EFFECTS OF CORN VS CORN PLUS WHEAT IN FORAGE-BASED DIETS CONTAINING BROILER LITTER ON FEED-INTAKE, RUMINAL DIGESTA CHARACTERISTICS AND DIGESTION IN CATTLE

Cattle consuming low-to moderate-quality forage were supplemented with corn or a 1:1 corn:wheat mixture with or without broiler litter to de termine effects on feed intake, ruminal digesta characteristics and di gestion. In the first experiment, mature beef steers (529 +/- 33 kg in itial body weight) with cannulas in the rumen and duodenum were fed pr airie hay and soybean meal alone (control) or with (dry matter basis) 0.3% body weight (BW) of ground corn (C), 0.15% BW of corn plus 0.15% BW of ground wheat (CW), corn plus 0.3% BW of broiler litter (C-L) or the corn-wheat mixture plus 0.3% BW of broiler litter (CW-L). Ruminal fluid ammonia nitrogen (N) concentration 2 h after feeding was increas ed (P < 0.05) by supplementation and was greater (P < 0.05) for C-L th an for CW-L (8.9, 9.3, 11.4, 27.6 and 21.4 mg dl(-1) for control, C, C W, C-L and CW-L, respectively). Neither duodenal microbial N how nor e fficiency of microbial growth was affected by treatment. In the second experiment, Holstein steers (129 +/- 11 and 219 +/- 17 kg initial and final BW, respectively) consumed ad libitum bermudagrass hay alone (c ontrol) or with (dry matter basis) 0.6% BW of corn (C), 0.3% BW of cor n plus 0.3% BW of wheat (CW), corn plus 0.6% BW of broiler litter (C-L ) or the corn-wheat mixture plus 0.6% BW of broiler litter (CW-L). Tot al organic matter (OM) intake was increased (P < 0.05) by supplementat ion and inclusion of broiler litter in supplements (4.34, 4.91, 5.14, 5.27 and 5.32 kg day(-1)); total tract OM digestion was increased (P < 0.05) by supplementation and was lower (P < 0.05) for supplement trea tments with than without broiler litter (57.2, 61.8, 63.0, 59.5 and 59 .9%); and digestible OM intake was increased (P < 0.05) by supplementa tion and was not altered by broiler litter inclusion in supplements (2 .51, 3.05, 3.25, 3.14 and 3.20 kg day(-1) for control, C, CW, C-L and CW-L, respectively). In summary, supplementation of a diet containing broiler litter with a corn-wheat mixture compared with corn alone decr eased ruminal ammonia N concentration early after feeding but did not change duodenal microbial N flow or efficiency of microbial growth. Gr ain source did not alter total feed intake by growing Holstein steers consuming diets with broiler litter, and an increase in total feed int ake when broiler litter was included in diets compensated for low dige stibility of broiler litter.