Abstract

An experiment was established at Waikeria, near Te Awamutu, to select for pubertal traits in Angus cattle, with selection first applied to the animals born in 1982. The aims of this paper are to report on genetic parameters for age at first oestrus (AFO) in heifers, weight at first oestrus (WFO) in heifers, scrotal circumference (SC), 13-month weight (W13) and calving day (CD), to compare the performance of young animals in the selection and control herds, and to assess prospects of achieving a correlated response in calving rate. Three selection herds and a control were set up, with single selection objectives being SC, AGE+ and AGE-, where '+' and '-' indicate selection for greater or lesser AFO. Phenotypic coefficients of variation were 15% for AFO, 11% for WFO, 8% for SC, and 8% for W13. Corresponding heritability estimates from Waikeria were 0.15, 0.30, 0.24 and 0.33, compared with those from other New Zealand research herds which averaged 0.34, 0.37, 0.38 and 0.36 respectively. The genetic correlation estimate for AFO and SC was - 0.81

TG, Watson, BC Hosking, DL Johnson, and AP Hurford

Proceedings of the New Zealand Society of Animal Production, Volume 53, , 359-362, 1993