【摘要】 用96头中国荷斯坦奶牛研究了热应激对其生理常值、血液生化指标、繁殖及泌乳性能的影响。结果表明：（1）夏季慢性热应激牛的直肠温度和呼吸频率极显著地高于冬季非热应激期（P＜0．01）。（2）与非热应激期（03～05月，09～11月，12～02月）相比，热应激期（06～08月），牛血清γ-球蛋白水平分别降低35．81％（P＜0．01），16．48％（P＞0．05）和39．51％（P＜0．01）。（3）热应激期牛血清中抗坏血政水平显著低于非热应激期。（4）热应激可显著降低牛血清钙、钾、销水平（P＜0．01），但对血清镁水平无影响（P＞0．05）。（5）与冬季相比，夏季牛血清中孕酮水平明显上升（P＜0．05），而T3、皮质醇、LH和雌二醇水平明显下降（P＜0．05）。（6）奶牛乳房炎和胎衣不下发病率随着温度的升高而增加，夏季牛乳房炎与股农不下发病率分别较冬季高9．42和23．33个百分点（P＜0.05）；夏季母牛受股率较冬季低13．1个百分点（P＜0．05）。（7）在热应激期，奶牛泌乳各阶段泌乳量显著低于非热应激期（P＜0．01），并且泌乳前期奶牛对效应激反应较泌乳中、后期敏感，产奶量下降幅度较大。更多还原

【Abstract】 96 Holstein cows were used in the present study to examine the influence of heatstress on physiological response, blood biochemical parameters, reproduction and milk perfor-mance of dairy cow. Results showed that: (1)Rectal temperature and breathing rate of Hol-stein cow in summer slow heat stress period were significantly higher than that in winter non -heat stress period. (2) Compared with non - heat stress period (Mar. to May, Sep. to Nov.,Dec. to Feb. ), the level of serum γ - globulin of cow during heat stress period (June to Aug.)was decreased by 35. 81 % (P< 0.01 ), 16. 48% (P >0.05) and 39. 51% (P<0.01), re-spectively. (3) The serum ascorbic acid level of cow during heat stress peried was significantlylower than that of cow during non - heat stress period. (4) During heat stress period, serumcalcium, potassium and sodium decreased significantly high (P<0.01). Heat stress had no in-fluence on the level of serum magnesium of cow (P >0.05). (5) The serum progesterone ofcow exposed to heat stress rose significantly (P < 0.05), T3, corticosteroid, LH and estradioldecreased significantly (P<0.05) compared with non - heat stress period. (6) The morbidityof mastitis and retained fetal membrane of cow rose significantly with the increment of environ-ment temperature; pregnancy rate of cow in summer was 13. 1 percentage unit lower than thatin winter (P<0.05). (7) The milk yield of various stages of lactation decreased significantlyhigh (P<0.01), but cow at eary - lactation was more sensitive to heat stress than at middleand late lactations.更多还原