Whole Farm Problems With Heat Stress – It’s Not Just for Lactating Dairy Cows

Abstract

Heat stress is a major problem in dairy cattle world-wide. Heat stress has been shown to decrease dry matter intake (DMI), milk production and reproductive success. It has also been shown to increase cull rate and death loss. In hot, humid areas of the United States, the monetary loss for all of these production parameters has been shown to be approximately $676 to 698 per cow per year. Heat stress has also been shown to involve more than just simply decreased DMI leading to decreased milk production. The total metabolism of the animal changes so that amino acids become more important for energy use by the animal. Monitoring of heat stress can be simpli ed by computing a temperature-humidity index (THI) using data for the area in which you live. Based on current research, cows begin to exhibit stress when that number exceeds 68 and the effect is greater the more hours per day the animal experiences this stress. Historically, we have focused on lactating cows, but new research is beginning to show that dry cows and calves can be affected; sometimes to a greater extent. For example, heat stress of calves has shown effects as much as two years later. Developing a whole-farm plan and prioritizing animals that require intervention is important for minimizing the impact of heat stress. Clean, fresh water that is constantly available is absolutely essential. In addition, a combination of shade, fans and soakers are suggested order to achieve maximal success. Making necessary nutritional changes should be considered. While it is true that you can’t change the weather, you can intervene and create a climate where dairy animals can be comfortable and in return be productive and pro table.