Simental em relação as vacas puras Holandês. Foram utilizadas duas propriedades, uma localizada no município de Bom Retiro em SC e outra em Carambeí no PR. Para avaliação de crescimento o ganho de peso dos animais foi avaliado mensalmente. Para obter dados produtivos e de sanidade de úbere foram utilizados dados do controle leiteiro oficial da propriedade. As avaliações de escore e peso vivo foram realizadas na propriedade com intervalo entre 60 e 90 dias no período de um ano, informações estas obtidas em uma das propriedades. As informações referentes a data de nascimento, data de parto, data e número de coberturas, foram obtidas junto aos software de gerenciamento de ambas as propriedades, gerando informações referentes ao intervalo entre partos (IEP), período parto primeiro serviço, taxa de concepção, idade ao primeiro parto. Em uma das propriedades foi feito o acompanhamento dos partos para quantificar a dificuldade de parto, da mesma forma, foram obtidas informações referentes ao descarte de animais para determinar a taxa de permanência no rebanho das vacas. Os dados foram analisados pelo pacote estatístico SAS, utilizando-se os procedimentos MIXED e GENMOD Para curva de crescimento, de produção e composição do leite bem como escore de condição corporal (ECC) e peso vivo foi utilizada a técnica de regressão não linear, do pacote estatístico SAS sendo que foram utilizadas as curvas de Gompertz (crescimento) e de Wood (produção e composição) por apresentarem o menor quadrado médio do erro. Vacas mestiças Holandês x Simental produziram mais leite 31,8 x 30,4 ( P < 0,05), com maior teor de lactose e proteína, sem diferença para teor de gordura. Vacas Holandês obtiveram maior escore de células somáticas (ECS) 4,49 x 2,93 (P < 0,0001) em relação as mestiças. Vacas mestiças Holandês x Simental obtiveram melhor ECC durante a lactação 3,65 x 2,94 (P < 0,0001) sem diferença para peso vivo em relação as vacas Holandês. Para crescimento de bezerras e novilhas não houve diferença entre os grupamentos genéticos. Vacas mestiças Holandês x Simental obtiveram melhor desempenho reprodutivo em relação as vacas puras, caracterizado através do menor IEP (381 x 445 dias), maior taxa de concepção (37,31 x 33, 64 %) bem como menor intervalo parto primeiro serviço (65,6 x 89,3 dias). Vacas mestiças Holandês x Simental apresentaram maior taxa de permanência no rebanho em relação as vacas puras (83 x 92 %). Conclui-se que vacas mestiças produzem mais leite, com maior teor de lactose e proteína, possuem menos ECS e maior ECC sem diferença para crescimento de novilhas e peso vivo na idade adulta. Apresentam ainda melhor desempenho reprodutivo e maior taxa de permanência no rebanho em relação as vacas puras Holandês

Devido á crise que afeta o setor de leite nos últimos anos e mais recentemente com a eliminação do sistema de cotas leiteira, aliado à instabilidade do preço de leite e à dificuldade de escoamento do produto principal, torna-se de vital importância a (re) análise e monotorização de todos os parâmetros que influenciam a rentabilidade das explorações de leite portuguesas. Sendo a eficiência reprodutiva um dos fatores de destaque na gestão das explorações torna-se importante perceber que influência exerce na rentabilidade das explorações. Este trabalho demostrou, através da análise económica, que o intervalo entre partos (IEP) influencia a rentabilidade das explorações. Na amostra utilizada, verificou-se um efeito significativo para o IEP igual ou inferior a 415 versus superior a 415 dias e para IEP igual ou inferior a 424 versus superior a 424 dias, em indicadores económicos como o saldo proveitosdespesas , margem bruta , margem líquida , taxa de rentabilidade global dos fatores e margem líquida por Kg leite . Aliado ao IEP, a dimensão das explorações também influencia a sua rentabilidade, sendo as explorações com dimensão média de 51 e 100 animais secos as mais rentáveis; Abstract: The effect of calving interval in the economic viability of dairy cattle farms Due to the crisis affecting the dairy sector in recent years and most recently with the elimination of the milk quota system, coupled with the instability of the milk price and the difficulty of disposing of the main product, it is of vital importance to (re)analyse and monitoring of all parameters that influence the profitability of Portuguese dairy farms. As the reproductive efficiency is one of the prominent factors in farm management. it becomes important to understand how it exerts influence on the profitability of farms. This work demonstrated through economic analysis, that the calving interval influences the profitability of farms. In the sample used, there was a significant effect on the IEP equal to or less than 415 versus more than 415 days and for IEP less than or equal to 424 versus more than 424 days in economic indicators such as "income-expenditure balance", "gross margin , "net margin", "global rate of return factors" and "net margin per kg milk . Coupled with the calving interval, the size of holdings also influences their profitability, and farms with an average size of 51 and 100 dry animals are the most profitable.

