Submitted to: World Congress of Genetics Applied in Livestock Production
Publication Type: Proceedings
Publication Acceptance Date: 3/13/2002
Publication Date: 8/19/2002
Citation: Leymaster, K.A., Cammack, K.M., Nielsen, M.K., Jenkins, T.G. 2002. Estimates of genetic parameters for daily gain, feed intake, and behavior traits in ram lambs of a composite population. Proceedings of the 7th World Congress of Genetics Applied in Livestock Production. CD-ROM Communication No. 10-09. Montpellier, France. Interpretive Summary: One approach to increase profitability of sheep production is to improve the conversion of feed into gain. Development of breeds by selection to improve feed efficiency requires estimates of genetic parameters for feed intake and daily gain. This study provides the first reliable estimate of the heritability of feed intake in sheep, indicating that 25% of the variation is genetically determined. Genes that influence feed intake also affect daily gain to a large degree (the estimate of the genetic correlation is 0.80). Therefore, it will be a challenge to develop selection procedures that favorably affect the relative levels of performance for feed intake and daily gain, for example, increase daily gain without increasing feed intake.
Technical Abstract: Data were recorded from 11 to 17 wk of age on 1,241 ram lambs of a terminal sire composite population. Individual feeding events (length and intake) of each lamb were recorded in a group situation. Estimates of (co)variance components were obtained using MTDFREML. Heritabilities were estimated for daily feed intake (0.25±0.06), event feed intake (0.33±0.07), daily time (0.24±0.05), event time (0.29±0.06), daily number of events (0.33±0.07), and average daily gain (0.27±0.06). The estimated genetic correlation between daily feed intake and average daily gain was 0.80, implying limited opportunity to select for improved efficiency. Remaining genetic correlations ranged from 0.19 to 0.55. Selection for average daily gain and/or daily feed intake is expected to change feeding behavior of ram lambs housed in a group situation.