Heritabilities and Genetic and Phenotypic Correlations for Prebreeding Traits, Reproductive Traits and Principal Components

Genetic variability of age and weight at puberty, ovulation rate and embryo survival in gilts and relations with production traits

“…The large phenotypic and genetic correlations between age and weight at puberty are in close agreement with most available literature estimates (Reutzel and Sumption, 1968;Young et al, 1978;Hutchens et al, 1981 (Reutzel and Sumption, 1968;Young et al, 1978, Hutchens et al, 1981, Rydhmer et al, 1992 …”

“…Conversely, the value obtained for weight at puberty is larger than most literature estimates (Young et al, 1978;Hutchens et al, 1981 (Neal et al, 1989) and with estimates obtained in mice and rabbits (Clutter et al, 1990;Blasco et al, 1993b (Young et al, 1977), 50 days of gestation (Neal et al, 1989) or at birth (Young et al, 1978) is observed. This may be due to differences in the populations studied, but may also indicate that uterine competition tends to increase throughout gestation.…”

Direct responses to selection for increased litter size, decreased age at puberty, or random selection following selection for ovulation rate in swine.

“…Similarly, realized heritability for age at puberty was about half as large as the estimate of .53 obtained from the sire component of variance using data from the first selection phase of this experiment (Young et al, 1978). Young and coworkers also obtained very small estimates of genetic correlations of age at puberty with ovulation rate and litter size.…”

Comparison of methods of estimating variance components in pigs.

“…The value for c( for LS might truly be zero as indicated by the magnitude of e and its large empirical CV (Table 3) and the fact that PE only yields positive estimates. Young et al (1978) by Young et al (1978). When the Nebraska Gene Pool population was developed, one of the motivations for producing a 14-breed synthetic line was to increase the additive genetic variance in the line above levels found in the foundation breeds.…”