Spring - Summer 2024 writeup

Shane Horrocks was raised on his family’s hunting/breeding ranch in Junction, Texas. As a youth, he possessed an avid interest in wildlife and conservation, and was involved in animal trapping, guiding hunts, and managing the family’s whitetail deer and exotic breeding operation consisting of greater than 40 combined animal species on 650 acres of land.

Shane received his Baccalaureate of Science in biology in May of 2004 from Tarleton State University and in December of 2006 earned his Master of Science degree in nutrition from Texas A&M University. As a graduate student, he spent two years at the United States Department of Agriculture Food & Feed Safety Research Unit, researching methods to reduce pathogenic bacteria in ruminant animals.

Upon receiving his Master’s degree in animal nutrition, Shane began expanding and improving his family’s whitetail and exotic feed business to develop what is now MaxRax® Wildlife Nutrition Inc., a company specializing in segmented feeding programs and providing detailed analyses for specialized feed formulations to feed mills and private farms/ranches across the United States. Then in early 2024, C&E BioSolutions™ was created by Jennifer (and Shane), with its own branch of healthcare supplements for the cervid and exotic breeding industry. 

This company, with a combined 40+ years of probiotic experience as well as specialized product experience over 15 years, is dedicated to animal health by providing beneficial bacteria (probiotics), antibodies, and various bio-nutrients to help reduce pathogenic bacterial growth in the digestive tract of Cervidae and exotic hoofstock.

Shane Horrocks, M.S.

Cervid & Exotic Nutritionist

MaxRax® Wildlife Nutrition, Inc.

C&E BioSolutions™

"Probiotics used for animal health have been around for over 30 years, however not until the last 10 or so years have they become extremely popular. The reasons for this are numerous based upon proven facts from university conducted research. But what exactly are “probiotics”?

Probiotics are live, microorganisms that are fed to animals to promote intestinal health thus leading to greater overall health. The Latin meaning of the word “probiotic”, actually means “for life”. When we talk about probiotics in deer microbiology or deer nutrition, we are usually referring to live beneficial bacteria. Beneficial bacteria can be naturally found in the digestive system of all living mammals, most residing in the small and large intestine. Ruminants, such as deer, have beneficial bacteria in the rumen, but those are different types of beneficial bacteria and will not apply to this article. For now, we will be focusing on the beneficial bacteria located in the intestinal tract.

There are many different species of probiotics and each will behave differently in the digestive system. Some probiotics help to produce enzymes to digest food, while others produce acids to defend themselves from harmful bacteria. Some grow and replicate in the colon (large intestine) instead of the small intestine. Some probiotics are more effective at fighting E. coli, while others are more effective against Salmonella spp. Some probiotics die very easily during temperature fluctuations while others are more tolerant of acidic environments and can live for thousands of years under very harsh conditions. Basically, not all probiotics are created equal and it is very important to use species specific probiotics to accomplish your goal. If your goal is to increase feed efficiency, there are probiotics for that. If your goal is to reduce E. coli in the small and large intestine, there are probiotics for that.

The way commercial probiotic companies decide on what probiotics to use in their products requires a large amount research and selective gene analysis to obtain the exact probiotic species to use. This is extremely critical to the effectiveness of the probiotic. Some companies will also go an extra step to microencapsulate the probiotics. This microencapsulation helps to protect the bacteria from heat, acids oxygen, and other environmental attacks that can be harmful to the bacteria. Some probiotic species are more beneficial to the first 30% of the small intestine, others are more beneficial to the last 30% of the small intestine, and some are more beneficial to the colon. Microencapsulation can help selective probiotics reach specific sections of the intestine where they can be the most effective promoting intestinal health. Probiotics used in the deer industry have many benefits when used ranging from increased feed efficiency, to reducing the shedding of pathogenic bacteria. A good product contains species specific, microencapsulated probiotics and covers a wide range of health benefits.

