Paulo Bahiense Ferraz Filho

Tendência Genética dos Efeitos Direto e Materno sobre os Pesos à Desmama e Pós-Desmama de Bovinos da Raça Tabapuã no Brasil

Data related to weights of animals of the Tabapua breed, born from 1959 to 1996, in several areas of Brazil, were analyzed with the objective of evaluating the direct and maternal genetic trends, for body weights adjusted for 205 (W205), 365 (W365) and 550 (W550) days of age. The (co)variance component estimates used in the calculation of the breeding values were obtained by the restricted maximum likelihood method (REML), with a model containing the random additive direct, maternal and permanent environmental effects, and the fixed effects of contemporary group (unit of the federation, farm, sex, season and year of birth of the animal) and the covariable age of the cow at calving (linear and quadratic effects). The genetic trends of the direct and maternal genetic effects were estimated by the regression of the breeding value annual means on year of birth of the animals. The genetic trends of the direct effects were 0.134, 0.199 and 0.276 kg/year, for W205, W365 and W550, respectively. The estimates of the maternal genetic trends were, in the same order, 0.019, -0.010 and -0.022 kg/year, respectively. Due to the existing genetic variability on the traits, the genetic changes attained are bellow the possible ones.

FATORES DO AMBIENTE SOBRE O PESO AO DESMAME DE BEZERROS DA RAÇA NELORE EM REGIÕES TROPICAIS BRASILEIRAS

This paper had the objective of studying the influence of non genetic effects on the weaning weight of 105,465 calves of the Nellore cattle breed, born in eight different Brazilian regions, in the period of 1978 to 1994. The statistical analysis was accomplished using the least squares method, GLM procedure (SAS, 1996), with a model that included the fixed effects of sex, month and year of birth of the calf, region, farm within region and the covariable age of dam. All sources of variation included in the model were significant (P<0.0001). The importance of these non genetic effects on body weight of calf at 205 days of age indicates the need to consider them when estimating genetic parameters and breeding values for selection purpose.

Análise da Distribuição de Pesagens em Diferentes Idades de Bubalinos da Raça Mediterrânea

O obje ti vo deste estudo foi anali sa r as distribu ic o es das ca ra cte ri sticas peso ao nascimento e dos pesos ajustad o s aos 205 , 365 e 5 50 d i as de i dade , util i zan do aborda g ens parame t rica , empregando a distribuicao normal , e nao parame t rica , ut i l izando a fu n cao Kerne l . Neste estudo estimaram - se tambem as correlacoe s d e P ears o n en t re e stas caracterist i cas. F or am utilizados 5.281 dados de peso ao nascimento e 4 . 797 dad o para os pesos a o s 205 (P205), aos 365 (P365) e aos 550 dias de idade (P550) de buba l i nos da r a ca Medi terrânea cri a do s no Brasi l . Os coeficientes de correlacao de Pearson en t re o P N e as o utras pes age ns f oram 0, 10; 0,06 e 0 , 05 , para P205, P 3 65 e P550, respect i vame n te . Par a P205 e P 36 5 e, P2 05 e P5 5 0 o valo r d a correlacao foi semelhante e igual a 0,83. Ja para P 365 o valo r da c or relacao foi de 0 , 99. A di s tribuicao do peso ao nascimento apresent o u evi d en t e di s crep ância e m relacao a distribuic a o norm a l . Entretanto, P205 , P365 e P550 apresentara m di st r ibui c oe s no rm a is .

Growth curves and nutritional requirements for maintenance of asymptotic weight of Nellore cattle

The objective of this study was to evaluate the growth curve of Nellore cattle raised in the Pantanal, Mato Grosso do Sul, in different groups of size (weight), sex, and birth season, as well as to estimate the nutritional requirements for maintenance of the asymptotic weigh. The nonlinear models were adjusted using the Gauss-Newton method, with information on weight and age of animals within each (total, upper, and middle) group. The asymptotic weight was influenced by sex (P<0.05) in all groups. Regarding maturity rates, females in the total herd and upper group were more precocious than males, whereas males and females in the middle group were similar. Animals born in the dry season of the year showed a greater asymptotic weight in the total herd and upper group, and significant difference was not observed only in the middle group. Regarding asymptotic weight for the growth curve of the total herd (318.5 ± 0.92 kg), the upper group (384.4 ± 1.74 kg) requires 15.1% more nutrients for their daily maintenance. The nutritional requirements for daily maintenance in the middle group (294.5 ± 1.00 kg) is 5.7% lower than in the total herd. The animals kept in the same herd (in the Pantanal conditions) showed different growth curves, as a function of the birth season and sex, indicating variations in growth and different energy requirements for their maintenance.

Divergência genética entre touros da raça Gir

We studied the genetic divergence among 73 Gyr bulls, through dissimilarity measures, grouping methods and graphic analysis by main components based on the differences expected in its progenies related to productive and reproductive characteristics. The mean Euclidian standardized distances obtained were 4.3743 among the most dissimilar ones and 0.1135 for the most similar ones. Four groups of reproducers with the same similarity were obtained through grouping methods by optimization. The three main components explained 82.01% of the total variance; the first one explained 37.09%, the second one responded by 26.58% and the third one by 18.34% of variance. Scores of the main components enabled the visual evaluation of genetic divergence, through dispersion graphics. The results allowed the identification, among the evaluated animals, of the most divergent ones, recommending that their progenies can be used as mating genitors in improvement programs which aim at producing calves with better performance than their parents.