Maternal Permanent Effects Research Articles

Genetic parameters for birth and weaning weight in a herd of Mediterranean buffaloes under tropical conditions

The objectives of the present study were to estimate variance components and genetic parameters for birth weight (BW) and weaning weight (WW). The data comes from Mediterranean buffalo calves born during the period from August 2003 to December 2021 on the Livestock Farm “Hacienda Caño Negro”, located near the population of Santa Barbara del Zulia, Venezuela. A total of 2225 records collected for BW and WW were included in the analysis. Variance components and genetic parameters were estimated by REML using the MTDFREML program, applying a bivariate animal model that includes direct, maternal, and permanent maternal effects. The population average BW of Buffalo calves was 42.7±0.1 kg, whereas for males, 43.9±0.2 and for females, 41.7±0.2 kg. The population average for WW was 174.5+0.9 kg. According to sex, the WW parameters were 178.5±1.3 kg and 170.5±1.1 kg in males and females, respectively. The direct heritability estimates were 0.03 and 0.23 for BW and WW, respectively, whereas maternal heritability values were 0.78 for BW and 0.24 for WW. The estimated total heritability for both characters was 0.23 (BW) and 0.32 (WW). The genetic correlation between BW and WW was 0.57, while the maternal genetic correlation for BW and WW was 0.01. The results indicated moderate total heritability value for BW and WW; further analysis is needed to estimate the genetic parameters, perhaps including other breed herds.

Genetic parameters and principal components analysis of breeding value for birth and weaning weight in Egyptian buffalo.

ObjectiveThe objectives of the current study were to study the main environmental factors affecting birth weight (BW) and weaning weight (WW), estimate variance components, genetic parameters and genetic trend and to evaluate the variability and relationships among breeding value of BW and WW using principal components analysis (PCA).MethodsA total of 16,370 records were collected from 8,271 buffalo calves. Genetic parameters and breeding values were estimated using a bivariate animal model which includes direct, maternal and permanent maternal effects. These estimates were standardized and used in PCA.ResultsThe direct heritability estimates were 0.06 and 0.41 for BW and WW, respectively whereas direct maternal heritability values were 0.03 and 0.14, respectively. Proportions of variance due to permanent environmental effects of dam were 0.455 and 0.280 for BW and WW respectively. The genetic correlation between BW and WWs was weak approaching zero, but the maternal correlation was 0.26. The first two principal components (PC1 and PC2) were estimated utilizing the standardized breeding values according to Kaiser method. The total variance explained by the first two PCs was 71.17% in which 45.91% and 25.25% were explained by PC1 and PC2, respectively. The direct breeding values of BW were related to PC2 but those of WW and maternal breeding values of BW and WWs were associated with PC1.ConclusionThe results of genetic parameters and PCA indicate that BW and WWs were not genetically correlated and improving growth traits of Egyptian buffaloes could be achieved using WW without any adverse effect by BW.

Genetic Parameters from Univariate and Bivariate Analyses of Egg and Weight Traits in Japanese Quail

Fully pedigreed records of a Japanese quail population were analyzed for genetic parameters of egg and BW traits. A restricted maximum likelihood (REML) procedure was applied in univariate and bivariate analyses. Quantitative genetic analyses, including maternal effects, were carried out on the records of 947 male and 861 female birds (total = 1,808). The traits were analyzed with bird as a random factor to fit the additive direct effect, bird being the individual for which the trait was recorded, namely hen (dam) for egg traits and chick (progeny) for BW. Permanent environmental effects (0.29 to 0.35) on egg traits were higher than corresponding heritabilities (0.18 to 0.25). Significant maternal genetic and maternal permanent effects were measured for hatching BW. The heritabilities of weekly BW were low, and decreasing by 5 to 6 wk of age. They were 0.07, 0.18, 0.19, 0.18, 0.19, 0.13, and 0.15 from hatching to 6 wk, respectively. Strong correlations were detected between direct genetic effects for egg traits and maternal genetic effect for BW traits. Applying such detailed analyses in the study of both egg and BW traits provides procedures to specifically evaluate Japanese quail and poultry in general. The results illustrated that the maternal permanent environmental effects made larger contributions to the variability of egg traits than did direct genetic effects. This situation implies that rearing of birds, healthcare, and feeding are very important determinants of egg characteristics.