不同锌源对湘东黑山羊生长性能及羊奶的成分、氨基酸和脂肪酸含量的影响

Effects of Different Zinc Sources on Growth Performance of Xiangdong Black Goat and Composition,Amino Acid and Fatty Acid Contents of Goat Milk

本试验旨在研究不同锌源对湘东黑山羊生长性能及羊奶的成分、氨基酸和脂肪酸含量的影响。选取体重(38.1±9.7) kg、胎次相近的21只怀双羔妊娠湘东黑山羊(妊娠日龄在90～100 d),随机分为3组,分别在基础饲粮(锌含量22.00 mg/kg DM)中添加硫酸锌(对照)、蛋氨酸螯合锌、甘氨酸螯合锌,各组锌添加量均为60 mg/kg DM。预试期为7 d,正试期为42 d。正试期3组妊娠母羊分别饲喂不同锌源饲粮,产后母羊饲喂无添加锌源的饲粮,母羊产后15 d采集奶样。结果表明:1)与对照组相比,蛋氨酸螯合锌组和甘氨酸螯合锌组妊娠母羊总增重和平均日增重显著增加(P<0.05); 2)与对照组相比,蛋氨酸螯合锌组和甘氨酸螯合锌组羊奶体细胞数量、乳脂、乳蛋白、乳糖、尿素氮、去脂干物质含量差异不显著(P>0.05),但蛋氨酸螯合锌组羊奶总干物质含量显著提高(P<0.05); 3)与对照组相比,蛋氨酸螯合锌组和甘氨酸螯合锌组羊奶氨基酸含量差异不显著(P>0.05); 4)与对照组相比,蛋氨酸螯合锌组羊奶正己酸、辛酸、月桂酸、十三酸、γ-亚麻酸含量显著提高(P<0.05),甘氨酸螯合锌组羊奶木蜡酸、顺-11-二十烯酸、γ-亚麻酸含量显著提高(P<0.05)。综上所述,蛋氨酸螯合锌可增加羊奶中的总干物质含量,甘氨酸螯合锌可增加羊奶中单不饱和脂肪酸含量,降低多不饱和脂肪酸含量,且均可提高妊娠母羊总增重和平均日增重,说明饲粮中添加蛋氨酸螯合锌和甘氨酸螯合锌均可提高妊娠母羊的生长性能并改变羊奶品质。

The aim of this trial was to investigate the effects of different zinc sources on growth performance of Xiangdong black goat and the composition,amino acid and fatty acid contents of goat milk.Twenty-one healthy Xiangdong black goats with twin pregnancy,similar parity and body weight(38.1±9.7)kg were randomly divided into 3 groups,and diets were a basal diet added with zinc sulfate(CON),methionine chelated zinc(Zn-Met)and glycine chelated zinc(Zn-Gly),respectively.The supplementation of zinc were all 40 mg/kg in groups.The pre-trial period was 7 days and the trial period was 42 days.During the trial period,pregnant ewes in those 3 groups were fed different zinc source diets and postpartum goats were fed diets without zinc addition.Milk samples were collected on day 15 after delivery.The results showed as follows:1)compared with CON group,total weight gain and average daily gain of pregnant ewes in Zn-Met and Zn-Gly groups were increased(P<0.05).2)The somatic cell count,milk fat,milk protein,lactose,urea nitrogen,and non-fat dry matter contents of milk in Zn-Met and Zn-Gly groups were not significantly different(P>0.05),but the total dry matter content in Zn-Met group was significantly increased(P<0.05).3)Compared with CON group,the amino acid contents in Zn-Met and Zn-Gly groups had no significant differences(P>0.05).4)Compared with CON group,hexanoic acid,caprylic acid,lauric acid,tridecanoic acid,γ-linolenic acid contents in Zn-Met group were significantly increased(P<0.05),while wood wax acid,Cis-11-eicosenoic acid andγ-linolenic acid contents in the Zn-Gly group were significantly increased(P<0.05).In conclusion,Zn-Met can increase the total dry matter content in goat milk.Zn-Gly can increase the contents of monounsaturated fatty acids and polyunsaturated fatty acids in goat milk,and increase the total weight gain and average daily gain of pregnant ewes,indicating that supplemental Zn-Met and Zn-Gly can improve the growth performance of pregnant ewes and change the quality of goat milk.