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This Article Full Text Full Text (PDF) All Versions of this Article: jas.2007-0751v1 86/12/3338    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Mc Parland, S. Articles by Berry, D. P. Search for Related Content PubMed PubMed Citation Articles by Mc Parland, S. Articles by Berry, D. P.

Inbreeding effects on postweaning production traits, conformation, and calving performance in Irish beef cattle

S. Mc Parland^*,,1, J. F. Kearney, D. E. MacHugh and D. P. Berry^*

^* Teagasc, Moorepark Dairy Production Research Centre, Fermoy, Co. Cork, Ireland; and Animal Genomics Laboratory, School of Agriculture, Food Science and Veterinary Medicine and Conway Institute for Biomolecular and Biomedical Research, College of Life Sciences, University College Dublin, Belfield, Dublin 4, Ireland; and Irish Cattle Breeding Federation, Bandon, Co. Cork, Ireland

¹ Corresponding author: sinead.mcparland{at}teagasc.ie

The objective of this study was to quantify the effect of inbreeding on carcass quality, growth rate, live conformation measures, and calving performance in purebred populations of Charolais, Limousin, Simmental, Hereford, and Angus beef cattle using data from Irish commercial and pedigree herds. Variables analyzed are reflective of commercial farming practices. Inbreeding was included in a linear mixed model as either a class variable or a linear continuous variable. Nonlinear effects were nonsignificant across all traits. Inbred animals had decreased carcass weight and less carcass fat. The effects of inbreeding were more pronounced in the British beef breeds. Effects for carcass weight ranged from –0.87 kg (Charolais) to –1.90 kg (Hereford) per 1% increase in inbreeding. Inbred Charolais and Hereford animals were younger at slaughter by 3 and 5 d, respectively, per percentage of increase in inbreeding, whereas the effect of inbreeding on age at slaughter differed significantly with animal sex in the Limousin and Angus breeds. Inbred Limousin and Angus heifers were younger at slaughter by 5 and 7 d, respectively, per percentage of increase in inbreeding. Continental animals were more affected by inbreeding for live muscling and skeletal conformational measurements than the British breeds; inbred animals were smaller and narrower with poorer developed muscle. Calf inbreeding significantly affected perinatal mortality in Charolais, Simmental, and Hereford animals. The effects were dependent upon dam parity and calf sex; however, where significant, the association was always unfavorable. Dam inbreeding significantly affected perinatal mortality in Limousin and Hereford animals. Effects differed by parity in Limousins. Inbred first-parity Angus dams had a greater incidence of dystocia. Although the effects of inbreeding were some-times significant, they were small and are unlikely to make a large financial effect on commercial beef production in Ireland.

Key Words: beef cattle • calving performance • carcass • growth • inbreeding depression