Inbreeding depression on beef cattle traits: Estimates, linearity of effects and heterogeneity among sire-families

Nuno Carolino; Luis T. Gama

doi:doi:10.1051/gse:2008018

Genet. Sel. Evol. 40 (2008) 511-527
DOI: 10.1051/gse:2008018

Inbreeding depression on beef cattle traits: Estimates, linearity of effects and heterogeneity among sire-families

Nuno Carolino¹ and Luis T. Gama^{1, 2}

¹ Estacção Zootécnica Nacional - INRB, 2005-048 Vale de Santare'm, Portugal
² Faculdade de Medicina Veterinária - Universidade Técnica de Lisboa, 1300-477 Lisboa, Portugal

Received 10 December 2007; accepted 25 March 2008; published online 12 August 2008

Abstract - Records from up to 19 054 registered cows and 10 297 calves in 155 herds of the Alentejana cattle breed were used to study the effects of individual (F $_{\rm i}$ ) and maternal (F $_{\rm m}$ ) inbreeding on reproductive, growth and carcass traits, as well as assessing the importance of non-linear associations between inbreeding and performance, and evaluating the differences among sire-families in the effect of F $_{\rm i}$ and F $_{\rm m}$ on calf weight at 7 months of age (W7M). Overall, regression coefficients of performance traits on inbreeding were small, indicating a minor but still detrimental effect of both F $_{\rm i}$ and F $_{\rm m}$ on most traits. The traits with the highest percentage impact of F $_{\rm i}$ were total number of calvings through life and calf weight at 3 months of age (W3M), followed by longevity and number of calves produced up to 7 years, while the highest effect of F $_{\rm m}$ was on W3M. Inbreeding depression on feed efficiency and carcass traits was extremely small and not significant. No evidence was found of a non-linear association between inbreeding and performance for the traits analyzed. Large differences were detected among sire-families in inbreeding depression on W7M, for both F $_{\rm i}$ and F $_{\rm m}$ , encouraging the possibility of incorporating sire effects on inbreeding depression into selection decisions.

Key words: Alentejana / cattle / inbreeding depression / individual inbreeding / maternal inbreeding

Corresponding author: genetica.ezn@mail.telepac.pt

© INRA, EDP Sciences 2008