Dissertations / Theses on the topic 'Dairy cattle Dairy farms Estrus'

Previous studies of dairy cattle have indicated that heifers and cows in hot, cold and moderate weather had different patterns of sexual activities. The purpose of this study was to compare distribution of sexual activities within estrus of dairy cattle. Three groups of lactating cows in hot, cold and moderate weather and a group of heifers in cold weather were observed. Estrus for each individual was divided into 12 equal periods. Sexual activities for 3 and 6 hours before and after estrus were also observed. The numbers of mounts and distribution of total sexual activities was analyzed. Mounts received per animal per period for all four groups were significantly different. Heifers had significantly more mounts than cows with 5.8 mounts per animal per period. Cows in hot weather had significantly less mounts than other groups with 1.2 mounts per animal per group. Cows in cold and moderate weather had similar numbers of mounts with 2.9 and 2.4 mounts per animal per period, respectively. This was significantly fewer mounts than were received by heifers but a significantly higher number of mounts than received by cows in hot weather. There was much individual variation; however, the distribution of mounts and activities per period did not significantly differ across groups. There were trends for cows in hot weather to have rest periods within estrus where less mounting occurred. Secondary sexual activities before and after standing estrus were less intense than during estrus. Secondary sexual activities were greater in the three hours before and after estrus compared to the three to six hours before and after estrus.

Thesis (M.S.)--Michigan State University. Dept. of Agricultural, Food, and Resource Economics, 2008.
Title from PDF t.p. (viewed on July 28, 2009) Includes bibliographical references (p. 105-108). Also issued in print.

A total of 450 isolates of Staphylococcus aureus were typed using multilocus sequence typing (MLST). They were isolated from the cattle and environment of a UK organic dairy farm, 43 dairy herds in the USA, the mammary glands of cattle in Chile and the UK, and also included the reference strain Newbould 305 (NCIMB 702892). Strains were compared to investigate differences between isolates from varying sites of isolation and the population detected on a single farm. MLST was suitable for the differentiation of bovine associated S. aureus, and thirty different sequence types were detected. These contained a number of novel alleles detected at each loci, agreeing with previous reports of host-specialisation, and indicating localised strain evolution. MLST was also able to discriminate between isolates detected in milk and on teat skin. The N ewbould 305 strain was significantly (p<0.05) associated with teat skin, and this may have important implications for future studies. The majority of isolates (87.4%) were present within one previously undescribed clonal complex (CC97), which contained representatives from all three geographic locations. Analysis of isolates from a single farrri demonstrated the clonality of the organism, supporting the theory of cow-to-cow spread of disease. No isolates were detected in heifer mammary secretions, suggesting transmission to these animals did not occur. Typing of multiple colonies from a single sample demonstrated strain heterogeneity within individual quarters. Environmental isolates were detected, though it is unlikely that they formed a significant reservoir of infection on the farm studied.

Améliorer la santé des vaches laitières en élevage agrobiologiques (AB) est bien souvent nécessaire, pour ces élevages ne répondant pas toujours aux principes de l’AB et aux attentes des consommateurs d’avoir un niveau de santé et bien-être animal élevé. Cette thèse explore des voies d’amélioration du conseil sanitaire en vue d'améliorer la santé animale dans ces élevages. Les résultats de nos travaux montrent que les vétérinaires ont le plus souvent un rôle de thérapeute dans les élevages laitiers AB. L'obtention d'un rôle de conseiller a été entravée par des spécificités liées à l’AB, telles que les différences entre éleveurs et vétérinaires dans les objectifs de gestion de la santé des animaux et les pratiques sanitaires. Une étude d'intervention a été effectuée pour tester un dispositif de conseil dans des élevages AB en France et en Suède, basé sur l’utilisation d’outils de surveillance et prévention de maladies de production. Le dispositif a été réalisé en utilisant une approche participative, impliquant l’éleveur et le conseiller ; la flexibilité de l’outil a permis de produire un protocole de surveillance adaptée à chaque élevage. Bien qu’aucun effet sur la santé du troupeau n’a été prouvé, le dispositif a été perçu pour contribuer à la santé du troupeau par ses utilisateurs. Il a rempli la plupart de ses fonctions prévues de surveillance et de prévention des maladies et a stimulé le dialogue entre éleveurs et conseillers. Des outils qui stimulent le dialogue et qui sont adaptables à chaque élevage sont une voie à suivre pour le développement du conseil en santé animale
Improving herd health on organic dairy farms is often needed, since organic dairy farms do not consistently meet the organic principles and consumers’ expectations of high animal health and welfare. This thesis explores ways to improve the pertinence of herd health advisory services in order to improve animal health on organic dairy farms. The results of our studies show that veterinarians mostoften have a role of therapist on organic dairy farms. Obtaining a more advisory role was hampered due to specificities of the organic sector, such as differences between farmers and veterinarians in animal health management objectives and practices. An intervention study was performed testing a Herd Health and Production Management (HHPM) program on organic dairy farms in France and Sweden, based on herd health monitoring and disease prevention activities. The program was built using a participatory approach, making farmer and advisor work together ; the adaptability of the program allowed to design farm specific herd health monitoring tools. Although no effecton herd health measured, the program was perceived to contribute to herd health by its users. The program fulfilled most of its intended functions in herd healthmonitoring and disease prevention and stimulated dialogue between farmers and their advisors. We consider that dialogue promoting and tools adaptable to farm specific situations are a possible way forward for the development of advisory services in animal health

The detection of estrus continues to be a primary factor contributing to poor reproductive performance in modern dairy cattle. The objectives of this research were 1) to evaluate performance of automated detection of estrus using a reference standard of ovulation detection with temporal progesterone patterns 2) to evaluate the efficacy of parameters measured by automated detection of estrus systems 3) to evaluate the efficacy of alerts generated by several commercially available systems used for automated detection of estrus and 4) to determine the differences in these parameters among cows with or without poor health conditions at the time of estrus. Systems used for automated detection of estrus can perform better than the previous original reference standard, visual observation for standing behaviors. All systems used for automated detection of estrus tested were similar for estrus detection efficiency.

Dissertação de Mestrado Integrado em Medicina Veterinária
The objective of this study was to determine the possibility of identifying dairy farms with poor welfare using a national cattle database. The welfare of dairy cattle was assessed using the Welfare Quality protocol on almost 2000 adult animals from 24 Portuguese dairy farms. More than 14 million records from national cattle database were analyzed to identify potential welfare indicators for dairy farms. Within the 24 dairy farms, one was scored as ‗enhanced‘, 18 were ‗acceptable‘ and five were ‗not classified‘, according to the Welfare Quality protocol. The main welfare problems identified were: presence of lesions and swellings mainly in the lower back legs and neck/back area; approximately 40% of moderate lameness; no pain management in disbudded calves; non-grazing production systems; insufficient or dirty drinkers; severe dirtiness of the udder and hindquarter; and high percentage of cows lying outside the stall. Twelve potential welfare indicators were identified. Within these only two, proportion of on-farm deaths and female/male births ratio, were significantly different between farms with good welfare (‗enhanced‘ and ‗acceptable‘) and poor welfare (‗not classified‘). A model to detect farms with poor welfare was created with J48 classifier and it had 75.86% accuracy.
RESUMO - Identificação de Indicadores de Bem-estar Animal em Explorações de Bovinos Leiteiros em Portugal - Este trabalho teve como propósito determinar a possibilidade de identificar vacarias de leite com baixos níveis de bem-estar através do Sistema Nacional de Identificação e Registo de Bovinos (SNIRB). Aplicou-se o protocolo Welfare Quality em cerca de 2000 animais adultos de 24 explorações portuguesas. Analisaram-se mais de 14 milhões de registos do SNIRB na tentativa de identificar potenciais indicadores de bem-estar nacionais. Tendo como base os princípios do Welfare Quality, uma exploração foi classificada como tendo um nível de bem-estar ―elevado‖, 18 obtiveram um nível de bem-estar ―aceitável‖ e cinco não obtiveram os requisitos mínimos de bem-estar. Os principais problemas encontrados foram: presença de lesões e tumefações principalmente nas regiões do curvilhão e dorso; percentagem média de claudicação moderada por volta dos 40%; descorna sem controlo de dor; sistemas de produção sem pastoreio; bebedouros insuficientes ou sujos; elevado nível de sujidade no quarto traseiro e úbere; elevada percentagem de vacas deitadas fora do cubículo. Identificaram-se doze potenciais indicadores de bem-estar nacionais. Apenas dois destes, ―morte na exploração‖ e ―rácio de nascimentos fêmea/macho‖, foram estatisticamente diferentes entre explorações com alto (―elevado‖ e ―aceitável‖) e baixo (sem requisitos mínimos) níveis de bem-estar. Usando o classificador J48 foi possível criar um modelo que detecta explorações com baixo nível de bem-estar e 75,86% das explorações foram correctamente classificadas.

