PASSIONATE BREEDERS
ARE ALWAYS LEARNING.

Hunting Dog Diet and Nutrition

Archive document IAMS COMPANY

Iams is since 1999 a registered trademark of The Procter & Gamble Company. This is an archive document used historically by the Iams Pet Food company or for Iams Pet Food products. Any and all mentions included herein needs to be replaced in context of the time and geography of its initial use as circumstances and products may have changed since then. Products and relative data are for US only. No assertion or further use of these documents can be made without P&G's authorization.

EFFECT OF DIET ON HUNTING PERFORMANCE

Gary M. Davenport, PhD
Presented 2002

INTRODUCTION

Hunting with dogs for sport or in competitive events is a popular pastime in the United States. The breed or type of dog that is used varies with the type of game that is hunted, as well as the terrain and distances that are covered. Regardless of these differences, the work associated with hunting typically involves several hours of endurance activity interrupted by short periods of intense running or sprinting.

The current understanding of the nutritional needs of hunting dogs is based primarily on nutritional studies conducted with racing Greyhounds, endurance sled dogs, or dogs exercising on treadmills in the laboratory setting.^1,2 Much less is known about the nutritional needs of other types of working dogs.

These other working dogs include, but are not limited to, those that are used for hunting, herding, obedience competitions, agility events and tracking tests, as well as dogs trained to assist the disabled and military. For each of these categories, the intensity of training and amount of required physical work can vary considerably.

ENERGY NEEDS

Working dogs have increased energy needs compared with the maintenance requirements of normal, adult dogs.³ At question is the magnitude of this increase, as well as the best way to supply energy and other essential nutrients to support maximum performance and overall well-being of these dogs.

There are typically two major nutritional concerns for dogs that are hunted often during a season: 1) feeding to promote optimal performance, and 2) providing enough calories to maintain body weight and body condition.

Weight loss is common in dogs that are hunted frequently, especially if weather conditions are harsh. Additionally, warm and humid weather conditions can significantly impact a hunting dog's ability to work and may adversely affect food intake and the ability to fulfill energy requirements.³

NUTRITIONAL MANAGEMENT

Nutritional programs for working dogs must be designed to provide ample energy and other nutrients to support muscle contraction during athletic events, while allowing the dog to benefit from training over the course of the season.⁴ Both the immediate needs of muscle as well as long-term concerns of aerobic capacity, proneness to injury, and blood volume must be met using an appropriate nutritional strategy.³

A principal component of this nutritional strategy involves the fulfillment of metabolic energy requirements using dietary sources of fat, protein, and carbohydrates.

Fat

Dietary fat provides the most concentrated form of energy of all the nutrients, is a source of essential fatty acids, and allows the absorption of essential fat-soluble vitamins. The caloric density of dietary fat is more than two-fold greater than protein or carbohydrate sources.

Therefore, increasing the level of dietary fat increases the energy density of the diet. Fat also contributes to the palatability and acceptable texture of commercially prepared dog foods. Common sources of fat include chicken fat, tallow, lard, corn oil, safflower oil, soybean oil, sunflower oil, fish oils, and flax oil.

Protein

Dietary protein is supplied by animal and plant sources. In general, high-quality animal-based protein provides superior digestibility, amino acid balance, and palatability. However, the quality of animal-based protein sources can vary depending on processing methods and conditions used during production.

Animal-based protein sources commonly included in commercial dog foods include chicken, chicken by-product meal, chicken meal, beef, egg, fish meal, meat and bone meal, meat by-products, meat meal, lamb, and lamb meal. Common sources of plant-based protein in dog foods include corn gluten meal, soy flour, soy grits, soybean meal, and wheat germ.

Lower cost dog foods that are primarily formulated with vegetable protein sources often use a combination of soy products and corn gluten meal to compensate for the low levels of the essential amino acid found in corn gluten (deficient in lysine and tryptophan) and soy products (deficient in methionine).

Carbohydrates

Ingredients that contribute digestible carbohydrates include various forms of corn, rice, wheat, sorghum, barley, potato, and oats. These ingredients contribute complex carbohydrates in the form of starch that is highly available when properly cooked. Other carbohydrate sources include molasses and certain types of hydrolyzed starches. Dietary carbohydrates provide sporting dogs with a readily available source of energy. A limited amount of carbohydrate can also be stored in the body as glycogen with the excess metabolized to fat for energy storage.

A NUTRITIONAL STUDY WITH HUNTING DOGS - Overview of the Study

The nutritional management of hunting dogs can have a significant impact on their overall hunting performance and working ability, based on the results of a 2-year study.⁵ Three commercial diets were fed to English Pointers during the quail-hunting season at a hunting plantation in southwest Georgia. Principle ingredients, nutrient content, and caloric distribution of each diet are presented in Tables 1 and 2. In the first year of the study, 23 adult Pointers were fed Eukanuba® Adult Premium Performance Formula (Eukanuba) or Diamond® Adult Dog Food (Diamond).