Today, due to antibiotic resistance, many companies are using probiotics to replace antibiotics. Probiotics that are fed to animals, find a place to inhabit in the small and large intestine, then compete in many ways with harmful bacteria to reduce their presence in the gut. First, probiotics compete for the same food as bad bacteria. If there is no food or nutrients for pathogenic bacteria to eat, they die. They also regulate intestinal pH levels which making it hard for pathogenic bacteria to live. Many probiotics favor different pH levels that E. coli or Salmonella spp. Most bacteria must have a very specific pH to live and reproduce. By regulating gut pH, probiotics can ensure their survival over the pathogenic bacteria. Some probiotics can also produce their own antibiotics! Yes that is correct, some probiotics produce antibiotics to combat pathogenic bacteria in the intestine! Probiotics can also reduce intestinal inflammation, diarrhea caused by bacterial pathogens (E. coli), and inhibit toxins produced by pathogenic bacteria. These types of competition often kill or remove the harmful bacteria from the animal’s body.

Probiotics are making headway in today’s cervid industry, but it is extremely important to understand what type of probiotics you are using and what they can do for your animals. Look into each probiotic company for quality and research. This will give you more confidence and comfort when your deer, and little fawns, have the probiotic protection they need and remember not all probiotics are created equal." Horrocks, S.M. (2010)

Shane Horrocks, M.S.

Cervid & Exotic Nutritionist

MaxRax® Wildlife Nutrition, Inc.

C&E BioSolutions™

"Fawn nutrition varies drastically from adult deer nutrition. The overall anatomy and physiology of the fawn is much different requiring different sources and concentrations of fat and protein. First, fawns are born without a functioning rumen which places them at a disadvantage when it comes to feeding on fibrous material. For the first few weeks of life, a fawn must consume milk only, a highly digestible product that contains excellent energy and protein with a moderate vitamins and mineral concentration. After consumption, the milk coagulates in the stomach (abomasum) forming a curd that contains protein and fat. Milk coagulation, caused by the protein casein, is required so that ingested milk remains in the stomach for longer time periods and allows stomach acids to slowly denature the casein protein prior to enzymatic digestion. However, acid production is very minimal for the first three days of a fawns life. The low amounts of hydrochloric acid allow the mothers antibodies to survive the stomach acid and make it into the intestine where they are absorbed. Hydrochloric acid production eventually increases over the next 3 days after birth to allow fawns to digest protein. With the milk curd in the stomach, the first material to pass into the small intestine is the whey fluid containing carbohydrates and soluble nitrogen. Approximately 3-4 hours later, casein is denatured and separated from the curd allowing it to pass out of the stomach and into the intestine for enzymatic digestion. The slow release of protein and fat from the milk curd provides a continuous supply of protein and fat to the intestinal tract. Feeding on milk allows the fawn to receive carbohydrates directly from milk sugar such as lactose and glucose. The glucose consumed is absorbed directly in the small intestine and is not altered by rumen fermentation. 

Digestive enzyme activity in fawns is constantly changing. Some digestive enzymes start working right before birth. After birth, activity for some digestive enzymes gradually increase, while others decrease. This change in enzyme production allows the fawns to transition from a milk diet to a solid diet. The transition from milk to a solid diet must occur gradually. Not all enzymes needed for solid feed digestion will be produced immediately and can take months. Protein digestibility for non-milk proteins (soybeans, corn, etc.) is very low for the first two weeks and increases from birth to two months. Rapid transition to feeds containing molasses (high in fructose) can cause severe diarrhea due to inadequate concentrations of enzymes needed to break down fructose. Research has shown that some ruminants need several weeks to properly adjust to solid feed if they are immediately removed from milk and placed on a solid diet. Typically, fawns will start to transition from milk sugars (glucose), to plant sugars (starch) between 3-8 weeks. 

Fawns should have access to fiber on day one. Fiber is needed to stimulate rumen and intestinal villi development. This refers to grass or hay and not just fiber in the feed (textured or pelleted feed). It could take a fawn up to two weeks before they start to ruminate (chew the cud), so allow fawns access to fiber at all times. When fawns are born, there is very little saliva production. Saliva produced contains natural buffers to help keep rumen pH normal. Fawns will need to be properly adjusted to fiber to develop adequate rumen buffering ability. After the rumen develops, they fermentation of volatile fatty acids from feed/grain can occur and provide the fawn with the primary sources of energy required for metabolism. Normal volatile fatty acid concentrations are generally achieved by 8 weeks of age. For the proper production of volatile fatty acids, the rumen must have a sufficient microbial population. Microbial populations begin to colonize immediately after birth. Allowing the fawn access to fiber will aid in establishing the correct microbial populations by about 4-6 weeks of age. 

