Estimation of direct, maternal, and grandmaternal genetic effects for weaning weight in several breeds of beef cattle.

Abstract

Weaning weights from nine parental breeds and three composites were analyzed to estimate variance due to grandmaternal genetic effects and to compare estimates for variance due to maternal genetic effects from two different models. Number of observations ranged from 794 to 3,465 per population. Number of animals in the pedigree file ranged from 1,244 to 4,326 per population. Two single-trait animal models were used to obtain estimates of covariance components by REML using an average information method. Model 1 included random direct and maternal genetic, permanent maternal environmental, and residual environmental effects as well as fixed sex x year and age of dam effects. Model 2 in addition included random grandmaternal genetic and permanent grandmaternal environmental effects to account for maternal effects of a cow on her daughter's maternal ability. Non-zero estimates of proportion of variance due to grandmaternal effects were obtained for 7 of the 12 populations and ranged from .03 to .06. Direct heritability estimates in these populations were similar with both models. Existence of variance due to grandmaternal effects did not affect the estimates of maternal heritability (m2) or the correlation between direct and maternal genetic effects (r(am)) for Angus and Gelbvieh. For the other five populations, magnitude of estimates increased for both m2 and r(am) when estimates of variance due to grandmaternal effects were not zero. Estimates of the correlation between maternal and grandmaternal genetic effects were large and negative. These results suggest that grand-maternal effects exist in some populations, that when such effects are ignored in analyses maternal heritability may be underestimated, and that the correlation between direct and maternal genetic effects may be biased downward if grandmaternal effects are not included in the model for weaning weight of beef cattle.

Comparison of models to estimate genetic effects of weaning weight of Angus cattle.

“…Any relationship of the estimates of the direct-grandmaternal correlation (r ag ), which ranged from −.36 to .37, with any of the other parameters was not obvious. Estimates with Model 5 generally agreed with previous studies in which a model with grandmaternal effects was applied (Dodenhoff et al, 1998(Dodenhoff et al, , 1999. Given a negative influence of the granddam's phenotype on the dam's maternal ability, Willham (1972) expected r mg to be negative, but he doubted that a nonzero covariance between direct and grandmaternal genetic effects existed.…”

“…Dodenhoff et al (1999) used such a "grandmaternal" model to estimate genetic parameters in beef cattle. Model 5 in this study was the "grandmaternal" model (Willham, 1972):…”

Heritable Variation in Maternal Yolk Hormone Transfer in a Wild Bird Population

“…The heritability of yolk T ( ) was high and 2 h p 0.75 comparable to the heritability of egg mass ( ) and 2 h p 0.84 yolk mass ( ) observed in our study as well as in 2 h p 0.97 other species (Christians 2002). This finding adds to the evidence for a genetic basis of prenatal maternal effects, which is well established for livestock (e.g., Meyer 1997;Dodenhoff et al 1999;Moce et al 2004) and plants (reviewed in Shaw and Byers 1998) but still scarce for freeliving animals. Yolk A4 deposition, on the other hand, was not heritable.…”

Genetic parameter estimates for birth and weaning weights in Raeini goats

“…Furthermore, Swalve (1993) suggested that the negative covariance between direct and maternal genetic effects may be the result of management system. However, an investigation conducted by Dodenhoff et al (1999) on several breeds of beef cattle indicates that dependences between direct and maternal effects are determined by breed. Moreover, showed that editing the database plays a role in estimating genetic parameters and includes a more complex pedigree as well as produces slightly different results.…”