T WO factors affect lambing rate: (1) frequency of lambing and (2) number of lambs born per pregnancy. Certain individual ewes have given birth to live normal lambs three times within a 12-mo. period. I t is thus apparent that under proper physiological conditions two lambings a year are possible. When the physiological processes involved and their mechanisms of action are more adequately under...

The growth endocrine axis influences reproduction. A QTL associated with enhanced ovulation exists on chromosome 5 in cattle and there are 6 genes underlying this region involved in the mechanisms of GH action. Resequencing exons, 5’ and 3’ untranslated regions and conserved non-coding regions of these genes in a multibreed resource population revealed 75 SNP usable for genotype to phenotype as...

Longevity and lifetime productivity are important factors influencing profitability for the cow-calf producer. Heifers that conceive earlier in the breeding season will calve earlier in the calving season and have a longer interval to rebreeding. Calves born earlier in the calving season will also be older and heavier at weaning. Longevity data were collected on 2,195 heifers from producers in ...

Data from 528 male and 645 female progeny of 63 sires were used to estimate genetic correlations between female and male reproductive traits. Data were from two Hereford herds involved in a long-term selection program of the North Carolina Agricultural Experiment Service. Testicular measurements of circumference, diameter, length and volume were obtained on bulls at 205 and 365 d. Testicular gr...

Two trials were conducted with a total of 91 lactating sows fed 0, 5 or 10 ppm dietary zearalenone (Z) and 0 or 15% dietary alfalfa in a factorial arrangement to evaluate their influence on reproductive performance to 40 d postbreeding. Feeding of Z did not alter the proportion of sows returning to estrus; however, the weaning-to-estrus interval increased when increased dietary Z was fed in Tri...