Three (intact) Angus males and three females which were half-sibs and born within 21 days of each other were selected for this study. Each animal was bled and biopsied periodically from suckling calves to mature slaughter weights, to determine the qualitative composition of lipoproteins and to differentiate the lactate lipogenic activity of subcutaneous tissue during growth and development. At slaughtered, a sample of intramuscular adipose tissue was taken to determine the lactate lipogenic activity at this location. Two days later, one side of each carcass was separated into wholesale cuts. Each wholesale cut was dissected into separable bone and soft tissue and sampled for protein, lipid and moisture determinations. The elution profiles of lipoproteins were similar for all animals. Major peaks observed were (1) very low density (VLDL), (2) low density (LDL) and (3) high density lipoproteins (HDL). Triglycerides, cholesterol and protein were not significant (P < .05) between males and females for the VLDL. At one year of age, females had large (P < .05) amounts of protein for the HDL. In both groups of cattle, largest (P > .05) amounts of protein were greater in the HDL at 9 months of age. Profiles of HDL apoproteins at all ages showed that in both groups of cattle, a distinct band with a weight of about 28,000 was present representing apo-AI. Apo-protein components of pooled LDL fractions showed a protein which was unable to enter the acrylamide gel (7.5 – 20%) used. The component may represent apo-B with a molecular weight of about 250,000. The lactate lipogenic activity of subcutaneous adipose tissue was larger in the males and only significant (P < .05) at 9 months of age. The lipogenic activity was higher (P > .05) in the subcutaneous tissue when compared to the intramuscular tissue at slaughter. In both cases, males showed to use more (P > .05) lactate for fatty acid synthesis in intramuscular and subcutaneous tissue than the females. Magnitude of quality and yield for carcass traits were better for the males than females. Bone, meat and lean weights were significantly (P < .05) greater for the males, however, on a percentage basis per side weight, differences were eliminated. In addition, no significant (P > .05) effect was present between male and female wholesale and side carcass composition.

The data for this study were taken from the calf crops born from 1950 through 1958 at the Beef (Battle Research Station, Front Royal, Virginia. These included 556 Angus, 556 Hereford, and 590 Shorthorn calves. / Master of Science

Call number: LD2668 .T4 1986 H66 / Master of Science

"December, 2004." / Bibliography: leaves 229-251. / xvi, 265 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, School of Agriculture and Wine, Disciplines of Animal Science and Biometrics SA, 2005?

Masculinization of the female fetus by administration of androgens has been studied in domestic and many laboratory species. Research concerned with cattle has been based solely on neonatal examination of the genital structures; no studies have reported on postnatal growth and development of androgenized offspring. In the present study, pregnant cows were treated with l 7α-methyl-testosterone (MET, 250 mg/d, sq) from day 40 through 60 of gestation to induce virilization of female fetuses. Control cows received no treatment. At parturition, the phenotypic characteristics of each calf were recorded, including birth weight, ano-genital distance and the appearance of the external genitalia. Calves were weighed every 28 days, and the effects of sex and age on body weight were determined. Blood serum was obtained twice weekly from female calves beginning at ≃230 days of age. Serum was analyzed for progesterone (P₄) concentration by radioimmunoassay and the P₄ profiles were used to estimate the age at puberty and estrous cycle lengths. At 4, 8 and 12 months of age blood samples were collected every 15 min for 12 h from three male, female and androgenized female calves. Serum was analyzed for growth hormone (GH), prolactin (PRL) and thyroxine (T₄) concentrations by radioimmunoassay. Visual examination of female calves born after MET exposure revealed that no external vulval opening was present; a penis, prepuce and scrotum had developed and gonads