Build the Gut for a Stress-Free Transition – Dr. Jenn Rowntree, Vita Plus

By Dr. Jenn Rowntree, Vita Plus calf and heifer specialist
The first 60 days of a calf’s life are the most expensive and labor-intensive times of the rearing period. It can be challenging to raise a healthy calf to weaning, let alone to a time where she relies 100 percent on rumen function to obtain nutrients necessary for both maintenance and continued growth.

So how does she get there? What are ways to improve a calf’s likelihood that she will have a successful transition period devoid of stressful situations and illness?

In addition to the basic principle of offering fresh starter grain and water to calves as early as three days of age, here are several other guidelines to ensure proper rumen development preweaning:

• Calves should consume at least 2 pounds of grain for three days in a row by the start of the weaning process (i.e., when milk amount is first decreased).
• The weaning process should be gradual enough to allow time for calves to transition onto a diet of solid feed. During this time, microflora in both the rumen and hind gut prepare for a life of consuming nutrients from forages and grain. We recommend feeding half the normal milk amount for at least five to seven days before cutting calves off milk. This can be done by dropping one feeding per day, or reducing the amount fed per feeding by half.
• Allow calves to remain in their preweaning environment for at least five to seven days following the last milk meal. This will help feeders recognize an individual calf that may fall behind in grain intake once she stops receiving milk. Instead of moving this calf, keep her in the hutch or pen for longer until grain intake increases.
• Water consumption promotes grain intake. Once water enters the rumen, it helps mix the grain and facilitate muscle contractions of the rumen, which will occur on average two to three times per minute for the rest of her life. Although it can be difficult to provide fresh water to calves during the cold winter months, strive to give each calf access to clean water after at least one feeding per day.
• Calves on a high amount of milk preweaning (greater than 8 quarts of milk per day) may benefit from a prolonged or delayed weaning program by one to two weeks.  This will vary by herd.  If calves consume 9 to 12 quarts of milk per day and are not consuming 2 pounds of grain by the start of your current weaning process, research shows delaying the start of weaning by one to two weeks, or a more gradual step-down weaning process, can help improve grain intake.
• If space is limited in the post-weaning phase, it is okay to keep calves in hutches for longer until space is available.  This is preferred versus pushing calves into a crowded pen and increasing the risk for post-weaning health challenges, such as pneumonia and coccidia.

Not only does grain provide substrate for the rumen to develop, it also teaches the immune system.  As grain passes through the hind gut, immune cells within the walls of the gastrointestinal tract (GI) are constantly sampling their environment.  Over time, these immune cells learn what is normal (nutrients, beneficial gut bacteria) and abnormal (harmful bacteria, viruses) within the GI tract.  A study in 2013 revealed that solid preweaning feed consumption was associated with beneficial changes in bacterial diversity, expression of genes involved in mucosal immune responses, as well as barrier functions of the GI tract.  In addition to being necessary for rumen development, starter grain also plays a critical role in the calf’s overall health and future productivity in the herd.