Browsing by Author "McDonnell, Michael F."

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Effects of barley cultivar and growing environment on feedlot performance and carcass characteristics of finishing beef cattle
(Montana State University - Bozeman, College of Agriculture, 2004) McDonnell, Michael F.; Chairperson, Graduate Committee: Janice G. P. Bowman.
Thirty-two crossbreed beef heifers (initial weight 349 kg ± 2.21 kg) were individually fed finishing diets for 84 d in a 2 X 2 factorial experiment examining the effects of barley cultivar (Harrington vs. Valier) and growing environment (irrigated vs. dryland) on animal performance, carcass characteristics, and nutrient digestibility. No differences in ADG (P = 0.46; average 1.78 kg/d) or final weight (P = 0.23; average 498 kg) were detected due to cultivar. Barley cultivar did not affect DMI (P = 0.80; average 9.8 kg/d), or feed efficiency (P = 0.63; average 18.3 kg gain/100 kg of feed). Growing environment did not influence ADG (P = 0.17; average 1.77 kg/d), or final weight (P = 0.20; average 498 kg). Heifers fed diets containing irrigated barley had lower (P = 0.009) DMI than heifers fed diets containing dryland barley (9.3 vs. 10.3 kg/d, respectively). Feed efficiency was higher (P = 0.001) for heifers fed diets containing irrigated barley than for those fed dryland barley (19.8 vs. 16.8 kg gain/100 kg of feed). Barley NEm (P = 0.38; average 2.15 Mcal/kg) or NEg (P = 0.38; average 1.46 Mcal/kg) were not affected by cultivar. Irrigated barley NEm and NEg (2.31 and 1.61 Mcal/kg, respectively) contents were higher (P = 0.001) than dryland barley NEm and NEg (1.98 and 1.32 Mcal/kg, respectively) content. No differences (P > 0.06) in carcass characteristics were detected due to barley cultivar, growing environment or their interaction. Dry matter digestibility was higher (P = 0.02) for diets containing Valier barley than for diets containing Harrington barley (77.6 vs. 74.9 %, respectively). Starch digestibility was not affected (P = 0.13) by cultivar. Growing environment did not affect (P > 0.06) nutrient digestibility. In summary, irrigated barley had higher starch content and lower ADF content than dryland barley. The higher starch content of the irrigated barley resulted in the irrigated barley having higher energy content than dryland barley, which resulted in the irrigated barley being a more efficient feed source.