作 者：
单强;马峰涛;金宇航;李洪洋;高铎;孙鹏
关键词：
富铬酵母;奶牛;热应激;生化;激素;抗氧化能力;微量元素
摘 要：
本试验旨在研究富铬酵母对热应激奶牛生产性能、血清指标及血浆和牛奶中微量元素含量的影响。选取产奶量[(28.9±1.4) kg/d]、泌乳天数[(105±5) d]、胎次(2～3胎)相近和健康状态良好的泌乳中期荷斯坦奶牛20头,随机分为4组,每组5头。对照组(CON组)饲喂不添加富铬酵母的基础饲粮,试验组分别在基础饲粮精料中添加0.4(Cr-0.4组)、0.8(Cr-0.8组)、1.2 mg/kg(Cr-1.2组)的富铬酵母(以铬计)。预试期14 d,正试期56 d。结果表明:1)随着富铬酵母添加剂量的增加,奶牛直肠温度和呼吸频率呈线性下降(P<0.05)。2)随着富铬酵母添加剂量的增加,奶牛干物质采食量、产奶量和乳蛋白率呈线性升高(P<0.05)。3)随着富铬酵母添加剂量的增加,血清尿素氮含量呈线性升高(P<0.05),血清葡萄糖含量呈先升高后降低的二次曲线变化(P<0.05)。Cr-0.8组血清葡萄糖含量显著高于CON和Cr-1.2组(P<0.05)。4)随着富铬酵母添加剂量的增加,血清超氧化物歧化酶活性和总抗氧化能力呈线性升高(P<0.05),血清谷胱甘肽过氧化物酶活性呈先升高后降低的二次曲线变化(P<0.05),血清丙二醛含量呈先降低后升高的二次曲线变化(P<0.05)。5)随着富铬酵母添加剂量的增加,血清胰岛素、皮质醇和甲状腺素含量呈线性升高(P<0.05),血清胰高血糖素和催乳素含量呈先升高后降低的二次曲线变化(P<0.05),血清三碘甲状腺原氨酸含量呈先降低后升高的二次曲线变化(P<0.05)。其中,Cr-0.4和Cr-0.8组血清胰高血糖素和催乳素含量显著高于CON组(P<0.05),Cr-0.4和Cr-0.8组血清三碘甲状腺原氨酸含量低于CON组(P<0.05)。6)随着富铬酵母添加剂量的增加,血浆中铬和锰及牛奶中铬含量呈线性升高(P<0.05),牛奶中铬和锰含量呈先升高后降低的二次曲线变化(P<0.05)。Cr-0.8组血浆中铬含量显著高于CON和Cr-0.4组(P<0.05);Cr-0.4、Cr-0.8、Cr-1.2组牛奶中铬含量显著高于CON组(P<0.05)。由此可见,饲粮中添加0.8 mg/kg富铬酵母可以改善热应激奶牛生产性能。饲粮中添加适宜剂量的富铬酵母可以降低血清尿素氮含量,调节血清激素含量,提高机体抗氧化能力,增加血浆及牛奶中铬含量。
译 名：
Effects of Chromium Yeast on Performance,Serum Indexes and Plasma and Milk Trace Element Contents of Heat-Stressed Dairy Cows
作 者：
SHAN Qiang;MA Fengtao;JIN Yuhang;LI Hongyang;GAO Duo;SUN Peng;State Key Laboratory of Animal Nutrition,Institute of Animal Science,Chinese Academy of Agricultural Sciences;
关键词：
chromium yeast;;dairy cows;;heat stress;;biochemical;;hormone;;antioxidant capacity;;trace element
摘 要：
The aim of this study was to investigate the effects of chromium yeast on performance,serum indexes and plasma and milk trace element contents of heat-stressed dairy cows. Twenty mid-lactation good health Holstein dairy cows with similar milk yield[(28.9±1.4)kg/d],lactation days[(105±5)d]and parity(2 to 3 parities)were selected and randomly divided into 4 groups with 5 cows in each group. Cows in the control group(CON group)were fed a basal diet without chromium yeast,while other in experimental groups were fed basal diet concentrates supplemented with 0.4(Cr-0.4 group),0.8(Cr-0.8 group)and 1.2 mg/kg(Cr-1.2 group)chromium yeast(as chromium count),respectively. The pre-experimental period lasted for 14 days,and the experimental period lasted for 56 days. The results showed as follows:1)with the supplemental dose of chromium yeast increased,the rectal temperature and respiratory rate of dairy cows were linearly decreased(P<0.05). 2)With the supplemental dose of chromium yeast increased,the dry matter feed intake,milk yield and milk protein percentage of dairy cows were linearly increased(P<0.05). 3)With the supplemental dose of chromium yeast increased,the serum urea nitrogen content was linearly increased(P<0.05),and the serum glucose content was increased firstly and then decreased quadratically(P<0.05). The serum glucose content of Cr-0.8 group was significantly higher than that of CON and Cr-1.2 groups(P<0.05). 4)With the supplemental dose of chromium yeast increased,the serum superoxide dismutase activity and total antioxidant capacity were increased linearly(P<0.05),the serum glutathione peroxidase activity was increased firstly and then decreased quadratically(P<0.05),and the serum malondialdehyde content was decreased firstly and then decreased quadratically(P<0.05). 5)With the supplemental dose of chromium yeast increased,the serum insulin,cortisol and thyroxine contents were linearly increased(P<0.05),the serum glucagon and prolactin contents were increased firstly and then decreased quadratically(P<0.05),and the serum triiodothyronine content was decreased firstly and then increased quadratically(P<0.05). Among them,the serum glucagon and prolactin contents of Cr-0.4 and Cr-0.8 groups were significantly higher than those of the CON group(P<0.05),and the serum triiodothyronine content of Cr-0.4 and Cr-0.8 groups was significantly lower than that of the CON group(P<0.05). 6)With the supplemental dose of chromium yeast increased,the contents of chromium and manganese in plasma and chromium in milk were linearly increased(P<0.05),and the contents of chromium and manganese in milk were increased firstly and then decreased quadratically(P<0.05). The plasma chromium content of Cr-0.8 group was significantly higher than that of CON and Cr-0.4 group(P<0.05),and the milk chromium content of Cr-0.4,Cr-0.8 and Cr-1.2 groups was significantly higher than that of the CON group(P<0.05). In summary,dietary supplementation of 0.8 mg/kg chromium yeast can improve the performance of heat-stressed cows. Dietary supplementation of appropriate dose chromium yeast can decrease the serum urea nitrogen content,regulate serum hormone content,improve body antioxidant capacity,and increase the contents of chromium in plasma and milk.[Chinese Journal of Animal Nutrition,2020,32(5):2198-2208]