In the second year of the study, 22 Pointers were fed Eukanuba or Purina Pro Plan® Chicken & Rice Formula (Pro Plan). Daily care and management of the dogs was provided by two professional handlers employed by the plantation. These handlers were unaware of the specific diet each dog received during the season. The respective diets were fed exclusively during the training and hunting seasons. Dogs were fed to maintain body weight. The selection of dogs for hunting and the amount of time they were allowed to hunt were at the discretion of the handlers. The handlers recorded the date of hunting, total time hunted, and the number of finds for each dog. Overall hunting performance was calculated for each dog by determining the total number of finds per hunting session and total hours hunted.

Results

The results of year 1 showed that all dogs remained healthy and consumed typical amounts of food throughout the hunting season. Dogs fed Eukanuba maintained or gained weight and body condition throughout the hunting season, while dogs fed Diamond lost significantly more (P<.05) body weight and condition (Figure 1).

Figure 1. Body weight of English Pointers fed two commercial diets during quail-hunting season - Year 1.

As a result, body weight and body condition scores at the end of the hunting season were significantly higher for dogs fed Eukanuba compared with those fed Diamond. No significant differences were observed in stool scores, despite a tendency for stools to be slightly softer for dogs fed Diamond. Dogs fed Eukanuba demonstrated significantly superior hunting performance compared with dogs fed Diamond, based on total finds per hunt and on number of birds located per hour of hunting (Figure 2).

Figure 2. Hunting performance (finds/hour) by English Pointers fed two commercial diets during quail-hunting season - Year 1.

For the season, dogs fed Eukanuba had an average of 55% more finds, which was equivalent to one more find per hour of hunting. There were 9 days during the season in which the heat index was rated as high or severe based on a temperature-humidity index. On each of these days, dogs fed Eukanuba maintained their superior hunting performance, compared with dogs fed Diamond (Figure 3).

Figure 3. Hunting performance (finds/hour) of English Pointers during periods of mild to severe heat stress - Year 1.

In year 2, there were no differences in body weight, body condition, stool scores or health status for dogs fed Eukanuba or Pro Plan. Despite these similarities, dogs fed Pro Plan required 11% more food to maintain body weight and condition (Figure 4).

Figure 4. Daily food intake by English Pointers fed two commercial diets during the quail-hunting season - Year 2.

This increased feeding amount was equivalent to 2/3 cup more food per day for each dog. Performance results showed that dogs fed Eukanuba had an average of 33% more finds during the season than dogs fed Pro Plan (Figure 5).

Figure 5. Hunting performance (finds/hunt) by English Pointers fed two commercial diets during the quail-hunting season - Year 2.

Although dogs were not subjected to any heat-stress conditions during this second year, post-hunting rectal temperatures showed that dogs fed Eukanuba ran cooler during hunting compared with dogs fed Pro Plan (Figure 6).

Figure 6. Pre- and post-hunting body temperatures of dogs fed two commercial diets during the quail-hunting season - Year 2.

Body temperature increases during hunting due to increased physical activity. Therefore, the lower post-hunt body temperature of the dogs fed Eukanuba implies that they were more efficient metabolically in capturing dietary energy in a form that could be used to sustain their increased physical activity.

In contrast, the higher body temperature of dogs fed Pro Plan implies that less dietary energy was captured in a usable form for work and more was wasted energy lost as heat, which contributed to the increase in body temperature.

Conclusions from the Study

The working ability of English Pointers was measured using the practical response criterion, hunting performance. In terms of the number of points or birds found during a hunting session, the dogs fed Eukanuba performed better than those fed Diamond or Pro Plan.

Although such assessments are not easily standardized in a field setting, the two handlers remained unaware of the dietary treatments during both hunting seasons. This control allowed comparisons to be made principally on the dog's hunting success during each season, when the only variation in management was the diet being fed to each group.

Several dietary factors may have influenced the hunting ability and body condition of these dogs. Pointers tend to be a highly active breed and individuals do not typically carry excess body fat. Furthermore, these dogs typically lose a considerable amount of body condition as the hunting season progresses. Weight loss, even when moderate, is always comprised of both fat and lean body tissue.⁶

Unfortunately, loss of lean tissue will negatively impact body condition and stamina, which are required for sustained performance as the hunting season progresses.

EFFECT OF DIET ON PERFORMANCE

The caloric density of a diet will affect the quantity of food that must be consumed to meet energy requirements. If the energy content of the diet is too low to support increased work, the quantity of food that must be consumed may exceed the physical capacity of the digestive tract. This may lead to an increased rate of passage and decreased diet digestibility, further exacerbating an energy deficit. The production of softer stools implies that a diet may be bulk limiting, which would ultimately affect energy intake, diet digestibility and nutrient availability.

