Submitted to: American Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: January 5, 1997
Publication Date: N/A
Technical Abstract: Traditional selection for litter size in pigs has had limited success since the trait has a low heritability and can only be measured in females. Two reports identified potential genetic correlations between serum concentrations of FSH in boars (FSH) and ovulation rate in gilts (OVR). However, neither study was designed to estimate genetic correlations accurately. We developed a four generation resource population which had measurements of OVR (n=101 gilts) and FSH (n=42 boars) selected from generation 3 to produce generation 4. Measurements for FSH (n=408 boars) and OVR (n=396 gilts) were recorded. In addition, age at first estrus (PUB) was also recorded for all females in both generations. MTDFREML was used to estimate heritabilities (h2) and genetic correlations (rg). The model included the fixed effect of year-season. Initially, each trait was analyzed separately to determine priors for direct (D), maternal (M), permanent environment (P) and residual variances. Estimates of M and P were negligible for PUB and OVR and these components were set equal to zero for subsequent analyses. Multiple trait analyses were conducted using the priors determined along with both positive and negative priors for genetic covariances. The converged estimates of h2 were moderate for all traits analyzed (.42, .45 and .42 for FSH, OVR and PUB, respectively). Contrary to prediction, rg of FSH with OVR (-.06) and PUB (.04) were near zero and rg between OVR and PUB was also low (-.09). These results indicate that FSH measurements in males is not a good indicator of their genetic potential for female reproduction in pigs.