Mestrado em Engenharia Zootécnica - Produção Animal - Instituto Superior de Agronomia / Faculdade de Madicina Veterinária
With an excellent milk production aptitude, the famous black brindles Friesian is the bovine breed with the greatest expansion in the world. During the past three decades, genetic breeding programs have been implemented in dairy cattle. Therefore, reproductive traits have been poor, leading to a steady increase in milk production. The present study aims to find the relationship between high milk production and reproductive effectiveness of Manuel dos Santos Miranda dairy farm. Data were extracted from headcount records, between 2009 and 2011. Primarily, the factors influencing reproductive traits were identified, in order to reveal its action and find possible improvements. Data were graphically treated to investigate parameters such as calving interval (CI), conception rate (CR), interval between calving and conception (ICC) and interval between calving and first insemination (IC1stAI). Although no differences were found in milk production during the study, the high production shown leads to reproductive traits, such as high CI (475 ± 5 days), CR (3.3), ICC (216.5 ± 8 days) and IC1stAI (109 ± 3 days). In comparison with literature, the results showed differences in the study indexes. These were believed to be mainly caused by low heat detection, inappropriate dairy farm management and inaccurate artificial insemination strategy

With the objective of estimating genetic parameters for stayability to 48 and 60 months of age (STAY48 and STAY60) and their association with milk production in the first lactation (P305), age at first calving (AFC) and first calving interval (FCI) data from 3,344 cows from six herds located in the states of Minas Gerais, São Paulo and Paraiba were analyzed. The (co) variances were estimated by Bayesian approach, using bi-characteristics animal models. For STAY48, STAY60 and AFC systematic effects farm-year-season of birth were include with model. For P305 and FCI, the model used included the systematic effects of farm-year-season of calving and age at calving (linear and quadratic) as a covariable. In addition to these systematic effects for all traits were also included the effects of random additive genetic and residual. The mean estimates of heritability were 0.25 ± 0.08, 0.32 ± 0.07, 0.31 ± 0.05, 0.28 ± 0.05 and 0.08 ± 0.04 for STAY48, STAY60, P305, AFC and FCI, respectively. The a posteriori estimates of genetic correlations between STAY48 and P305 AFC and FCI were 0.90 ± 0.10, -0.55 ± 0.24 and 0.64 ± 0.33. The estimated genetic correlations between STAY60 and P305, AFC and FCI were 0.94 ± 0.07, -0.54 ± 0.21 and 0.83 ± 0.18. The genetic and phenotypic correlations estimated between stayability to 48 and 60 months of age and milk production in the first lactation indicate that production in the first lactation may be used as a selection criterion for longevity. Similarly, the selection to reduce the age at first calving can cause, for a correlated response female.
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Com o objetivo de estimar parâmetros genéticos para stayability aos 48 e 60 meses de idade (STAY48 e STAY60) e suas associações com produção de leite na primeira lactação (P305), idade ao primeiro parto (IPP) e primeiro intervalo de partos (PIDP), foram analisados dados de 3.344 vacas pertencentes a seis rebanhos localizados nos estados de Minas Gerais, São Paulo e Paraíba. Os componentes de (co)variância foram estimados por abordagem Bayesiana em análises bi-características. Para as características STAY48, STAY60 e IPP, foram incluídos os efeitos sistemáticos de fazenda-ano-estação de nascimento. Para P305 e PIDP, o modelo utilizado incluiu os efeitos sistemáticos de fazenda-ano-estação de parto e idade da vaca ao parto com covariável (efeitos linear e quadrático) como covariável. Além desses efeitos sistemáticos, para todas as características estudadas, foram considerados os efeitos aleatórios genético aditivo direto e residual. As herdabilidades médias estimadas foram 0,25±0,08, 0,32±0,07, 0,31±0,05, 0,28±0,05 e 0,08±0,04 para STAY48, STAY60, P305, IPP e PIDP, respectivamente. As estimativas a posteriori das correlações genéticas obtidas entre STAY48 com P305, IPP e PIDP foram de 0,90±0,10, -0,55±0,24 e 0,64±0,33. As correlações genéticas estimadas entre STAY60 com P305, IPP e PIDP foram de 0,94±0,07,-0,54±0,21 e 0,83±0,18. As correlações genética e fenotípica estimadas entre a stayability aos 48 e 60 meses de idade e produção de leite na primeira lactação indicam que a produção na primeira lactação pode ser usada como critério de seleção para longevidade. De forma semelhante, a seleção para reduzir a idade ao primeiro parto pode provocar, por resposta correlacionada, em melhorias na longevidade das fêmeas.

