Matras J, Bartle S J, Preston R L
Dept. of Anim. Sci, Texas Tech University, Lubbock 79409.
J Anim Sci. 1991 Jan;69(1):339-47. doi: 10.2527/1991.691339x.
The potential interaction between grain (starch) and protein sources with varying ruminal degradation rates on N utilization in growing lambs was evaluated. Three grain sources with varying ruminal degradation rates, (barley greater than steam-flaked sorghum [SFSG] greater than dry-rolled sorghum [DRSG]) and three protein sources (urea greater than a 50:25:25 mixture of urea: blood meal:corn gluten meal [N basis, U/BC] greater than 50:50 mixture of meal:corn gluten meal [N basis, BC]), were evaluated in a 3 x 3 factorial arrangement. Supplemental protein sources provided 33% of dietary N (CP = 11.0%). For each grain-protein combination, a 3 x 3 Latin square metabolism trial was conducted using two sets of three lambs and three periods. Within-square treatments were 1.4, 1.7 and 2.0 times maintenance intake levels. No interactions were observed (P greater than .2) between dietary treatments and intake level. Grain sources did not differ (P greater than .2) in N balance or the proportion of N retained. Lambs fed urea diets retained less N (3.6 vs 4.2 and 4.1 g/d for urea vs U/BC and BC, respectively; linear, P = .07; quadratic, P = .12) and utilized N less efficiently (43.1 vs 51.9 and 52.5%, respectively; linear, P less than .001; quadratic, P = .10) than lambs fed BC diets. The grain x protein interaction was significant for most variables. Nitrogen utilization was most efficient (24 to 27% of N intake retained) when rapidly degraded sources (barley and urea) and slowly degraded sources (sorghum and BC) were fed together or when U/BC was the supplemental protein source (interaction P less than .08). An advantage was found for selection of starch and protein sources with similar ruminal degradation rates.
评估了瘤胃降解率不同的谷物（淀粉）和蛋白质来源对生长羔羊氮利用的潜在相互作用。采用3×3析因设计，评估了三种瘤胃降解率不同的谷物来源（大麦＞蒸汽压片高粱[SFSG]＞干压片高粱[DRSG]）和三种蛋白质来源（尿素＞尿素：血粉：玉米蛋白粉50:25:25混合物[N基础，U/BC]＞血粉：玉米蛋白粉50:50混合物[N基础，BC]）。补充蛋白质来源提供了日粮氮的33%（粗蛋白=11.0%）。对于每种谷物-蛋白质组合，使用两组三只羔羊和三个时期进行了3×3拉丁方代谢试验。方内处理为维持摄入量的1.4、1.7和2.0倍。日粮处理和摄入量水平之间未观察到相互作用（P＞0.2）。谷物来源在氮平衡或氮保留比例方面没有差异（P＞0.2）。与饲喂BC日粮的羔羊相比，饲喂尿素日粮的羔羊保留的氮较少（分别为3.6 vs 4.2和4.1 g/d，尿素组vs U/BC组和BC组；线性，P = 0.07；二次曲线，P = 0.12），氮利用效率较低（分别为43.1% vs 51.9%和52.5%；线性，P＜0.001；二次曲线，P = 0.10）。谷物×蛋白质相互作用对大多数变量具有显著意义。当快速降解来源（大麦和尿素）和缓慢降解来源（高粱和BC）一起饲喂或当U/BC作为补充蛋白质来源时，氮利用效率最高（保留氮摄入量的24%至27%）（相互作用P＜0.08）。发现选择瘤胃降解率相似的淀粉和蛋白质来源具有优势。