Dissertação de Mestrado Integrado em Medicina Veterinária
There is an increasing understanding that lack of biosecurity and antimicrobial resistance are crucial points in animal production and the Animal Health Law emphasizes these two aspects. By implementing a questionnaire based on Biocheck from Ghent University‟s biosecurity assessment, this project aimed to make a characterization of dairy farms‟ biosecurity in North and Centre of Portugal, it aimed to create a biosecurity index, evaluate possible risk factors, characterize antibiotics use and create a tool that allows veterinarians to help and advise farmers. The questionnaire was implemented in 151 dairy farms through personal interview and through Googleforms; a report was built and sent to the veterinarians that participated in the project. The biosecurity aspects present in both questionnaire and final report are related to animal purchase, reproduction management, hygiene and disinfection, people and animal movements, health, calving, calf, adult animals, dairy and feed and drinking water management, with one group also added for antibiotic and vaccine use. A difference was observed between total biosecurity scores that went from 42 to 80.4 (in 100 points) and external and internal biosecurity mean scores of 71.3 and 67.7 (in 100 points) respectively. Variables with bigger influence in biosecurity scores were the ones related to the use of individual protective equipment, hands hygiene, cleaning of calving and sick pens and putting animals in quarantine. Regarding antibiotics‟ use, every farm treated animals with antibiotics, but only 47.4% had an antibiotic protocol for its responsible use. This means that there is still a lot to improve regarding biosecurity and awareness regarding the use of antibiotics, although a bigger sample should be taken to make a more reliable and significant characterization.
RESUMO - Biossegurança em explorações de bovinos leiteiros no Norte e Centro de Portugal - Existe um entendimento crescente de que a falta de biossegurança e a resistência aos antimicrobianos são pontos cruciais na produção animal e a Lei de Saúde Animal enfatiza esses dois aspetos. Ao implementar um questionário baseado na avaliação de biossegurança do Biocheck da universidade de Ghent, este projeto teve como objetivos caracterizar a biossegurança em explorações leiteiras no Norte e Centro de Portugal, criar um índice de biossegurança, avaliar possíveis fatores de risco, caracterizar o uso de antibióticos e criar uma ferramenta que permitisse aos veterinários ajudar e aconselhar os produtores. Foram amostradas 151 explorações leiteiras, implementando o questionário através de entrevista pessoal e online através do Googleforms, foi criado um relatório em html, o qual foi enviado aos veterinários que participaram no projeto. Os aspetos de biossegurança contidos no questionário e no relatório estão relacionados com compra de animais, maneio reprodutivo, higiene e desinfeção, movimento de pessoas e animais na exploração, controlo de pragas e contacto com outros animais, maneio sanitário, maneio de partos, de vitelos e de animais adultos, maneio de alimentação e abeberamento, tendo-se adicionado também um ponto referente à utilização de antibióticos e vacinas. Observou-se que havia grandes variações nas pontuações de biossegurança total, que iam do mínimo de 42 até máximo de 80,4 pontos (em 100 pontos), com pontuações médias de biossegurança externa e interna de 71,3 e 67,7 (em 100 pontos) respetivamente. As variáveis com maior influência nas pontuações de biossegurança foram as relacionadas com o uso de equipamentos de proteção individual, higiene das mãos, limpeza de maternidades e enfermarias e colocação de animais em quarentena. Em relação ao uso de antibióticos, apesar de os mesmos serem administrados em todas as explorações, apenas 47,4% possuíam um protocolo de utilização de antibióticos. Isto significa que ainda há muito a melhorar em relação à biossegurança e na sensibilização em relação ao uso de antibióticos, no entanto para obter uma caracterização mais confiável e representativa da realidade, uma amostra maior deveria ser coletada.
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Poor estrus detection can limit the reproductive performance of a dairy herd. One objective of this research was to evaluate an alternative method to traditional estrus detection in the form of automated monitoring technologies. To accomplish this, the first study considered the ability of automatically monitored parameters (activity, number of steps, lying bouts, lying time, feeding time, rumination time, and temperature) to detect estrus. A second study compared automated activity monitoring to timed artificial insemination as reproductive management strategies on commercial herds. The other objective of this research was to evaluate the economic potential of automated estrus detection technologies. This was accomplished by creating and evaluating a farm specific decision support tool to determine the net present value of adopting an automated estrus detection technology.

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.

Ethiopia maintains an extensive livestock population; however, reproductive performance of cattle and their breeding management are unsatisfactory. Currently, the sole diagnostic tool in the country is rectal palpation, which is inaccurate for early pregnancy in cattle. The study assessed reproductive performance and major reproductive problems using questionnaire survey, and evaluated simple, cost-effective alternative monitoring approaches using on-farm diagnostic tools to determine milk and serum progesterone (P4) and evaluate reproductive status. There were 177 dairy farms (range 1-115 cattle per farm) included in the questionnaire survey. Of these, 47 participated in the quantitative determination of P4 and estradiol profiles that used an enzyme-linked immunosorbent assay (ELISA) and in the on-farm diagnostic trial that used qualitative ELISA (Target P4 and Dipstick (P4 Rapid), and the reproductive status of 319 crossbred [Holstein Friesian (HF) X Zebu] dairy cattle was assessed. Questionnaires indicated that heifers in the study area reach puberty at older age and calve late, and cows have long postpartum estrus and calving interval. Anestrus, repeat-breeding, dystocia, retained fetal membranes (RFM), endometritis and abortion as the major reproductive problems in dairy cattle in the study area. Serum, milk, saliva and urine P4 and serum estradiol profiles of cattle at different reproductive status was determined using quantitative laboratory ELISA. High P4 levels was detected in pregnant and diestrus cattle than cattle that were anestrus and in-heat. Estradiol level was higher in cattle that were in-heat than cattle in other reproductive conditions. On-farm P4 ELISA indicated in-heat (estrus) 10 (3.1%), anestrus 77 (24.2%), repeater (follicular cyst) 9 (2.8%), normally cycling 69 (21.6%) and pregnant 154 (48.3%). The field P4 ELISA findings were validated using quantitative laboratory P4 ELISA, and similar results were obtained. The sensitivity and specificity of on-farm and laboratory P4 ELISA tests for diagnosing pregnancy were 88.6 & 99.4% and 98.1 & 100%, respectively. Once reproductive problems were identified using on-farm P4 ELISA and per rectal palpation, along with reproductive history, 122 cattle (75 cows and 47 heifers) were assigned to a 10-day Controlled Internal Drug Release (CIDR) in combination with prostaglandin F2-alpha (PGF2α) and equine chorionic gonadotrophin (eCG) based estrus synchronisation protocol to study the estrus response and conception rate. The overall estrus response and conception rates were 97.5% and 78.3%, respectively, with no significant differences in parity, pre-treatment reproductive status (anestrus or cycling (repeat-breeding/silent-estrus)) and farming system (smallholder vs organised commercial farms). The study has shown high estrus response and conception rate. Hence, this protocol is highly recommended to enhance fertility of dairy cattle in the study area and other regions. Finally, the study has determined the macronutrient composition of milk and assessed the effect of reproductive status, farm (nutritional) management, stages of lactation, parity and breed on milk composition in 246 dairy cows. This consisted of 184 crossbred cows from smallholder (n= 76: 36 non-pregnant and 40 pregnant) and organised commercial dairy farms (n= 108: 62 non-pregnant and 46 pregnant) in and around Mekelle, Ethiopia and by way of comparison, 62 HF cows (25 non-pregnant and 37 pregnant), either managed indoors or outdoors in a commercial farm in Edinburgh, United Kingdom. The mean milk fat, protein, lactose, total solid (TS) and solid-no-fat (SNF) recorded were 2.36%, 3.46%, 4.37%, 10.39% and 7.82%, in crossbred dairy cows, compared with 5.05%, 3.71%, 4.72%, 13.68% and 8.43%, in HF cows, respectively. Significantly lower (p < 0.05) level of macronutrient was recorded in milk from crossbred cows than HF cows. Milk fat in both breeds was affected by reproductive status, farm (nutritional) management and stages of lactation, but not by parity. In both cattle breeds, the milk fat content was significantly higher (p < 0.05) in pregnant than non-pregnant cows. Milk protein content was significantly (p < 0.05) affected by reproductive status (in crossbreds) and stages of lactation (in both breeds), but not by farm management or parity. Reproductive status (in crossbreds), stages of lactation (in both breeds) and parity (in crossbreds) affected lactose level; however, farm management had no effect on lactose level in both breeds. Milk fat was the most affected macronutrient content in both breeds. Low milk fat level in crossbred cows could be as a result of samples obtained from early milking coupled with nutritional management. In conclusion, the present study has determined the major reproductive problems in crossbred dairy cattle, assessed their actual reproductive status using rapid, cost effective, simple and applicable on-farm P4 tests, and established P4 and estradiol profiles at different reproductive status. The major breeding problem was poor estrus detection evidenced when animals reported anestrus were confirmed normally cycling using on-farm as well as laboratory P4 assays. These studies offer opportunities for establishing simple field reporting of reproductive status in these crossbred dairy cattle, which can have a major impact on breeding management and productivity.