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PROMOP
The current scenario of the national milk production is in constant transformation. The current economic situation in the milk production requires producers operate with maximum efficiency to maintain profitability. To achieve maximum production cows should foal at regular intervals. This is only possible if the females becoming pregnant within a restricted period. That way the adoption of simple reproductive management techniques that can promote improved reproductive performance indexes, will provide higher returns to producers with no need for large investments.The objective of this study was to evaluate the impact of three management systems reproductive and economic efficiency of dairy cows in semi-intensive production systems. The cows were selected by reproductive history, production and corporal condition and subjected to a full gynecological examination, including vaginoscopy and ultrasonography between 30-40 days postpartum. The animals were randomly allocated into one of three treatments: 1 - Estrus Detection (ED) - Consists of traditional management of artificial insemination (AI) after spontaneous estrus postpartum. The animals in this group were inseminated on the first estrus after 50 days in milk (DEL), 12 hours after the start of the estrus detection. Treatment 2 - Prostaglandin F2α (PGF2α) - Between 50-60 days postpartum, each cow received a dose of 0.5 mg of d-cloprostenol and marking with marker bat, being inseminated 12 hours after detection of estrus. Cow not entering into heat, they received a second dose of 0.5 mg d-cloprostenol 11 and / or 14 days later. Treatment 3 - FTAI. The FTAI protocol started 50-60 days postpartum by applying (D0) intravaginal progesterone implant and intramuscular (IM) of estradiol benzoate (EB, 2.0 mg). In D8, the implant removed and administered 150μg of PGF2a and 1 mg estradiol cypionate. The FTAI performed 48 hours after implant removal. To verify the effect of treatments on DEL variables for the first insemination, calving to conception interval (IPC) used the analysis of variance followed by Tukey's test. For analysis of the proportion of data (conception rate to first insemination and pregnancy rate to 150 LED) used the analysis of "Deviance" considering 5% significance level. The results showed higher rate of conception after 1˚ artificial insemination (AI), reduced birth-conception interval and economic benefit with the use of FTAI in dairy cows in semi-intensive production systems. The conditions under which the experiment was conducted, can be concluded that FTAI increases the conception rate in the first postpartum AI reduces the interval between calving and first AI and birth-conception range, raises the profitability of dairy farms
O cenário atual da produção leiteira nacional está em constante transformação. A atual situação econômica na produção de leite exige que os produtores operem com máxima eficiência, para manter a rentabilidade da atividade. Para alcançar a máxima produção, as vacas devem parir em intervalos regulares. Esta situação só é possível se as fêmeas tornarem-se gestantes dentro de um período restrito de tempo. Dessa forma, a adoção de técnicas de manejo reprodutivo simples, que possam promover a melhora dos índices zootécnicos reprodutivos, proporcionará maior retorno financeiro aos produtores, sem necessidade de investimentos de grande porte. O objetivo deste trabalho foi avaliar o impacto de três manejos na eficiência reprodutiva e econômica de vacas leiteiras em sistemas de produção semi-intensivo. As vacas foram selecionadas pelo histórico reprodutivo, produtivo e condição corporal e submetidas a um exame ginecológico completo, incluindo vaginoscopia e ultrassonografia entre 30-40 dias pós-parto. Os animais foram alocados aleatoriamente em um dos três tratamentos: Tratamento 1 – Detecção de Estro (DE) - Consiste de manejo tradicional de inseminação artificial (IA) após cio espontâneo no pós-parto. Os animais deste grupo foram inseminados no primeiro cio após os 50 dias em lactação (DEL), 12 horas após a detecção do início do mesmo. Tratamento 2 – Prostaglandina F2α (PGF2α) – Entre 50-60 dias pós-parto, cada vaca recebeu uma dose de 0,5 mg de d-cloprostenol e marcação com bastão marcador, sendo inseminadas 12 horas após a detecção do cio. Vacas que não entraram em cio, receberam uma segunda dose de 0,5 mg de d-cloprostenol 11 e/ou 14 dias mais tarde. Tratamento 3 - IATF. O protocolo de IATF começou entre 50-60 dias pós-parto com aplicação (D0) de implante intravaginal de progesterona e aplicação intramuscular (IM) de benzoato de estradiol (BE; 2,0 mg). No D8, o implante foi retirado e administrado 150μg de PGF2α e 1 mg de cipionato de estradiol. A IATF foi realizada 48 horas após a retirada do implante. Para verificar o efeito dos tratamentos nas variáveis DEL para a primeira inseminação, intervalo parto-concepção (IPC) utilizou-se a análise de variância seguida do teste de Tukey. Para análise dos dados de proporção (Taxa de concepção a primeira inseminação e Taxa de prenhez aos 150 DEL) utilizou-se a análise de “Deviance” considerando o nível de 5% de significância. Os resultados mostraram aumento da taxa de concepção após a 1˚ inseminação artificial (IA), redução do intervalo parto-concepção e benefício econômico com uso de IATF em vacas leiteiras em sistemas de produção semi-intensivo. Nas condições em que foram realizadas o experimento, conclui-se que IATF aumenta a taxa de concepção na primeira IA pós-parto, reduz o intervalo entre o parto e a primeira IA e o intervalo parto/concepção e eleva a lucratividade de estabelecimentos leiteiros

