A NOTE ON GENETIC CORRELATIONS BETWEEN PUBERTAL TRAITS OF MALES OR FEMALES AND LIFETIME PREGNANCY RATE IN BEEF-CATTLE

Genetic correlations were estimated between pubertal traits of males o r females and yearling or lifetime pregnancy rate (PR) in beef cows, u sing 269 paternal half-sib groups. Lifetime PR was recorded from up to 5 mating/calving years for each cow. The genetic correlations between age at first oestrus (AFO) or standardised age at first oestrus (SFO) and yearling PR were -0.30 +/- 0.26 and -0.67 +/- 0.44, whilst corres ponding estimates with lifetime PR were -0.29 +/- 0.26 and -0.76 +/- 0 .68. For scrotal circumference (SC), genetic correlation estimates wit h yearling PR were 0.53 +/- 0.66 and with lifetime PR 0.34 +/- 0.40. T he data generally supported the concept of a favourable genetic correl ation between pubertal traits (higher SC or lower AFO and SFO) and lif etime PR.