Abstract

Faecal egg count (FEC) is used commonly as a guide to nematode parasite burdens in animals in vivo. The objective of this study was to estimate the heritability and repeatability of FEC in commercial beef calves, along with breeding values for FEC in the calves and their sires, for future quantitative and molecular analyses. In 2008-2011, faecal samples from 4,621 weaned beef calves were obtained for FEC1 from 11 herds (mainly Angus or Hereford). FEC1 represented the first sample after weaning generally between May and July); a second sample (for FEC2) was taken by September from all calves in some herds, with FEC1 and FEC2 samplings separated by an effective anthelmintic drench. Calves were sired by a total of 325 and 57 separate Angus and Hereford sires, respectively. Heritability estimates for loge(FEC+50) in Angus at Times 1 and 2 were 0.28 ± 0.05 (standard error) and 0.11 ± 0.09, respectively, with a genetic correlation of 0.89 ± 0.22 between them. Treating FEC1 and FEC2 as repeated measurements of the same trait, the repeatability estimate for loge(FEC+50) was 0.38 ± 0.04. The parameters estimated for loge(FEC+50) in weaned beef calves under commercial grazing conditions were similar to those from experimental beef calves.

CA, Morris, and NC Amyes

Proceedings of the New Zealand Society of Animal Production, Volume 72, Christchurch, 236-239, 2012