35—50 kg黑头杜泊羊×小尾寒羊F1代杂交羊饲粮中适宜NFC/NDF比例研究

【目的】通过体外产气和动物饲养试验，以动物试验为主，探讨肉用绵羊饲粮中非纤维性碳水化合物（NFC）/中性洗涤纤维（NDF）最佳比例。【方法】75只黑头杜泊羊×小尾寒羊F1代肉用绵羊，采用单因素完全随机区组试验设计，分为5个处理，每个处理10只母羊和5只公羊，每5只为1个重复，公母分圈饲养。饲喂粗蛋白质水平为11.90%，NFC/NDF比例分别为1.36﹕1，1.07﹕1，0.82﹕1，0.60﹕1，0.46﹕1的试验饲粮，试验期为56 d。试验羊体重在50kg左右时进行为期4 d的粪袋全收粪试验，测定饲粮营养成分的表观消化率。在动物试验之前利用体外产气方法进行体外试验，测定产气参数和发酵参数。【结果】体外产气试验结果表明：随着NFC/NDF比例的降低，72 h产气量、产气速率、有机物降解率、总挥发性脂肪酸、丙酸丁酸比例显著降低（P＜0.01）；而72 h发酵液pH、乙酸比例以及乙酸/丙酸显著升高（P＜0.01）。当NFC/NDF比例为0.82时，微生物蛋白的产量显著高于其他组（P＜0.01）；动物试验结果表明：动物生长性能，公羊与母羊的净增重以及平均日增重各组间均无显著差异（P＞0.05），但在表观数值上公母羊均表现为0.82组＞1.36组＞1.07组＞0.60组＞0.46组。试验羊的干物质采食量与饲粮NFC/NDF比例呈现正相关关系(R2=0.6573，P=0.0002），料重比各组间没有显著性差异（P＞0.05）。饲粮NDF水平对干物质（DM）、有机物（OM）、粗蛋白质（CP）、粗脂肪（EE）、中性洗涤纤维（NDF）和酸性洗涤纤维（ADF）的表观消化率存在极显著影响（P＜0.01），各营养成分表观消化率均以0.82组为最佳。【结论】在以羊草和苜蓿干草为饲粮NDF来源，粗蛋白质水平为11.90%的肉羊饲粮中，35—50 kg肉用绵羊饲粮中最佳NFC/NDF比例为0.82，或者饲粮NDF的适宜水平为42.21% 。

Research on Proper Dietary NFC/NDF Ratio for 35-50 kg Dorper × Small Tail Han Crossbred Lambs

【Objective】Dorper × Small Tail Han sheep crossbred lambs from 35 to 50 kg of live weight were used in a feeding trail, combined with in vitro gas production, to study proper dietary non-fiber carbohydrate to neutral detergent fiber(NFC/NDF) ratio.【Method】 Fifty female lambs and 25 male lambs were randomly assigned into five groups of ten female lambs and five male lambs each (five lambs/replication). Female and male lambs were separated in feeding. Each group was fed with one of the five diets which have the same crude protein level(11.90%) and different NFC/NDF ratios. The NFC/NDF ratios of the five diets were 1.36:1, 1.07:1, 0.82:1, 0.60:1, and 0.46:1，respectively. The experiment lasted for 56 d. Growth performance was measured, and a digestive trail was conducted after the sheep reached 50 kg of live weight. 【Result】 The in vitro gas production results showed as follows: As the dietary NFC/NDF ratio decreased, the gas production at 72 h, the ratio of gas production, in vitro digestibility of organic matter (IVDOM), total volatile fatty acids (TVFA),the ratios of propionate to butyrate were decreased significantly(P＜0.01), but the pH values of fermentation liquor, the ratio of acetate and acetate/propionate(A/P) were increased significantly(P＜0.01), the microbial crude protein(MCP) was higher than other groups when the NFC/NDF ratio was 0.82﹕1. The feeding trail results showed as follows: There were no significant effects of dietary NFC/NDF ratios on net body gains, average daily gains (P＞0.05) of the lambs; but gender of lambs played a significant role on this(P＜0.05). The order of body gains was 0.82＞1.36＞1.07＞0.60＞0.46 groups. Dry matter intake of the lambs had a positive correlation with dietary NFC/NDF ratios(R2=0.6573, P=0.0002), and showed a notable difference among five groups (P＜0.01), but dietary NFC/NDF ratios had no significant effects on feed conversion ratios (P＞0.05). NFC/NDF ratios had significant effects on apparent nutrient digestibility of dry matter, organic matter, crude protein, ether extract and fiber (P＜0.01), they were the highest in 0.82 group than in others. 【Conclusion】From the results of the experiment it is recommended that 0.82 is the proper dietary NFC/NDF ratio or 43.21% is the proper dietary NDF level for 35-50 kg Dorper × Small Tail Han sheep crossbred lambs while the dietary crude protein level is 11.90% and the NDF comes from Chinese wildrye and alfalfa hay.