Les micotoxines són metabòlits secundaris tòxics produïts per fongs filaments que poden contaminar una àmplia varietat de productes agrícoles tant en etapes precollita com en etapes postcollita. La gestió de la contaminació per micotoxines durant la cadena de producció de la llet és essencial per evitar la presència d'aflatoxina M1 (AFM1) en la llet com a conseqüència de l'exposició d'animals productors de llet a pinsos contaminats per aflatoxina B1 (AFB1). L'objectiu d'aquesta tesi va ser l'estudi de la contaminació per micotoxines en pinsos i ingredients per a pinsos per a vaques lleteres i la seva transferència a la llet. La presència d'aflatoxines i micotoxines de Fusarium es va avaluar mitjançant l'anàlisi de mostres de ració total barrejada (TMR) i diferents tipus d'ensitjats per a vaques lleteres. Mostres de llet procedents de vaques alimentades amb les mostres de TMR recollides es van analitzar per estimar la transferència de AFB1 en el pinso a AFM1 en la llet. Per saber si el tractament tèrmic afecta el contingut de AFM1 en la llet durant el seu processat, es van provar diferents tractaments tèrmics en llet contaminada natural i artificialment.
Las micotoxinas son metabolitos secundarios tóxicos producidos por hongos filamentos que pueden contaminar una amplia variedad de productos agrícolas tanto en etapas precosecha como en etapas poscosecha. La gestión de la contaminación por micotoxinas durante la cadena de producción de la leche es esencial para evitar la presencia de aflatoxina M1 (AFM1) en la leche como consecuencia de la exposición de animales productores de leche a piensos contaminados por aflatoxina B1 (AFB1). El objetivo de esta tesis fue el estudio de la contaminación por micotoxinas en piensos e ingredientes para piensos para vacas lecheras y su transferencia a la leche. La presencia de aflatoxinas y micotoxinas de Fusarium se evaluó mediante el análisis de muestras de ración total mezclada (TMR) y diferentes tipos de ensilados para vacas lecheras. Muestras de leche procedentes de vacas alimentadas con las muestras de TMR recogidas se analizaron para estimar la transferencia de AFB1 en el pienso a AFM1 en la leche. Para saber si el tratamiento térmico afecta al contenido de AFM1 en la leche durante su procesado, se probaron diferentes tratamientos térmicos en leche contaminada natural y artificialmente.
Mycotoxins are toxic secondary metabolites produced by filamentous fungi which can contaminate a wide variety of agricultural commodities either at pre-harvest or post-harvest stages. Through the milk supply chain, the management of mycotoxin contamination is essential in order to avoid the presence of aflatoxin M1 (AFM1) in milk as a consequence of the exposure of lactating animals to aflatoxin B1 (AFB1)-contaminated feed. The aim of this Thesis was to evaluate the mycotoxin contamination of feed and feed ingredients for dairy cows and their transference to milk. The occurrence of aflatoxins and Fusarium mycotoxins was evaluated through the analysis of total mixed ration (TMR) samples and different types of silages for dairy cows. Milk samples collecting from cows fed with the sampled TMR were analysed so as to estimate the transference of AFB1 form feed to AFM1 in milk. In order to know whether heat treatment affect to the AFM1 content in milk during processing, different heat treatments were tested in artificially and naturally contaminated milk.

