缓解奶牛热应激的新策略.pdf

New strategies for managing heat stress in dairy cattle 缓解奶牛热应激的新策略 Pierre Cronjé 热应激的影响Effects of heat stress Heat stress decreases 热应激降低 feed intake 采食量 growth rate 生长速率 • -0.4 kg/d for each degree increase in rectal temperature • 直肠温度每增加1 ℃，日增重降低了0.4kg milk yield 产奶量 milk protein content 乳蛋白含量 milk fat content 乳脂含量 Fertility 繁殖力 • -3% at a rectal temp of 39C 直肠温度39℃繁殖力降低3% • -17% at a rectal temp of 40C 直肠温度40 ℃繁殖力降低17% • -43% at a rectal temp of 41C 直肠温度41 ℃繁殖力降低 43% Libido 性欲 Semen quality 精液品质 Embryo survival 胚胎生命力 Resistance to parasitic and non-parasitic diseases 抗寄生虫和非寄生虫导致的疾病 Why does heat decrease milk production? 为什么受热会降低奶产量？ Intake decreases 采食量会下降 • Why does feed intake decrease? • 为什么采食量会下降？ • Digestion and metabolism of feed generates heat • 饲料在消化和代谢过程中产热 How can we increase feed intake during heat stress? 在热应激发生时怎样增加奶牛的采食？ Feed diets that generate less heat喂产热少的日粮 • Fiber Protein Carbohydrate Fat • 产热量：纤维蛋白碳水化合物脂肪 • Replace fiber with carbohydrate? • 用碳水化合物代替粗纤维？ • Acidosis at 60-65% grain • 精料在日粮中含量超过60%-65%时，会发生酸毒症 • Replace fiber with fat? • 用脂肪代替粗纤维？ • Results inconclusive • 结果并不完美 Is heat stress only about heat generated by feed? 热应激仅仅是关于食物产生的热量吗？ growth rate 生长速度 milk yield 产奶量 Fertility 繁殖力 Libido 性欲 Semen quality 精液品质 Embryo survival