João Cláudio do Carmo Paneto

Estudo de Características Quantitativas de Crescimento dos 120 aos 550 Dias de Idade em Gado Nelore

With the aim of a better understanding of quantitative growth traits in Nellore cattle, some parameters were estimated: variance components and heritability coefficients of weight gains between the standardized ages of 120 and 240, 240 and 365, 365 and 455, and 455 and 555 days, and of scrotal circumference gains between the standardized ages of 365 and 455, and 455 and 555 days; and (co)variance components and genetic correlations between weight and scrotal circumference gains. Information from 29,769 records of weight gain and 15,676 records of scrotal circumference gain were analyzed to obtain the (co)variance component estimates. The restricted maximum likelihood, derivative free, under an animal model was the method of choice. The results were the following: 0.32 for the direct genetic heritability and 0.13 for the maternal genetic heritability coefficients for weight gain between 120 and 240 days of age; 0.16, 0.22 and 0.23 for the direct genetic heritability coefficients for weight gain between the ages of 240 and 365, 365 and 455, and 455 and 550 days respectively; 0.24 and 0.18 for the direct genetic heritability coefficients for scrotal circumference gain between the ages of 365 and 455, and 455 and 550 respectively; and genetic correlation of 0.18 between the weight and the scrotal circumference gains.

Comparação entre análises para permanência no rebanho de vacas Nelore utilizando modelo linear e modelo de limiar

Heritability and expected progeny difference (EPD) for stayability based on progeny records of 4,180 sires from the Programa de Melhoramento Genetico da Raca Nelore were estimated. Bayesian analyses for threshold and linear models were performed using the software multiple trait Gibbs sampler for animal model. Gibbs size chain of 225,000, burn-in of 25,000 and thinning interval of 1,000 cycles were considered for implementation purpose. The heritability estimated by linear model (.065) was lower than for threshold model (0.158). The heritability estimate for transformed continuous threshold scale was .13±.05 which is close to the heritability estimate for threshold model. The high rank correlation between the solutions from both models (97%) suggests the stayability analysis under Bayesian perspective does not influence the rank of the animal EPD. Therefore linear model analysis for transformed threshold stayability data, which has a reduced processing time, should be used.

Estudo de definição alternativa da probabilidade de permanência no rebanho para a raça Nelore

Uma definicao alternativa de permanencia no rebanho foi estudada em comparacao a definicao usual. Na definicao usual, foram consideradas vacas com pelo menos tres partos ate os 76 meses de idade como valor 1 e vacas com menos de 3 partos com valor zero. A definicao alternativa considerou os valores 0, 1, 2 e 3, respectivamente, para vacas com menos de tres, com tres, quatro ou cinco partos ate os 76 meses de idade. Foram obtidas estimativas de herdabilidade e preditas as DEPs (Diferencas Esperadas na Progenie) para probabilidade de permanencia no rebanho de 4.180 touros com filhas na base de dados do Programa de Melhoramento Genetico da Raca Nelore (PMGRN-USP). Utilizaram-se o modelo linear unicarater de touro avo-materno e a analise Bayesiana, por meio do software MTGSAM_threshold (Multiple-Trait Gibbs Sampler for Animal Models). Considerou-se tamanho de cadeia de Gibbs de 225 mil, periodo de descarte amostral de 25 mil e tomada de amostra a cada 1.000 rodadas. A correlacao entre classificacoes foi calculada por meio do SAS. As estimativas de herdabilidade foram de menor magnitude para a caracteristica padrao (0,07 vs 0,08). A correlacao de posto foi de 87,5%, ou seja, houve consideravel alteracao na classificacao dos touros avaliados. Dados os valores das estimativas de variância de touro, de herdabilidade e de variacoes nas DEPs preditas, concluiu-se que a caracteristica alternativa de permanencia no rebanho possui maior capacidade de deteccao da variabilidade genetica que a caracteristica padrao, sob modelo linear.

Indicadores de desempenho em rebanho da raça Holandesa: curvas de crescimento e altura, características reprodutivas, produtivas e parâmetros genéticos

Data on weight, height, productive and reproductive performance of 1,272 Holstein heifers, born from 1990 to 1998, were used to evaluate the growth and height patterns of these females from birth to first calving, and the following traits: weight at first calving (PP), age at first calving (IP), milk production in the first lactation (PL) and first calving interval (IEP), and to estimate genetic parameters of these traits. The von Bertalanffy fitted models were: Yi=802.10 (1-0.630EXP (-0.0022t)) for weight, and Yi=1.40 (1-0.208EXP (-0.0038t)) for height. The average performance of heifers were: height 140cm, weight 602kg and 27 month of age at first calving. The total milk yield was 8,026kg and first IEP was 420 days. The (co)variance components estimates were obtained by a derivative-free algorithm with the DFREML. The estimates of heritabilities were 0.31, 0.35, 0.34, respectively for PP, IP and PL, and 0.10 for IEP. The genetic correlations estimates between PP and PL, PL and IP and IEP and PL were low. The correlation between IEP and PP was 0.49 and between IEP and IP was, -0.69, sugesting an antagonism between the two last traits.

Alternativas para seleção de touros da raça Nelore considerando características múltiplas de importância econômica

The data set is from 234 Nelore bulls which participate of a progeny test in the period from 1996 to 2003. The expected progeny diference (EPDs) of seven economic traits, weights at 120 e 210 days of age, maternal effect (DMPP120 and DMPP210), weights and scrotal circumferences at 365 e 450 days of age, direct effects (DDP365, DDP450, DDPE365 and DDPE450), and age at first calving (DDIPP), were used in order to classify these animals in three groups and verify which EPDs showed greatest discriminating power in forming the groups. The statistical applied techniques were: k-means clusters analysis and principal components analysis. From the three groups formed, two of them stood out in relation to values of the EPDs means. Evidence of the importance of these two groups was observed in the principal component analysis that associate to them higher values of direct EPDs of weight and scrotal circumference. The two first principal components accounted for 70.22% of the total original variability. Both techniques could be an important tools to sire classification, variable discrimination, as well as to resume multivariate information, and they could be applied to help selection in animal breeding program.

Causas de variação nos preços de bovinos nelore elite no Brasil

This study aimed to understand the causes of variation in the marketing prices of elite flock nelore cattle commercialized by auction, especially to verify the influences of EPDs and visual assessment. The selling prices of 426 animals from the nelore breed commercialized during 12 auctions held in various Brazilian locations, between the years 2002 and 2005, were considered in the analysis. The average price was R

PERFIL BIOQUÍMICO DE BOVINOS NATURALMENTE INFECTADOS POR Trypanosssoma vivax

3.325,49, with a minimum of R

PERFIL HEMATOLÓGICO DE BOVINOS NATURALMENTE INFECTADOS POR Trypanosssoma vivax

1.400,00 and a maximum of R

Economic values for an example of beef cattle production system with the Nelore breed in Brazil and their variation under different genetic levels and marketing conditions.

10.500,00. The data used in a first analysis included the sex of each animal, the name of the auction and the EPDs of each animal informed in a catalog provided to the buyers during the auctions. A second analysis considered the EPDs of the sires of the commercialized animals, and the accumulated punctuation of these sires through their progeny judged through visual assessment during traditional animal shows in Brazil. Variance analysis and k-means clustering were applied to run the statistical analysis of the data. It was observed that animals with better EPDs, direct and maternal effects, on growth traits were sold with higher prices during the auctions. The punctuation by visual assessment did not significantly affect the prices.