Luciano Pinheiro da Silva

Heterogeneidade de variância residual em modelos de regressão aleatória na descrição do crescimento de codornas de corte

In order to compare the residual heterogeneity variance influence on the genetic parameters estimated for the growth curve of meat quail, data from 26835 and 27447 observations, from 3909 and 4040 meat quails of the UFV-1 and UFV-2 strains, respectively, were used. Body weight was evaluated, for the two strains, at 1, 7, 14, 21, 28, 35 and 42 days of age, through an animal model at random regression, considering residual variances in the age classes. Loge L showed increase, significant by the likelihood ratio test (LRT), with an increase in the number of heterogeneous classes. In the modeling, the following residual variances were considered in the age classes of: homogeneous: CL1 (one class): 1-42 days; and heterogeneous: CL2 (two classes): 1 and 7-42 days; CL3 (three classes): 1, 7 and 14-42 days; CL4 (four classes): 1, 7, 14 and 21-42 days; CL5 (five classes): 1, 7, 14, 21 and 28-42 days; CL6 (six classes): 1, 7, 14, 21, 28 and 35-42 days; CL7 (seven classes): 1, 7, 14, 21, 28, 35 and 42 days of age. The model that considered residual variance homogeneity showed unsuitable. Variance estimates, heritability and correlations were influenced by the modeling of the residual variance. The use of residual variance heterogeneity (CL7) to model the variances associated with the growth curve of meat quail is necessary.

Supplementation with Cashew Nut and Cottonseed Meal to Modify Fatty Acid Content in Lamb Meat.

This study evaluates the effect of cashew nut meal (CNM), whole cottonseed (WCS), and calcium salts of long-chain fatty acids (Ca-LCFA) on the fatty acid profiles of meat from hair lambs. Thirty-five 60-d-old, male, noncastrated Santa Ines lambs with an initial average body weight of 13.00 ± 1.80 kg were used in a randomized complete-block design with 7 blocks and 5 treatments. The experimental treatments consisted of a control diet (CON) without supplemental lipids and 4 test diets with different lipid supplements that were selected according to the degree of protection from ruminal hydrogenation and their polyunsaturated fatty acid richness. The tests diets included the following modifications: supplementation with WCS, supplementation with CNM, supplementation with both cottonseed and CNM (CSCNM), and supplementation with Ca-LCFA. The C18:1n9c content was highest in the meat of the animals fed the CNM diet (42.00%). The meat from lambs fed the WCS and Ca-LCFA diets had higher C18:0 contents (25.23 and 22.80%, respectively). The C16:1 content was higher in the meat from the animals fed the CNM and CON diets (1.54 and 1.49%, respectively). C18:2c9t11 concentration was higher in the meat from the animals fed the Ca-LCFA and CNM diets. The estimated enzyme activity of Δ9-desaturase C18 was highest in the muscles of the lambs fed the CON, CNM, and CSCNM diets. The use of cashew nuts in the diet resulted in an increase in the C18:2c9t11 content of the lamb meat, which improved the nutritional characteristics of the fat.

Genetic parameters for rank of the Santa Inês sheep in agricultural fairs using Bayesian procedures

Abstract The aim of this study was to estimate the genetic parameters for the ability of a sheep to rank among the top three in its age category (ABI3) and for its total score (TS) on the judgement championships held in different agricultural fairs in Brazil. Data files included 3180 records referring to 1896 animals for ABI3 and 4383 records referring to 2170 animals for TS. The relationship matrix was composed by 4069 animals. Variance components were estimated fitting threshold and linear animal models for ABI3 and TS, respectively, by Bayesian analysis using the Gibbs sampler. The posterior means of the heritability and repeatability were, respectively, 0.10 ± 0.07 and 0.57 ± 0.11 for ABI3 and 0.12 ± 0.04 and 0.31 ± 0.02 for TS. The low values for the heritabilities related to these traits reveal a strong influence of the environmental factors, as the differential management offered to the animals before and during the fair. The repeatability values for ABI3 suggest high correlation among the animal classifications in different fairs. However, for TS, the observed performance has moderate confidence to be repeated over time. We conclude that although reduced, there is genetic variability for the animal’s performance in agricultural fairs. Nevertheless, due to the low heritability estimates, the expected response to direct selection for ABI3 and TS will be low.