半胱胺对夏季水牛泌乳性能、抗氧化性能和瘤胃微生物多样性的影响

本试验旨在研究水牛饲粮中添加半胱胺对水牛泌乳性能、瘤胃发酵参数、抗氧化性能和瘤胃微生物组成的影响。选取体重（615 kg±21 kg）、胎次（3~5胎）和产奶量（6 kg/d±1 kg/d）相近的健康泌乳中期尼里-拉菲奶水牛20头，采用单因素随机区组设计，分为4组，每组5头水牛。在基础饲粮中分别添加0（对照组）、15、30和45 g/d半胱胺。预饲期1周，试验期4周。结果表明：与对照组相比，①添加半胱胺对水牛体表温度、直肠温度和呼吸频率均无显著影响（P>0.05）。②添加30和45 g/d半胱胺显著提高了水牛干物质采食量（DMI）和酸性洗涤纤维（ADF）表观消化率（P<0.05）。③添加半胱胺显著提高了水牛产奶量、4%乳脂校正乳产量、乳蛋白率、乳总固形物和乳非脂固形物含量（P<0.05）。④添加45 g/d半胱胺显著提高了水牛瘤胃微生物蛋白（MCP）含量（P<0.05）；添加半胱胺对水牛瘤胃液细菌和真菌数量无显著影响（P>0.05）；添加15 g/d半胱胺显著降低了原虫数量（P<0.05），而半胱胺添加剂量为30 g/d时瘤胃液原虫数量则显著增加（P<0.05）。⑤添加半胱胺能显著降低乳中C14：1n5、C18：3n6含量，显著增加乳中C18：1n9t、C19：0、C20：3n6含量（P<0.05）。添加30 g/d半胱胺显著降低乳中C16：0、C18：0和饱和脂肪酸（SFA）含量（P<0.05）；添加30和45 g/d半胱胺显著降低乳中C20：4n6（ARA）和不饱和脂肪酸（UFA）含量（P<0.05）。⑥添加半胱胺组水牛血清总抗氧化能力（T-AOC）显著提高（P<0.05）；15和30 g/d半胱胺组水牛血清丙二醛（MDA）含量显著降低（P<0.05）；30和45 g/d半胱胺组谷胱甘肽过氧化物酶（GSH-Px）活性、总蛋白、球蛋白水平显著增加（P<0.05）；15和45 g/d半胱胺组皮质醇（Cor）显著降低（P<0.05）；30 g/d半胱胺组谷草转氨酶（AST）活性显著增加（P<0.05）。综合试验结果，饲粮中添加半胱胺能够提高泌乳中期水牛泌乳性能与抗氧化能力，影响水牛瘤胃发酵、乳脂脂肪酸含量和瘤胃原虫数量。在本试验条件下，建议半胱胺在水牛饲粮中的适宜添加量为30 g/d。

Effects of Cysteamine on the Lactation Performance,Antioxidant Performance and Rumen Microbial Diversity of Buffalo in Summer

The purpose of this experiment was to study the effect of adding cysteamine to the buffalo diet on the lactation performance,rumen fermentation parameters,antioxidant performance,and rumen microbial diversity of the buffalo.Twenty healthy Nili-Ravi buffaloes with similar body weight(615 kg±21 kg),parity(3~5 births)and milk production(6 kg/d±1 kg/d)were selected and divided into 4 groups with 5 buffalo in each group as a single-factor randomized block design.0(control group),15,30 and 45 g/d cysteamine was added to the diet,respectively.The pre-feeding period was 1 week and the test period was 4 weeks.The results showed that:Compared with the control group,①Adding cysteamine had no significant effect on buffalo body surface temperature,rectal temperature and respiratory rate(P>0.05).②The addition of 30 and 45 g/d cysteamine in the diet significantly increased the DMI and the apparent digestibility of ADF(P<0.05).③The addition of cysteamine in the diet could significantly increase the milk production of buffalo,4%milk fat corrected milk production,milk protein rate,total milk solids and the milk non-fat solids content(P<0.05).④Dietary supplementation with 45 g/d cysteamine significantly increases the buffalo rumen MCP content(P<0.05).Dietary supplementation with cysteamine had no significant effect on the number of bacteria and fungi in rumen fluid of buffalo(P>0.05).Adding 15 g/d cysteamine significantly reduced the number of protozoa(P<0.05).When the dosage of cysteamine was 30 g/d,the number of rumen fluid protozoa was significantly increased(P<0.05).⑤The addition of cysteamine in the diet significantly reduced the content of C14∶1n5,C18∶3n6 in milk and significantly increased the content of C18∶1n9t,C19∶0,C20∶3n6 in milk(P<0.05).Adding 30 g/d cysteamine to the diet significantly reduced the content of C16∶0,C18∶0 and SFA in milk(P<0.05).Dietary supplementation of 30 and 45 g/d cysteamine significantly reduced the content of C20∶4n6(ARA)and UFA in milk(P<0.05).⑥The buffalo serum T-AOC in cysteamine groups were significantly higher(P<0.05);MDA in the diet supplemented with 15 and 30 g/d cysteamine group was significantly lower than the control group(P<0.05);GSH-Px,total protein and globulin in the 30 and 45 g/d cysteamine group was significantly increased compared with the control group(P<0.05);Cor of the 15 and 45 g/d cysteamine group was significantly lower than that of the control group(P<0.05).The activity of AST in the 30 g/d cysteamine group was significantly increased compared with the control group(P<0.05).In conclusion,the addition of cysteamine in the diet could improve the lactation performance and antioxidant capacity of the buffalo in the mid-lactation period,and affect the rumen fermentation,milk fat fatty acid content and the number of rumen protozoan in the buffalo.Under the conditions of this experiment,the recommended amount of cysteamine added to the diet was 30 g/d.