Effects of level of broiler litter in diets containing wheat straw on performance of Alpine doelings

Thirty-two Alpine doelings (15 weeks of age; 12 +/- 2.05 kg BW) were used in a completely randomized design 12-week experiment to compare performance with diets based on wheat straw (WS) supplemented with different levels of broiler litter to WS supplemented with a conventional protein source or ammoniated through urea treatment (TWS). Treatments were feeding of a corn-based concentrate at 1.5% of BW (DM basis) with TWS (U) and the U supplement plus approximately 0.4% BW of soybean meal (S) or 0.8 or 1.6% BW of broiler litter (LL and HL, respectively) with WS. Nitrogen concentration was 0.47 and 2.07% DM and in vitro DM digestibility was 47.7 and 67.8% for WS and TWS, respectively; concentrate N concentration was 1.27, 3.16, 2.35 and 2.66% for U, S, LL and HL, respectively. Crude protein intake in week 6 was approximately 11.0, 14.6, 9.4 and 11.7% of total DM intake (DMI) for U, S, LL and HL, respectively. Organic matter digestibility was greater (P < 0.05) for S than for the mean of LL and HL (68.9, 78.2, 68.3 and 68.8; SE = 3.3), but there was an opposite trend (P < 0.10) in digestible OM intake (256, 272, 323 and 339 g/day for U, S, LL and HL, respectively; SE = 27.9). Average WS intake in the entire experiment was similar among treatments (223, 167, 207 and 191 g/day) and total DMI was lower for U than for the mean of other diets, lower for S than for the mean of LL and HL and lower for LL vs. HL (P < 0.05; 433, 429, 536 and 651 g/day for U, S, LL and HL, respectively). Average daily gain (ADG) did not differ among treatments (61, 70, 63 and 66 g/day), although the ratio of ADG to DMI was lower for the mean of LL and HL compared with S (P < 0.05; 145, 170, 122 and 104 g/kg for U, S, LL and HL, respectively). In conclusion, supplementation of WS with a natural protein source such as soybean meal or with broiler litter can support a rate of growth of young Alpine doelings as great as feeding of TWS, although under conditions of this experiment efficiency of feed usage was lower for broiler litter than for soybean meal.