This winter has presented us with nearly every weather scenario possible: fluctuating barometric pressures, bitter cold temperatures and wind chills around Christmas, and more recent mild temperatures with rain, ice and fog. These changing weather systems have an impact on dairy cows and milk production. Factors such as age and breed of cattle along with housing type and environment greatly impact how animals respond to these weather changes. Dairy cattle must maintain their core body temperature of about 101 degrees. When it is cold, cows can divert their energy into maintaining body temperature instead of producing milk. There are a few management considerations to minimize the impact of cold stress on milk production. Preparation for winter Cattle have three different processes to prepare themselves for winter: growing winter hair, adding fat beneath the skin for insulation and increasing metabolic rate. A cow’s winter hair coat is her first protection against the cold. When hair coats remain dry, cows are generally able to handle cold temperatures with minimal impacts. Dairy cows will generally not start experiencing cold stress until about 5 degrees under most conditions. Provide a shelter for cattle to get them out of the elements. A wind break is one solution; however, providing a roof is ideal. Situations where cattle get wet from rain, snow or wet bedding will result in additional challenges during cold and freezing temperatures. Feed intake, energy needs In the cold weather, cattle need more calories to keep warm. Estimates of increased maintenance requirements range from 10% all the way up to 50% depending on the severity of cold and other environmental factors. Under diverse environmental conditions, it is critical that dietary energy be adjusted during extremely cold weather days. Discuss with your nutritionist the ideal feeding options for your herd and facilities. When it gets cold, cows can increase dry matter intakes as much as 5% to 10% to consume more ration energy. It is important to allow for greater total mixed ration refusals during cold weather to compensate for this additional intake. Impact of frozen feed One issue that is often not considered during winter is the impact of cold temperatures on the feed cows are consuming. Wet forages and byproducts can freeze during long stretches of very cold temperatures, resulting in chunks of feed and sorting in the bunk. Even if dry feeds do not appear frozen, they are typically stored outside and likely the same temperature as the environment. This means the temperature of the TMR itself may be very cold. Besides keeping themselves warm from cold environmental temperatures, milk cows also need to warm up the more than 100 pounds of TMR they consume each day to above 100 degrees. This requires additional energy. While it is difficult to find scientific research on the impacts of feeding frozen feed on the rumen microbial population, it is a safe assumption that dumping “ice cubes” in the rumen has a negative impact on the controlled environment desired by the rumen bugs. Monitor waterers Water is often referred to as the most critical nutrient, and adequate consumption is important to milk production. Water intake will decline in cold weather. Cows prefer water between 40-65 degrees. Make sure tank heaters are in proper order in the winter months to achieve this target. Monitor frozen troughs and other drinking points, and make sure water refresh rates are sufficient to allow cows to drink 3-5 gallons per minute. Keeping the water itself thawed is usually the first priority, but access to waterers also needs to be considered. During extended periods of freezing temperatures, ice can build up around waterers and on floors due to splashing and dripping after drinking. Animals need to be able to easily access the waterer without stretching or slipping on the floor around the unit. Concentrating on strategies to keep cows dry and comfortable will help mitigate challenges during the freezing temperatures. Providing increased energy and plenty of access to water during cold weather is necessary to maintaining health and performance of animals. Barry Visser is a nutritionist for Vita Plus.