were not palpable in the scrotum. Mean birth weights were similar among male, untreated female and androgenized female calves, whereas weanling and yearling weights were greater (P < .07) in males and androgenized females than in untreated females. Androgen exposure did not affect the initiation or length of estrous cycles in female calves, however, puberty occurred at an earlier age (P < .05) compared with untreated heifers. Concentrations of GH in serum from androgenized female calves were generally lower than both males and untreated females, whereas concentrations of PRL and T₄ were similar to those of control female calves. / Master of Science

Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The aim of this study was to evaluate the Simbra breed of cattle for certain non-genetic as well as genetic parameters influencing live weight traits in the breed. Live weight traits included birth weight (BW), weaning weight at 200 days of age (WW), yearling weight at 400 days of age (YW) and 600 day weight. The Simmental and Simbra Breeders’ Society of Southern Africa availed 148751 records for analysis from the year 1987 till 2009. Due to deficiencies of various kinds in the data and the restrictions imposed for the purposes of the analysis, 56.44% of the records were discarded for BW, 76.55% for WW, 91.54% for YW and 96.32% for 600-day weight. Non-genetic parameters affecting BW, WW, YW and 600-day weight were analysed using the General Linear Models procedure of the Statistical Analysis System (SAS, 2004) software. During this procedure sex of calf, breed composition of calf, breeder of calf, month of birth, year of birth and dam age were fitted in the models. BW, WW, YW and Mature Cow Weight (MCW) were fitted as covariates where possible. It was determined that the fixed effects of sex, dam age, breeder, year and month had a significant (P < 0.05) effect of BW and WW while dam age was not significant (P > 0.05) for YW or 600-day weight. Breed was found non significant for YW. Breeder of the calf accounted for the most variation in BW, WW, YW as well as 600-day weight with a contribution of 17.55%, 25.77%, 18.35% and 10.71% respectively. Tukey’s multiple range tests were performed for testing differences between least square means. Results indicated male calves to be significantly heavier than females for all four traits measured. Breed composition differences were found significant until WW. Calves with higher Brahman percentage weighted more at birth while calves with higher Simmental percentage weighed more at weaning. Middle-aged dams were found to account for heavier calves at both BW and WW while very young dams and very old dams produced lighter calves for the two live weight traits. A number of years showed a significant difference from each other for all the traits measured as well as month of birth. (Co) variance components and the resulting genetic parameters were estimated using single-traits and three-traits analysis by means of Restricted Maximum Likelihood procedures (Gilmour et al., 2002). Appropriate models were selected by means of Log likelihood ratios tests and implemented to estimate genetic parameters for each of the traits studied. Direct additive heritabilities for BW, WW, YW and 600-day weight in the Simbra were respectively 0.56 ± 0.08, 0.67 ± 0.09, 0.70 ± 0.11 and 0.10 ± 0.03 when the most suitable animal model was fitted in single-trait analyses for each trait. Single traits analysis also included maternal additive as well as the correlation between direct additive and maternal additive for BW, WW and YW. Maternal additive heritability estimates of 0.24 ± 0.07, 0.33 ± 0.06 and 0.38 ± 0.07 was obtained for BW, WW and YW. Correlation estimates between direct additive and maternal additive were -0.75 ± 0.07, -0.93 ± 0.07 and -0.85 ± 0.08 for BW, WW and YW respectively. Furthermore, dam permanent environment was included as an additional random effect that increased the log likelihood value significantly. A value of 0.04 ± 0.05 was obtained for dam permanent environment estimate for WW. When a three traits analysis was done for the same traits, but using a significantly smaller data set, direct additive heritabilities of 0.24 ± 0.07 for BW, 0.33 ± 0.06 for WW and 0.38 ± 0.07 for YW were obtained. Genetic and environmental correlation estimates of 0.18 ± 0.16 and 0.09 ± 0.06 between BW and WW; 0.27 ± 0.16 and 0.07 ± 0.06 between BW and YW; as well as 0.52 ± 0.10 and 0.45 ± 0.05 between WW and YW were obtained during the three-trait analysis. The magnitude of the heritabilities obtained in this study indicates that the opportunity exists to make genetic progress through proper selection objectives. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die Simbra bees ras te evalueer op grond van sekere niegenetiese so wel as genetiese parameters wat lewende gewig beïnvloed. Gereelde en akkurate opnames van lewende gewig, is ‘n goeie indikasie van groei potensiaal en is ‘n minimim vereiste vir meeste beesras telings genootskappe. Lewende gewigs eienskappe sluit in geboorte gewig (BW), speen gewig gemeet op 200 dae (WW), jaaroue gewig gemeet op 400 dae (YW) en finale gewig gemeet op 600-dag gewig. Die Simmentaler en Simbra genootskap van Suid Afrika het 148751 rekords beskikbaar gestel vir evaluasie vanaf die jaar 1987 tot 2009. Daar was egter groot tekort komings aan die gewewe data en dus is daar 56.44% van die rekords vir BW nie gebruik nie, 76.55% vir WW, 91.54% vir YW en 96.32% vir 600-dag gewig. Nie-genetiese parameters wat die onderskeie lewende gewigte beïnvloed het, is geanaliseer deur Algemene Lineêre Modelle met behulp van die Statistiese Analitiese Sisteem (SAS, 2004) sagteware. Gedurende die analise is geslag van die kalf, ras samestelling, teler van die kalf, maand van geboorte, jaar van geboorte asook moeder ouderdom gepas in die modelle vir die onderskeie gewigte. Geboorte gewig, speen gewig, jaaroue gewig asook volwasse koei gewig is gepas in elk van die modelle as ko-variate. Volgens die resutate is daar vasgestel dat geslag van die kalf, moeder ouderdom, teler, jaar, maand en volwasse koei gewig almal ‘n betekenisvolle (P < 0.05) invloed gehad het op BW en WW. Die moederouderdom was nie betekenisvol (P > 0.05) vir YW of 600-dag gewig nie. Die ras samestelling was ook nie betekenisvol gevind vir YW. Teler van die kalf was verantwoordelik vir die meeste variasie in BW, WW, YW asook 600-dag gewig met ‘n bydrae van 17.55%, 25.77%, 18.35% en 10.71% onderskeidelik. Tukey se veelvuldige vergelykings toets is gebruik om onderskeid te tref tussen “least square means”. Resultate het aangedui dat manlike diere swaarder weeg as vroulike diere tot en met finale gewig. Ras samestelling vir BW en WW was betekenisvol verskillend vir die diere. Kalwers met ‘n hoër Brahmaan persentasie het swaarder BW opgelewer as dié met ‘n hoër Simmentaler persentasie, terwyl kalwers met ‘n hoër Simmentaler persentasie swaarder geweeg het met speen en dus ideal is vir speen kalwer produksie stelsels. Middel-jarige moeders het swaarder kalwers geproduseer met geboorte en speen as baie jong en - ou moeders. Sommige jare waarin van die kalwers gebore is, het ook betekenisvol van mekaar verskil asook die maand waarin die kalf gebore is. Ko) variansie faktore en opeenvolgende genetiese parameters is bepaal met behulp van enkeleienskap analises asook meervuldige-eienskap analises deur middel van die “Restricted Maximum Likelihood” prosedure (Gilmour et al., 2002). Modelle is opgestel vir elk van die gewigte deur die geskikte genetiese terme toe te voeg en te toets met behulp van “Log likelihood tests” om sodoende die onderskeie genetiese parameters te bepaal. Direkte genetiese oorerflikhede bepaal deur enkeleienskap analises vir die Simbra ras was as volg, 0.56 ± 0.08 vir BW, 0.67 ± 0.09 vir WW, 0.70 ± 0.11 vir YW en 0.10 ± 0.03 vir 600-dag gewig. Die direkte maternale genetiese oorerflikhede tydens dieselfde enkel-eienskap analise vir die onderkeie gewigte was 0.24 ± 0.07 vir BW, 0.33 ± 0.06 vir WW en 0.38 ± 0.07 vir YW. Korrelasies tussen direkt genetiese en direk maternale eienskappe was sterk negatief. ‘n Waarde van -0.75 ± 0.07 is bepaal vir BW, -0.93 ± 0.07 vir WW en -0.85 ± 0.08 vir YW. ‘n Adisionele faktor was ook ingelsuit vir WW, naamlik die permanente omgewing van die moeder, wat ‘n waarde opgelewer het van 0.04 ± 0.05. Tydens die veelvuldige-eienskap analise het die oorerflikhede merkwaardig verminder vir die betrokke gewigte en kan ook waargeneem word as die meer korrekte genetiese weergawe. Direkte genetiese oorerflikhede