L'objectiu general d'aquesta tesi doctoral va ser desenvolupar una eina d'avaluació de riscos per a donar suport a la presa de decisions de priorització de mesures de bioseguretat en granges lleteres. En el primer estudi, es va desenvolupar un model d'anàlisi de risc estocàstic per quantificar la probabilitat d'introducció de Virus de la Diarrea Vírica Bovina (BVDV) i de l'Herpesvirus Boví tipus 1 (BoHV-1) a través de el moviment d'animals, és a dir , compra o introducció d'animals, recria criada fora de la granja i moviments a fires de bestiar. Els paràmetres es van obtenir a partir de literatura científica, així com de la base de dades de moviments animals de l'administració, enquestes de bioseguretat i opinió dels veterinaris de camp. En l'anàlisi es van incloure 46 granges de Galícia i Catalunya que van moure animals durant el 2017. La probabilitat anual d'introducció de BVDV i BoHV-1 va ser molt heterogènia, sent propera a 0 en algunes granges i en altres proper a 1. La mitjana d' la probabilitat anual d'introducció de BVDV va ser 12% i per BoHV-1 9%, amb un rang interquartílic entre 1.2% i 28% per BVDV i 3% a 23% per BoHV-1. Les probabilitats més altes estaven associades a el moviment local d'animals (i.e., dins de la mateixa comunitat autònoma) i a el fet de compartir el vehicle de transport entre granges. A l'avaluar l'efecte de les mesures de bioseguretat en una granja, la implementació d'una correcta quarantena i el no compartir el transport amb altres granges disminueixo considerablement aquesta probabilitat. En el segon estudi, es va quantificar la probabilitat d'introducció de BVDV i BoHV-1 a través de contactes indirectes per la qual cosa també es va desenvolupar un model d'anàlisi de risc estocàstic. Es van considerar els vehicles que transporten vedells, animals a l'escorxador, cadàvers i barreja d'alimentació, així com els visitants, entre els quals es van incloure veterinaris, podòlegs, treballadors de les granges i veïns. Per a aquest estudi es van avaluar les 127 granges que van participar en el projecte i la informació per a l'estimació dels paràmetres de el model, a més de les fonts citades anteriorment, es va obtenir d'entrevistes a podòlegs, transportadors d'animals i una empresa de recollida de cadàvers. Els resultats van mostrar que la mitjana de la probabilitat anual d'introducció per BVDV va ser de 2.1% i per BoHV-1 3.9%, en un rang de 0.5% a 14.6% i de 1.0% a 24.9% per BVDV i BoHV-1, respectivament . L'entrada de el vehicle de transport de vedells i les visites dels veterinaris van ser les vies d'entrada amb major risc. Les mesures de bioseguretat amb un major impacte en la disminució de la probabilitat d'introducció dels dos virus van ser l'ús de botes i roba propis de la granja i evitar que el conductor que transporta animals entri en contacte amb els animals de la granja. Els dos models van permetre establir les vies d'entrada més perilloses per a cada granja estudiada i d'aquesta forma són una eina útil per prioritzar les mesures de bioseguretat que s'han d'implementar o millorar per reduir la probabilitat de l'ingrés de BVDV i BoHV-1 en una granja.
El objetivo general de esta tesis doctoral fue desarrollar una herramienta de evaluación de riesgos para apoyar la toma de decisiones de priorización de medidas de bioseguridad en granjas lecheras. En el primer estudio, se desarrolló un modelo de análisis de riesgo estocástico para cuantificar la probabilidad de introducción del Virus de la Diarrea Vírica Bovina (BVDV) y del Herpesvirus Bovino tipo 1 (BoHV-1) a través del movimiento de animales, es decir, compra o introducción de animales, recría criada fuera de la granja y movimientos a ferias de ganado. Los parámetros se obtuvieron a partir de literatura científica, así como de la base de datos de movimientos animales de la administración, encuestas de bioseguridad y opinión de los veterinarios de campo. En el análisis se incluyeron 46 granjas de Galicia y Catalunya que movieron animales durante el 2017. La probabilidad anual de introducción de BVDV y BoHV-1 fue muy heterogénea, siendo cercana a 0 en algunas granjas y en otras cercano a 1. La mediana de la probabilidad anual de introducción de BVDV fue 12% y para BoHV-1 9%, con un rango intercuartilico entre 1.2% y 28% para BVDV y 3% a 23% para BoHV-1. Las probabilidades más altas estaban asociadas al movimiento local de animales (i.e., dentro de la misma comunidad autónoma) y al hecho de compartir el vehículo de transporte entre granjas. Al evaluar el efecto de las medidas de bioseguridad en una granja, la implementación de una correcta cuarentena y el no compartir el transporte con otras granjas disminuyo considerablemente esta probabilidad. En el segundo estudio, se cuantifico la probabilidad de introducción de BVDV y BoHV-1 a través de contactos indirectos para lo cual también se desarrolló un modelo de análisis de riesgo estocástico. Se consideraron los vehículos que transportan terneros, animales a matadero, cadáveres y mezcla de alimentación, así como los visitantes, entre los que se incluyeron veterinarios, podólogos, trabajadores de las granjas y vecinos. Para este estudio se evaluaron las 127 granjas que participaron en el proyecto y la información para la estimación de los parámetros del modelo, además de las fuentes citadas anteriormente, se obtuvo de entrevistas a podólogos, transportadores de animales y una empresa de recolección de cadáveres. Los resultados mostraron que la mediana de la probabilidad anual de introducción para BVDV fue de 2.1% y para BoHV-1 3.9%, en un rango de 0.5% a 14.6% y de 1.0% a 24.9% para BVDV y BoHV-1, respectivamente. La entrada del vehículo de transporte de terneros y las visitas de los veterinarios fueron las vías de entrada con mayor riesgo. Las medidas de bioseguridad con un mayor impacto en la disminución de la probabilidad de introducción de los dos virus fueron el uso de botas y ropa propios de la granja y evitar que el conductor que transporta animales entre en contacto con los animales de la granja. Los dos modelos permitieron establecer las vías de entrada más riesgosas para cada granja estudiada y de esta forma son una herramienta útil para priorizar las medidas de bioseguridad que deben implementarse o mejorarse para reducir la probabilidad del ingreso de BVDV y BoHV-1en una granja.
The general aim of this PhD thesis was to develop a risk assessment tool to support biosecurity measures prioritization decision making in dairy farms. In the first study, a stochastic risk analysis model was developed to quantify Bovine viral diarrhea virus (BVDV) and Bovine herpesvirus type 1 (BoHV-1) introduction through animal movements. Purchasing cattle, rearing replacement heifers offsite and showing cattle at competitions, were considered in the model. Besides a review of the scientific literature, parameters were estimated using animal movement database, biosecurity surveys and the opinion of field veterinarians. In this model, 46 farms from Galicia and Catalonia that moved animals during 2017 were included. Results showed that the annual probability of BVDV and BoHV-1 introduction was very heterogeneous, being close to 0 in some farms and in others close to 1. The median of the probability of introduction of BVDV was 12% and for BoHV-1 9%, with an inter-quartile range from 1.2% to 28% for BVDV and 3% to 23% for BoHV-1. The highest probabilities were associated with local movements of cattle (i.e., inside the same autonomous community) and the fact of sharing the transport vehicle between farms. By evaluating the effect of biosecurity measures on a selected farm, implementation of a correct quarantine or not sharing transport with other farms greatly decreased this probability. In the second study, the probability of BVDV and BoHV-1 introduction through indirect contacts was quantified also with a stochastic risk analysis model. Vehicles transporting calves, cattle to slaughterhouse, dead animals, and food mix, as well as visits by veterinarians and hoof trimmers, farm workers and contacts with neighbors were considered in the model. For this study were included the 127 farms that participated in the project. Data to estimate model parameters was obtained from the sources indicated before as well as from interviews with hoof trimmers, animal transporters and a rendering company. Results evidenced that the median annual probability of introduction for BVDV was 2.1% and for BoHV-1 3.9%, in a range of 0.5% to 14.6% and 1.0% to 24.9% for BVDV and BoHV-1, respectively. The calf transport vehicle and veterinarians’ visits were the routes with the highest risk. The biosecurity measures with the greatest impact in reducing the probability of introduction of both viruses were the use of boots and clothing belonging to the farm and avoiding the driver that transports cattle coming into contact with the animals on the farm. The two models allowed establishing the riskiest pathways for each studied farm and thus are a useful tool to prioritize biosecurity measures that must be implemented or improved to reduce the probability of BVDV and BoHV-1 introduction into a farm.

The efficiency of utilization of dietary nitrogen can be monitored using milk urea nitrogen (MUN). Overfeeding or underfeeding of protein can be identified through the observation of deviations from target MUN concentrations. This will assist in lowering feed costs of dairy farms, and improving nutrition management of herds. Higher efficiency of utilization of dietary nitrogen might result in a reduction in environmental pollution. Non-genetic factors affecting variation in MUN were herd-test-day (HTD), lactation stage and year of calving. The contribution of HTD was the highest, ranging from 58.56% to 63.18% in parity 1 to 3. Lactation stage had the second largest contribution to the MUN variation. Differences in least squares means for MUN in various years of calving were observed. The heritability estimate for MUN was 0.09±0.01 in the first parity, and remained constant at 0.11±0.01 in the second and third parity. Heritability estimates for milk, fat and protein yield ranged from 0.40±0.01 to 0.43±0.01, 0.21±0.01 to 0.26±0.01, and 0.32±0.01 to 0.38±0.01, respectively. These estimates were within acceptable ranges for South African Holstein cattle. Genetic correlations between MUN and milk production traits were low and positive, ranging from 0.01±0.003 to 0.10±0.004 across parities. Phenotypic correlations ranged from 0.02±0.11 to 0.16±0.07, being generally higher than the genetic correlations. The positive associations between MUN and milk production traits are undesirable as the dairy cows would be less efficient in utilizing dietary protein and may result in increased environmental pollution. The genetic trend for MUN was 0.44, 0.007 and 0.049 mg/dl in the first, second and third parity, respectively. Results of the current study indicate that MUN has potential as a management tool in South African Holstein dairy herds. It might be a good indicator of the efficiency of dietary protein utilization of dairy herds, and has practical advantage as it is currently collected by the national dairy herd recording and improvement scheme.
Dissertation (MSc Agric)--University of Pretoria, 2013.
gm2014
Animal and Wildlife Sciences
unrestricted

Tuberculosis (TB) is an ancient infectious disease that has been infecting different populations around the globe and it has also been considered as one of the most successful human and animal disease. TB found in animals such as cattle and other known bovids is known as bovine tuberculosis. Bovine tuberculosis (BTB) is an infectious disease found in cattle mainly caused by Mycobacterium bovis. M. bovis is a member of the Mycobacterium tuberculosis complex (MTC) together with M. tuberculosis, M. africanum, and M. canetti where the natural host is humans; whereas M. caprae, M. microti and M. pinnipedii usually have animals as their natural host. In this study the molecular characterization of the MTC from cow milk in the Eastern Cape was investigated. One hundred and twenty samples (40 ml each) were collected from three dairy farms in the Eastern Cape, South Africa. These samples were processed using a modified Petroff decontamination method. Sample processing was followed by DNA isolation using a Zymo Bacterial/Fungal DNA Kit and the amplification and detection of the MTC was done using the Seeplex MTB Nested ACE assay. The drug susceptibility tests were done using GenoTypeMTBDRplus assay which detects mutations and resistance to INH (isoniazid) and RMP (rifampicin). The milk isolates were further analyzed using a spoligotyping method which is based on the PCR amplification of a highly polymorphic direct repeat locus in the M. tuberculosis genome which detects and types the MTC. A percentage of 20.8 % samples were found to be positive for MTC using the Seeplex MTB Nested ACE assay. There were 42.1 % samples that were resistant to both INH and RMP with the rest sensitive to either INH or RMP. The spoligotyping method showed that 78.3 % samples resembled Family 33 strains and the rest (21.7 %) resembled a spoligotyping signature known to be that of M.africanum. Both these strains belong to the Ancestral lineage with Indo-Oceanic and West Africa 2 lineage. The outcomes of our study showed that molecular methods for detection of MTC can be applied directly on milk samples without the need for culturing.

