J. C. de Souza

Genetic and phenotypic trends for growth traits of buffaloes in Brazil

Abstract The objectives this paper were to estimate genetic parameters genetic phenotypic trends of birth weight (BWT) weights adjusted to 205 (WT205) 365 (WT365) 550 (P550) days of age of beef buffaloes born from 1985 to 2003 in Brazil. For BWT WT205 the model included direct maternal genetic maternal environment as random effects contemporary genetic groups as fixed effects. For WT365 WT550 the same model was used except without direct maternal maternal environmental effects. The genetic phenotypic trends were estimated by regression of means of dependent variables on birth year of animals. Regressions were obtained by using two methodologies: 1) linear regression; 2) non-parametric splined regression. The direct heritability estimates were 0.09 0.45 0.46 0.58 for BWT WT205 WT365 WT550 respectively. The direct genetic trends from linear regression were 0.01 0.23 0.58 1.40 kg per year for PN WT205 WT365 WT550 respectively (P<0.001 for all). Phenotypic trends were strongly positive while genetic trends were consistently positive but small. Genetic parameters indicate potential for increased rate of genetic change with full implementation of genetic improvement programs.

Genetic and environmental effects over milk production of buffalo cows in Brazil

Abstract The objective of this paper was to evaluate the relevance of environmental and genetics effects on milk production of buffalo cows in Brazil. The data were based on the Buffalo Genetic Improvement Program - PROMEBUL, using information of 1,911 cows (107 Jafarabadi, 101 Mediterranean, 1,056 Murrah and 647 crossbred females) with parturition between 1982 and 2003. The mathematic model for evaluating milk production included the fixed effects of herd, parturition year (1982 to 2003) and month (January to December), calf’s sex (male or female), genetic group (Jafarabadi, Mediterranean, Murrah, and crossbreed), number of milking (one or two), lactation order (1 to 12) and duration of lactation (as a linear effect). The mean milk production in herds was 1,590.36 ± 609.25 kg. All sources of variation were significant (P<0.05) for the studied characteristics, except calf’s sex. The mean milk production per genetic group was 1,651.4; 1,592.2; 1,578.3 and 1,135.5 kg, for Murrah, Mediterranean, Crossbred and Jafarabadi, respectively. The duration of lactation was the most important source of variation over milk production, followed by the year of parturition, herd, parturition order, genetic group and month of parturition.

Univariate and bivariate distribution of growth traits in beef buffaloes from Brazil

Abstract The aim of this study was to analyze the weight at birth (BW) and adjusted at 205 (W205), 365 (W365) and 550 (W55O) days in beef buffaloes from Brazil, using two approaches: parametric, by normal distribution, and non-parametric, by kernel function, and thus estimating the genetic, environmental and phenotypic correlation among traits. Information of 5,169 animals at birth (BW), 3,792 at 205 days (W205), 3.883 at 365 days (W365) and 1,524 at 550 days of age (W550) were used. The birth weight distribution presented an evident discrepancy in relation to the normal distribution. However, W205, W365 and W550 presented normal distributions. The birth weight presented weak genetic, environmental, and phenotypic associations with the other weight measurements. On the other hand, the weight traits at 205, 365, 550 days of age showed a high genetic correlation.