半胱胺盐酸盐对泌乳中期热应激奶牛生产性能的影响

本试验旨在研究散栏式饲养方式下,饲喂半胱胺盐酸盐对泌乳中期热应激奶牛生产性能的影响。选择48头健康荷斯坦奶牛体重(562.25±37.85)kg,泌乳天数(123.64±10.67)d,胎次(1.23±0.42)胎,日产奶量(26.58±1.58)kg],根据体重、泌乳天数、产奶量相同或相近的原则,随机分成4组(每组12头),对照组饲喂基础饲粮,试验组分别在基础饲粮中添加半胱胺盐酸盐3、15、30 g/kg。预试期12 d,正试期30 d。结果显示:随半胱胺盐酸盐添加剂量的增加,奶牛呼吸频率和直肠温度呈显著的线性降低(P0.05);干物质采食量、乳脂较正乳产量、能量校正乳产量、乳脂率、乳蛋白率均呈先升高后降低的显著的二次曲线变化(P0.05),并且以添加3 g/kg组的效果较好;正试期末,3、15 g/kg组血清甲状腺素浓度显著低于对照组(P0.05),15 g/kg组血清皮质醇浓度显著高于对照组(P0.05)。结果提示,半胱胺盐酸盐能有效缓解散栏饲养的泌乳中期奶牛热应激,提高产奶量和乳品质,本试验条件下,饲粮中添加3 g/kg半胱胺盐酸盐较为适宜。

Effects of Cysteamine Hydrochloride on Performance of Heat-Stressed Mid-Lactating Dairy Cows

This study aimed at researching the effects of cysteamine hydrochloride ( CSH) on performance of mid-lactating cows suffered from heat stress in free stall barn. Forty-eight healthy mid-lactation Holstein dairy cows with body weight of (562.25±37.85) kg, milk yield of (26.58±1.58) kg, (1.23±0.42) parities and (123.64±10.67) d in milk were randomly divided into 4 groups (12 cows per group). Cows in 4 groups were fed diets containing 0 ( control) , 3, 15 and 30 g/kg CSH in diet, respectively. The pre-trial lasted for 12 d, and the trial lasted for 30 d. The results showed as follows: with the increase of CSH supplemental level, re-spiratory rate and rectal temperature was linearly significantly reduced ( P<0.05); dry matter intake, 4% fat-corrected milk yield, energy-corrected milk yield, milk fat percentage and milk protein percentage were qua-dratically significantly change of firstly increased and then decreased (P<0.05), and 3 g/kg group showed better effects; at the end of trial period, compared with control group, serum thyroxin concentration in 3 and 15 g/kg groups was significantly decreased ( P<0.05) , and serum cortisol concentration in 15 g/kg group was significantly increased ( P<0.05) . The results indicate that CSH can effectively relief heat stress of mid-lacta-ting cows in free stall barn, and increase milk yield and milk quality. The optimum CSH supplemental level in diet is 3 g/kg under the conditions in the present study.