The availability of dietary fat may also affect performance during periods of strenuous work. Dietary fat affects body composition of exercising dogs, as lower fat diets result in a loss of lean tissue and body fat compared with highfat diets.⁷ The dog is an efficient aerobic athlete that performs best when fed a diet that supplies a large proportion of its energy as fat.^8,9 Controlled studies using treadmill-exercised dogs have shown that endurance is positively correlated with dietary fat intake and diet digestibility.^7,10

In addition, the source of dietary fat may affect hunting ability based on changes in olfactory function. Previous research has shown that olfactory sensitivity is compromised in dogs fed diets containing a greater percentage of saturated fatty acids.¹¹

Therefore, inferior performance of hunting dogs could be attributed to the source of dietary fat used in commercial dog foods. For example, the use of beef tallow in the Pro Plan formula may have negatively impacted olfactory functionality and hunting performance of the Pointers compared with the performance of dogs fed Eukanuba with poultry fat because the beef tallow provides a greater percentage of saturated fatty acids.

Common folklore among dog trainers asserts that feeding a high-fat diet to working dogs can predispose them to heat stress during hot weather. However, this belief was not supported by the performance data during year 1 of the study. The increased fat consumed by dogs fed Eukanuba compared with Diamond did not negatively affect the working ability or stamina of the dogs during periods of heat stress. These results are also supported by previous research showing that a reduced-fat diet produced higher rectal temperatures in dogs after one hour of treadmill exercise compared with a high-fat diet.⁷

Therefore, a high-fat diet appears to be more beneficial to a working dog during periods of hot weather based on its ability to reduce core body temperature. In addition, the source of fat used in the formula may affect thermoregulation based on the lower post-hunting body temperatures of dogs consuming Eukanuba with poultry fat compared to Pro Plan with beef tallow.

Current evidence indicates that aerobic training imposes an increased need for dietary protein in dogs.¹² Athletic conditioning results in adaptive physiological changes that facilitate the efficient delivery of oxygen and nutrients to working muscles. These changes include increases in blood volume, red blood cell mass, capillary density, mitochondrial volume, and the activity and total mass of metabolic enzymes.^11,13

The increased tissue mass and requirement for gluconeogenic amino acids during hunting and exercise necessitate increased protein intake by working dogs. The protein content of the diet may also affect the capacity of blood to oxygenate tissues and transport energy-containing nutrients needed by working muscles.¹¹

Although the protein content of a diet may be within the recommended range to provide for maintenance needs, a slight reduction in protein content and (or) amino acid availability may become metabolically significant during periods of physical activity due to its inability to supply sufficient amino acids to exercising tissues.

CONCLUSIONS

Dogs are exceptional aerobic athletes, and those trained for endurance events perform best when fed a diet that has been formulated to meet their increased energy and nutrient demands. The results of the plantation study demonstrate that the food selected for working dogs directly affects their performance and working ability, based on the superior hunting performance of dogs fed Eukanuba® Adult Premium Performance Formula compared with Diamond® Adult Dog Food or Purina Pro Plan® Chicken & Rice Formula.

These results provide valuable information for trainers, handlers, and veterinarians who are concerned with the nutritional management of working dogs and the promotion of maximum performance and overall health and well-being. Permission was granted by Veterinary Learning Systems to reprint portions of this article.

REFERENCES

1. Kronfeld DS. Diet and the performance of racing sled dogs. J Am Vet Med Assoc 1973; 162:470-473.
2. Rose RJ, Bloomberg MS. Responses to sprint exercise in the greyhound: Effects on hematology, serum biochemistry and muscle metabolites. Res Vet Sci 1989; 47:212-218.
3. Reinhart GA. Nutrition for Sporting Dogs. In: Bloomberg MS, Dee JF, Taylor RA, eds. Canine Sports Medicine and Surgery. Philadelphia: WB Saunders, 1998; 348-356.
4. Grandjean D, Paragon BM. Nutrition of racing and working dogs. Part I. Energy metabolism of dogs. Compendium 1992; 14:1608-1615.
5. Davenport GM, Kelley RL, Altom EK, Lepine AJ. Effect of diet on hunting performance of English Pointers. Vet Therap 2001; 2:10-23.
6. Burgess NS. Effect of a very-low-calorie diet on body composition and resting metabolic rate in obese men and women. J Amer Diet Assoc 1991; 91:430-434.
7. Altom E. Effect of dietary fat and physical conditioning on the metabolic and physiological responses of the canine athlete [dissertation]. Auburn, AL: Auburn University; 1999.
8. Reynolds AJ, Fuhrer L, Dunlap HL, et al. Lipid metabolite responses to diet and training in sled dogs. J Nutr 1994; 124:2754S-2759S.
9. Reynolds AJ, Hoppler H, Reinhart GA. Sled dog endurance: A result of high fat diet or selective breeding? FASEB 1995; 9:A996.
10. Downey RL, Kronfeld DS, Banta CA. Diet of beagles affects stamina. J Am Anim Hosp Assoc 1980; 16:273-277.
11. Kronfeld DS, Hammel EP, Ramberg CF Jr, et al. Hematological and metabolic responses to training in racing sled dogs fed diets containing medium, low, or zero carbohydrate. Am J Clin Nutr 1977; 30:419-430.
12. Adkins TO, Kronfeld DS. Diet of racing sled dogs affects erythrocyte depression by stress. Can Vet J 1982; 23:260-263.
13. Querengaesser A, Iben C, Leibetseder J. Blood changes during training and racing in sled dogs. J Nutr 1994; 2760S- 2764S.