Blood serum concentration of @entity4208 was analyzed to determine its relationship with individual postweaning feed efficiency (gain/feed) of 36 crossbred steer @entity291 fed at three levels of feed intake (n = 12 at each level). Diets consisted of a @entity4336 silage-based growing diet for 84 d followed by a 91% concentrate finishing diet for 56 d. Dietary intake levels were at 80, 90, or 100% of ad libitum. Diets were formulated to ensure equal daily intake of protein, vitamins, and minerals across intake treatment levels. Intake was measured daily; @entity7156 , DMI, and feed efficiency were calculated at 28-d intervals, through d 140. Individual weights and serum samples were collected at the beginning of the study and at 28-d intervals thereafter. The @entity4208 concentrations were determined with a RIA. Data were analyzed as a multivariate split-plot in time. Imposed dietary intake restrictions did not affect serum @entity4208 concentration (P = .90) or individual feed efficiency (P = .36), even though the least squares means for @entity4208 concentration tended to decrease and the feed efficiency means tended to increase under the restricted intake levels. Serum @entity4208 concentration, @entity7156 , and feed efficiency were affected (P < .001) by collection date. Residual correlations between @entity4208 concentrations at adjacent 28-d sampling times averaged .72. Diet intake level x sampling time interactions existed for @entity7156 (P = .02) and feed efficiency (P < .001). Positive residual correlations of .28 (P < .001) and .16 (P = .07) existed between @entity4208 and @entity7156 and between @entity4208 and feed efficiency, respectively. Regression analysis indicated that a 1 ng/mL increase in serum @entity4208 concentration was associated with a .00135 kg/d increase in @entity7156 (P < .001) and a .0001 kg gain/kg feed increase in feed efficiency (P = .04). These results support the hypothesis that serum @entity4208 plays a role in growth and in efficiency of feed utilization in beef @entity291 .

Relationship between blood serum insulin-like growth factor I concentration and postweaning feed efficiency of crossbred XXXX at three levels of dietary intake.

@entity4208 :: ('104978413', 'Gene') :: ['IGF-I'] @entity4336 :: ('381124', 'Species') :: ['corn'] @entity291 :: ('9913', 'Species') :: ['cattle', 'calves'] @entity7156 :: ('102657752', 'Gene') :: ['ADG']
@entity291 :: (9913,Species) :: ['cattle']