When bottle feeding fawns, the most important nutrients for fawns are protein and calories with the majority of calories coming from fat. Please consider both quantity and quality of each. The source of your protein needs to be considered because some protein sources can have a much lower digestibility, and may be low in essential amino acids such as lysine and methionine. Milk proteins are very digestible while it is common practice to add additional lysine and methionine to neonatal diets. Consider small management practices such as mildly heating the milk or milk replacer because  overheating milk or milk replacers reduce protein digestibility, and may cause diarrhea. Fat sources (animal fat vs vegetable fat) should also be considered for appropriate energy concentrations and weight gains. Lecithin (phosphatidylcholine) and glycerol monostearate are common fat emulsifiers and help to improve digestibility of some fats when added to milk replacers. Milk is usually low in vitamins (primarily A & B12) and minerals. While the rumen is non-functioning at birth and unable to produce B vitamins, milk replacers should be fortified with B vitamins, especially since liver concentrations of these vitamins are fairly low at time of birth. Adequate colostrum intake can usually provide vitamins A, E, B12, choline and minerals more so than milk, so adequate colostrum intake can provide the fawn with a fair dose of vitamins and minerals. Grains have some vitamins and minerals and should help to meet vitamin/mineral requirements once fawns begin to feed on a solid diet. When transitioning a fawn to a solid diet, make sure the feed is properly balanced and fortified with all vitamins, mineral and essential amino acids needed for rapid growth and development in fawns. Using high quality, mildly process grains (roasted beans or steam flaked grain) can improve digestibility and nutrient absorption of the feed." Horrocks, S.M. (2011)

Shane Horrocks, M.S.

Cervid & Exotic Nutritionist

MaxRax® Wildlife Nutrition, Inc.

C&E BioSolutions™

"Vitamins are compounds that originate from plants and are required in minute amounts (micrograms or milligrams per day) for health, normal body growth and reproduction. Whitetail Deer, like all animals, need vitamins daily to maintain a healthy metabolism.

There are two different types of vitamins; fat soluble and water soluble. Fat soluble vitamins (Vitamin A, D, E, and K) require fats to be properly absorbed while water soluble vitamins (Vitamin C, B vitamins) require water to be absorbed. When animals do not receive their daily vitamin requirements, deficiencies can develop with evastating effects to the animal’s health by causing physical ailments such as, dermatitis, dyspnea, bone eformation, severe weight loss and, in extreme cases, death. All deer feeds should be supplemented with fat soluble vitamins, especially A and E, to ensure optimal animal performance. Deer produce vitamin D (from sunlight) and vitamin K in appreciable amounts on their own, however, deer in production (antler growth, gestating, lactating) or under stress may need supplementation with additional fat soluble vitamins. Rumen microorganisms produce sufficient amounts of B vitamins to meet daily requirements, however during times of high stress or increased production (milk, gestation), additional B vitamins (especially thiamin and niacin) may be required.

Newborn fawns have minimal stores of fat soluble vitamins and do not have a functional rumen capable of synthesizing adequate amounts of B vitamins. Colostrum is rich in vitamins, if the doe was provided a diet adequate in vitamins, and should always be given to a fawn immediately after birth. Fawns will not start synthesizing significant amounts of B vitamins in the rumen for at least a week after birth. In mature deer, fat soluble vitamins are stored in appreciable amounts and can be used in times of deficient intake, however, many B vitamins are not stored in quantifiable reserves. A consistent, continuous supply of B vitamins are needed to avoid deficiencies. Confined deer may be more susceptible to vitamin deficiencies when the demands of production increase metabolic requirements. Unbalanced diets, low fiber diets, high starch and high fat diets can disrupt B vitamin production in the rumen. If additional vitamins are desired in a feed, check with an animal nutritionist for appropriate vitamin supplementation and to avoid the addition of vitamins into feed at toxic concentrations.

