饱和脂肪酸对泌乳中期热应激奶牛产奶性能、采食量和能量代谢的影响

研究饱和脂肪酸对泌乳中期热应激奶牛产奶性能、采食量和能量代谢的影响。选择产后150~210 d的中国荷斯坦奶牛48头,采用完全随机区组试验设计,根据产奶量、分娩时间和胎次分为对照组、1.5%和3%饱和脂肪酸试验组。试验期间牛舍最小湿热指数(THI)在72以上。结果显示,日粮添加饱和脂肪酸显著提高奶牛产奶量(P0.05),1.5%与3%脂肪组之间差异不显著;乳脂和总固体产量,3%脂肪组显著高于1.5%脂肪组和对照组(P0.05),1.5%脂肪组显著高于对照组(P0.05)。饱和脂肪酸对DMI无影响,净能和粗脂肪采食量随脂肪添加量而呈线性增加(P0.01)。3%和1.5%脂肪组分别比对照组净能转化率提高5.69%和6.04%;粗蛋白转化率分别提高8.48%和6.20%,体重和体况三组间无差异。血液中NEFA含量,3%脂肪组显著低于对照组(P0.05);血糖、胆固醇、BHBA、胰岛素三组间无差异。饱和脂肪酸可以提高奶牛产奶性能和维持能量平衡,对能量代谢、采食量、体重和体况无明显影响。

Effects of Supplemental Saturated Fatty Acids on Mid-Lactating Heat Stress Dairy Cows

To investigate the effect of supplemental saturated fatty acids on mid-lactating heat stress dairy cows, forty eight Chinese Holstein cows (150～210 DIM) were divided into three groups according to random block design with milk yield, DIM and parity. The animals were fed with diets contained 0%, 1.5% and 3% saturated fatty acids for group 1 ( control), group 2 and group 3, respectively. The minimum THI was normally more than 72 during experimental period. Results: The milk yield is significantly improved by supplemental saturated fatty acids (P< 0.05). The yield of milk fat and total solid for group 3 is significant higher than that for group2 or control (P< 0.05), and that for group 2 is higher than for control (P<0.05). There is no difference among the cows in dry matter intake. The intake of NEI and EE linearly increases with the increase of fat supplementation (P<0.01 ). Compared with control, the conversions of NEL and CP for group3 are 5.69% and 8.48% higher respectively, and for group 2 are 6.04% and 6.20% higher respectively. There is no difference among the groups in body weight gain and body condition score. The concentration of serum NEFA for group 3 is significantly lower than control (P<0.05). There is no difference among the cows in concentrations of serum glucose, cholesterol, BHBA, and insulin. It is concluded that supplemental saturated fat acids are benefit to mid-lactating heat stress dairy cows in performance and energy balance, no evident effect on energy metabolism, dry matter intake, body weight gain and body condition score.