DRYLOT PERFORMANCE AND RUMINAL PAPILLAE DEVELOPMENT OF LAMBS EXPOSED TO A HIGH CONCENTRATE DIET WHILE NURSING

In 1986 (trial 1), lambs were exposed with their mothers to WB-PMP (whole barley and protein-mineral pellet) for 15 min/d for 0, 2, 4, 8 or 16 d. In 1987 (trial 2), they were exposed for 0, 4 or 8 d; two treatments for 8 d, with one receiving four times more WB-PMP (8H) than the other (8L). Following exposure to WB-PMP in both years, lambs and their dams grazed on summer range for 2 months before the drylot tests. Exposure for 4 d increased (P < 0.05) intake of WB-PMP during the first week it was offered in drylot in 1986, but not (P > 0.05) in 1987. Lambs exposed for 2, 8 or 16 d in 1986 did not consume more WB-PMP than controls (P > 0.05). In 1987, lambs in treatment 8L consumed more (P < 0.05) WB-PMP than controls during the first 2 weeks in drylot. Amount of WB-PMP offered affected intake of WB-PMP in drylot. Lambs in treatment 8H consumed more (P < 0.05) than controls during the first 3 weeks in drylot. Lambs with high WB-PMP intakes during weeks 1 and 2 in both years consumed less WB-PMP during weeks 3 and 4, especially in 198 7. The reduction in intake was greater for lambs previously exposed to WB-PMP than for controls. In 1986, 81% of the lambs exposed for 4 or 8 d and 64% of the lambs for 16 d achieved slaughter condition by week 8 in drylot, while only 50% and 33% of the lambs exposed for 0 or 2 d reached slaughter condition by that time (P < 0.05). In 1987, lambs on WB-PMP did not reach slaughter condition sooner than controls, probably due to severe decrease in intake that occurred during weeks 3 and 4 in drylot. Lambs exposed to WB-PMP for 8 d in 1987 entered the drylot with ruminal papillae that had 38% more surface area than did lambs not exposed to WB-PMP; however, the differences disappeared within 3 weeks. Results indicate that exposing lambs to a WB-PMP diet early in life enhanced performance in drylot. Development of rumen papillae as a result of exposure may contribute to this performance.