The stability of vitamins in feeds should always be considered. Maintaining a rapid feed turnover and keeping an inventory of fresh feed can significantly reduce vitamin degradation. All vitamins are subject to degradation when exposed to light, heat, water and minerals. Vitamins are necessary and vital to animal health and are needed to allow animals to properly and efficiently use other nutrients in the diet. When feeding deer, consider stage of production, stress level, age, gender and feed quality to better target vitamin needs and achieve optimal animal performance.

Listed below are commonly used vitamins and how each functions when added to deer diets:

Vitamin A – Supports normal eye function, cell growth, and bone growth

Vitamin D – Facilitates absorption of calcium and phosphorus into the bloodstream

Vitamin E – Provides antioxidant action for cell protection

Vitamin K –Aids blood clotting

Vitamin C – Facilitates cartilage formation, immune response

B VITAMINS

Thiamin (B1) – Supports carbohydrate metabolism and neural function

Riboflavin (B2) – Aids carbohydrate, amino acid, and fat metabolism

Niacin (B3) – Involved in all aspects of metabolism

Pantothenic acid (B5) – Supports protein, fat and carbohydrate metabolism

Pyridoxine (B6) – Mediates growth, cognitive development, steroid hormone activity, immune function

Folic Acid – Involved in all aspects of metabolism. Works with vitamin B6 and B12. Involved in DNA synthesis and normal cell division (embryogenesis)

Cyanocobalamine (B12) – Facilitates red blood cell synthesis, production of glucose from propionate.

Choline – Supports nerve impulse, and fat metabolism."

Horrocks, S.M. (2011)

Shane Horrocks, M.S.

Cervid & Exotic Nutritionist

MaxRax® Wildlife Nutrition, Inc.

C&E BioSolutions™

"Fertility and conception in deer is determined by numerous factors such as time of year, light conditions, stress levels, body condition and nutrition. Specific nutrient requirements for protein, energy, vitamins and minerals influence fertility and conception in Whitetail Deer. Before breeding, please consider the following nutrient needs of the buck and doe prior to breeding.

ENERGY & PROTEIN

The most critical nutrient required for fertility and conception is energy. Inadequate intake of sufficient amounts of energy will result in delayed sexual maturity and lower conception rates. Consider the energy in the feed when you want to breed a buck fawn or doe fawn. Proper energy concentrations will help to grow a larger deer, capable of reaching the necessary weight to achieve sexual maturity. In research trails, it has been concluded that body weight influences sexual maturity more so than age. This makes it quite possible to breed yearling deer as long as they reach sexual maturity determined by a healthy, mature body weight. Conception rates are usually higher in deer that are either maintaining or gaining weight at time of coverage or AI. Deer in a negative energy balance, or deer not consuming sufficient amounts of energy needed for proper growth and weight gain, may not even ovulate. To achieve optimal conception, does should have a small layer of fat covering their body, This layer of fat is responsible for producing leptin, a hormone required for proper ovulation. Protein deficiency is not as big of an issue as energy deficiency, but can lead to delayed puberty in both bucks and does. This is more important for a young growing deer rather than a mature deer. Be sure to always provide a high quality protein (balanced amino acids) to optimize growth and development. For reproductive measures, certain amino acids such as methionine can be supplemented to lower protein feeds to overcome infertility in a low protein diet. Overfeeding protein, can lead to poor conception due to pH changes in the cervix from the high amounts of nitrogen found in protein.

VITAMINS

B vitamins are involved in all aspects of metabolism including energy production, tissue growth, and hormone production. If a well balanced feed is to be used, B-vitamin production by rumen microorganisms is usually sufficient to meet demands, but depending on the diet, body condition, and stress level, B-vitamins may need to be added.

Fat soluble vitamins (A, D, E, and K) are the most important for fertility and conception. Vitamin A is needed for embryonic tissue growth and development and can delay puberty. Most problems with vitamin A deficiency occur later in gestation and parturition. Overall, vitamin A deficiency can lead to reduced conception rates, ovarian cysts and embryonic mortality. Vitamin D deficiency can cause symptoms similar to a vitamin A deficiency such as delayed puberty and suppression of the estrus cycle. Vitamin E deficiency generally does not have an effect on fertility unless selenium is also deficient.

