甜高粱与苜蓿混合青贮对卡拉库尔羊生长的影响及其消化机理研究

Sheep breeding is a traditional and dominant industry in the Southern Areas of Xinjiang. However, high quality forage resources are scarce because of the harsh natural environment conditions. A potential way to mitigate the shortage of high quality forage resources in South Xinjiang is to combine alfalfa and sweet sorghum for ensiling, which not only can overcome the difficulty of ensiling alfalfa alone, but also can solve the problems of protein deficiency and in sweet sorghum alone silage. Our previous research showed that high quality mixed silages can be made by sweet sorghum and alfalfa with ratios of 2:8 and 4:6. However, the animal experiment is needed to validate the result of selected silage ratios, together with sensory evaluation and chemical analysis. So far, limited study had detailed investigation of different silage mixtures made by sweet sorghum and alfalfa on the animal growth, digestion and metabolism. Therefore, the aim of this research is to study the effects of sweet sorghum and alfalfa mixed silages on the growth performance of Karakul Sheep, using feeding-growth trials, digestion analysis, gastrointestinal metabolite quantification and analysis of intestinal morphology and rumen microbial diversity, which can be used for investigating digestion mechanism of the mixed silages on Karakul Sheep from nutrients digestibility, dominant metabolites，gastrointestinal main microbial community and intestinal morphology. This study will provide practical solution to the shortage of high quality forage resources for sheep breeding industry in Southern Xinjiang, and it also can provide a scientific basis for promoting the economic development of animal husbandry in South Xinjiang.

养羊业是南疆畜牧业的优势产业。受自然条件限制，南疆养羊业优质粗饲料资源极度匮乏。选择苜蓿与甜高粱混合青贮，不仅能克服苜蓿单一青贮难以成功的缺限，而且还能解决甜高粱单独青贮纤维素偏高、蛋白质偏低的问题，是缓解南疆优质粗饲料不足的重要途径。研究表明，甜高粱与苜蓿以2:8或4:6的比例混合可获得优质青贮，然而，基于感官评价和化学分析为主要评价方法筛选的优质混合青贮，尚缺乏动物验证研究。不同比例混合青贮对动物生长及消化代谢的影响也未见报道。为此，本研究以前期研究为基础，通过动物饲养试验、消化试验、胃肠道代谢产物检测、微生物多样性和肠道组织形态分析等研究手段，研究甜高粱与苜蓿混合青贮对卡拉库尔羊生长性能的影响，从养分消化、主要代谢产物、胃肠道微生物和组织形态结构等角度，探讨混合青贮影响卡拉库尔羊生长的消化机理。本研究可为解决南疆养羊业粗饲料优质化问题提供解决方案，为促进南疆畜牧经济发展提供科学依据。

为研究甜高粱与苜蓿混合青贮（混贮）对肉羊生长的影响，使用动物试验验证前期筛选的优质甜高粱与苜蓿混贮的结果，项目按甜高粱与苜蓿比例为20:80（20%SS）、40:60 (40%SS)、60:40（60%SS）、80:20 (80%SS)和100:0 (100%SS)制作混贮，以甜高粱与苜蓿混贮为基础配制全混合日粮，以卡拉库尔羊（卡羊）为试验动物，进行了饲养试验、消化试验和屠宰试验。得到如下结论：.（1）饲养试验研究结果表明，甜高粱占比为60%、40%和20%的混贮可以提高卡羊的采食量和日增重，促进瘤胃发酵，瘤胃微生物多样性得到增加，有利于复胃及小肠组织形态的发育。（2）消化试验的结果表明，以甜高粱占比为40%的混贮可提高饲料消化率，促进消化道酶类的活性；（3）屠宰试验的研究表明，甜高粱占比40%的混贮可提高试验羊的活重、胴体重、屠宰率、眼肌面积和皮下脂肪厚度，肉质最好。（4）瘤胃中NH3-N浓度在甜高粱占比60%、40%及20%时显著高于甜高粱占比100%及80%的混贮。基于项目研究结果，我们认为优质甜高粱与苜蓿混贮是通过能-氮平衡，增加瘤胃微生物多样性，促进瘤胃发酵和消化酶的活性，提高饲料的消化率，进而促进肉羊生长发育。.可见，甜高粱与苜蓿混贮可以提高卡羊的生长性能，提高羊肉品质；综合采食量、日增重、饲料消化率等指标，可以确定甜高粱占比为40%的混贮为优质甜高粱与苜蓿混贮的最佳比例。这一研究结果与我们前期的研究结果是一致的。本项目的研究成果可以为甜高粱与苜蓿混贮的生产加工提供科学依据。.项目研究发表学术论文7篇，其中SCI收录论文1篇，培养硕士研究生2名。