Effects of the FecL Major Gene on Mean and Variance of Litter Size in the Lacaune Meat Sheep Population

Abstract Text: The major gene FecL controlling prolificacy and evidenced in the meat Lacaune population was routinely genotyped in the Ovi-Test selection nucleus on all serving sires since 2002 and all replacement ewes since 2010. Litter size at lambing of these genotyped females have been collected and analysed. The population was composed of 71% homozygous ++, 27% heterozygous L+ and 2% mutated LL females. Analyses were performed with a threshold animal mixed model which showed an interaction between thresholds and genotypes. Polygenic heritability on the underlying scale was 0.11 and the gene accounted for 42% of the total additive genetic variance. On average L+ ewes produced 0.4 more lambs than ++ ewes. A new parameterization of the underlying variables and thresholds showed that the gene had an effect on the variability of the trait additionally to the direct variability increase induced by the mean change.

Keywords:

Major gene

Sheep

Prolificacy