|Smith, Timothy - Tim|
Submitted to: Journal of Animal Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/28/2006
Publication Date: 12/1/2006
Citation: White, S.N., Casas, E., Allan, M.F., Keele, J.W., Snelling, W.M., Wheeler, T.L., Shackelford, S.D., Koohmaraie, M., Smith, T.P. 2007. Evaluation in beef cattle of six deoxyribonucleic acid markers developed for dairy traits reveals an osteopontin polymorphism associated with post-weaning growth. Journal of Animal Science. 85:1-10. Interpretive Summary: A genetic marker in the SPP1 (osteopontin) gene has been published previously for selection of dairy cattle for milk yield, fat yield, fat percent, and protein percent. This study demonstrates the association of this SPP1 gene marker with post-weaning growth in beef cattle. Under the conditions of this study, cattle with two copies of the T10 allele weighed 10.5-11.5 kg (23.1-25.4 lbs) more at slaughter than cattle with only one copy of the T10 allele. This was true in two populations with very different genetic backgrounds, so this genetic marker should be useful for post-weaning growth in beef cattle of many breeds. However, more studies will be necessary to determine the optimal feeding and growth conditions to best utilize cattle with this desirable genetic composition.
Technical Abstract: Six DNA markers have been reported to be associated with variation in dairy production traits. The objectives of this study were to 1) estimate allele frequencies in U.S. beef cattle and 2) evaluate association of marker genotype with beef production traits. Several genetic markers have been associated with milk yield or composition, including polymorphisms in secreted phosphoprotein 1 (SPP1; also called osteopontin), growth hormone receptor (GHR), casein S1 (CSN1S1), diacylglycerol O-acyltransferase 1 (DGAT1), peroxysome proliferator-activated receptor gamma coactivator-1alpha (PPARGC1A), and ATP-binding cassette, sub-family G (white), member 2 (ABCG2). Allele frequencies for these six markers and association with 21 phenotypes were evaluated in two crossbred beef cattle populations that sample influential industry sires. Five of six markers were segregating in beef cattle populations; the exception was ABCG2. The SPP1 marker was associated with yearling weight (P = 0.025), live weight at slaughter (P = 0.016), post-weaning average daily gain (P = 0.007), and hot carcass weight (P = 0.007) in a large, multi-sire population representing the seven most populous beef breeds in the U.S. Post-weaning growth trait associations were confirmed in an independent population of similar construction including sires from tropically adapted breeds. The SPP1 marker was associated with yearling weight (P = 0.034), live weight at slaughter (P = 0.011), and post-weaning average daily gain (P = 0.015), and showed a trend toward association with hot carcass weight (P = 0.083) in this population. While DGAT1, GHR, and CSN1S1 polymorphisms did show association with some traits in individual populations, the lack of consistent predictive merit between populations indicates they may not be generally suited for beef cattle selection. No significant associations were observed for the PPARGC1A marker and any of 21 recorded traits, indicating this marker had no apparent value in selection for the beef cattle traits tested in these populations. The SPP1 marker had consistent associations and effect sizes (10.5-11.5 kg live weight at slaughter) in both populations, providing strong evidence for utility of the SPP1 marker for post-weaning growth in beef cattle.