Weiss D, Helmreich S, Möstl E, Dzidic A, Bruckmaier R M
Physiology Weihenstephan, Technical University, Munich, Germany.
J Anim Sci. 2004 Feb;82(2):563-70. doi: 10.2527/2004.822563x.
In conventional milking systems, dairy cows are driven to the milking stall twice or thrice daily, whereas in automatic milking systems (AMS), the cows enter the milking stall voluntarily. In this study, noninvasive methods were used to analyze the physiological reaction of 17 cows toward the changeover from conventional to automatic milking. Milk yield and composition were analyzed. Heart rate was recorded continuously, and feces was sampled twice daily to determine cortisol metabolites (11, 17-dioxoandrostanes) for a period of 2 wk. During the first visit to the AMS (without milking), heart rate was elevated compared with parlor milking by 35 +/- 3 beats per minute (bpm) above basal heart rate (P < 0.05). Heart rate during the first milking in AMS (eighth visit) was already similar to the heart rate previously measured during milking in the parlor (18.1 +/- 2.2 bpm above basal level). Concentration of fecal cortisol metabolites was unchanged during the change-over compared with parlor milking. A decreased (P < 0.05) milk yield of 68 +/- 7% relative to previous parlor yield during the first AMS milking indicated a disturbance of milk ejection in most cows. Individual yields ranged from 8 to 96% of the previous parlor yield. To examine the relationship between adrenal cortex sensitivity and the coping process, an ACTH challenge experiment was performed after the changeover period. Cows that released more cortisol after ACTH injection, indicating a higher adrenal cortex sensitivity, had a less enhanced heart rate and a near normal milk ejection during the first AMS milkings (P < 0.05). In conclusion, the reactions toward the changeover to AMS milking varied widely within cows. Adaption to the AMS was easier in animals with a higher adrenal cortex sensitivity to ACTH.
在传统挤奶系统中，奶牛每天被驱赶至挤奶棚两次或三次，而在自动挤奶系统（AMS）中，奶牛会自愿进入挤奶棚。在本研究中，采用非侵入性方法分析了17头奶牛从传统挤奶方式转换为自动挤奶时的生理反应。对产奶量和奶成分进行了分析。连续记录心率，并且每天采集两次粪便样本，以测定2周内的皮质醇代谢物（11,17 - 二氧雄烷）。在首次进入AMS（不挤奶）时，与在挤奶厅挤奶相比，心率高于基础心率35±3次/分钟（bpm）（P < 0.05）。在AMS中首次挤奶（第八次访问）时的心率已经与之前在挤奶厅挤奶时测得的心率相似（高于基础水平18.1±2.2 bpm）。与挤奶厅挤奶相比，转换期间粪便皮质醇代谢物浓度没有变化。在首次AMS挤奶期间，相对于之前在挤奶厅的产奶量，产奶量下降了68±7%（P < 0.05），这表明大多数奶牛的排乳受到了干扰。个体产奶量范围为之前在挤奶厅产奶量的8%至96%。为了研究肾上腺皮质敏感性与应对过程之间的关系，在转换期后进行了促肾上腺皮质激素（ACTH）激发试验。注射ACTH后释放更多皮质醇的奶牛，表明肾上腺皮质敏感性更高，在首次AMS挤奶期间心率增加较少且排乳接近正常（P < 0.05）。总之，奶牛对转换为AMS挤奶的反应差异很大。肾上腺皮质对ACTH敏感性较高的动物更容易适应AMS。