A cross-sectional study was conducted from February 2011 to August 2012 to investigate the status and identify risk factors for Bovine Tuberculosis (BTB) and cattle Brucellosis. A total of 1277 cattle from 6 selected dairy farms were tested. The farms were purposively selected on suspected risk. Samples were analysed using Rose Bengal Test (RBPT) and Complement Fixation Test (CFT) for Brucellosis and Comparative Intradermal Tuberculin Test (CITT) for BTB. The results revealed the overall prevalence of 1.6% for Brucellosis and no BTB was found. Logistic regression analysis revealed that age of cattle, herd size and number of calves a cow has had significant association with Brucellosis with p-values 0.0071, 0.0490 and 0.000 respectively. The role of location (p>0.05), gender (p>0.05) and breed (p>0.05) in the occurrence of the disease was not statistically significant at α=0.05, although higher rates were obtained in females and Jersey breed. Questionnaires were also administered to 47 individuals a total of 12 females and 35 males. Most respondents were not aware about cattle brucellosis and cattle tuberculosis. Consumption of raw or unpasteurized milk still occurs with 74.75% of respondents revealed.

Four studies were conducted in the Texas Panhandle during the summer of 2007 to evaluate methods for cooling cattle in three phases of production (unweaned calves in hutches, weaned heifers on pasture and lactating cows). Unweaned calves (n = 20) housed in polyethylene hutches, covered with reflective aluminum and bubble film insulation, were compared to calves (n = 18) in similar, un-insulated hutches. Mean thermal heat index (THI) for the trial was 71.9 ± 5.5 (SD). Insulation treatment did not affect body weight gain (P > 0.044). Insulation affected interior hutch temperature, calf body temperature, and respiration rate (P < 0.05), indicating insulation may moderate temperature extremes within the hutch. Weaned heifers (n = 55) on pastures with shade were compared to similar heifers (n = 62) in pastures without shade. Mean THI for the trials was 70.8 ± 6.2 (SD). Shade treatment increased body temperature (P = 0.03) and decreased body weight gain. The effect of shade on foraging behavior was dependant on THI. Shade use by heifers was dependant on THI and wind speed. Heifers utilized shade when THI was above 72, especially when wind speed was low. Feed bunk attendance was compared among pens (n = 3) of lactating cows where the feed bunk was equipped with water sprinklers that sprayed the backs of cows and pens (n = 2) without feed bunk sprinklers. Mean THI for the trial was 70.8 ± 5.7 (SD). Feed bunk sprinklers mediated the affect of elevated THI on decreasing bunk attendance, but overall bunk attendance was not different among treatments. Lactating dairy cows, cooled with water sprinklers and fans three times each day in the holding pen prior to milking, were compared with similar cows cooled in the holding pen by fans only. Mean THI for the trial was 69.9 ± 5.3 (SD). Body temperature, milk yield and somatic cell count were not different among treatments. Sprinkled cows had lower milk fat and total protein than control cows. Sprinkling cows in the holding pen when THI is less than 70 may negatively affect milk production.

The aim of was to develop management protocols to improve reproductive efficiency in dairy cattle. The objective of Experiment 1 was to compare two methods of estrus synchronization. Eighty-nine dairy animals (67 cows and 22 heifers) were randomly assigned to either the Ovsynch or the Prostaglandin F[sub 2α] (PGF[sub 2α]) treatment group. Animals in the Ovsynch group received gonadotropin-releasing hormone (GnRH) followed by PG[sub 2α] on day 7 and second GnRH on day 9. Animals in the PGF[sub 2α] group were given two injections of PGF[sub 2α] 14 days apart. Both synchronization methods were followed by timed artificial inseminations. Milk progesterone (P₄) concentrations during the cycle were used to asses corpus Luteum (CL) function. Pregnancy was diagnosed 35 days after insemination. Estrus synchrony, based on Kamar heat mount detector and milk P₄ concentrations < lng/ml on the day of breeding, was not significantly different between the two groups. Mean milk P₄ during the synchronized cycle was also not significantly different between the two groups. Pregnancy rates were higher (P<0.05) for cows in the Ovsynch group (57.5%) than those in the PGF[sub 2α] group (38.4%). No difference in pregnancy rate was observed in heifers. The objective of Experiment II was to determine the effect of treatment with GnRH at various times after breeding on the induction of accessory CL, P₄ concentrations and pregnancy rates. Each month, estrus was synchronized in 12 to 15 postpartum cows using the Ovsynch protocol followed by timed inseminations. Cows were then randomly assigned to receive GnRH on d7 (n=34), d14 (n=34), or d7 and 14 (n=35) after breeding or to serve as controls (n=33). During the first two months, six cows from each group underwent ultrasonographic examination of the ovaries on days, 7, 11, 14, 18, and 21 after insemination to observe the formation of any additional CL. Blood and milk samples were also taken at these times to determine P₄ concentrations. Pregnancy was diagnosed 35 days after insemination. Eighty-three percent of cows ovulated in response to GnRH on d7 as opposed to only 17 percent on d14. Mean milk P₄ concentrations in treated cows did not differ from control cows. Pregnancy rates did not differ between the groups. It is concluded from this study that a) pregnancy rates of dairy cows and heifers can be managed effectively without estrus detection by using the Ovsynch estrus synchronization protocol followed by timed artificial inseminations and b) treatment with GnRH following synchronized breeding does not increase pregnancy rates in postpartum dairy cows.

