Animal Nutrition and Diet Development

Principles of Developing Diets for Different Animal Species

• The Three-Step Process of Diet Formulation

  • Step 1: Estimate Nutrient Requirements: Use information specific to the animal, recognizing that requirements vary based on the stage of life (e.g., a lactating dairy cow versus a non-milking cow, or a puppy versus an old dog).

  • Step 2: Evaluate Available Foodstuffs: Determine which ingredients will meet the estimated requirements.

  • Step 3: Determine Proportions: Decide on the specific mix of particular foodstuffs to optimize nutrition and economy.

• Key Nutritional Guidelines and Resources

  • National Research Council (NRC): Publishes nutritional recommendations for most domestic species. Information can be obtained from agricultural extension offices, the National 4-H Council, or the US Food and Drug Administration (FDA).

  • Board on Agriculture and Natural Resources (BANR): A unit of the National Research Council (part of the National Academies of Sciences, Engineering, and Medicine) that oversees the Animal Nutrition Program.

  • BANR Focus Areas: Environmental quality, animal production, food safety, and animal/human health.

• Evaluating Foodstuffs and Ration Considerations

  • Nutrient Contribution Analysis: Feeds are evaluated based on their contribution to crude protein, crude fat, crude fiber, and ash.

  • Definition of Ash: The weight of a foodstuff after it has been heated in a furnace to $500^\circ \text{C}$ or $600^\circ \text{C}$.

  • Balancing the Ration: It is rare for a single foodstuff to contain all necessary nutrients without excesses. A mix of feeds provides a balanced ration and prevents ingredient waste.

  • Economical Factors: A cheap source for one species may be inappropriate for another. For example, urea is a cheap protein source for herbivores but cannot be used for carnivores. Meat and fish meals are affordable for poultry and omnivores but too expensive for herbivores.

  • Realistic Amounts: Analysis must be based on a ration size the animal is actually capable of consuming.

  • Other Influences: Processing, taste, storage, mixing, packaging, and additives must be considered. In pet food markets (dogs and cats), packaging often appeals to the owner, but the focus must remain on nutritional quality.

  • Computerized Formulation: Mathematical complexity has led to computer software developed by universities and private enterprises. This requires accurate laboratory analysis measurement to be effective.

Diet Supplementation and Individual Variation

• The Role of the Nutritionist

  • Duties include producing a diet through science and trial that meets all nutritional requirements.

  • Professionals must read labels to understand ingredient variations between manufacturers.

• Supplementing Major Feed Sources

  • Roughage: Defined as coarse, bulky, largely indigestible material. Essential for wild and domestic herbivores. Omnivores can survive on it but show decreased productivity.

  • Herbivore Supplements: Use dry forage and silage to improve diet quality.

  • Omnivore and Carnivore Supplements: Use concentrates, protein concentrates, and animal byproducts (meat meal, bone meal, blood meal).

  • Biological Value: Fish meal and soybean meal possess higher biological value than meat/bone meal, which varies based on bone and tendon content.

• Vitamin and Mineral Considerations

  • Excess minerals can be harmful. Intake exceeding requirements increases excretion and absorption of that mineral, but can also bind to other minerals, preventing their absorption.

  • Individual Characteristics: Factors like appetite and metabolic rate dictate diet. "Picky eaters" or animals prone to obesity require tailored approaches.

Feeding Companion Animals: Dogs and Cats

• General Requirements for Mature Adults

  • Adults refers to animals with normal activity levels that are not pregnant, lactating, or working.

  • Commercial dry, semi-dry, or moist foods are recommended. Fresh water must be available at all times.

• Canine Feeding Guidelines

  • Medium-sized Dogs ($35$ to $50\,\text{lb}$): Require $0.33$ to $0.5\,\text{oz}$ of dry food per pound of body weight, or $1$ to $1.5\,\text{oz}$ of canned food per pound.

  • Health Focus: Dogs should be kept lean to avoid disease. Table food/scraps should not exceed $15\%$ of the diet and should only be used to increase palatability.

• Feline Feeding Guidelines

  • Metabolic Needs: Cats sleep approximately $20\,\text{hours}$ per day, requiring careful energy management to prevent obesity.

  • Feeding Amounts ($7$ to $9\,\text{lb}$ cat): Require $2.5$ to $3.2\,\text{oz}$ of dry food daily. Canned food should be provided in weights $2$ to $3$ times more than dry food.

  • Prevention of Finicky Behavior: Avoid unnecessary supplementation or frequent diet switching.

Feeding Ruminants

• Defining the Ruminant

  • Mammals that digest plant-based foods via the rumen (the first stomach compartment). They regurgitate semi-digested matter called "cud" for further chewing.

