枯草芽孢杆菌对7~28日龄羔羊生长和器官发育及肌肉脂肪酸的影响

旨在研究代乳粉中添加枯草芽孢杆菌（Bacillus subtilis）对7~28日龄羔羊生长性能、组织器官、腹泻率及肌肉组织脂肪酸含量的影响。本研究选取体况发育良好的7日龄湖羊公羔（双羔）30只，按同质性原则将羔羊随机分为2组，每组15只，每只为1个重复，给2组羔羊分别饲喂枯草芽孢杆菌含量为0和0.2%的代乳粉，试验期为21 d。在7、14、21和28日龄晨饲前进行称重，计算各生长阶段的平均日增重（average daily gain，ADG）。并且每天饲喂羔羊的同时观察羔羊腹泻情况，计算羔羊腹泻率。在28日龄时每组随机选择8只羔羊进行屠宰，屠宰后称量各组织器官重量，计算其相对指数，并采集羔羊背最长肌和肱二头肌，测量肌内脂肪含量。结果表明：1）枯草芽孢杆菌显著降低了7~14日龄羔羊的末重（P<0.05），显著提高了15~21日龄和22~28日龄羔羊的平均日增重（P<0.05），有提高7~28日龄羔羊平均日增重的趋势（P=0.100）；对7~28日龄羔羊腹泻率的无显著影响（P>0.05）。2）枯草芽孢杆菌显著降低了7~28日龄羔羊胰腺重量（P<0.05），显著增加了蹄占宰前活重比例（P<0.05），对其他组织器官没有显著影响（P>0.05）。3）枯草芽孢杆菌对7~28日龄羔羊皮张发育无显著影响（P>0.05）。4）枯草芽孢杆菌显著降低了羔羊背最长肌不饱和脂肪酸（unsaturated fatty acid，UFA）、单不饱和脂肪酸（monounsaturated fatty acid，MUFA）、棕榈酸、硬脂酸、二十烷酸、棕榈烯酸、油酸含量和MUFA∶多不饱和脂肪酸（polyunsaturated fatty acid，PUFA）（P<0.05），显著提高了十五烷酸、肉豆蔻烯酸、神经酸含量和饱和脂肪酸（saturated fatty acid，SFA）∶UFA （P<0.05）；显著降低了羔羊肱二头肌UFA、SFA、MUFA、棕榈酸、硬脂酸、二十烷酸、棕榈烯酸、油酸含量和MUFA∶PUFA （P<0.05），显著提高了PUFA、n-6PUFA、肉豆蔻烯酸、神经酸含量和SFA∶UFA、PUFA∶SFA （P<0.05）。结果表明，在代乳粉中添加枯草芽孢杆菌对7~28日龄湖羊羔羊腹泻率、器官和皮张的发育无显著影响，但羔羊平均日增重和胴体重有升高趋势。枯草芽孢杆菌显著降低了湖羊羔羊背最长肌中UFA、MUFA、MUFA∶PUFA的含量和肱二头肌UFA、SFA、MUFA、MUFA∶PUFA的含量，显著提高了湖羊羔羊背最长肌中SFA：UFA的含量和肱二头肌中PUFA、n-6PUFA、SFA∶UFA、PUFA∶SFA的含量，表明枯草芽孢杆菌可通过对肌内脂肪酸组成比例和含量的影响，起到改善湖羊羔羊肉品质的作用。

Effects of Bacillus Subtilis on Growth Performance,Organs Development and Muscle Fatty Acids in 7-28 Days Old Lambs

The purpose of this experiment was to study the effect of adding Bacillus subtilis to milk replacer on the growth performance, tissues and organs development, diarrhea rate and fatty acids deposition in muscle in 7-28 days old Hu lambs. Thirty 7-day-old Hu male lambs (twins) with well-developed body conditions were selected and divided into 2 groups randomly according to the principle of homogeneity, 15 lambs in each group and each one as a repeat. Lambs in the two groups were fed milk replacer with a Bacillus subtilis content of 0 and 0.2%, respectively. The test lasted for 21 days. The lambs were weighed before morning feeding at 7, 14, 21 and 28 days of age, and then the average daily gain (ADG) of each growth stage was calculated. The feces conditions were observed during the whole feeding trial, and the lamb diarrhea rate was calculated. At the age of 28 days, 8 lambs in each group were randomly selected for slaughter. After slaughter, the weight of each tissue and organ was weighed, and the relative index was calculated. The longissimus dorsi and biceps brachii of lamb were collected to measure the intramuscular fat content. The results showed that:1) Bacillus subtilis significantly reduced the final weight of 7-14 days old lambs (P<0.05), significantly increased the ADG of 15-21 and 22-28 days old lambs (P<0.05). Bacillus subtilis increased the ADG of 7-28 days old lambs (P=0.100). Bacillus subtilis had no significnat impact on the diarrhea rate of lambs (P>0.05). 2) Bacillus subtilis significantly reduced the pancreas weight of 7-28 days old lambs (P<0.05), and significantly increased the proportion of hooves weight to live weight before slaughter (P<0.05). Bacillus subtilis had no significant effect on other tissues and organs of lambs (P> 0.05). 3) Bacillus subtilis had no significant effect on the skin and wool development of 7-28 days old lambs (P>0.05). 4) Bacillus subtilis significantly reduced the content of unsaturated fatty acid (UFA), monounsaturated fatty acid (MUFA), palmitic acid, stearic acid, eicosanoic acid, palmitoleic acid, oleic acid and MUFA:polyunsaturated fatty acid (PUFA)(P<0.05), and significantly increased saturated fatty acid (SFA):UFA and content of pentadecane acid, myristoleic acid and nervonic acid in longissimus dorsi of lambs (P<0.05). Bacillus subtilis significantly reduced the contents of UFA, SFA, MUFA, palmitic acid, stearic acid, eicosanic acid, palmitoleic acid, oleic acid and MUFA:PUFA(P<0.05), and significantly increased the content of PUFA, n-6PUFA, myristoleic acid, nervonic acid and SFA:UFA, PUFA:SFA in biceps brachii of lambs (P<0.05). Supplementing Bacillus subtilis to milk replacer did not affect the diarrhea rate, organs and skin development of 7-28 days old Hu lambs, however, the ADG and carcass weight of lambs tended to increase. Supplementing Bacillus subtilis significantly reduced the content of UFA, MUFA, and MUFA:PUFA in the longissimus dorsi and the content of UFA, SFA, MUFA, and MUFA:PUFA in the biceps brachii of Hu lambs, while significantly increased the SFA:UFA in the longissimus dorsi and the contents of PUFA, n-6PUFA, and SFA:UFA, PUFA:SFA in the biceps brachii of Hu lambs. The result shows that supplementating Bacillus subtilis can improve the meat quality of Hu lambs by regulating the composition and content of intramuscular fatty acids.