No description available.

No description available.

Data from 946 Angus and 351 Simmental females were used to quantify relationships between calfhood and early-life traits of females with fertility in the first two breeding seasons, and with calf production in the first, in three and in eleven years of life. These traits were used to develop prediction equations for fertility using logistic regression methodology. For productive performance, three methodologies were compared: least squares, ridge regression and principal components regression. For heifers of both breeds, fertility was associated with birth date, weaning weight ratio and weaning-yearling relative growth rate (RGR). The only calfhood trait that consistently affected fertility in the second breeding season was birth weight of the cow. Fertility of first parity Simmentals was also associated with birth-yearling RGR. First calving season traits explained a higher proportion of variation in second breeding season fertility than calfhood traits of the cow. Among these traits, calving date, calving ease score and sex of the calf were the most important. The combination of birth date and weaning-yearling RGR produced the best models to predict heifer fertility for both breeds. Fertility in the second breeding season was best predicted for Angus cows when calving date, calving ease score and sex of the calf were used as regressors. For Simmental cows, fertility in the second breeding season was best predicted from birth weight of the calf and calving ease score. The regression of weaning weight of the first calf on pre-selected calfhood traits was used to evaluate models produced by least squares, ridge regression and principal components regression. Although biased, the regression coefficient estimates produced by ridge and principal components regression had smaller variances than estimates obtained from least squares. Between the two alternatives to least squares, ridge regression produced better results than principal components regression. Ridge and least squares regression were quite similar in their regression coefficient estimates, in prediction sum of squares (PRESS)-like statistics and, to a lesser extent, in conceptual predictive criteria (C_p)-like statistics. For prediction, the performance of models produced by least squares and by ridge regression were very similar. For analyses of the production traits, least squares regression models for all possible combinations of pre-selected regressor variables were fit. Birth date of the female was negatively associated with the weaning weight of the first calf, and with number of calves weaned, total weaning weight of calves produced and average weaning weight of calves in the first three years of productive life. Age of the dam affected early-life production traits of daughters, as well as the average weaning weight of calves produced per year of productive life and calf survival in eleven years. Heavier females at birth tended to produce smaller number of calves and lower calf weaning weight through their lives than females lighter at birth. Overall female productivity was consistently more positively associated with yearling than with weaning growth traits. Among traits observed in the first calving season, calving date, calving ease score, sex and weaning weight of the calf were associated with subsequent production. Weaning weight of the first calf was always positively associated and it was the most important variable to predict female production, except for survival rate. Prediction equations for production in three years included birth date, birth weight of the female, calving ease in the first parturition, sex of the calf and weaning weight of the first calf. This latter variable was the only one useful to predict production in eleven years. Average calf weaning weights in the first three years of production were best predicted using yearling weight ratio or weaning-yearling ADG and first calf weaning weight. Models including age of the female’s dam best predicted weaning weight of calves per year of productive life in eleven years and calf survival. / Ph. D.

Thesis (MPhil (Animal Sciences))--University of Stellenbosch, 2006. / South Africa produces only 0,50 % of the world’s milk. Although the number of milk producers is decreasing in South Africa, the milk production per se is increasing. The total number of small producers is decreasing while the number of big producers is increasing. The cost to raise replacement heifers is very high. Replacement heifers are the cows of tomorrow and should be seen as a valuable investment for the longterm survival and profitability of the dairy farm. A successful heifer rearing program is one in which: • Heifers are economically raised to be of adequate size and body condition to calve at a reasonable age. • Heifers produce high levels of milk during the first lactation. In the current study, the effect of Flavomycin and Mamalvite supplementation to young calves was investigated. According to manufacturer’s claims, Flavomycin would result in improved gains, improved conception rates, shorter calving intervals, increased milk production and improved weaning weights. Mamalvite, according to the manufacturer, should reduce risk of infections, increase feed utilization, increase feed intake and production, and also increase rumen microbial efficiency. Thirty two Holstein calves, four days of age, were randomly divided into four groups of eight. All calves received 4 kg whole milk daily and had free access to calf starter pellets. Treatments were: 30 ml Mamalvite daily supplemented in the milk and 5 g Flavomycin daily per os (Treatment 1), 30 ml Mamalvite daily supplemented in the milk (Treatment 2), 5 g Flavomycin daily per os (Treatment 3) and a control group that received milk only (Treatment 4). All the calves were weighed weekly. According to the results obtained in the current study, neither Flavomycin, nor Mamalvite, nor a combination of the two resulted in an improvement in calf weight gains. It was concluded that it does not appear to be an economically viable option to supplement Mamalvite or Flavomycin to calves that are reared in a well managed environment.

