I am attending the ADSA Discover conference on the development of feeding and management of dairy calves for growth, health and later performance.
Last evening Dr. Amelia Woolums, University of Georgia, commented on vaccinating young calves. I captured her point about the large metabolic demands that result from vaccinating.
She pointed out that when the vaccine works properly huge amounts of both protein and energy are diverted from growth. These resources are used to make the new cells that are stimulated by the vaccine.
Depending on the demands of the environment for maintaining core body temperature and the level of feeding energy newly vaccinated calves can go into negative energy balance. That is, they begin to use energy from their body to maintain themselves and respond to the vaccine.
If the shortage of energy is severe enough the calves may even become ill - most likely with a respiratory infection.
She was reminding us that we need to have well-fed calves with ample energy supplies (usually in young calves coming from milk) if we are going to avoid the negative consequences of vaccinating.
This is something to think about when either very hot or cold weather places high energy demands on our young calves - do we have enough surplus energy in the ration to not only respond successfully to the vaccination but also to support both routine maintenance and good growth of the calves?