|Wells, James - Jim|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/10/2013
Publication Date: 7/1/2014
Publication URL: http://handle.nal.usda.gov/10113/58979
Citation: Davis, M.P., Freetly, H.C., Kuehn, L.A., Wells, J. 2014. Influence of dry matter intake, dry matter digestibility, and feeding behavior on body weight gain of beef steers. Journal of Animal Science. 92(7):3018-3025.
Interpretive Summary: Feed is the most expensive input cost associated with raising beef cattle. Cattle differ in the efficiency that they convert nutrients to body tissue. Understanding the underlying biological mechanism that contributed to the differences in efficiency of feed utilization will help producers to optimize management strategies to improve the efficiency of beef production. The research conducted in this study demonstrated that body weight gain increased with increased food intake, and cattle that more completely digested their food gained more body weight. Understanding what controls appetite and what biological mechanism control extent of digestion will be important to select individual animals that have a greater feed efficiency.
Technical Abstract: This study was conducted to determine the relative contribution of feeding behavior, DM intake, apparent DM digestibility (DMD), and passage rate on variation in BW gain. One hundred forty-three crossbred steers were used in this study to determine the factors that contribute to variation in BW gain. Steers were 304 ± 1 d of age and had an initial BW of 338 ± 3 kg. Steers had ad libitum access to feed, and fresh feed was offered at 0800 h and 1500 h daily. Individual feed intake and BW gain were determined for 106 d. Titanium dioxide was used as an external marker to estimate apparent DMD and passage rate. A multiple regression analysis was used to determine the relative contribution of initial BW, feed intake, feeding behaviors, digestibility, and passage rate to variance in BW gain. Dry matter intake, initial BW, and apparent DMD accounted for 35% of the variation in BW gain. Initial BW was negatively associated with BW gain and accounted for 53.1% of the described variance. Dry matter intake was positively related to BW gain and accounted for 45.4% of the variance. When total meals and meal size were substituted for DMI in the regression analysis, the regression accounted for 32% of the variation in BW gain. Apparent DMD accounted for a similar proportion (1.7%) of variation in the previous regression; however, the proportion described by initial BW decreased (7.1%). Substituting passage rate for apparent DMD resulted in a regression that accounted for 28% of the variation in BW gain. Passage rate accounted for 0.1% of the variation. Substituting total meals and meal size for DMI did not increase the amount of variance in BW gain accounted for by the regression models. Both apparent DMD and passage rate accounted for small proportions of the variance suggesting that they are minor contributors toward variance in BW gain.