Two trials using 32 heifers each evaluated response to undegraded intake protein (UIP) (30 or SO% CP), energy (supporting .S9 or .91 kg ADG), and source of UIP (blood meal or combination protein supplement). Trial one was a 2x2 factorial, with two levels of energy and UIP. High UIP was achieved with blood meal supplementation. From 6-13 mo of age (phase I), high energy increased ADG and DMI, and high UIP decreased DMI. DM efficiencies (kg DMIlkg BW gain) improved with high energy and high UIP, and roN efficiencies (kg IDN/kg BW gain) improved with high UIP. From 13 mo until calving (phase n), heifers were housed together and fed a common diet. Low energy, high UIP treatment had the highest ADG (1.01 kg/day) for phase I, but the lowest for phase n (.33 kg/day), and low energy, low UIP treatment had the lowest ADG (.62 kg/day) for phase I, but the highest for phase n (.S3 kg/day). Overall ADG from 6 mo until calving averaged .S9 kg/day, and was not affected by energy or UIP. In trial 2, two levels of energy and two sources ofUIP were compared, resulting in four treatments: low energy, high UIP with combination protein supplement; low energy, high UIP with blood meal; low energy, low VIP with soybean meal; and high energy, low UIP with soybean meal. Combination protein supplement contained blood meal, com gluten meal, and fish meal. Trial was 300 days long, and began at 6.5 mo. of age. Dry matter intake and ADO were increased with high energy, but not affected by VIP. Overall DM efficiency was not affected by VIP or energy level. Results of both trials indicate VIP may improve feed efficiency of growing Holstein heifers. / Master of Science

Growth and body composition of 121 Holstein heifers (4.6 to 18 mo and 129 to 407 kg) reared on pasture, drylot and pasture-drylot systems were evaluated in 6 experiments. Heifers were switched from drylot to pasture or the reverse to study carry-over effects from previous treatments; both systems were satisfactory. Alternate 28-day periods of supplement feeding to grazing heifers did not affect final body weight nor wither height, but ADF and heart girth varied during 2 yr. When switching drylot heifers previously fed low and high TDN, to pasture, gains were best for heifers fed the lower TDN diet; also, gains on pasture were best for light heifers. Gains by all heifers grazing mainly orchardgrass-clover pasture were acceptable, but supplementing with a 19% CP concentrate or lasalocid, usually improved gains. Heifers with lowest BW during grazing made compensatory gains in drylot. Urea space estimation technique showed that compensatory gains were mainly fat. Lasalocid feeding increased daily gain and subcutaneous fat deposition but reduced feed intake and ribeye area. When moving grazing heifers to drylot a total mixed ration with fishmeal or soybean meal as protein sources gave similar responses. DM intake of grazing heifers ranged from 8.1 to 10.1 kg/d, vs 7.5 kg/d for arylot. Supplementing grazing heifers with degradable or undegradable protein gave similar responses in growth and body composition. Based on growth and body composition, seasonal grazing of Holstein heifers may reduce costs for rearing replacement heifers. A corn silage-alfalfa silage-orchardgrass hay mixed ration without concentrates when fed ad libitum to heifers in drylot resulted in gain of 934 g/d. Pasture alone heifers gained from 368 to 755 g/d depending on drought and heifer age. Calculations of costs of rearing Holstein replacement heifers were prepared accounting for observations of response to grazing, supplements to grazing and drylot diets. Well managed grazing reduces costs of rearing. / Ph. D.

