Tip of The Day - October 21, 2016

Photo by Tom Semadeni

Snowy Road

1988 Litter Size in Swine

Olwen Southwood and Brian Kennedy

Estimation of heritability for litter size through daughter-dam regression or maternal half-sib analyses may be biased by maternal effects. These effects are assumed to have their largest impact in the gilt litter, mainly from a negative environmental effect of fraternity size, i.e. the litter size in which the gilt was born. By using an animal model with complete relationships and including all significant sources of environmental variation, more accurate estimates of additive direct and maternal genetic variances may be obtained.

First parity records from purebred Landrace and Yorkshire swine were available from the Sow Productivity and Management Program in Quebec from 1977 to 1987. There were over 4300 records on number born, number born alive, and number alive at weaning. Derivative-Free REML was used to estimate the variances and covariances. The additive genetic variance in Yorkshire was 0.10 for direct and 0.03 for maternal.

Photo by Tom Semadeni

Stream in Snow