Feeding Deer in Late Spring and Summer

By: Michael L. Schlegel, PhD, PAS. Dipl. ACAS-Nutrition
Nutritionist, Wildlife and Small Ruminant Technical Innovation
Purina Animal Nutrition LLC
Originally appeared in the Spring 2019 Issue of Whitetails of Louisiana

The deer herd has survived the winter and early spring and is entering the most energy and nutrient demanding period of the year. Bucks have antlers developing, does are finishing gestation and starting to lactate, and fawns are growing at their peak rate.
By late spring, most bucks are already growing antlers. Not only is antler growth energy demanding, but nutrient intake is critical as well. The growing antler is 80% protein and 20% ash (mineral) (Demarais and Strickland, 2011) and the bucks require high-quality dietary protein to be able to reach their genetic potential for antler growth. This increased energy and nutrient demand will continue until the antlers harden in the fall.

During late spring, the doe hopefully is pregnant with at least twin fawns. During the last third of gestation (pregnancy), approximately the last 67 days of a 200-day gestation period (Ditchkoff, 2011), the fawns grow the most and the does' energy and nutrient requirements increase as well, (NRC, 2007). When fawns are born, the does energy and nutrient requirements further increase to support milk production. Milk production peaks 10-37 days after fawning (Sadleir, 1980). During lactation, a doe with twin fawns will have a 54% and 36% increase in energy and protein requirements, respectively, compared to late gestation (NRC, 2007). During early lactation, the fawns' demand for milk puts a significant demand on the doe’s resources that often causes the doe to lose body condition, especially if the doe is already in poor condition (Bahnak et al., 1979). To help maintain the doe’s body condition during lactation, supplemental feeding will offset changes in native forage availability. Fawn survival and growth is dependent on milk consumption. If the doe does not receive sufficient nutrition, the amount of milk produced may be inadequate for the fawns, resulting in reduced growth rates and reduced survival (Ditchkoff, 2011; Verme and Ullrey, 1984; Youatt et al., 1965). Towards the end of summer, milk production begins to decrease with an associated decrease in energy and nutrient needs and the fawns are weaned and eating dry feed.

Fawns grow at the most rapid rate early in life. Fawns begin foraging when they are a few weeks old and become functional ruminants at about two months of age (Short, 1964) and therefore high-quality nutrition in the form of native forage or supplemental feed will help the fawns reach their full growth potential.

If areas are overpopulated or if the summer is hot and dry, available native forage could become limiting. As discussed, the summer is a nutritional demanding period for bucks, does, and fawns. Ensuring adequate nutrition is critical to support antler development, lactation and growth. Supplemental feeding will help the animals meet their energy and nutrient requirements.

Literature Cited

Bahnak, B.R., J.C. Holland, L.J. Verme, J.J. Ozoqa. 1979 Seasonal and nutritional effects on serum nitrogen constituents in white-tailed deer. Journal of Wildlife Management. 43:454-460

Demarais, S. and B.K. Strickland. 2011. Antlers. In: D.G. Hewitt, ed., Biology and Management of White-tailed deer, CRC Press Taylor & Francis Group, Boca Raton, FL. Pp 107-145

Ditchkoff, S.S. 2011. Anatomy and physiology. In: D.G. Hewitt, ed., Biology and Management of White-talled deer, CRC Press Taylor & Francis Group, Boca Raton, FL. Pp 43-73
[NRC] National Research Council. 2007. Nutrient Requirements of Small Ruminants. National Academy Press, Washington, DC.

Sadleir, R.M.F.S. 1980. Milk yield of black-tailed deer. Journal of Wildlife Management. 44:472-478.

Short, H.L. 1964. Postnatal stomach development of white-tailed deer. Journal of Wildlife Management. 28:445-458.

Verme, L.J. and D.E. Ullrey. 1984. Physiology and Nutrition. ln:White-tailed Deer Ecology and Management, L.K. Halls, ed. Stackpole Books, Harrisburg, PA.

Youatt, W.G., . L.J. Verme, and D.E. Ullrey. 1965. Composition of milk and blood in nursing white-tailed does and blood composition of their fawns. Journal of Wildlife Management. 29:79-84.