Whitetail Health: Nutrition Vital in Immune Response and Resistance to Parasites

By Dale A Hill, PhD, PAS

What are the basics of nutrition, immunity and parasite infestations in deer? The simple answer is that there isn't very much published research working directly with deer, so we must look at the published research information using other animal species, because most animals will respond in the same manner. There are four main points to consider.

1. First, there is a metabolic cost associated for the animal to respond to an immune challenge, whether it is a response to bacteria, virus or a parasite. The immune response requires the body to build specific proteins (taken from dietary sources and muscle tissue), and to use energy (calories) to build these proteins. Many of the biochemical processes within the body needed to build these specific proteins for the immune response also require specific minerals and vitamins. With that in mind, we can more easily understand that when there is increased intake of dietary nutrients, the animal will be able to better respond to immune challenges. This becomes very important when we consider that animals (including humans) generally do not eat as much during periods of illnesses, which can reduce available nutrients used by the body for this immune response process.

2. Second, just as an immune response is needed to combat and reduce bacteria and virus infections to a level that the body can tolerate (respiratory infections, for example), the body also generates an immune response to internal parasites (intestinal worms) as well as external parasites (ticks, mosquitoes). The redness and swelling observed around tick and mosquito bites is only the visible response to this attack on body tissues and is only a small part of the body’s overall immune response.

3. Third, as with humans exposed to certain diseases, animals also build up immunity to diseases and parasites through time. It is well understood that adult animals have a higher immunity than young animals, and that infant animals are much more susceptible to disease than adults that have been exposed to these immune challenges. The best way to increase the ability of very young animals to resist bacterial and viral infections and parasites is to provide good nutrition to the mother. The mother will pass some of her immunity to the young animals through her milk.

4. The fourth factor in the process is the body being able to repair the tissues damaged by the bacteria, viruses and parasites. This requires proteins, energy, minerals, vitamins and other nutrients, just as we have considered for the immune response.

The simple explanation is that better the nutrition level and nutrient stores in the body of the animal, the faster the animal will be able to respond to immune challenges and to repair damaged tissues. When the body uses nutrients to fight diseases and parasites, there are not as many nutrients available to the animal for tissues. As a result, muscle, skeletal and antler growth will be decreased during immune challenges. Those animals that are not able to adequately respond to immune challenges and to repair damaged tissues because of inadequate nutrition may not survive.