Summary: Swaziland has long had a disparity between the supply and demand of milk. Even at present milk production continues to be less than the market demand. The quantitative contribution of smallholder dairy farmers to local milk production remains unknown because of poor record keeping. This study was aimed at attaining a clear understanding of the dynamics of smallholder dairying in Swaziland, including the identification and understanding of the constraints faced by farmers in dairying, with the hope of devising workable solutions to them. A sample of 118 smallholder dairy farms were covered in this study, with a total herd of 306 lactating cows, comprising mainly of Jerseys and Holstein Friesians, with some cross breeds. There were no significant differences in mean milk yield/cow with respect to farmer gender (P > 0.05) and Agro-ecological zone location (P > 0.05) of the farms. Milking frequency had a significant effect on milk yield, since cattle milked once a day had lower (P < 0.05) milk yields than those milked twice a day. The cattle had extensively long calving intervals i.e. 448 ± 166 days, ranging from 292 to 1082 days. Low milk yield and poor reproductive performance of cattle were found to be mainly due to poor nutrition, breeding practices and stock quality. These are primarily a result of insufficient farmer training and inadequate technical assistance, scarce availability of quality stock, lack of investment resources and market support that includes favourable milk prices for farmers to make money. This performance of the Swazi smallholder dairy herd was then evaluated by comparing it to the performance of a larger, well-managed herd of known pedigree. Lactation records from 252 Jersey cows and 108 Holstein Friesian cows were obtained from Cedara Agricultural Research Institute, covering the periods; July, 2002 to July, 2004 and November, 2002 to April, 2004, respectively. Cows were grouped by parity and calving season and the gamma function proposed by Wood (Y = An(b) e(-cn)) was used to fit standard lactation curves on group data. The curve parameters A and b increased with parity, while that of c and s (persistency of lactation at peak) decreased, producing standard lactation curves save for the Holstein Friesian summer calvers, which produced atypical curves. The R(2) values (goodness of fit) increased with parity. Animal parity and calving season were found to influence the peak and shape of the lactation curves and their parameter estimates. The performance of the Swazi smallholder herd showed a mean deviation of the observed daily milk yield of the Holstein Friesian breed from the expected yield to be - 3.47 (SD 6.052) kg and that of the Jersey breed was - 16.92 (SD 5.473) kg. The mean proportional deviation of observed milk yield from the expected yield for the Holstein Friesian breed was - 0.3 (SD 0.37) and that of the Jersey breed to be - 0.6 (SD 0.19). The proportional milk yield deviation of the Holstein Friesian breed can be explained using the equation Y = O.1322(SE = 0.1293) x - 2.3581 (SE = 0.20639), where x = expected milk yield and Y is the proportional deviation of the observed milk yield deviation from the expected milk yield. With respect to the smallholder Jersey breed, no relationship was found that could explain the proportional milk yield deviation. The smallholder herd was shown to be underperforming, considering the potential for higher milk yields of the two breeds. In the quest to gain a greater understanding of the dynamics of smallholder dairying, the sample of 118 farmers was further analysed using multivariate statistics to categorise them based on their herd sizes, herd structures, management and success perceptions in dairying. The analysis produced three clusters (categories): cluster 1 had the largest herd sizes and poor milk production efficiency; cluster 2 had intermediate herd sizes, the highest number of farmers and more efficient milk production per cow. This cluster, however, had the highest proportion of calf mortalities. Cluster 3 had the smallest herd size, the lowest calf to cow ratio and the second highest calf mortality. Record keeping across all clusters was very poor and the average milk yield per cow was generally low. Most of the farmers do not appreciate the importance of annual calving of their cows as an integral part of the success of their dairy projects and winter feed supplementation is very poor across all the clusters. There remains a great need for the enlightenment of the farmers on the importance of good nutrition, breeding, calf rearing and record keeping in successful dairying.
Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

Bovine maternal antibodies are not transferred across the placenta during pregnancy and newborn calves are unable to produce their own antibodies within the first weeks after birth. As neonates are born agammaglobulinemic they need to acquire immunoglobulins (Ig) from their dam’s colostrum to acquire passive immunity. Colostrum fed to dairy calves, which is not timeous, of inadequate quantity and of unverified quality, might result in decreased neonate health. The aim of this study was to conduct a survey of the management of colostrum on commercial dairy farms, to estimate the quality of the Ig titre of colostrum fed to neonates and finally to recommend methods and techniques critical to the successful management of colostrum. The methods used included a questionnaire which was conducted as a structured interview on a one-on-one basis among 50 randomly selected commercial dairy farmers in the Eastern Cape Coastal Region of South Africa. The estimation of the colostrum Ig titre of colostrum fed to neonates was made by the on-farm measurement of specific gravity (SG) by making use of a commercially available KRUUSE colostrometer (Fleenor and Stott, 1980). A pooled colostrum sample, from each of the four quarters, from 90 randomly selected post-partum cows was collected on a leader commercial dairy farm. This method was used to compare colostrum samples from cows run under similar management practices. These samples were collected for analysis within 6 hrs of calving and were done over 3 seasons (autumn, winter and spring). Survey - The colostrum mass and timing of the initial feed are the most important factors when aiming to achieve adequate passive immunity. The results of the survey indicated that most of the farmers of this region feed an inadequate mass of colostrum (volume and Ig concentration) and only 52% of farmers surveyed feed colostrum less than 6 hrs post- partum. The majority (78%) of surveyed farmers did not follow up their initial colostrum feeding.Colostrum sampling - At the trial site only 10% (9 from 90 colostrum samples measured), were found to be of adequate SG quality. Cow age (parity), season of calving and colostrum temperature had an influence on the estimated colostrum SG. However, season of calving was found to have the greatest influence on SG values. These results were consistent with findings from previous studies that SG values from the cooler months were higher than those of the hotter months. Tables 4.7 (P=0.330), 4.8 (P=0.012) and 4.9 (P=0.005) showed that regression analysis confirmed that LS means across seasons were inadequately below the required 50 mg/ml Ig required for sufficient passive immunity. Tables 4.1 (P=0.164), 4.2 (P=0.011) and 4.3 (P=0.021) shows that season of calving had a much greater effect on CR than did parity, Table 4.5 (P=0.177). Table 4.4 shows that colostrum temperature has an significant effect on SG value. Recommendations for methods and techniques critical to the successful management of colostrum were made. These recommendations were based on the analysis of the data obtained from the questionnaire and the on-farm colostrum sampling study. The most important and critical management practices surveyed includes the timing of the cow and calf separation where it was found that only 30 from the 50 (60%) of the farms surveyed separate calves and dams at day (0), 19 from 50 farms (38%) separate at day (3-5) and 1 from 50 farms (2%) separate only at day 7 or later. Thus 40% of surveyed farms allow cows to nurse their calves. With regards to early exposure to pathogens this is a high risk management practice. Further to that, only 2 from 50 surveyed farms (4%) measure the colostrum quality fed to their calves and 48 from 50 farms (96%) feed colostrum of unmeasured quality. The mass of colostrum fed to calves is an important parameter for successful transmission of Ig. In the survey it was found that 28 from 50 farms (56%) feed 2L – 4L of colostrum and 11 from 50 farms (22%) feed 2L of colostrum. Thus 78% of farms feed approximately 50% of the amount of colostrum required for successful transmission of Ig. Finally only 1 from 50 farms (2%) freeze excess colostrum and 1 from 50 farms (2%) pool excess colostrum. Both these farms measure colostrum quality by colostrometer.
Agriculture Animal Health and Human Ecology
M. Sc. (Agriculture)

Thesis (M.S.)--University of Georgia, 2005.
Directed by William Graves. Includes articles submitted to American registry of professional animal scientists and Journal of dairy science. Includes bibliographical references (leaves 81-88).