MINERALS

Most infertility issues that arise due to a deficiency in minerals typically point to a phosphorus deficiency. Low phosphorus can delay puberty and estrus while a moderate phosphorus deficiency may be associated with poor conception. Visual symptoms of phosphorus deficiency may lead animals to lick or chew on various objects. Trace minerals involved in fertility and conception include selenium, zinc, copper manganese and cobalt. In areas where selenium and copper deficiency occur, it is beneficial to use chelated selenium (selenium yeast) and chelated copper (copper –lysine, copper proteinate). Adequate selenium intake promotes normal ovarian function and can help to reduce ovarian cysts. Cobalt and zinc also help to increase sperm production and sperm quality.

The amount of energy, protein, vitamins and minerals necessary to promote optimal fertility and conception will depend on numerous factors and breeding conditions. If your feeding program needs restructuring to provide the necessary nutrients for the breeding season, feed changes should be made at least 4 weeks before breeding. Some feeding programs may require you to feed a supplement for an additional 4 weeks after conception while other feed changes may require you to continue feeding the diet change until parturition. To provide accurate nutrient requirements and proper nutrient ratios to deer during the breeding season, contact your nutritionist to discuss protein, energy, vitamin and minerals concentrations in the feed." Horrocks, S.M. (2011)

Shane Horrocks, M.S.

Cervid & Exotic Nutritionist

MaxRax® Wildlife Nutrition, Inc.

C&E BioSolutions™

"Whitetail Deer, like other ruminant animals, have a four compartment stomach: the rumen, reticulum, omasum and abomasum. The rumen is the largest compartment with a volume of approximately 1.85 gallons for a 225lb deer, and has a pH between a 6 and 7.2 depending on feed, age and season. It serves as a storage site for ingested feed that is later regurgitated and re-chewed, as a fermentation vat for the production of volatile fatty acids (primary energy source in ruminants), a environment capable of producing proteins and vitamins (B, and K), and houses a large, diverse microbial population (beneficial bacteria, protozoa and fungi). The rumen is comprised of a muscle layer that contracts and relaxes to assist the mixing of ingested feed, which allows microorganisms to attach to and utilize swallowed feed particles. The muscle layer also assists with regurgitation of feed for further mastication and passage of feed material out of the rumen and eventually into the intestines. The inner wall of the rumen is made up of specialized epithelial tissue responsible for absorbing volatile fatty acids produced in the rumen and nitrogen from plants. Volatile fatty acids are eventually used

as energy, where the nitrogen is eventually recycled back to the rumen via the saliva to be assimilated into more rumen microorganisms and protein for the deer to use. The consistent work performed by the rumen plays a very critical role in total animal health and must remain in excellent condition and overall balance (pH, microbial density, and nutrient quality and quantity) to achieve optimal animal performance.

The overall heath and efficiency of the rumen to produce nutrients for the animal will be determined by factors such as diet, stress level of the animal and the health of the rumen microbial population. Microorganisms are responsible for producing energy, protein and vitamins the animal uses for proper tissue growth, reproduction, and lactation. When a deer consumes hay or grain, the beneficial microorganisms in the rumen will ferment fibrous (cellulose and hemicellulose) portions of the grain and produce energy products called volatile fatty acids. Volatile fatty acids are made into sugars, like glucose, which are then used to sustain the deer’s energy needs. Microorganisms can also utilize non protein nitrogen from the grains or hay to reproduce themselves and to make what ruminant nutritionists refer to as microbial protein. Microbial protein is the protein that makes up the microorganisms in the rumen. Microorganisms that are passed out of the rumen and into the deer’s intestine are digested and the protein from the cells are absorbed just like protein from soybeans or alfalfa. The deer can then use the microbial protein to meet some of their daily protein requirements. For this reason, ruminant feeds are specifically developed and balanced to maintain specific amounts of protein, non protein nitrogen, and carbohydrates that can be used for efficient production and turnover of rumen microorganisms. 