van 0.24 ± 0.07 vir BW, 0.33 ± 0.06 vir WW en 0.38 ± 0.07 vir YW was bepaal. Hierdie matig tot hoë parameters dui op genetiese vordering deur middel van korrekte seleksie prosedures. Genetiese- en omgewing korrelasies is ook bepaal tydens die analise en het positiewe waardes opgelewer. ‘n Genetiese korrelasie waarde van 0.18 ± 0.16 tussen BW en WW is bepaal asook ‘n waarde van 0.27 ± 0.16 tussen BW en YW en ‘n waarde van 0.52 ± 0.10 tussen WW en YW. Hierdie korrelasies dui daarop dat na-speengewigte vermeerder kan word deur te selekteer vir verhoogde WW sonder om BW dramties te vermeerder. Omgewings korrelasie waardes van 0.09 ± 0.06 tussen BW en WW, 0.07 ± 0.06 tussen BW en YW asook ‘n waarde van 0.45 ± 0.05 tussen WW en YW is gevind. Genetiese neigings is bepaal vir die onderskeie gewigte deur die gemiddelde voorspelde teelwaardes aan te teken teenoor elke jaar wat bereken was tydens die enkel-eienskap analises vir die onderskeie gewigte. Groot variasie asook negatiewe tendense vir WW en YW is ondervind van jaar tot jaar en dui daarop dat die seleksie doelwitte vir lewendige gewig nie in plek gestel is nie en is dit nodig om te her evalueer.

The aim of the study was to determine the effects of different dietary fibre levels on methane production and growth performance of Bonsmara and Nguni steers. Nine Bonsmara and nine Nguni male weaners aged 8 – 9 months were used for the study. On arrival, animals were fed Eragrostis curvula hay on ad libitum basis for the first 14 days as part of adaptation to the feedlot environment. Animals were gradually adapted to treatments to prevent metabolic disorders. The study was conducted as a 3 x 3 x 2 factorial experiment. Treatments were allocated in a completely randomised design. Data were submitted to analysis of variance (ANOVA). Student's t-LSD was calculated at the 5 % level (P < 0.05) to compare treatment means for significant effects. Feeding a diet that is low in crude fibre content had significantly increased (P < 0.05) growth performance in both breeds. Bonsmara steers had significantly higher growth performance (P < 0.0001) across all treatment diets compared to Nguni steers. High rumen total microbial count was observed in animals that received diets with low crude fibre. Reducing dietary crude fibre resulted in reduced methane production. Low dietary fibre showed low rumen archaea counts. There was a positive correlation between rumen pH and methane emission for both Bonsmara (R2 = 0.9105) and Nguni (R2 = 0.9517) steers. However, a negative correlation was observed between rumen total microbial count and feed conversion ratio for both Bonsmara (R2 = 0.8286) and Nguni (R2 = 0.7208) steers. The low rumen archaea counts were detected from the Bonsmara. Feeding diets with low fibre levels is recommended for improving growth performance and reducing methane production for Bonsmara and Nguni steers. / Agriculture and  Animal Health / M. Sc. (Agriculture)

A predição da variância fenotípica é de grande importância para que os sistemas de produção de bovinos de corte consigam aumentar a rentabilidade otimizando o uso de recursos. Modelos mecanicistas dinâmicos do crescimento bovino vêm sendo utilizados como ferramentas de suporte à tomada de decisão em sistemas de manejo individual do gado. Entretanto, a aplicação desses modelos ainda fundamenta-se em parâmetros populacionais, sem qualquer abordagem para que se consiga capturar a variabilidade entre sujeitos nas simulações. Assumindo que modelos mecanicistas sejam capazes de simular o componente de desvio ambiental da variância fenotípica e considerando que marcadores SNPs possam predizer o componente genético dessa variância, esse projeto objetivou evoluir em direção a um modelo matemático que considere a variabilidade entre animais em seu nível genético. Seguindo conceitos de fisiologia genômica computacional, nós assumimos que a variância genética da característica complexa (i.e. produto do comportamento do modelo) surge de características componentes (i.e. parâmetros dos modelos) em níveis hierárquicos mais baixos do sistema biológico. Esse estudo considerou dois modelos mecanicistas do crescimento de bovinos - Cornell Cattle Value Discovery System (CVDS) e Davis Growth Model (DGM) - e ao questionar se os parâmetros de