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The genetic improvement programs for dairy cattle give more focus in production traits, with negative consequences in the genetics for functional traits like fertility, longevity and health. Selection for conformation can minimize the negative effects for some characteristics, like the mammary health, with gains on longevity. Farmers and technicians have used selection for conformation, especially rump, aiming improve fertility, although without scientific evidence of its efficacy. In this way, this work aimed to study the influence of some linear type traits on calving interval in Holstein cows in South of Brazil. The Holstein Cattle Breeder´s Association of Paraná State (APCBRH) supplied the data for this study. Linear type traits with possible influence on fertility (width and rump angle, chest width, body depth, rear leg side view, foot angle and angularity) were studied using a scale from 1 to 9 points. Calving interval (CI) was used as fertility trait. After editing the data comprised linear classification of 23,014 cows, from 248 herds, classified from 2000 to 2010, daughters of 797 sires. Variance components for heritability and genetic correlation were estimated with Restricted Maximum Likelihood method (REML), using MIXED procedure of statistics package SAS. Heritability for type traits and CI were estimated, as well as genetic correlations among type traits and these with CI. For heritability evaluation for CI and genetic correlation of type traits with CI, information about 51,237 calving intervals of 24,740 cows, of 294 herds, calved between 2000 and 2010, daughters of 1,003 sires were utilized. To evaluate the effect of the conformation of the cows in the CI, the cows were divided in three scores for each trait type, with low score (linear classification 1 to 3), middle score (linear classification 4 to 6) and high score (linear classification 7 to 9). Heritability estimates ranged from 0,09 to 0,24, with the lower values for traits of the category legs and feets. Heritability estimation for CI too was of low magnitude (0,05). Genetic correlation estimations among type traits were also, in general, of low magnitude, with the higher value between chest width and body depth (0,52). Rump width and rump angle showed negative genetic correlation (-0,33), with selection for rump width can lead to an increasing in cows with high pins. Genetic correlation estimations between type traits and CI were, mostly, low. The ones with higher genetic correlation with CI were: foot angle (0,41), rear leg side view (-0,36), rump width (-0,33) and angularity (0,32). Rump angle did not show genetic correlation with CI, however, cows with high pins (score 1 to 3) showed phenotypically longer CI, although with discrete differences in relation to cows with intermediate rumps or low pins (2,5 and 4,7 days, respectively). Rump width did not affect the phenotypic value of CI. Selection for this character may lead to few gains for fertility, although with negative effects to rump angle and rear leg side view, due to negative genetic correlations (-0,33 and -0,35, respectively). For angularity, unfavorable genetic correlation with CI was observed and substantially longer CI were related to more angular cows too, particularly in older cows. We concluded that the estimated genetic correlations of some type traits with calving interval provided information for the practice of selection for type , with the purpose of providing improvements in in the reproductive efficiency of dairy herds. The selection order to avoid cows with inverted rump does not determine genetic gain for fertility. However, cows with high pins have reversed phenotypically calving interval slightly longer. Selection for increased width of rump may bring some increase in fertility, however, with negative consequences on the genetic merit of other type traits. Selection for high angularity should be prevent due the reduction of fertility
Os programas de melhoramento genético têm dado maior ênfase à seleção para as características produtivas, com consequências negativas sobre características funcionais, tais como fertilidade, longevidade e sanidade. A seleção para conformação tem conseguido minimizar parcialmente os efeitos negativos para algumas características, como, por exemplo, a sanidade da glândula mamária, com ganhos sobre longevidade. Produtores e técnicos tem utilizado a seleção para conformação, em especial da garupa, com o intuito de melhorar a fertilidade das vacas, faltando, entretanto, a devida comprovação científica de sua eficácia. Neste sentido, objetivou-se estudar a influência de algumas características lineares de tipo sobre o intervalo de partos em vacas da raça Holandesa no Sul do Brasil. Os dados utilizados foram fornecidos pela Associação Paranaense de Criadores de Bovinos da Raça Holandesa (APCBRH). Estudaram-se