High quality, well balanced feeds can improve rumen health by promoting a diverse microbial population capable of utilizing, carbohydrates, protein, and fatty acids and decrease potential rumen problems associated with unbalanced feeds. For example, as carbohydrates (fibrous and non-fibrous) and proteins are utilized by the microorganisms in the rumen, gases, such as carbon dioxide and methane, will be produced. A healthy rumen is capable of expelling these gasses, however, unbalanced diets, high grain diets, high legume diets, or the use of drugs can impact the rumen, inhibiting the deer’s ability to release the gasses. Grain overload in ruminant diets can alter the rumen microbial population many ways. Some grains utilized by rumen microorganisms will produce lactic acid. If a ruminant consumes too much of a particular grain (like corn), a high amount of lactic acid can be produced causing a severe decrease in the rumen pH. A very acidic rumen environment can kill many microorganisms sensitive to the acidic environment (mostly fiber degrading microorganisms), causing an unbalance in the microbial population and leading to lactic acidosis. Acidosis can destroy the epithelial tissue responsible for absorbing nutrients through the rumen wall and into the blood stream. Other problems that can occur with an unbalanced microbial population are bloat (acute or chronic), and reduction or elimination of B vitamin synthesis (if this happens animals can go blind) within the rumen. These potential health threats can all be avoided with a sound, and balanced daily feed. A good quality feed has safe concentrations of soluble carbohydrates (starch), adequate levels of fiber, and is well balanced to provide accurate nutrition to not only the animal consuming it, but the microbial population within the rumen environment." Horrocks, S.M. (2011)

Shane Horrocks, M.S.

Cervid & Exotic Nutritionist

MaxRax® Wildlife Nutrition, Inc.

C&E BioSolutions™

"Whitetail Deer are adapted to utilize fibrous plant material as a daily source of energy or carbohydrates. Fibrous material is composed of cellulose, hemicellulose, pectin, and lignin, where hemicellulose and cellulose are the primary sources of energy. Fiber is broken down in the rumen by enzymes produced by microorganisms, then converted to energy, proteins, and vitamins. But why feed fiber if you are already providing the deer with protein, energy, and vitamins?

The importance of feeding adequate fiber in deer diets (total daily consumption) is to maintain optimal rumen function. In order to maximize deer production, the correct concentrations and ratios of protein, energy and fiber must be present in the diet. 

Fiber must be of good quality and quantity to facilitate rumen health. Crude fiber, or total fiber, is important to consider, but accurate amounts of Neutral Detergent Fiber (NDF) and Acid Detergent Fiber (ADF), two different qualities of fiber, must also be considered and balanced to achieve proper rumen health and accurate use of the total fiber. Neutral Detergent Fiber is more digestible fiber, while Acid Detergent Fiber will promote cud chewing. When a deer chews their cud, they are mechanically breaking down the fiber which allows greater fermentation of the fiber in the rumen. As fermentation occurs, acids are constantly produced and secreted into the rumen, which lowers rumen pH. However, saliva contains an antacid known as sodium bicarbonate, that balances the acidity of the rumen. Saliva production increases as a result of more cud chewing, which occurs when accurate amounts of good quality fiber are present in the diet.

Particle size is also critical to fiber digestion and utilization. If fiber particle size is small, it is more easily passed through the rumen and into the intestine. Good fiber should remain in the rumen long enough to be fermented, which is why supplemental hay and grass (or natural browse) can be beneficial. Particle size also impacts rumen muscle stimulation. The rumen tissue is partially comprised of muscle that is constantly contracting and relaxing, allowing for proper mixing of feed and hay. When fiber particles rub or scratch the inside of the rumen wall, they stimulate muscle contraction. Without muscle contraction, feed digestion in the rumen is reduced and can lead to inefficient bacterial growth.

Additional benefits from fiber are the production of volatile fatty acids like acetate and butyrate. Acetate and butyrate are produced from the fermentation of fiber and are used as an energy sources. During lactation, does can utilize acetate to produce more milkfat, and acetate is also responsible for the development and growth of the rumen in fawns, which occurs approximately two weeks after birth. Butyrate helps to facilitate the growth of rumen villi responsible for absorbing energy and nitrogen. Butyrate can also cause the villi in the small intestine to grow in length, which increases the intestinal surface area available for absorption of nutrients (amino acids, fat, carbohydrates) from the feed. 

