饲粮中全株玉米青贮比例对杜湖杂交母羔生长性能、瘤胃发酵、养分消化率及血清学指标的影响

【目的】研究饲粮中添加不同比例全株玉米青贮对杜湖杂交母羔生长性能、瘤胃发酵特性、养分消化率、血清生化代谢指标、抗氧化能力和免疫功能的影响,为全株玉米青贮在肉羊产业中的推广利用提供科学依据。【方法】选择健康状况良好、体重相近（16±1.5）kg杜湖（杜泊羊♂×湖羊♀）杂一代断奶母羔羊72只,随机分为4组,每组6个重复,每个重复3只羊。Ⅰ组为对照组,饲喂以花生秧作为粗饲料来源的基础饲粮,Ⅱ、Ⅲ和Ⅳ组为试验组分别用20%、40%和60%（DM）全株玉米青贮代替基础饲粮中花生秧。试验共115 d,其中预试期15 d,正试期100 d,包括饲养试验90 d和消化代谢试验10 d。【结果】（1）与基础饲粮I组相比,Ⅲ组羊1—30 d日增重显著提高（P＜0.05）,且1—30 d、1—90 d料重比显著降低（P＜0.05）。（2）饲粮中添加全株玉米青贮可以改善试验羊瘤胃发酵。随着全株玉米青贮比例增加,试验羊瘤胃液中乙酸、丁酸比例及乙酸/丙酸显著降低（P＜0.05）,丙酸比例显著升高（P＜0.05）,Ⅳ组羊瘤胃液中氨态氮浓度显著高于Ⅰ、Ⅱ、Ⅲ组（P＜0.05）。（3）与I组相比,Ⅲ、Ⅳ组干物质、总能表观消化率显著增加（P＜0.05）,Ⅱ、Ⅲ、Ⅳ组有机物、氮表观消化率显著提高（P0.05）;粪氮排出量随着饲粮全株玉米青贮比例的增加显著降低（P＜0.05）,Ⅱ、Ⅲ、Ⅳ组粪氮排出量显著低于Ⅰ组（P＜0.05）;Ⅳ组尿氮排出量显著升高（P＜0.05）,使得Ⅳ组氮沉积率显著低于Ⅲ组（P＜0.05）。（4）Ⅲ组羊血清中葡萄糖浓度在90 d时显著高于Ⅰ和Ⅱ组（P＜0.05）。（5）Ⅲ组羊血清总抗氧化力在90 d时显著高于Ⅰ组（P＜0.05）,而丙二醛浓度显著低于Ⅰ组（P0.05）;Ⅳ组羊血清中超氧化物歧化酶、谷胱甘肽过氧化物酶活性在60 d和90 d时显著高于Ⅰ组（P＜0.05）;Ⅳ组羊血清中免疫球蛋白A、免疫球蛋白M水平在60 d和90 d时显著高于Ⅰ组（P＜0.05）,肿瘤坏死因子水平显著低于Ⅰ组（P＜0.05）。【结论】当饲粮中添加40%（DM）全株玉米青贮时,可以显著改善肉羊瘤胃发酵,提高养分消化率,增强肉羊的抗氧化能力和免疫功能,促进肉羊健康生长。

Effects of Whole Plant Corn Silage Ratio in Diet on Growth Performance,Rumen Fermentation,Nutrient Digestibility and Serological Parameters of Dorper×Hu Crossbred Female Lambs

【Objective】The aim of this study was to explore the effects of different proportions of the whole-plant corn silage on growth performance, rumen fermentation, nutrient digestibility, serum biochemical indexes, antioxidative enzymes’ activities, and immune function at different stages of Doper ×Hu crossbred female lambs.【Method】Seventy-two female lambs (Dorper sheep×Hu sheep) with good body condition and an approximate weight (16 ± 1.5) kg were selected and randomly divided into four groups, each group with six replicates, each replicate with three lambs. Group I as the control group was fed with peanut vine as the basis of roughage source in diet, Group Ⅱ, Ⅲ, and Ⅳ for experimental groups were respectively fed 20%, 40%, and 60% the whole-plant corn silage (dry matter basis) instead of peanut vine in the diet. The experiment lasted for 115 days, of which the pre-test period was 15 days and the formal test period was 100 days, including 90 days for a feeding trial and 10 days for a digestibility trial.【Result】(1) Compared with I group, average daily gain in group III increased significantly (P＜0.05) from 1 to 30 days, and feed conversion ratio significantly reduced (P＜0.05) from 1 to 30 days and 1 to 90 days. (2) The addition of whole-plant corn silage in the diet could improve the rumen fermentation of lambs. With the increase of proportions of whole-plant corn silage, acetate, butyrate, and acetate/propionate decreased significantly in rumen fluid of lambs (P＜0.05); the ratio of propionate increased significantly (P＜0.05); group IV had a considerably higher concentration of NH₃-N than group I, II, and III in rumen fluid of lambs (P＜0.05). (3) The apparent digestibility of DM, GE of group III and IV was significantly higher than those of group I (P＜0.05), the apparent digestibility of OM, the nitrogen of group II, III, and IV were markedly higher than those of group I (P＜0.05). With the increase of proportions of whole-plant corn silage in diet, the fecal nitrogen excretion of lambs decreased significantly (P＜0.05). And the fecal nitrogen excretion of group II, III, and IV was markedly lower than that of group I (P＜0.05). Lambs in group IV had significantly higher urinary nitrogen excretion (P＜0.05), which resulted in a lower nitrogen retention rate than that of group III (P＜0.05). (4) Serum glucose concentration in group III was significantly higher than in group I and II on the 90th day (P＜0.05). (5) Group III had a considerably higher serum T- AOC and lower serum MDA concentration than group I did on the 90th day (P＜0.05); serum SOD and GSH-Px activities in group IV were significantly higher than those in group I on the 60th day and 90th day(P＜0.05). Group IV had significantly higher serum IgA and IgM concentration (P＜0.05) and significantly lowered the levels of TNF-α than group I did on the 60th day and 90th day (P＜0.05).【Conclusion】Forty percentage of whole-plant corn silage in diet could improve the rumen fermentation, increase nutrient digestibility, enhance the antioxidant ability and immunity, and promote the healthy growth of lambs.