características lineares de tipo, com possível influência sobre fertilidade (largura e inclinação de garupa, largura de peito, profundidade corporal, pernas vista lateral, ângulo de casco e angulosidade), sendo as mesmas avaliadas na escala de 1 a 9 pontos. O indicador de fertilidade avaliado foi o intervalo de partos (IP). O arquivo utilizado continha 23.014 vacas classificadas no período de 2000 a 2010, oriundas de 248 rebanhos, filhas de 797 touros. Os componentes de variância para a estimativa das herdabilidades e das correlações genéticas foram obtidas pelo método da Máxima Verossimilhança Restrita (REML), utilizando-se o procedimento MIXED do pacote estatístico SAS. Foram estimadas as herdabilidades para características de tipo e IP, assim como as correlações genéticas entre características de tipo e destas com IP. Para estimativa da herdabilidade do IP e das correlações genéticas das características de tipo com o IP foram utilizadas informações de 51.237 intervalos de parto de 24.740 vacas, paridas entre 2000 e 2010, filhas de 1003 touros, pertencentes a 294 rebanhos. Para avaliar o efeito da conformação das vacas, as mesmas foram divididas em três escores de pontuação para cada característica de tipo, sendo escore baixo (pontuação linear de 1 a 3), escore intermediário (pontuação linear de 4 a 6) e escore alto (pontuação linear de 7 a 9). As estimativas de herdabilidade variaram de 0,09 a 0,24, sendo os valores mais baixos para as características da categoria pernas e pés. A estimativa de herdabilidade para IP foi de baixa magnitude (0,05). As estimativas das correlações genéticas entre as características de tipo foram, em geral, de pequena magnitude, sendo o maior valor observado entre largura de peito e profundidade corporal (0,52). As características largura e inclinação de garupa apresentaram correlação genética negativa (- 0,33), sendo que, a seleção para garupa larga poderá levar a um aumento na frequência de vacas com garupa invertida. As estimativas de correlações genéticas entre as características de tipo e IP foram, em sua maioria, baixas. Dentre as características de tipo as que apresentaram maior correlação genética com IP foram: ângulo de casco (0,41), pernas vista lateral (-0,36), largura de garupa (-0,33) e angulosidade (0,32). A inclinação de garupa não apresentou correlação genética com IP, entretanto, vacas com garupa invertida (escore 1 a 3) apresentaram fenotipicamente IP significativamente mais longos, porém com diferenças discretas em relação às vacas com garupa intermediária ou escorrida (2,5 e 4,7 dias, respectivamente). A largura de garupa não afetou o valor fenotípico do IP (P > 0,05). A seleção para esta característica poderia trazer pequenos ganhos para fertilidade, porém com efeitos negativos sobre a inclinação de garupa e pernas vista lateral, devido a correlações genéticas negativas com estas características (-0,33 e -0,35, respectivamente). Para angulosidade, além da correlação genética desfavorável com intervalo de partos, também foram observados IP substancialmente mais longos em vacas mais angulosas, especialmente em vacas mais velhas. Conclui-se que as correlações genéticas estimadas de algumas características de tipo com intervalo de partos fornecem subsídios para a prática de seleção para tipo, com a finalidade de proporcionar melhorias na eficiência reprodutiva dos rebanhos leiteiros. A seleção visando evitar vacas com garupa invertida não determina ganhos genéticos para fertilidade. Entretanto, vacas com garupas invertidas apresentam fenotipicamente intervalos de partos discretamente mais longos. A seleção para aumento da largura de garupa poderá trazer algum incremento em fertilidade, porém, com consequências negativas sobre o mérito genético de outras características de tipo. A seleção para elevada angulosidade deve ser evitada devida à redução da fertilidade

Dissertação de Mestrado Integrado em Medicina Veterinária
O impacto das mastites na eficiência reprodutiva dos bovinos leiteiros, tem sido estudado ao longo dos últimos anos, por diversos autores. O objetivo do presente estudo, foi analisar a possível associação causal entre a ocorrência de mastites subclínicas e a alteração do desempenho reprodutivo. Recorrendo a uma base de dados de contraste leiteiro, na qual existiam registos provenientes de 9 explorações nacionais, introduzidos entre 1996 e 2016, procedeu-se à análise da relação da contagem de células somáticas, com o intervalo parto-conceção. Os resultados obtidos demonstraram que, à medida que aumenta a contagem de células somáticas, aumenta o intervalo parto-conceção. Tais resultados foram estatisticamente significativos e mais pronunciados para os dados relativos à segunda lactação. Observou-se ainda que, para cada aumento do número de eventos, cuja contagem de células somáticas se encontra acima do limiar de distinção entre infetado e saudável, o intervalo parto-conceção aumenta 28,7 dias para a primeira lactação e 27,9 dias para a segunda. Tais resultados, sugerem a hipótese de haver uma relação da cronicidade da infeção, com a fertilidade. Assim, à semelhança do reportado por autores anteriores, os resultados obtidos apontam a existência de uma relação entre as mastites subclínicas e o desempenho reprodutivo dos bovinos leiteiros.