  • Examples: Cattle, sheep, goats, deer, llamas, and alpacas.

• Components of the Ruminant Diet

  • Forages and Roughages (Fodder): Plants/plant products high in fiber and low in energy. Composed mainly of carbohydrates.

  • Cellulose (Crude Fiber): Found in plant stems; less digestible than starch. Often referred to as cell walls or acid-detergent fiber in analysis.

  • Starch (Reserve): Found in plant seeds; more digestible than cellulose.

  • Roughage Classification: Feeds high in cellulose, including hay, straw, and silage.

  • Concentrates: Feeds low in crude fiber and highly digestible, such as seeds and their byproducts.

• Forage Plants and Crops

  • Alfalfa: The most important forage crop; suitable for all farm animals.

  • Tame Hay: Specifically grown for feed. Common types include clover, timothy, oats, and cereal/legume mixtures. Barley and wheat may be used if growing conditions do not favor grain maturity.

  • Silage Crops: Corn is the most popular, followed by oats and vetch or poor-quality first-cutting alfalfa.

• Nutritional Comparison of Forage Species

  • Wheat grasses: Hardy and drought-resistant.

  • Bent grasses: Lowest palatability.

  • Meadow foxtail: Leafy and palatable for pasture.

  • Bluestems: Dependable, though palatability drops with maturity.

  • Carpet grass: Low in nutrients; cannot be used alone for a balanced diet.

  • Grama grasses: Reliable forage for range and pasture.

  • Bromegrasses: One of the most important and palatable species.

  • Bermuda grass: Used for pasture and nutritious hay.

  • Orchard grass: Maximum tonnage of silage early in the season when grown with legumes.

  • Wild rye grasses: Relatively unpalatable and susceptible to ergot (a deadly dried fungus).

  • Love grasses: Valuable for low-fertility soils.

  • Perennial fescues: Excellent for forage.

  • Perennial ryegrass: Used for livestock grazing while other grasses establish.

  • Panic grasses (Millet-related): Livestock prefer these when green and succulent.

  • Poa: Usefulness genus of bluegrasses.

• Legumes for Feed

  • Alyce clover: Summer annual for hay.

  • Peanuts: Straw has excellent feed value after seed harvest.

  • Soybeans: Oil meal is a highly concentrated feed for all livestock.

  • Rough pea: Used for pasturage; matures plants may contain poisons.

  • Lespedeza: Hay yields similar to clover.

  • Trefoils: Grown where alfalfa/clover fails.

  • Lupines: Contains a poisonous alkaloid; not widely used.

Factors Affecting Forage Quality and Mineral Imbalances

• Harvest Timing and Storage

  • Energy and protein are highest in the cool season during the young vegetative state.

  • Legumes are cut at $10\%$ bloom; perennial grasses (orchard grass, timothy, ryegrass) just before budding.

  • Corn Silage: Harvested at the hard dough stage ($33$ to $37\%$ dry matter).

  • Particle Size: Ideal size is $7\,\text{mm}$. Too fine targets rapid rumen exit; too large causes poor packing and spoilage.

  • Storage Temperature: Excess heat in dry silage inactivates vitamins A and E and reduces protein/energy availability.

• Mineral and Supplemental Needs

  • Calcium-Phosphorus: Grains are low in calcium. Forages are high in calcium but have an imbalance that requires phosphorus supplementation.

  • Sodium: Standard vegetable foodstuffs lack sodium; owners provide salt licks.

  • Iodine and Goitrogens: Some plants inhibit iodine concentration in the thyroid (goitrogenic). Examples include soybeans, linseed, peas, peanuts, and cruciferous plants (mustard family).

  • Toxins: Selenium-rich soils can lead to toxic plant concentrations. Peat/muck soils high in molybdenum cause diarrhea.

  • Manganese: Corn is extremely low in manganese; diets must be supplemented, especially if using animal byproducts (also low in manganese).

  • Zinc: Requirement is higher for plant-protein diets than animal-protein diets.

• Sweet Clover Disease

  • Occurs in calves fed spoiled sweet clover. Bacteria in hay create dicoumarin, a chemical that inhibits vitamin K.

  • Result: Prevented blood clotting leading to massive internal hemorrhages.

Specialized Ruminant Feeding Recommendations

• Feeding Microorganisms: The goal is to meet the nutritional needs of the billions of bacteria and protozoa in the rumen first.

• Fiber Levels: Dry matter should be $15$ to $17\%$. Fiber must be fed in coarse form (not ground) to promote rumination.

• Consumption Rates:

  • Pasture Forage: $100$ to $200\,\text{lb}$ per day ($30$ to $60\,\text{lb}$ dry matter).

  • Hay Only: $2$ to $3\,\text{lb}$ per $100\,\text{lb}$ of body weight.

