Genetic parameters of direct and maternal effects for calving ease in Dutch Holstein-Friesian cattle

Abstract

Genetic parameters of direct and maternal effects for calving ease in Dutch dairy cattle were estimated using 677,975 calving ease records from second calving. Particular emphasis was given to the presence and impact of environmental dam-offspring covariances on the estimated direct-maternal genetic correlation. Moreover, a measure of heritability for traits affected by maternal effects was developed. In contrast to previous parameters, this parameter reflects the amount of genetic variance that can be used to generate a response to selection in maternally affected traits. Estimated genetic correlations between direct and maternal effects on calving ease have often been moderately negative, particularly in beef cattle. Environmental dam-offspring covariances have been put forward as an explanation for such estimates. We investigated the impact of environmental dam-offspring covariances by fitting correlated residuals between dam and offspring records in the statistical model, and by comparing results of a sire-maternal grandsire model with those of an animal model. Results show that calving ease in Dutch dairy cattle has a direct heritability of approximately 0.08, a maternal heritability of approximately 0.04, a direct-maternal genetic correlation of approximately -0.20, and a total heritable variance equal to approximately 11% of phenotypic variance. Results of animal models and sire-maternal grandsire models were very similar. The direct-maternal environmental covariance was near zero, and consequently had very little impact on the estimated genetic parameters. Transformation of observations to a liability scale did not affect the estimated genetic parameters and yielded a nearly identical ranking of sires.

Indirect Genetic Effects for Survival in Domestic Chickens (Gallus gallus) Are Magnified in Crossbred Genotypes and Show a Parent-of-Origin Effect

“…The heritable effect of an individual on the phenotype of a conspecific is known as an indirect genetic effect (IGE) in evolutionary literature, and as an associative, competition, or social effect in animal, plant, and tree breeding literature (Griffing 1967;Kirkpatrick and Lande 1989;Moore et al 1997;Muir 2005;Bijma et al 2007;Van Vleck et al 2007;Bergsma et al 2008). The most frequently studied IGE is a maternal genetic effect, which is the heritable environmental effect of a mother on the phenotype of her offspring (Willham 1963;Cheverud 1984;Kirkpatrick and Lande 1989;Koerhuis and Thompson 1997;Mousseau and Fox 1998;Eaglen and Bijma 2009;Bouwman et al 2010).…”

Genetic parameters of calving ease in dairy cattle using threshold and linear models

“…CE data are routinely recorded by farmers and scoring was conducted according to a 6-grade scale: 1 ¼ normal (not assisted), 2 ¼ moderate assistance, 3 ¼ hard pull, 4 ¼ caesarean, 5 ¼ fetonomy, 6 ¼ abortion. Hence, higher scores indicate greater calving difficulty, although the trait usually is referred to as calving ease rather than calving difficulty (Eaglen and Bijma 2009). For this study, the number of classes is reduced to 4.…”

“…CE scores were directly used as dependent variable (LM1) or are transformed into values on an underlying continuous liability scale (LM2, LM3) (Figure 1). This transformation does not make CE scores continuous; it merely alters the differences between scores (Eaglen and Bijma 2009).…”

“…Calving affects animal welfare, with dystocia being ranked as one of the most painful conditions of cows (Huxley and Whay 2006;Eaglen and Bijma 2009). Calving difficulty affects herd profitability because of increased labour and veterinary costs, increased calf mortality, and reduced subsequent fertility and survival of the cow (Hickey et al 2007).…”

“…The TM takes into account the asymmetry and extreme incidence of some categories. However, in several studies, preference was given to the use of linear models (Carnier et al 2000;Eaglen and Bijma 2009). The purpose of this research was to estimate variance components and genetic parameters for CE using TM and three linear models (LM) and to compare breeding values ranking lists achieved from the two methodologies.…”