ABSTRACT - Dairy Production Medicine: studies of the relationship between reproductive performance and mastitis - The impact of mastitis on reproductive performance of dairy cattle has been studied throughout the last years, by several authors. The objective of this study was to evaluate the possible causal association between the occurrence of subclinical mastitis and altered reproductive performance. Through the analysis of a database, in which there was access to milk recording data from 9 national dairy farms, introduced from 1996 to 2016, the relationship between the somatic cell count and the calving-to-conception interval was analyzed. The obtained results showed that, as the somatic cell count increases, the calving-to-conception interval increases. These results were statistically significant and more pronounced on the second lactation. Furthermore, it was observed that, with increases in the number of mastitis episodes, in which somatic cell counts were above the considered threshold between infected and healthy, the calving-to-conception interval progressively increased 28,7 days for the first lactation and 27,9 days for the second. These results support the existence of a relationship between the chronicity of the episodes and fertility. As such, similarly to results presented by previous authors, this study supports the existence of a direct relationship between mastitis and the reproductive performance of dairy cattle.
N/A

Dissertação de Mestrado Integrado em Medicina Veterinária
A situação económica mundial criou nos produtores de bovinos de carne em regime extensivo a necessidade de utilizarem práticas de maneio eficientes para se aumentar a rentabilidade dos seus sistemas de produção. A eficiência reprodutiva afeta de forma considerável o resultado económico de uma exploração produtora de bovinos de carne em regime extensivo, Assim, surge a necessidade de identificar as causas responsáveis por uma baixa eficiência e possíveis medidas corretivas do maneio reprodutivo. A exploração em estudo, apresentou em anos anteriores, taxas de fertilidade abaixo do desejável e intervalo entre partos longos, tendo o produtor demonstrado junto do médico veterinário a vontade de melhorar estes indicadores no sentido de aumentar a eficiência produtiva da sua exploração. Neste âmbito, o estudo consistiu na aplicação de um protocolo de sincronização de estro no final da época reprodutiva após diagnóstico de gestação. Analisou-se a variação do intervalo entre partos e da taxa de gestação, bem como a forma como a alteração da época reprodutiva influencia a eficiência reprodutiva da vacada. O estudo possibilitou ainda a identificação das causas dos problemas reprodutivos e a sugestão de possíveis soluções. O protocolo foi aplicado a 24 fêmeas das quais 15 ficaram gestantes. A taxa de gestação do grupo sincronizado foi de 62%. A aplicação deste protocolo significou um aumento de 13% na taxa de gestação da amostra (122 fêmeas) de 53% para 66%. A média dos intervalos entre partos previsionais foi de 449 dias, havendo uma redução de 46 dias do último intervalo entre partos da amostra. Pode concluir-se deste modo que o controlo técnico reprodutivo pode efetivamente melhorar a performance reprodutiva dos efetivos, aumentando a sua eficiência e consequentemente a rentabilidade económica da exploração.
ABSTRACT - Optimizing reproductive efficiency in extensively kept beef cattle in Alentejo – Case Study - Given the global economic situation extensively kept beef cattle producers, are increasingly required to use effective management practices in order to increase the profitability of their production systems. Reproductive efficiency is directly related to the economic performance of beef cattle farms, so it is crucial to identify the causes for a low efficiency, and so seek potential corrective measures through reproductive management. The beef cattle farm in this study presented in previous years fertility rates below the desirable and long calving intervals. In this context the producer showed the veterinarian the desire to improve these indicators in order to increase the production efficiency of his farm. Thus, the present study includes the application of a synchronization protocol of estrus at the end of the reproductive season after pregnancy diagnosis. We analyzed the variation in calving intervals and the variation in the rate of pregnancy, as well as how the change in the reproductive season influenced reproductive efficiency of the farm. The study also allowed the identification of the causes of reproductive problems as well as the definition of possible solutions. The protocol was applied to 24 cows, 15 of which became pregnant. The pregnancy rate of the synchronized group was 62%. The application of this protocol meant a 13% increase in the pregnancy rate of the sample (122 cows) from 53% to 66%. The average of estimated calving intervals was 449 days, which represents a reduction of 46 days when compared with the last calving intervals. It can be concluded therefore that adequate reproductive management can effectively improve the productive performance of farms, increasing its efficiency and consequently their economic viability.

