Effects of method of offering broiler litter and level of prairie hay intake on growth of Boer × Spanish wethers

Thirty-four Boer × Spanish wethers (18 ± 0.3 kg initial BW; 5 months of age) were used in a 12-wk experiment (2 × 2 + 1 factorial arrangement of treatments) to determine effects of ad libitum consumption of broiler litter (B) alone or mixed with corn (60% B; BC) and of ad libitum vs. restricted ®) prairie hay intake on feed intake and growth performance. Treatments were: Control = ad libitum intake of hay plus an average of 26 g/day of a mineral-based supplement; AH-B = ad libitum intake of hay and B offered separately; AH-BC = ad libitum intake of hay and BC; RH-B = restricted intake of hay (approximately 1% BW; DM basis) and ad libitum intake of B; RH-BC = restricted intake of hay and ad libitum intake of BC. Average corn DM intake (DMI) was 179 and 170 g/day for AH-BC and RH-BC, respectively, and B DMI was similar among supplement treatments (P > 0.05; 258, 271, 299 and 258 g/day for AH-B, AH-BC, RH-B and RH-BC, respectively). Hay DMI averaged 494, 442, 336, 175 and 160 g/day (SE = 16.7), and total DMI was 516, 700, 782, 474 and 585 g/d (SE = 26.2) for Control, AH-B, AH-BC, RH-B, and RH-BC, respectively. Overall ADG ranked (P < 0.05) AH-BC > AH-B and RH-BC > Control and RH-B (-6, 34, 79, 3 and 50 g), and the ratio of ADG:DMI ranked (P < 0.05) AH-BC and RH-BC > AH-B > Control and RH-B (-13, 49, 97, 5 and 85 g/kg) for Control, AH-B, AH-BC, RH-B and RH-BC, respectively. Total tract OM digestibility in period 2 ranked (P < 0.05) Control < AH-B, AH-BC and RH-B < RH-BC (34.0, 46.6, 49.8, 50.0 and 63.7% for Control, AH-B, AH-BC, RH-B and RH-BC, respectively). Ruminal fluid ammonia N concentration was lowest among treatments (P < 0.05) at 2 and 6 h after supplementation for Control (e.g., 6 h: 4.0, 19.5, 17.2, 38.2 and 25.8 mg/dl for Control, AH-B, AH-BC, RH-B and RH-BC, respectively; SE = 2.69). The ratio of acetate:propionate was greatest among treatments (P < 0.05) at 0, 2 and 6 h for Control (e.g., 6 h: 5.27, 4.04, 3.28, 3.64 and 3.10 for Control, AH-B, AH-BC, RH-B and RH-BC, respectively; SE = 0.218). In conclusion, depending on production goals and availability of high-quality feedstuffs such as cereal grains, free-choice consumption of B may be a simple and useful method of supplementing low-quality forage.