tais modelos mapeariam regiões genômicas que englobam QTLs já descritos para a característica complexa, verificou as suas interpretações biológicas esperadas. Tal constatação forneceu uma prova de conceito de que os parâmetros do CVDS e do DGM são de fato fenótipos cuja interpretação pode ser confirmada através das regiões genômicas mapeadas. Um método de predição genômica foi então utilizado para computar os parâmetros do CVDS e do DGM. Os efeitos dos marcadores SNPs foram estimados tanto para os parâmetros quanto para os fenótipos observados. Nós buscamos qual o melhor cenário de predição - simulações dos modelos com parâmetros computados a partir das informações genômicas ou predição genômica conduzida diretamente nos fenótipos complexos. Nós encontramos que enquanto a predição genômica dos fenótipos complexos pode ser uma melhor opção em relação aos modelos de crescimento, simulações conduzidas com parâmetros obtidos a partir de dados genômicos estão condizentes com simulações geradas com parâmetros obtidos a partir de métodos regulares. Esse é o principal argumento para chamar atenção da comunidade científica de que a abordagem apresentada nesse projeto representa um caminho para o desenvolvimento de uma nova geração de modelos nutricionais aplicados capazes de capturar a variabilidade genética entre bovinos de corte confinados e produzir simulações com variáveis de entrada específicas de cada genótipo. Esse projeto é a primeira abordagem no Brasil conhecida dos autores a usar genótipos Bos indicus para o estudo da aplicação de genômica integrada à modelos mecanicistas para o manejo e comercialização de animais na pecuária. / The prediction of phenotypic variance is important for beef cattle operations to increase profitability by optimizing resource use. Dynamic mechanistic models of cattle growth have been used as decision support tools for individual cattle management systems. However, the application of such models is still based on population parameters, with no further approach to capture between-subject variability. By assuming that mechanistic models are able to simulate environmental deviations components of phenotypic variance and considering that SNPs markers may predict the genetic component of this variance, this project aimed at evolving towards a mathematical model that takes between-animal variance to its genetic level. Following the concepts of computational physiological genomics, we assumed that genetic variance of the complex trait (i.e. outcome of model behavior) arises from component traits (i.e. model parameters) in lower hierarchical levels of biological systems. This study considered two mechanistic models of cattle growth - Cornell Cattle Value Discovery System (CVDS) and Davis Growth Model (DGM) - and verified their expected biological interpretation by asking whether model parameters would map genomic regions that harbors QTLs already described for the complex trait. This provided a proof of concept that CVDS and DGM parameters are indeed phenotypes whose expected interpretations may be stated by means of their mapped genomic regions. A method of genomic prediction to compute parameters for CVDS and DGM was then used. SNP marker effects were estimated both for their parameters and observed phenotypes. We looked for the best prediction scenario - model simulation with parameters computed from genomic data or genomic prediction on complex phenotypes directly. We found that while genomic prediction on complex phenotypes may still be a better option than predictions from growth models, simulations conducted with genomically computed parameters are in accordance with those performed with parameters obtained from regular methods. This is the main argument to call attention from the research community that this approach may pave the way for the development of a new generation of applied nutritional models capable of representing genetic variability among beef cattle under feedlot conditions and performing simulation with inputs from individual\'s genotypes. To our knowledge, this project is the first of this kind in Brazil and the first using Bos indicus genotypes to study the application of genomics integrated with mechanistic models for the management and marketing of commercial livestock.