Mestrado em Engenharia Agronómica - Instituto Superior de Agronomia
The aim of this study was to identify the most effective way to produce cattle, considering season of birth, age of weaning, calving intervals and weaning weights and their market prices. Another objective was to try to discover if there was any relationship between the age of weaning and calving interval to ensure larger profitability. Fertility of the cows, in general, increases with their age and spring is the season when cows have higher fertility. The daily average gain since birth to weaning also increases with the age of the cows, and it occurs during the spring season, when the winnings are lower. Observing the weight at 90 and 205 days remains the case that there is a positive relationship with the age of the cow, and it’s at the autumn and winter that calves weight more at 205 days. The calving interval is influenced very significantly by year, for the farm, season of calving, age at calving but not for age at weaning. However for the ratio between weight weaned and calving interval the season of birth have no influence but the season of weaning and age of the calf influence a lot. Was concluded that isn’t the extension of the calving intervals or weaning period that the efficiency increases. It’s because the management feeding override the effects of variability of the system.

Die Arbeit liefert eine umfassende Beschreibung der Managementmethoden von Milcherzeugerbetrieben unter dem Fokus Herdenfruchtbarkeit. Die Studie analysiert Einflüsse des Managements auf Reproduktions- und Milchleistung und verfolgt hierzu einen bio-sozialen Forschungsansatz. Die Daten wurden 2007 in Interviews mit Herdenmanagern und Stallrundgängen anhand von Fragebögen in 84 v.a. Brandenburger Milcherzeugerbetrieben erhoben. Die Fragen betrafen u.a. Haltungsumwelt, Stressvermeidung, Herden-, Reproduktions- und Personalmanagement. Die Leistungsdaten der Herden entstammen der Milchleistungsprüfung 2007. Die Datenanalyse umfasste qualitative und quantitative Methoden. Abhängige Variablen waren Zwischenkalbezeit (ZKZ) und 305-Tage-Milchleistung (ML). Im Mittel betrug die Herdengröße 306,3 Kühe (+/-238,3), die ZKZ 413,2d (+/-18,73) und die ML 8555kg (+/-1132,9). Die ZKZ sank tendenziell mit steigender ML (r=-0,188, p=0,10). Die ML stieg mit der Herdengröße (r=0,29, p=0,01). Die Laufgänge (LG) waren in 71,25% der Betriebe nass und rutschig. Hier war die ZKZ tendenziell länger (+16,6d, p=,055) als bei trockenen, rutschfesten LG. Die Liegeflächen (LF) waren in 29,9% der Betriebe trocken und elastisch. Hier war die ML höher (+1110kg, p=0,011) als bei nassen, harten LF. Eine eindeutige Zuordnung der Verantwortung für die Brunstkontrolle wirkte tendenziell positiv auf die ZKZ (-6,3d, p=0,129). Akademisch ausgebildete Herdenmanagerinnen erzielten eine höhere ML als gleichqualifizierte Männer (+752,9kg, p=0,005) bei gleicher ZKZ und damit eine günstigere Relation von Reproduktions- und Milchleistung. Motivierung durch materielle und soziale Anreize bzw. Verantwortungsübertragung und gute Kommunikation war mit einer höheren ML verbunden als Motivierung durch Leistungslohn (+ ca. 1000kg, p=0,009). Die Studie belegt die Notwendigkeit verbesserter Haltungsbedingungen und bietet eine Grundlage für vertiefende Studien zum Personalmanagement in Milchviehbetrieben.
This study provides a comprehensive characterization of current management methods of dairy farms, focusing on herd fertility. Relations of management factors to fertility and milk performance are analyzed following a bio-social approach. In 2007 a questionnaire survey including face-to-face interviews and direct observations was conducted in 84 East German dairy farms, mostly located in Brandenburg. Questions referred to housing, stress prevention, and management of herds, reproduction and personnel. Herd performance data stem from milk performance testing in 2007. Data analysis combined qualitative and quantitative methods. Calving interval (CI) and 305-day-milk yield (MY) were used as dependent variables. Mean values of herd size, CI and MY were, respectively, 306.3 cows (+/-238.3), 413.2d (+/-18.73d) and 8555kg (+/-1132.9). CI tended to decrease with increasing MY (r=-0.188, p=0.10). MY increased with rising herd size (r=0.29, p=0.01). Floors were wet and slippery in 71.25% of farms. In these farms CI tended to be longer (+16.6d, p=0.055) compared to farms with dry and non-slippery floors. Lying areas were in 29.9% of the farms dry and flexible. Here MY was higher (+1110kg, p=0.011) than in farms with wet and hard lying areas. A clear assignment of responsibility for heat detection showed a trend of decreasing CI (-6.3d, p=0.129). Female herd managers with academic qualification achieved a higher MY than likewise qualified men (+752.9kg, p=0.005), with no difference in CI. Thus, herds managed by highly qualified women showed a better MY:CI ratio. Employee motivation by material and social incentives or by allocating responsibility to workers and pursuing good communication was related to higher MY than motivation by performance pay alone (+1000kg, p=0.009); CI remained unaffected. Performance pay had no positive effect on targeted parameters. Results underscore the need for improved housing and recommend further study into personnel management in dairy farms.