Orientador: Lucia Galvão de Albuquerque / Banca: Danísio Prado Munari / Banca: Márcio Cinachi Pereira / Resumo: Os objetivos deste estudo foram estimar associações genéticas entre o perímetro escrotal obtido aos 9 (PE9), 12 (PE12) e 18 meses de idade (PE18) e características reprodutivas medidas diretamente em novilhas tais como: idade ao primeiro parto (IPP), ocorrência de prenhez aos 16 meses de idade (Pr16) e reconcepção de fêmeas primíparas (REC), utilizando inferência Bayesiana, com intuito de verificar a possibilidade de incluí-las como critérios de seleção em programas de melhoramento genético de bovinos de corte. Foram analisados 158.148 dados de animais da raça Nelore, nascidos entre 1990 e 2006 e pertencentes ao arquivo zootécnico da Agropecuária Jacarezinho Ltda., localizada no município de Valparaíso, São Paulo. Foram realizadas análises uni e bi-características. Em análises bicaracterísticas, as estimativas de herdabilidade foram iguais a 0,22±0,05; 0,39±0,09; 0,20±0,06; 0,20±0,01; 0,54±0,03 e 0,17±0,03 para PE9, PE12, PE18, IPP, Pr16 e REC, respectivamente. As correlações genéticas estimadas entre PE9 e IPP, Pr16 e REC foram de -0,48±0,13; 0,51±0,13 e 0,02±0,19, respectivamente. As correlações genéticas entre PE12 e IPP, Pr16 e REC foram de -0,41±0,12; 0,35±0,12 e -0,16±0,17, respectivamente. As correlações genéticas entre PE18 e IPP, Pr16 e REC foram de - 0,29±0,13; 0,28±0,14 e -0,03±0,18, respectivamente. Esses resultados sugerem que a seleção de animais com maior perímetro escrotal, principalmente aos 12 meses de idade deverá ocasionar maior ocorrência de prenhez aos 16 meses e menor idade ao primeiro parto em fêmeas da raça Nelore / Abstract: The objectives of this study were estimate genetic associations between scrotal circumference obtained at 9 (SC9),12 (SC12) and 18 months of age (SC18) and reproductive traits measured directly in heifers as: age at first calving (AFC) occurrence of pregnancy at 16 months of age (HP16) and heifers subsequent rebreeding (HSR), using Bayesian inference, in order to verify the possibility of including them as criteria for selection in breeding programs for beef cattle. It were analyzed 158,148 records from Nelore cattle, born between 1990 and 2006 and belonging to Agropecuária Jacarezinho Ltda., located in Valparaíso council, São Paulo state. Single and two-trait analyses were accomplished. In two-trait analysis, the heritability estimates were equal to 0.22 ± 0.05, 0.39 ± 0.09, 0.20 ± 0.06, 0.20 ± 0.01, 0.54 ± 0.03, and 0.17 ± 0.03 for SC9, SC12, SC18, AFC, HP16 and HSR, respectively. The genetic correlation between AFC and SC9, HP16 and HSR were -0.48±0,13, 0.51±0,13 and 0.02±0,19, respectively. Genetic correlations between SC12 and AFC, HP16 and REC were -0.41±0,12, 0.35±0,12 and - 0.16±0,17, respectively. Genetic correlations between SC18 and AFC, HP16 and HSR were -0.29±0,13, 0.28±0,14 and -0.03±0,18, respectively. These results suggest that selection of animals with larger scrotal circumference, especially at 12 months of age should result in a higher incidence of pregnancy at 16 months and a decrease in age at first calving in Nellore females / Mestre

Made available in DSpace on 2014-06-11T19:26:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-25Bitstream added on 2014-06-13T19:12:54Z : No. of bitstreams: 1 terakado_apn_me_jabo.pdf: 667390 bytes, checksum: 399d8e8c22f913c5f186b90a10416c4e (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Os objetivos deste estudo foram estimar associações genéticas entre o perímetro escrotal obtido aos 9 (PE9), 12 (PE12) e 18 meses de idade (PE18) e características reprodutivas medidas diretamente em novilhas tais como: idade ao primeiro parto (IPP), ocorrência de prenhez aos 16 meses de idade (Pr16) e reconcepção de fêmeas primíparas (REC), utilizando inferência Bayesiana, com intuito de verificar a possibilidade de incluí-las como critérios de seleção em programas de melhoramento genético de bovinos de corte. Foram analisados 158.148 dados de animais da raça Nelore, nascidos entre 1990 e 2006 e pertencentes ao arquivo zootécnico da Agropecuária Jacarezinho Ltda., localizada no município de Valparaíso, São Paulo. Foram realizadas análises uni e bi-características. Em análises bicaracterísticas, as estimativas de herdabilidade foram iguais a 0,22±0,05; 0,39±0,09; 0,20±0,06; 0,20±0,01; 0,54±0,03 e 0,17±0,03 para PE9, PE12, PE18, IPP, Pr16 e REC, respectivamente. As correlações genéticas estimadas entre PE9 e IPP, Pr16 e REC foram de -0,48±0,13; 0,51±0,13 e 0,02±0,19, respectivamente. As correlações genéticas entre PE12 e IPP, Pr16 e REC foram de -0,41±0,12; 0,35±0,12 e -0,16±0,17, respectivamente. As correlações genéticas entre PE18 e IPP, Pr16 e REC foram de - 0,29±0,13; 0,28±0,14 e -0,03±0,18, respectivamente. Esses resultados sugerem que a seleção de animais com maior perímetro escrotal, principalmente aos 12 meses de idade deverá ocasionar maior ocorrência de prenhez aos 16 meses e menor idade ao primeiro parto em fêmeas da raça Nelore / The objectives of this study were estimate genetic associations between scrotal circumference obtained at 9 (SC9),12 (SC12) and 18 months of age (SC18) and reproductive traits measured directly in heifers as: age at first calving (AFC) occurrence of pregnancy at 16 months of age (HP16) and heifers subsequent rebreeding (HSR), using Bayesian inference, in order to verify the possibility of including them as criteria for selection in breeding programs for beef cattle. It were analyzed 158,148 records from Nelore cattle, born between 1990 and 2006 and belonging to Agropecuária Jacarezinho Ltda., located in Valparaíso council, São Paulo state. Single and two-trait analyses were accomplished. In two-trait analysis, the heritability estimates were equal to 0.22 ± 0.05, 0.39 ± 0.09, 0.20 ± 0.06, 0.20 ± 0.01, 0.54 ± 0.03, and 0.17 ± 0.03 for SC9, SC12, SC18, AFC, HP16 and HSR, respectively. The genetic correlation between AFC and SC9, HP16 and HSR were -0.48±0,13, 0.51±0,13 and 0.02±0,19, respectively. Genetic correlations between SC12 and AFC, HP16 and REC were -0.41±0,12, 0.35±0,12 and - 0.16±0,17, respectively. Genetic correlations between SC18 and AFC, HP16 and HSR were -0.29±0,13, 0.28±0,14 and -0.03±0,18, respectively. These results suggest that selection of animals with larger scrotal circumference, especially at 12 months of age should result in a higher incidence of pregnancy at 16 months and a decrease in age at first calving in Nellore females

