Estimating non-genetic and genetic parameters of pre-weaning growth traits in Raini Cashmere goat

Abstract

Data and pedigree information used in the present study were 3,022 records of kids obtained from the breeding station of Raini goat. The studied traits were birth weight (BW), weaning weight (WW), average daily gain from birth to weaning (ADG) and Kleiber ratio at weaning (KR). The model included the fixed effects of sex of kid, type of birth, age of dam, year of birth, month of birth, and age of kid (days) as covariate that had significant effects, and random effects direct additive genetic, maternal additive genetic, maternal permanent environmental effects and residual. (Co) variance components were estimated using univariate and multivariate analysis by WOMBAT software applying four animal models including and ignoring maternal effects. Likelihood ratio test used to determine the most appropriate models. Heritability (h(a)(2)) estimates for BW, WW, ADG, and KR according to suitable model were 0.12 ± 0.05, 0.08 ± 0.06, 0.10 ± 0.06, and 0.06 ± 0.05, respectively. Estimates of the proportion of maternal permanent environmental effect to phenotypic variance (c(2)) were 0.17 ± 0.03, 0.07 ± 0.03, and 0.07 ± 0.03 for BW, WW, and ADG, respectively. Genetic correlations among traits were positive and ranged from 0.53 (BW-ADG) to 1.00 (WW-ADG, WW-KR, and ADG-KR). The maternal permanent environmental correlations between BW-WW, BW-ADG, and WW-ADG were 0.54, 0.48, and 0.99, respectively. Results indicated that maternal effects, especially maternal permanent environmental effects are an important source of variation in pre-weaning growth trait and ignoring those in the model redound incorrect genetic evaluation of kids.

The comparison of standard and fully recursive multivariate models for genetic evaluation of growth traits in Markhoz goat: predictive ability of models and ranking of animals

“…Goat production is one of the major sources of income for farmers in the arid and semi-arid regions of the world (Barazandeh et al . 2012). Increasing meat, milk and fibre production of goats is not out of reach for farmers by using accurate and precise selection programmes (Moghbeli et al .…”

Investigating maternal effects on production traits in Duroc pigs using animal and sire models

“…Ignoring maternal effects resulted in the overestimation of direct heritability in goats (Barazandeh et al . ), which may cause an upward bias in predicted responses to selection. This may be partly attributed to the negative correlation between direct and maternal genetic effects that have an effect of slowing down genetic progress in traits where maternal effects are important (Eler et al .…”

Clinicians learn less and less about more and more until they know nothing about everything; researchers learn more and more about less and less until they know everything about nothing: Discuss

“…For the mathematics involved in estimating maternal effects, see, for example, Bijma (2006) and Chevrud and Wolf (2009). 2 As researchers in animal breeding have persistently noted, direct heritability and the response to selection are overestimated when maternal effects are not considered (Barazandeh et al 2012;Gregory et al 1985;Koivula et al 2009;Maniatis and Pollott 2002;Russell & Lummaa 2009;). They also note that the genetic analysis of maternal effects has proven enormously difficult.…”