放牧和舍饲对滩羊肌肉及脂肪组织中脂肪酸组成的影响

Effects of Grazing and House Feeding on Fatty Acid Composition in Muscle and Adipose Tissue of Tan Sheep

该研究旨在分析放牧和舍饲2种饲养方式对滩羊肌肉及脂肪组织中脂肪酸组成的影响。选择体重接近、健康的4月龄滩羊羯羊24只,随机分为舍饲组和放牧组,每组各12只。饲养至9月龄后每组随机挑选6只屠宰,采集滩羊背最长肌、膈肌、股二头肌、皮下脂肪、肾周脂肪和尾部脂肪,利用气相色谱法分析其脂肪酸的种类和含量。结果表明:(1)在短链饱和脂肪酸中,放牧组膈肌中C4:0含量显著高于舍饲组(P<0.05);在中链饱和脂肪酸中,放牧组股二头肌和皮下脂肪中C12:0的含量显著高于舍饲组(P<0.05),皮下脂肪中C11:0的含量显著低于舍饲组(P<0.05);长链饱和脂肪酸中,放牧组皮下脂肪中C14:0、C16:0、C18:0、C24:0,背最长肌、膈肌和各脂肪组织中C20:0,肾周脂肪中C21:0、C22:0的含量均显著(P<0.05)或极显著(P<0.01)高于舍饲组,但背最长肌、膈肌和各脂肪组织中C17:0,尾部脂肪中C15:0以及肾周脂肪中C16:0的含量均显著(P<0.05)或极显著(P<0.01)低于舍饲组。(2)不饱和脂肪酸中,放牧组各肌肉组织中单不饱和脂肪酸的含量低于舍饲组但差异不显著(P>0.05),肾周脂肪中单不饱和脂肪酸的含量显著低于舍饲组(P<0.05);多不饱和脂肪酸中,放牧组股二头肌、肾周脂肪和尾部脂肪中n-6多不饱和脂肪酸的含量均显著(P<0.05)或极显著(P<0.01)低于舍饲组;而放牧组各体组织中n-3多不饱和脂肪酸的含量均显著(P<0.05)或极显著(P<0.01)高于舍饲组。(3)与舍饲相比,放牧滩羊肉中n-6多不饱和脂肪酸/n-3多不饱和脂肪酸的比值更合理。综上可知,放牧和舍饲2种饲养方式对滩羊不同体组织脂肪酸组成存在明显影响,放牧方式提高了羊肉的营养价值。

The purpose of this study was to analyze the effects of two feeding methods,grazing and house feeding,on the fatty acid composition of Tan sheep muscle and adipose tissue.Twenty-four healthy 4-month-old castrated Tan sheep with close weights were selected,and they were randomly divided into a house-raising group and a grazing group,with 12 in each group.After being raised to 9 months of age,6 sheep were randomly selected from each group for slaughter.The longissimus dorsi,diaphragm,biceps femoris,subcutaneous fat,perrenal fat and tail fat of Tan sheep were collected and the types and contents of fatty acids were analyzed by gas chromatography.The results showed that(1)among the short-chain saturated fatty acids,the C4:0 content in the diaphragm of the grazing group was significantly higher than that in the house feeding group(P<0.05);among the medium-chain saturated fatty acids,the content of C12:0 in the biceps femoris and subcutaneous fat of the grazing group was significantly higher than that of the house-fed group(P<0.05),and the content of C11:0 in subcutaneous fat was significantly lower than that of the house-fed group(P<0.05);among the long-chain saturated fatty acids,C14:0,C16:0,C18:0,C24:0 in the subcutaneous fat of the grazing group,C20:0 in the longissimus dorsi muscle,diaphragm and various adipose tissues,and C21:0 and C22:0 in the perrenal fat were all significantly(P<0.05)or highly significantly(P<0.01)higher than that in the house-feeding group,but the contents of C17:0 in longissimus dorsi,diaphragm and various fat tissues,C15:0 in tail fat,and C16:0 in perrenal fat were significantly(P<0.05)or extremely(P<0.01)lower than the house feeding group.(2)Among the unsaturated fatty acids,the content of monounsaturated fatty acids in the muscle tissues of the grazing group was lower than that of the house-fed group but the difference was not significant(P>0.05),and the content of monounsaturated fatty acids in the perrenal fat was significantly lower than that of the house-fed group(P<0.05);among the polyunsaturated fatty acids,the content of n-6 polyunsaturated fatty acids in biceps femoris,perrenal fat and tail fat in the grazing group were all significantly(P<0.05)or extremely(P<0.01)lower than that of the house-fed group;while the contents of n-3 polyunsaturated fatty acids in the tissues of the grazing group were significantly(P<0.05)or extremely(P<0.01)higher than that of the house-fed group.(3)Compared with house feeding,the ratio of n-6 polyunsaturated fatty acid/n-3 polyunsaturated fatty acid in grazing mutton is more reasonable.To sum up,it can be seen that the two feeding methods of grazing and house feeding have significant effects on the fatty acid composition of different body tissues of Tan sheep,and the grazing method has improved the nutritional value of mutton.