Master of Science / Department of Animal Sciences and Industry / Daniel W. Moser / The purpose of this study was to estimate the heritability of calving rate and age at first calving in Hereford heifers, and evaluate whether age at calving would add accuracy to a genetic evaluation of calving rate. Pedigree and performance data on Hereford heifers born between 2001 and 2007 was provided by the American Hereford Association. After editing to exclude animals that did not fit inclusion criteria, the evaluated dataset contained 94,709 heifers with calving status information. Data were analyzed using single and two-trait animal models to obtain heritability estimates, and genetic correlation between calving rate and age at first calving was determined using MTDFREML. Contemporary groups for calving traits were defined as heifers that were in the same yearling weight contemporary group, and remained in the ownership of the same breeder through the age that they would be expected to calve. Estimates of heritability for calving rate and age at first calving from single-trait models were 0.25, and 0.12, respectively. Genetic correlation between calving rate and age at first calving was -0.01. Calving rate is moderately heritable in Hereford heifers, and can be used in genetic evaluation of sires to improve the trait through selection. Age at first calving has minimal genetic relationship to calving rate, and is not useful in increasing accuracy of selection for calving rate.

Master of Science / Department of Animal Sciences and Industry / John Jaeger / Cattle grazing dormant native range (< 7% crude protein; CP) require supplementation of additional protein to sustain body weight (BW) and body condition score (BCS). Daily delivery of these supplements is an economic burden to cattle producers faced with challenging economic circumstances. Supplementing cows infrequently (as little as once/week) has produced equivalent BW and BCS changes compared to daily delivery. Dried distiller’s grains with solubles (DDGS) provides more ruminally-undegradable protein (RUP; 50-60%) compared to traditional oilseed-meal supplements (i.e. soybean meal) that are >50% ruminally-degradable protein (RDP). Therefore, our objective was to evaluate the effects of supplementation frequency on performance, reproductive success, eating behavior, and subsequent calf performance of spring-calving cows supplemented with DDGS. No differences in ending BW (P = 0.69) and BCS (P = 0.49), or changes in BW and BCS over the supplementation period (P = 0.82 and 0.70, respectively) were observed among cows supplemented every d, every 3 d, or every 6 d. Calf BW at birth, weaning weight (WW), and average daily gain (ADG) were similar among treatments (P = 0.19, 0.12, and 0.10, respectively). First-service conception rate (FSCR) and final pregnancy rate (PR) were also not affected by supplementation frequency (P = 0.62 and 0.76, respectively). The development of replacement heifers is a large expense for cow-calf producers. Improved breeding and heifer development strategies aimed at ensuring the success of replacement females have been developed but reproductive failure still remains a problem. The stress associated with breeding and handling procedures may decrease reproductive success. Therefore, the objective was to determine if intramuscular administration of flunixin meglumine (1.1 mg/kg BW) 14 days post-breeding would improve FSCR and PR in non-transported replacement heifers. Under the conditions of our study, flunixin meglumine did not improve (P = 0.87) first service conception rate above that of control heifers (41.2% and 42.3%, respectively). Final pregnancy rate also was not different between treatments and averaged 81.8% (P = 0.40).