利用CNCPS法评价川西北舍饲牦牛养殖区常见粗饲料的营养价值

Evaluating the nutrient composition of conventional roughages in the major northwestern house-fed yak raising regions of Sichuan Province using the Cornell net carbohydrate and protein system(CNCPS)

本试验旨在利用康奈尔净碳水化合物-蛋白质体系（CNCPS）评价川西北舍饲牦牛养殖区常见粗饲料营养价值并探究不同类型粗饲料的组成规律。分别从汶川、茂县、小金和金川等川西北地区采集5类13种23份舍饲牦牛养殖区常见粗饲料进行常规营养分析,再利用CNCPS法对碳水化合物和蛋白质的组成进行分析。结果表明,5类粗饲料中,青贮氨化类、秸秆类和干草类碳水化合物（CHO）含量显著高于酒糟类和鲜草类（P〈0.05）;淀粉和果胶占碳水化合物（CB1/CHO）比例在5类粗饲料中差异不显著（P〉0.05）;酒糟类不可利用纤维占碳水化合物（CC/CHO）比例显著高于青贮氨化类、秸秆类和干草类（P〈0.05）,非结构性碳水化合物占碳水化合物（NSC/CHO）比例显著高于秸秆类和干草类（P〈0.05）,糖类占碳水化合物（CA/CHO）比例显著高于秸秆类（P〈0.05）;秸秆类可利用纤维占碳水化合物（CB2/CHO）比例显著高于其他类型粗饲料（P〈0.05）;不同类型粗饲料中蛋白质组分结构相似,仅酒糟类和秸秆类中不可降解蛋白质占粗蛋白质（PC/CP）比例显著高于其他类型粗饲料,其余4种可降解蛋白质差异不显著（0.05）。由此可见,川西北舍饲牦牛养殖区常见粗饲料中CHO含量较高,CHO中以结构性碳水化合物为主,结构性碳水化合物中主要是CB2,粗蛋白质中以非蛋白氮（PA）和中速降解蛋白质（PB2）为主。综合分析本试验多项指标,提示鲜草类和干草类中碳水化合物与蛋白质中各组分比例更符合牦牛等反刍动物的消化特性,而酒糟类和秸秆类在牦牛等反刍动物饲粮中使用时应控制其用量。

The present study was conducted to evaluate the nutritional values and structural compositions of conventional roughages produced in the major northwestern house-fed yak raising regions of Sichuan Province using the model of the Cornell net carbohydrate and protein system（ CNCPS）. A total of 23 roughage samples,classified into 5 types and 13 subtypes,were collected from the areas of Wenchuan,Maoxian,Xiaojin and Jinchuan. Proximate analysis was used to determine the nutrient contents in the roughage samples,and CNCPS was used to analyze the composition of carbohydrates and proteins in different types of roughages. The results showed that carbohydrate（ CHO）contents in ammoniated silage,straws and hays were significantly higher than in distillers＇ grains feed and fresh grass（ P〈0. 05）. The contents of starch and pectin（ CB1） of carbohydrates in the five types of roughages（ 0. 05） showed no significant differences. In distillers＇ grains feed,the ratio of unavailable carbohydrate（ CC） to carbohydrate was significantly higher than that in ammoniated silage,straws and hays（ P〈0. 05）,the radio of non-structural carbohydrates to total carbohydrates（ NSC/CHO） was significantly higher than that in straw and hay（ P〈0. 05）,and the ratio of sugar to carbohydrate（ CA/CHO） was significantly higher than that in straws（ P〈0. 05）. In straws,the ratio of available fiber to total carbohydrates（ CB2/CHO） was significantly higher than that in distillers＇ grains feed,fresh grasses and hays（ P 0. 05）. The protein contents were similar in different types of roughage,but the ratio of non-degradable protein to crude protein（ PC/CP）was higher in distillers＇ grains feed and straws in the other types of roughage（ P〈0. 05）,but the four degradable proteins showed no significant differences（ 0. 05） in content. Inferably,the content of carbohydrate is quite high in the conventional roughages for house-feeding yaks in the northwest Sichuan areas. Most of the carbohydrates are structured,and most of the structured carbohydrates are available fibers（ CB2）.Most of the crude proteins are non-protein nitrogen（ PA） and intermediately degraded protein（ PB2）. To sum up,the proportion of carbohydrate and protein in fresh grass and hay are in favor of digestion in yaks and other ruminants which implies that distillers＇ grains feed and straws should be limitedly used for the animals.