The influence of maternal effects on litter size in pigs.
1989
Joergensen J.N.
Investigations of 826 first litter records showed that gilt litters were influenced by season, inbreeding and age at mating. Heritability estimates using pooled paternal halfsib estimates and paternal granddam-granddaughter regression for number of piglets born, born live, at 3 weeks and weaned were 0.35, 0.21, 0.13 and 0.19 respectively. Maternal granddam-granddaughter regression gave estimates of 0.27, 0.26, 0.34 and 0.20 respectively. Low estimates from the dam-daughter regression of 0.06, 0.11, 0.07 and 0.13 respectively, indicate an influence of maternal effect. The maternal effect was estimated by the m-value to be -0.11, -0.09, -0.04. Higher birth weight at three weeks and at weaning of the gilt increased gilt litter size. This regression tended to be larger for gilts born in litter with at least 11 pigs than for gilts born in litters with at most 10 pigs. Maternal influence measured by body weight varied between 45% and 65% of the m-value.
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