A predição da variância fenotípica é de grande importância para que os sistemas de produção de bovinos de corte consigam aumentar a rentabilidade otimizando o uso de recursos. Modelos mecanicistas dinâmicos do crescimento bovino vêm sendo utilizados como ferramentas de suporte à tomada de decisão em sistemas de manejo individual do gado. Entretanto, a aplicação desses modelos ainda fundamenta-se em parâmetros populacionais, sem qualquer abordagem para que se consiga capturar a variabilidade entre sujeitos nas simulações. Assumindo que modelos mecanicistas sejam capazes de simular o componente de desvio ambiental da variância fenotípica e considerando que marcadores SNPs possam predizer o componente genético dessa variância, esse projeto objetivou evoluir em direção a um modelo matemático que considere a variabilidade entre animais em seu nível genético. Seguindo conceitos de fisiologia genômica computacional, nós assumimos que a variância genética da característica complexa (i.e. produto do comportamento do modelo) surge de características componentes (i.e. parâmetros dos modelos) em níveis hierárquicos mais baixos do sistema biológico. Esse estudo considerou dois modelos mecanicistas do crescimento de bovinos - Cornell Cattle Value Discovery System (CVDS) e Davis Growth Model (DGM) - e ao questionar se os parâmetros de tais modelos mapeariam regiões genômicas que englobam QTLs já descritos para a característica complexa, verificou as suas interpretações biológicas esperadas. Tal constatação forneceu uma prova de conceito de que os parâmetros do CVDS e do DGM são de fato fenótipos cuja interpretação pode ser confirmada através das regiões genômicas mapeadas. Um método de predição genômica foi então utilizado para computar os parâmetros do CVDS e do DGM. Os efeitos dos marcadores SNPs foram estimados tanto para os parâmetros quanto para os fenótipos observados. Nós buscamos qual o melhor cenário de predição - simulações dos modelos com parâmetros computados a partir das informações genômicas ou predição genômica conduzida diretamente nos fenótipos complexos. Nós encontramos que enquanto a predição genômica dos fenótipos complexos pode ser uma melhor opção em relação aos modelos de crescimento, simulações conduzidas com parâmetros obtidos a partir de dados genômicos estão condizentes com simulações geradas com parâmetros obtidos a partir de métodos regulares. Esse é o principal argumento para chamar atenção da comunidade científica de que a abordagem apresentada nesse projeto representa um caminho para o desenvolvimento de uma nova geração de modelos nutricionais aplicados capazes de capturar a variabilidade genética entre bovinos de corte confinados e produzir simulações com variáveis de entrada específicas de cada genótipo. Esse projeto é a primeira abordagem no Brasil conhecida dos autores a usar genótipos Bos indicus para o estudo da aplicação de genômica integrada à modelos mecanicistas para o manejo e comercialização de animais na pecuária. / The prediction of phenotypic variance is important for beef cattle operations to increase profitability by optimizing resource use. Dynamic mechanistic models of cattle growth have been used as decision support tools for individual cattle management systems. However, the application of such models is still based on population parameters, with no further approach to capture between-subject variability. By assuming that mechanistic models are able to simulate environmental deviations components of phenotypic variance and considering that SNPs markers may predict the genetic component of this variance, this project aimed at evolving towards a mathematical model that takes between-animal variance to its genetic level. Following the concepts of computational physiological genomics, we assumed that genetic variance of the complex trait (i.e. outcome of model behavior) arises from component traits (i.e. model parameters) in lower hierarchical levels of biological systems. This study considered two mechanistic models of cattle growth - Cornell Cattle Value Discovery System (CVDS) and Davis Growth Model (DGM) - and verified their expected biological interpretation by asking whether model parameters would map genomic regions that harbors QTLs already described for the complex trait. This provided a proof of concept that CVDS and DGM parameters are indeed phenotypes whose expected interpretations may be stated by means of their mapped genomic regions. A method of genomic prediction to compute parameters for CVDS and DGM was then used. SNP marker effects were estimated both for their parameters and observed phenotypes. We looked for the best prediction scenario - model simulation with parameters computed from genomic data or genomic prediction on complex phenotypes directly. We found that while genomic prediction on complex phenotypes may still be a better option than predictions from growth models, simulations conducted with genomically computed parameters are in accordance with those performed with parameters obtained from regular methods. This is the main argument to call attention from the research community that this approach may pave the way for the development of a new generation of applied nutritional models capable of representing genetic variability among beef cattle under feedlot conditions and performing simulation with inputs from individual\'s genotypes. To our knowledge, this project is the first of this kind in Brazil and the first using Bos indicus genotypes to study the application of genomics integrated with mechanistic models for the management and marketing of commercial livestock.