Text in English, Tswana
Low nutrient intake affects metabolism and growth in pregnant heifers and limits milk production in lactating cows on communal area smallholder dairy farms of the subtropics. Two studies were conducted during the current research. The first study evaluated effects of nutrient supply in standardized dairy diets on the growth and body reserves of pregnant Jersey heifers raised on communal area smallholder farms in a semi-arid zone of South Africa. Twenty-two farms with a total of 42 heifers, aged 22 to 28 months which were seven months pregnant at the beginning of the study were selected for the study. These represented the total number of farms with dairy cows in the area that were supported through a structured Dairy Development Program (DDP) of South Africa. Each farm had at least two pregnant Jersey heifers during the summer season of 2016. Each heifer was supplied 2.5 kg of a far-off (60-30 d prepartum) dry cow concentrate and increased to 3.3 kg of the same concentrate at close-up period (29-0 d prepartum). Feeding of concentrate was based on a standardized feeding program as recommended by DDP. During this study, no feeding treatment was imposed on the heifers. Eragrostis curvula hay was supplied by DDP. Daily intake of 7.2 and 5.4 kg; respectively for heifers at 60-30 d prepartum and 29-0 d prepartum was determined based on residual hay. Heifer diet (HD1) and heifer diet HD2 were therefore simulated respectively for cows at 60-30 d preparpartum and 29-0 d prepartum, respectively. Diets were assessed for nutrient composition using chemical analyses and in vitro ruminal degradation. Post ruminal nutrient absorption and animal responses were predicted using the Large Ruminant Nutrition System (LRNS) version 1.0.33 (level 1). Actual measurements of body weight (BW), body condition score (BCS) were done and blood was collected and analysed for proteins monthly. Heifers’ responses were validated against the model predicted values and comparative analysis of animal performance during pregnancy was done against the National Research Council (NRC, 2001) reference values. Relative to the minimum requirement for ruminants, both HD1 and HD2 diets had relative feed value (RFV) below 144. About 35% of HD1 dietary crude protein (CP) was within the slowly degrade neutral detergent fibre (NDF) fraction which is the neutral detergent fibre insoluble crude protein (NDFICP) while 32% was not available as the acid detergent insoluble crude protein (ADICP). Equally, HD2 diet had effectively 5.2% of CP as available protein and the fraction of the slowly degraded NDF constituted only 52.3% of the effective available protein. Energy density of HD1 and HD2 were 25% and 16% higher than expected at far-off and close-up period, respectively. The intake of metabolzable protein (MP) were 32 and 25% higher than predicted for the far-off and close-up period, respectively. Supply of MP was 37 % and was higher than NRC predictions of daily requirement in Jersey cow. This allowed BW gain of 29 kg and BCS of 0.33 which was within 25th percentile for pregnant heifers. Mean concentration of blood urea at both far-off and close-up periods deviated by 25% from NRC values. Creatinine (CR) concentration was 145 μmol /L at far-off and 155 μmol /L at close-up period. The second study assessed the adequacy of two lactation diets fed to 42 primiparous Jersey cows, aged 24 to 30 months during early (1-30 d postpartum) and peak (31-60 d postpartum) periods on the lactation performance of the cows. Cows received 4.5 and 5 kg of dairy concentrate at 1-30 d postpartum and peak milk (31-60 d postpartum) respectively. Eragrostis curvula hay was supplied ad libitum and dry matter intake (DMI) was estimated at 7.2 kg of hay/cow/day from residual hay. No feeding treatment was imposed except for the standardised diets typical to the production environment. Two simulated lactation diets (LD1 and LD2) were prepared based on dry matter intake (DMI) of grass hay and lactation concentrate. Diets were assessed for nutrient composition using wet chemistry and in vitro ruminal degradation. Nutrient supply of diets and absorption from the small intestines as well as cows’ responses were predicted using the Large Ruminant Nutrition System (LRNS) version 1.0.33 (level 1). Body weight and BCS were monitored, blood was collected and analysed for proteins monthly. A record of milk yield was taken daily, and milk was analysed for fat, protein, lactose and urea nitrogen weekly. Cows had DMI of 11.2 kg which was 12% higher than the expected at 1-30 d postpartum period and 11.6 kg which was 21% higher than the expected in 31-60 d postpartum cows. Diets had low available protein as % of dietary protein (LD1=46%; LD2=45%) and the slowly degraded NDF fraction (NDFICP) constituted 64% of the available protein. Intake of energy was 20% and 17% lower than the predicted value for the cows, respectively, at 1-30 d postpartum and 31-60 d postpartum period. Cows had negative energy balance of -6.5 and -5.6 Mcal respectively at 1-30 d postpartum and 31-60 d postpartum cows. Protein intake of lactating cows was low, which resulted in negative protein balance of 59% and 42% of cow’s daily requirement, respectively, at 1-30 d postpartum period and 31-60 d postpartum period. There was loss of BW and BCS, low milk yield, energy corrected milk (ECM: 9.50 kg/d) and feed efficiency (FE) of less than 1 (LD1= 0.85; LD2 =0.89) in cows at both periods. Composition of fat, protein and lactose in milk were negatively affected by the low level of dietary protein. Somatic cell count (SCC) in milk was 121 ± 13 x 103/ml and cows did not show signs of illness. Mean milk urea nitrogen (MUN) concentration was 12 ± 2.7 mg/dl reflecting the low protein status of the lactating cows. Cows had high creatinine concentration of 116 and 102 μmol /L at 1-30 d postpartum and 31-61 d postpartum period, respectively, which may indicate muscle breakdown due to heat stress relative to the hot production environment. Results showed that diets fed to dairy cows on communal area smallholder farms in Sekhukhune and Vhembe districts in Limpopo province had low feeding value and their low nutrient supply affected rumen fermentation, heifers’ ‘growth, body reserves and early lactation in Jersey dairy cows. In conclusion, diets supplied to dairy cows raised on smallholder farms are low in nutrients and do not support efficient growth in heifers and optimal milk production in early lactation. Development of a nutrition plan for improved dairy diets is required to maximise production and longevity in cows and enhance sustainability of dairy production on the smallholder farms in South Africa.