Thesis (M.S.)--University of Wisconsin--Madison, 1993.
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In presented thesis the chosen parameters of reproduction {--} days to first service, days open, calving interval, insemination index - were evaluated in dairy cattle. There were 222 of dairy cows observed (53 Czech Pied and 169 Holstein cows). The results of reproduction were evaluated as unsatisfactory. Length of calving interval overreached recommended 400 days in 56,25 % of Holstein and in 33,33% of Czech Pied cows. Also the mean value of insemination index 2,39 exceeds the optimum of 1,8-2,0.

The northern Australian beef industry is dominated by cow-calf operations where reproductive efficiency has a major effect on profitability, particularly related to extended post-partum anoestrus intervals and high perinatal losses. Recording the post-partum anoestrus interval (PPAI) and distinguishing causes of perinatal loss requires the date and location of calving to be accurately known, both of which are traditionally laborious and costly. The original contribution to knowledge of this research is through the use of autonomous data collection systems to enable the recording of date and location of calving and assigning maternal parentage. The thesis firstly investigates the precision of an automated radio location device in a static array. Secondly, the device is further researched for its ability to derive date and location of calving when used in an intravaginal apparatus. The third experiment investigates the use of Walk-over-Weighing (WoW) technology to derive maternal parentage based on the temporal sequence with which cows and calves had their identity recorded. The final experiment investigates the use of WoW to derive the date of calving based on the weight loss associated with parturition.

碩士
東海大學
畜產與生物科技學系
95
Reduce calving intervals and increase production life of dairy cattle through endocrine regulating of the ovarian function Reproductive management is very important for the dairy farm business. Effective management can hasten the recovery of postpartum ovarian function and improve the profit in dairy business. The purpose of this study was to investigate the relationship among various postpartum production traits , and to regulate the ovarian function to reduce the calving interval by using exogeneous hormone, hence to increase the lifespan of dairy cattle. Experiment 1 was conducted to observe the relationship among various blood constituents and production profiles. From calving to 45 days postpartum, five primiparous and four multiparous lactating dairy cows were used to measure body condition score(BCS)、dry matter intake(DMI)、and BW on a weekly basis；Milk were collected twice a week and milk constituents were analyzed accordingly；Blood were collected twice a week and serum were harvested for progesterone(P4)、glucose、insulin、and cholesterol analysis. The results showed that DMI、energy balance(EB)、milk yield(MY)、serum glucose、insulin、and cholesterol were starting to increase from week2 or week3 postpartum. BW was decreased after calving until week 4 postpartum. And then the lost BW was gradually recovered until week 7 postpartum. BCS was decreased from calving to week 7 postpartum. Experiment 2 was conducted to study the effects of various systematic breeding programs on reproductive performance of postpartum dairy cattle. The Ovsynch treatment group (n=11) received an injection (100μg) of GnRH at a random stage of estrus cycle , followed 7days later by an injection of 25 mg PGF2α and a second injection of GnRH (100μg) 2 days later .Cows were inseminated at a fix time 24h after final GnRH of Ovsynch. Pregnancy diagnosis was performed 35d later by palpation per rectum of uterine contents. The Presynch treatment group(n=10) started at d24 postpartum, and two PGF2α at a 14 d interval were used to synchronize the estrus , then the Ovsynch program would be followed 12 days later. The initial step of the Resynch program(n=10) was identical to the Presynch program. After TAI, the CIDR driver was inserted and a o.6mg E2 injection was performed 13 days later. The CIDR driver was removed 7 days later and a second E2(0.6mg) injection was performed 24 hours later preparing to detect estrus and AI in 24 hours. Presynch and Resynch groups has a better synchronization rate (P<0.05) than the Ovsynch group. Presynch protocol has higher incidence of ovulation (90% vs. 45.5%, P<0.05)、better conception rate (50% vs. 9.1%, P<0.05), and need less service per conception than Ovsynch treated cows. In conclusion, dairy cows after calving that increase DMI can decrease negative energy balance and resumption of ovarian cyclicity postpartum. And presynchronization before treated cows with Ovsynch protocol has the potential to enhance reproductive efficiency of dairy cattle. Key word：dairy cattle、reproductive efficiency、synchronization、Ovsynch、Presynch、Resynch