By Angela Breneman
As temperatures drop in the colder months, ensuring consistent average daily gains for young dairy calves can become a challenge. Calves like to live in a climate around 55-75 degrees Fahrenheit. When temperatures drop below that, the effects of cold stress, such as reduced growth, can be observed. As a dairy producer, being proactive versus reactive in this situation will save time and labor and help your calves thrive.
At birth, dairy calves don't have a lot of stored energy reserves. Only 2-4% of their body composition is fat. As temperatures decrease, calves don't have a lot of excess calories to aid in maintaining their body temperature (Barrett, 2021). Thus, the nutrient requirements of the calf increase, and they need more to stay warm. Not only do calves need extra nutrients for growth, but they also need to maintain their body temperature. This is why the calorie content of our calves' feedstuff during winter is key. The amount of feed presented is important, but more important is the composition of the feedstuff.
To understand why we need increased nutrition during the winter months, we need to first understand calf anatomy. When a calf is born, it is functionally a non-ruminant (Drackley, 2008). This is why calves rely on milk to receive most of their nutrition in the first 2-3 weeks of life. While in the pre-ruminant phase, the solids from the milk or milk replacer fed to calves are broken down by enzymes in the calf's abomasum and small intestine (Drackley, 2008). Since the rumen is not functioning at this point, the calf relies on a reflex closure called the esophageal groove to ensure milk bypasses the rumen and goes directly to the omasum and abomasum. This allows the calf to efficiently break down milk proteins, lactose, and triacylglycerols for energy use. Also, at this point, calves are not able to break down starches (Drackley, 2008). Because of this lack of functionality during this stage in life, calves consume very little of their energy from starter grains. The nutrition they receive from their milk or milk replacer is crucial.
Milk Volume & Supplementation
An increased plane of nutrition from milk during the colder months is critical to successful growth and aids in combating cold stress. Increasing the milk volume is also one way to increase calorie consumption. This can be accomplished by increasing the number of feedings in a day or by increasing the milk volume with the same number of feedings. This method can be done with whole milk or milk replacer. Feeding between 15-20% of the calf's body weight with milk or milk replacer is recommended (Welboren et al., 2020). While this is an easy way to increase the plane of nutrition for calves, it does require a little extra labor. Additionally, adding a fat supplement to milk replacers is an easy way to increase the calorie content while using the same milk replacer, and it requires a little extra labor. Feeding both more milk volume with added fat supplementation will help maximize calf growth potential during the winter. Switching to a higher-fat milk replacer during the colder months is also an option to reduce the amount of mixing and additives. In this scenario, impacts on the calf are minimal if the protocol is changed over a few feedings.
Supplementing Whole Milk
Feeding whole milk is a beneficial option for pre-weaned calves in any season. When feeding whole milk, it is crucial to observe the nutrient content, especially during the winter months. Whole milk should be pasteurized when fed to calves. This helps kill the harmful bacteria that could potentially put calves at risk for disease. This is especially important when utilizing waste milk as a feed source. All pasteurized milk for calves should be tested regularly. The bacteria count, or standard plate count should be at 100,000 cfu/ml or below to be considered eligible to be fed to calves. Anything above this can put calves at risk to infections.
When assessing nutrient quality, also pay attention to composition. Whole milk naturally contains around 12.5% milk solids (Welboren et al., 2020), but this can vary depending on the stage of lactation, the health status of the cow(s), and whether the cow(s) is fresh. All these factors affect the quality of the milk, which is why it should be tested regularly. Total solids can easily be tested with a manual or digital BRIX refractometer. You can find more information on the proper use of the BRIX refractometer at the Penn State Extension website. If the quality is compromised, adding a milk balancer can be an effective tool. This helps increase the total solids of lower-quality milk while also increasing protein, fat, vitamin, and mineral content. Glossen et al., (2015) demonstrated milk balancers given to calves increased average daily gains and higher body weights. This is an easy tool for improving the plane of nutrition for the calf in the winter months or when nutrition from the cow is compromised. Most milk balancers can be added directly to the pasteurizer or added to bottles or pails. Use caution when increasing milk solids and utilize the BRIX refractometer to check total solids. Milk solids of over 15% can lead to digestive upset, scours, and dehydration (Azevedo et al., 2023)
Water Consumption
The final key to winter calf growth success is water intake. Water intake is essential for all body processes and animal health at all times. It also is a main driver of feed intakes. Wickramasinghe et al. (2019) reported calves with access to free drinking water drank 300g more milk, achieved greater gains, and had higher feed efficiency pre-weaning. Even though young calves get most of their water intake from milk or milk replacer, it is still important to offer free choice water, especially through the winter when the incidence of scours is high. Colder temperatures can make offering water a challenge but try offering small quantities multiple times a day. Another option is to feed warmed water to calves to encourage drinking and to help maintain body temperature.
The winter months can be challenging for dairy producers and calves. Cold stress can lead to decreased average daily gains, decreased body weight, and a suppressed immune system. With proper preparation, calves can thrive during the winter. Adjusting protocols to increasing milk volume, assessing milk quality and providing free choice can assist producers in battling cold stress. Increasing the plane of nutrition for calves and utilizing tools such as supplements and balancers can help ease the extra labor of wintertime chores. Help your calves thrive this winter!
Source : psu.edu