Color Coded Calf Rearing- Day 30 to Weaning
Raising replacement heifers is the second highest cost on a dairy farm. The replacement program is costly because it takes time for the animal to generate any return on her investment. The most expensive phase of raising replacements is the liquid milk feeding phase. While the least expensive phase, is the first phase after weaning. Proper preparation and management of transitioning the calf from liquid milk feeding to concentrate grain will result in maintaining adequate gains, sufficient rumen development, and prepare the animal for future milk production.
Growth and Rumen Development
Although she has 4 compartments to her stomach when she is born, a calf starts out functioning more like a monogastric. Milk feeding stimulates closure of the esophageal groove, and allows milk to bypass the rumen and clot in the abomasum. The calf needs to eat concentrate grains to aid in the development of the rumen. The bacteria that colonize the rumen come from the calf’s environment, and from the food she eats. As the calf starts to eat more solid feed, that feed will determine the bacteria that dominate in the rumen. The bacteria that digest starch produce butyrate and propionate. Cells in the rumen wall will use the butyrate for energy and growth.
Encouraging grain intake stimulates the growth of rumen papillae, increases the surface area of the rumen, and maximizes the animals ability to absorb nutrients. Once the calf begins consuming 1/2 lb. (227 g.) of starter grain per day establishment of the rumen will begin to take place. It will take 2-3 weeks of grain intake for the bacterial population to become fully established and to begin to efficiently digest grain. This timing is very important as we manage calves through the stress of weaning. If the rumen is not properly developed as calves are transitioned off milk, they may not eat enough, or be able to utilize nutrients from solid feeds, this may result in sickness and delayed growth.
High milk feeding in the early weeks of life, is beneficial to deliver adequate nutrients for health and growth. However, the longer high levels of milk are fed, the longer it will take for calves to eat enough grain to stimulate rumen development. Even in accelerated milk feeding programs fresh, clean starter grain (18-21% protein) should be offered to the calf by 3-7 days of age. Milk volume should be stepped down appropriately to initiate adequate grain intake before weaning.
When to Wean
Dairy Calf and Heifer Association (DCHA) gold standards indicate that calves should double their birth weight by 8 weeks of age. This standard is very achievable and can be accomplished by various milk feeding programs, and differing weaning ages. Some milk feeding programs will push milk to achieve greater gains, other milk programs may feed moderate amounts of milk to push early grain intake, and earlier transition to dry feed. Weaning criteria should not solely be determined by age. Factors including successfulness of passive transfer, health, environment, grain intake, and weather may contribute appropriate weaning age on your operation.
The weaning process can begin when calves consume 2 lbs. (908 g.) of grain per day for 3 consecutive days. Depending on milk feeding rate, health, and environmental factors this may occur anywhere from 4-9 weeks of age. Once the target grain intake is reached, weaning can be initiated and milk volume can be decreased by 50%. Allow the calve to adjust for a 3-7 days, and then continue removing or reducing the other milk feedings. Do not wean a calf that is sick, or not eating enough grain. These calves can be left in their hutches or moved to a recycle row for further treatment and/or attention.
Pen Moves After Weaning
Once calves are weaned it is important to gradually make changes to reduce stress. If calves are housed in individual hutches leave them there for about a week to ensure they have transitioned well to dry feed. If possible, limit the first grouping to 4-6 animals to ease the stress of socialization and group competition. The first group is the most important for social adaptation. After the first grouping subsequent groups can be much larger.
Stress caused by weaning and pen movements may depress the immune system. Plan ahead to allow the best possible circumstances for moving animals to a group pen. Avoid bad weather days, dehorning, and vaccinating around this time. Ensure that group housing is clean, well bedded, and ventilation is adequate to limit exposure to pathogens. Allow appropriate bunk (14 in. or 35.5 cm. per animal) and water space (2 in. or 5 cm. per animal) for the number of animals in each pen. Provide free choice grain, forage, and water. A smooth transition at weaning will give the calf a better chance to stay healthy and grow well during the next phase!
Written by: Mariah Gull, M.S.