Abstract

Heat stress is one of the most important problems that dairy cows have to face and the use of cooling systems is becoming more and more important. The first reaction that has the animal to cope with the environmental variations is to modify its behaviour. This study was aimed to investigate the effect of heat stress and a cooling system on the feeding behaviour of Italian Holstein Friesian dairy cows in late lactation. Two experiments were performed. In the first experiment, eight dairy cows were firstly kept 7 d under thermoneutral condition, and then under mild heat stress (temperature humidity index, THI, ranging between 72 and 78) for others 7 d. The second experiment consisted of 8 dairy cows used in a two-period cross-over design where the treatment was the use or not of a sprinkler system for cooling cows under mild heat stress. Cows were equipped with a noseband pressure sensor able to detect rumination and eating time, number of rumination and eating chews, number of rumination boluses and rumination intensity. Heat stress reduced rumination time, number of rumination chews and boluses (p < .05), and tended to reduce the number of eating chews (p < .10). Cooled cows increased rumination and eating time (p < .05), rumination intensity (p < .01), and the number of rumination and eating chews (p < .05). In conclusion, feeding behaviour was deeply influenced even by mild heat stress, which was effectively improved by the use of a sprinkler system.

• HIGHLIGHTS

• Mild heat stress reduced rumination time, number of rumination chews and boluses of dairy cows in late lactation

• Cooling cows with sprinklers was effective in alleviating heat stress in terms of feeding behaviour

摘要

热应激是奶牛必须面对的最重要的问题之一，冷却系统的使用变得越来越重要。动物应对环境变化的第一个反应是改变其行为。本研究旨在研究热应激和冷却系统对意大利荷斯坦黑白花奶牛泌乳后期喂养行为的影响。进行了两个实验。在第一个实验中，首先将8头奶牛在热中性条件下饲养7 d，然后将7 d在温和的热胁迫（温度湿度指数，THI，介于72和78之间）下保持7 d。第二个实验由8个奶牛组成，它们在两个周期的交叉设计中使用，其中的处理是使用或不使用洒水系统在温和的热胁迫下为奶牛降温。母牛配备了能够检测反刍和进食时间，反刍和进食咀嚼次数，反刍弹丸数和反刍强度的鼻带压力传感器。热应激减少了反刍时间，反刍咀嚼和大丸剂的数量（p  <.05），并且倾向于减少进食的咀嚼物数量（p  <.10）。冷却的母牛增加了反刍和进食时间（p  <.05），反刍强度（p  <.01）以及反刍和进食咀嚼的数量（p  <.05）。总之，即使是轻度的热应激，进食行为也会受到深深的影响，通过使用洒水系统可以有效地改善这种行为。

• 强调

• 轻度的热应激减少了泌乳后期泌乳牛的反刍时间，反刍次数和弹丸

• 用洒水器给奶牛降温可以有效地缓解饲喂行为中的热应激