Go ja dijo tse di nang le dikotla tse di kwa tlase go ama metaboliseme le kgolo ya meroba e e dusang mme e ngotla tlhagiso ya mašwi ya dikgomo tse di tlhagisang mašwi mo dipolaseng tse dinnye tse di tlhakanetsweng mo mafelong a a mogote. Go dirilwe dithutopatlisiso di le pedi jaaka karolo ya patlisiso ya ga jaana. Thutopatlisiso ya ntlha e sekasekile ditlamorago tsa tlamelo ya dikotla mo dijong tsa teri tse di rulagantsweng mo kgolong le dirasefe tsa mmele tsa meroba ya Dijeresi e e dusang mo dipolaseng tse dinnye tse di tlhakanetsweng mo karolong e e batlileng e nna sekaka mo Aforika Borwa. Go tlhophilwe dipolase di le 22 tse di nang le meroba e le 42, e e bogolo jo bo magareng ga dikgwedi tse 22 le 28 mme e na le dikgwedi tse supa e ntse e dusa kwa tshimologong ya thutopatlisiso. Tsone di emetse palogotlhe ya dipolase tse di mo karolong eo tse di tshegediwang ke Lenaneo le le rulaganeng la Tlhabololo ya Teri (DDP). Polase nngwe le nngwe e ne e na le bonnye meroba ya Jeresi e le mebedi e e dusang ka paka ya selemo sa 2016. Moroba mongwe le mongwe o ne o fepiwa ka 2.5 kg ya dijo tse di omileng tsa dikgomo tsa fa go sa ntse go le kgakala (malatsi a le 60-30 pele ga go tsala) mme tsa okediwa go nna 3.3 kg fa malatsi a atamela (malatsi a le 29-0 pele ga go tsala). Dijo tseno di ne di di rulagantswe go ya ka lenaneo le le rulagantsweng la kotlo le le atlenegisitsweng ke DDP. Mo nakong ya thutopatlisiso eno, ga go na kalafi epe ya kotlo e e neng e patelediwa meroba. DDP e ne e tlamela ka furu ya eragrostis curvula. Go ja ga letsatsi le letsatsi ga meroba ga 7.2 le 5.4 kg ka nako ya malatsi a le 60-30 pele ga go tsala le malatsai a le 29-0 pele ga go tsala go ne go ikaegile ka furu e e setseng. Ka jalo go ne ga tlhagisiwa gape kotlo ya meroba ya 1 (HD1) le kotlo ya meroba ya 2 (HD2) mo dikgomong tse di mo malatsing a le 60-30 pele ga go tsala le malatsi a le 29-0 pele ga go tsala. Dikotlo tseno di ne tsa sekwasekwa go bona go nna gona ga dikotla mo go tsona go dirisiwa tshekatsheko ya dikhemikale mo mogodung. Go ne ga bonelwa pele monyelo ya dikotla morago ga go feta mo mpeng ya ntlha le tsibogo ya diphologolo go ya ka Thulaganyo ya Kotlo ya Diotli tse Dikgolo (LRNS) mofuta wa 1.0.33 (legato 1). Go dirilwe tekanyo ya boima jwa mmele (BW) le maduo a seemo sa mmele (BCS) mme go ne ga tsewa madi le go a sekaseka go bona diporoteini kgwedi le kgwedi. Tsibogo ya meroba e ne ya tlhomamisiwa ka dipalo tse di bonetsweng pele tsa sekao mme ga dirwa tshekatsheko e e tshwantshanyang ya tiragatso ya diphologolo ka nako ya go dusa go dirisiwa dipalo tsa Lekgotla la Bosetšhaba la Dipatlisiso (NRC, 2001). Malebana le ditlhokegopotlana tsa diotli, HD1 le HD2 di ne di na le boleng jo bo tshwantshanyegang jwa kotlo (RFV) jo bo kwa tlase ga 144. Poroteini e e tala (CP) ya dijo e e ka nnang 35% ya HD1 e ne e le mo karolwaneng ya tekanyetso ya faeba e e bolang ka iketlo (NDF) e leng poroteini e e tala ya faeba e e lekanyediwang (NDFICP), fa 32% di ne di seyo jaaka poroteini e tala e e sa monyelegeng ya esete (ADICP). Fela jalo, HD2 e na le 5.2% tsa CP e e dirang jaaka poroteini e e teng mme karolo ya NDF e e bolang ka iketlo e ntse fela 52.3% tsa poroteini e e dirang e e gona. Bogolo jwa maikatlapelo a HD1 le HD2 bo ne bo le kwa godimo ka 25% le 16% go na le jaaka go ne go solofetswe mo dipakeng tse di kgakala le tse di atamelang. Go jewa ga poroteini e e silegang (MP) go ne go le kwa godimo ka 32% le 25% go na le jaaka go ne go solofetswe mo dipakeng tse di kgakala le tse di atamelang. Tlamelo ya MP e ne e le 37%, e leng e e kgolwane go na le diponelopele tsa NRC tsa ditlhokego tsa letsatsi le letsatsi tsa dikgomo tsa Jeresi. Seno se letlile gore go nne le koketsego ya BW ya 29 kg le BCS ya 0.33 e leng se se neng se le mo diperesenteng tsa bo25 tsa meroba e e dusang. Go nna teng ga urea ya madi mo dipakeng tse dikgakala le tse di atamelang go ne go farologane ka 25% go tswa mo dipalong tsa NRC. Go nna teng ga kereitini (CR) e ne e le 145 μmol/L mo pakeng e e kgakala le 155 μmol/L mo pakeng e e atamelang. Thutopatlisiso ya bobedi e sekasekile ditlamorago tsa dijo tse pedi tsa tlhagiso ya mašwi mo tiragatsong ya tlhagiso ya mašwi ya dikgomo tsa Jeresi di le 42 tse e leng la ntlha di tsala tsa bogolo jwa dikgwedi tse di magareng ga 24 le 30 mo pakeng ya ntlha (malatsi a le 1-30 morago ga go tsala) le ya setlhoa (malatsi a le 31-60 morago ga go tsala). Dikgomo di amogetse 4,5 le 5 kg ya motswako wa teri mo dipakeng tsa mašwi tsa ntlha (malatsi a le 1-30 morago ga go tsala) le tsa setlhowa (malatsi a le 31-60 morago ga go tsala). Go ne go tlamelwa ka furu ya eragrostis curvula go ya ka tlhokego mme go ja dijo tse di omileng (DMI) go ne go lekanyediwa go 7.2 kg ya furu/ka kgomo/ka letsatsi go tswa mo furung e e neng e setse. Go ne go sa patelediwe kalafi epe ya phepo, kwa ntle fela ga dijo tse di rulagantsweng tse di tshwanetseng tikologo ya tlhagiso. Go ne ga baakanngwa dijo tsa tlhagiso ya mašwi tse di tlhagisitsweng gape (LD 1 le LD 2) di ikaegile ka go jewa ga tse di omileng (DMI) e leng furu ya tlhaga le metswako ya tlhagiso ya mašwi. Go nna teng ga dikotla ga dijo tseno go ne ga lekanyediwa go dirisiwa khemisitiri e e bongola le go bola mo mpeng ga in vitro. Go ne ga bonelwa pele tlamelo ya dikotla ya dijo, monyelo go tswa mo maleng a mannye mme go ne ga bonelwa pele tsibogo ya dikgomo go dirisiwa Thulaganyo ya Kotlo ya Diotli tse Dikgolo (LRNS) mofuta wa 1.0.33 (legato 1). Go ne ga elwa tlhoko boima jwa mmele le BCS, go ne ga tsewa madi mme a sekasekwa go bona diporoteini kgwedi le kgwedi. Go ne ga rekotiwa tlhagiso ya mašwi letsatsi le letsatsi mme mašwi a sekasekwa go bona mafura, poroteini, laketose le urea naeterojini beke le beke. Dikgomo di ne di na le DMI ya 11.2 kg, e e neng e le kwa godingwaga ka 12% go na le jaaka go ne go solofetswe mo pakeng ya malatsi a le 1-30 morago ga go tsala, le DMI ya 11.6 kg, e e neng e le kwa godingwana ka 12% go na le jaaka go ne go solofetswe mo dikgomong tse di nang le malatsi a le 31-60 di tsetse. Dijo di ne di na le poroteini e e gona e e kwa tlase jaaka peresente ya poroteini ya dijo (LD1=46% le LD2=45%) mme karolwana ya NDF e e bodileng ka bonya (NDFICP) e nnile 64% tsa poroteini e e gona. Go jewa ga maikatlapelo go ne go le kwa tlasenyana ka 20% le 17% go na le dipalo tse dineng di bonetswe pele mo dikgomong mo dipakeng tsa malatsi a le 1-30 morago ga go tsala le malatsi a le 31-60 morago ga go tsala. Go rekotilwe balanse ya maikatlapelo a a tlhaelang a dikgomo ya -6.5 le -5.6 Mcal mo malatsing a le 1-30 morago ga go tsala le 31-60 morago ga go tsala. Go jewa ga poroteini ke dikgomo tse di tlhagisang mašwi go ne go le kwa tlase, mme seo sa baka balanse e e tlhaelang ya poroteini ya 59% le 42% tsa ditlhokego tsa letsatsi le letsatsi tsa dikgomo mo pakeng ya malatsi a le 1-30 morago ga go tsala le malatsi a le 31-60 morago ga go tsala. Go rekotilwe tatlhegelo ya BW le BCS, tlhagiso e e kwa tlase ya mašwi, mašwi a a baakantsweng maikatlapelo (ECM: 9.50 kg/ka letsatsi) le bokgoni jwa furu (FE) jo bo kwa tlase ga 1 (LD1=0.85; LD2=0.89) mo dikgomong mo dipakeng tseo tsotlhe. Go nna teng ga mafura, poroteini le laketouse mo mašwing di amegile ka tsela e e sa siamang ka ntlha ya seelo se se kwa tlase sa poroteini e e kwa tlase. Tekanyetso ya disele tsa somatiki (SCC) mo mašwing e ne e le 121±13x10³/ml mme dikgomo ga di a bontsha matshwao ape a bolwetsi. Motswako wa urea naeterojini ya mašwi (MUN) e ne e le 12±2.7mg/dl, e leng se se bontshang seemo se se kwa tlase sa poroteini sa dikgomo tse di tlhagisang mašwi. Dikgomo tseno di ne di na le motswako wa kereitine wa 116 le 102 μmol/L mo dipakeng tsa malatsi a le 1-30 morago ga go tsala le malatsi a le 31-61 morago ga go tsala, mme seo se ka supa go fokotsega ga mesifa ka ntlha ya kgatelelo ya mogote e e bakwang ke tikologo e e mogote e go tlhagisiwang mo go yona. Dipholo di bontshitse gore dijo tsa dikgomo tsa teri mo dipolaseng tse dinnye tse di tlhakanetsweng mo dikgaolong tsa Sekhukhune le Vhembe kwa Porofenseng ya Limpopo di na le boleng jo bo kwa tlase jwa kotlo le gore dijo tse di nang le dikotla tse dinnye di amile titielo ya dijo, kgolo ya meroba, dirasefe tsa mmele le tlhagiso ya mašwi ka bonako mo dikgomong tsa teri tsa Jeresi. Kwa bokhutlong, dijo tsa dikgomo tsa teri tse di godisediwang mo dipolaseng tse dinnye di na le dikotla tse di kwa tlase mme ga di tshegetse kgolo e e mosola ya meroba le tlhagiso e e siameng ya mašwi mo nakong ya ntlha ya tlhagiso ya mašwi. Go tlhokega leano la dikotla go tokafatsa dijo tsa teri go tokafatsa tlhagiso le go tshela sebaka ga dikgomo le go tokafatsa go nnela leruri ga tlhagiso ya teri mo dipolaseng tse dinnye mo Aforika Borwa.
Agriculture and  Animal Health
Ph.D. (Agriculture)