Finally, fiber present in the small intestine can also help to irreversibly bind toxins circulating in the bloodstream so they are safely excreted in the feces.

A good quality plane of nutrition for deer always has good fiber quantity and quality. Deer should always consume appropriate amounts of good quality fiber on a daily basis. If fiber is not present in the feed, be sure to supplement fiber in the form of hay or high quality browse/grass. The amount of fiber needed in the feed on a daily basis will depend on several factors such as animal age, sex, stage of production, current diet, available browse, and amount of hay supplemented daily. Consult a wildlife nutritionist to determine appropriate fiber concentrations in your feed." Horrocks, S.M. (2011)

Shane Horrocks, M.S.

Cervid & Exotic Nutritionist

MaxRax® Wildlife Nutrition, Inc.

C&E BioSolutions™

"Throughout the fall/winter months, many breeders change feeds to accommodate the changes that occur in a deer’s metabolism. But what kind of metabolic changes actually occur? Most breeders, biologists, and nutritionists, will tell you that a deer’s metabolic rate decreases in the winters months to help the deer conserve energy. Typically deer will lose about 30% of their fat stores in the winter months, but does this have anything to do with a change in metabolic rate? Metabolism is influenced by numerous factors such as genetics, physical activity, hormone production, and environmental temperature fluctuations.

Feed changes in the fall/winter can be dramatic with the majority of changes involving a reduction in protein concentration. Some feeds can be as low as 12% protein in the fall/winter. Protein is important for numerous biological factors including muscle growth, immune system/antibody production, digestive enzyme production, and sperm cell production. Vitamins, minerals, carbohydrates, and fats are also extremely important since all of these nutrients contribute to the overall health of the animal, especially during the rut. When deer rut, their metabolism increases due to increased hormone production and physical activity. At the same time, feed intake decreases due to hormone production and physical activity (especially for bucks). If metabolic demands for nutrients (protein, fat, vitamins, etc..) are increased due to breeding and physical activity, is it best to decrease certain nutrient concentrations in the feed? When bucks take a few minutes to eat during the rut, wouldn’t it be best if they consumed as much protein, carbs, fat, vitamins and minerals as possible? Absolutely. 

After the rut, physical activity decreases and deer instinctually become less active during the winter months to conserve energy in consideration of food scarcity. Deer will bed down and spend less time feeding. However, does this mean that metabolism slows down to compensate for lower feed intake? Metabolism decreases when the physical demands of breeding are complete, but when a deer is outside in the cold winter months (and outside their comfortable thermal range or thermal neutral zone), they will shiver to generate heat. Shivering increases metabolism, and the colder it is the more they shiver to keep warm. Similarly, in the summer time when it gets hot, respiration increases to release heat and cool themselves, also increasing metabolic activity.

Although you may have heard that a deer’s metabolism decreases in the winter months, recent research states that winter and summer metabolism is not significantly different. The key to keeping a deer healthy and in good condition is to feed them like you would any other time. For the winter, I believe decreasing protein to below 16% is not optimal because feed intake is already lower. At the same time diets too high in protein during the winter can have a negative effect on energy (takes a lot of energy to convert protein to energy and excrete additional protein). Supplementing hay (alfalfa, or quality fiber that deer prefer to eat) can help when temperatures are low because the fiber will ferment in the rumen and release heat thus helping to keep the deer warm. Some breeders use corn for this purpose, and although corn will generate heat when fermented, hay will typically generate more because it will ferment longer in the rumen due to a slower passage rate. Carbohydrates and fat levels in the feed should also remain high to compensate for higher energy demands when the temperatures decrease. More carbohydrates and fat in the feed can supply the needed energy to stay warm which ultimately helps body condition and antler growth in the spring. 

When feeding deer in the winter months a good quality feed can really put you ahead. Be careful when trying to go to a cheaper feed of poor quality. Lower quality feeds may work for you financially, but a high quality feed fed year round can offer the most benefit to your breeding stock." Horrocks, S.M. (2010)

Read Shane Horrocks's Master's thesis, cataloged in the OAKTrust Library at Texas A&M University, here: https://oaktrust.library.tamu.edu/handle/1969.1/5022