  • Silage-to-Hay Ratio: $2.5$ to $4.5\,\text{lb}$ of silage equals $1\,\text{lb}$ of hay.

  • Hay-to-Grain Ratio: $3\,\text{lb}$ of hay supplies the same energy as $2\,\text{lb}$ of grain.

• Ration Design: Usually formulated for groups rather than individuals, including margins of safety for environmental factors.

Feeding Horses, Swine, and Birds

• Horse Nutrition

  • Requirements depend on body weight and work (energy, vitamins, minerals, protein).

  • Protein Needs: Foals ($18\%$) versus adults ($12$ to $14\%$).

  • Intake: $2$ to $2.5\%$ of body weight in dry feed daily. Idle/Light work horses on high-grain diets may eat only $1.5\%$. Foals and lactating mares require $3\%$.

  • Calculation Example: An $1100\,\text{lb}$ horse eating $2\%$ consumes $22\,\text{lb}$ of feed.

  • Component Characteristics:

    • Grains: High TDN (total digestible nutrients) and phosphorus; low fiber and calcium.

    • Grass hays: High fiber; low protein/TDN/phosphorus.

    • Legume hays: High protein, calcium, and fiber.

  • Standard Ration: Mixture of oats, rolled corn/sorghum, soybean meal, limestone, and trace mineralized salt ($12$ to $15\%$ protein; $69$ to $70\%$ TDN).

• Swine Feeding

  • Pigs eat to meet energy requirements; low-energy diets lead to higher consumption volumes.

  • Nutrients expressed as a percentage of diet "as-fed" ($90\%$ dry matter).

• Avian Feeding (Poultry and Psittacines)

  • Psittacines: Order including parrots and parakeets. Data largely based on cockatiels.

  • Protein Requirements:

    • Breeding: $20$ to $25\%$ crude protein.

    • Maintenance: $20\%$ crude protein.

    • Chicks: Up to $28\%$ protein.

Feeding Reptiles, Rodents, Rabbits, Ferrets, and Amphibians

• Reptile Nutrition

  • Energy needs are metabolic; proportions are estimated from natural history and habitat.

  • Carnivores: Fuel sources are fat and protein ($25$ to $60\%$ protein; $30$ to $60\%$ fat).

  • Herbivores: Reliant on soluble carbohydrates and fermented fiber ($>50\%$ calories from carbs; $15$ to $35\%$ protein; $<10\%$ fat).

  • Feeding Strategy: Vertebrate prey is usually balanced. Insects can be "gut loaded" (e.g., feeding calcium-rich diets to crickets).

• Rodent Nutrition

  • Consume approximately $5\,\text{g}$ of food per $100\,\text{g}$ of body weight daily.

  • Analysis: $16$ to $24\%$ protein, $60$ to $65\%$ carbohydrate, $5$ to $7\%$ fat.

  • Specifics: Gerbils (< $4\%$ fat); Hamsters (utilize soybean meal better than fishmeal); Complex carbs (cornstarch) are better than simple carbs.

  • Guinea Pigs: Must have a dietary source of Vitamin C.

• Rabbit Nutrition

  • Hindgut Fermenters: Large cecum requires coprophagy (eating night feces) to conserve water, B vitamins, and protein.

  • Digestible Energy: Maintenance ($2100\,\text{kcal/kg}$); Development/Gestation/Lactation ($2500\,\text{kcal/kg}$).

  • Protein/Fat: $12$ to $17\%$ crude protein and $5$ to $10\%$ fat.

• Ferret Nutrition

  • Ratio: Calorie-to-protein ratio of $16:1$.

  • Intake: Adult ($1.5\,\text{kg}$) consumes $40$ to $70\,\text{g}$ of dry food. Adult energy need is $200$ to $300\,\text{kcal/kg}$ body weight.

  • Fat content: $9$ to $28\%$. Growth/reproduction requires high density ($5000\,\text{kcal/kg}$).

• Amphibian Nutrition

  • Larvae (Tadpoles): Aquatic; can be herbivores, omnivores, or carnivores. Feed flakes or invertebrates.

  • Adults: All are carnivores (except one tropical fruit-eating frog). Mostly insectivores.

Management of the Anorexic Animal

• Consequences of Anorexia

  • Anorexia is defined as a diminished appetite or aversion to food.

  • Physical Effects: Immune system dysfunction, delayed wound healing (requires protein), enteric lining alterations leading to septicemia (bacteria/toxins entering circulation), and decreased liver metabolism.

  • Liver Impact: Drugs may become toxic (failure to degrade) or ineffective (failure to activate).

• Clinical Evaluation of Anorexia

  • Diagnosis Questions: Gradual vs. acute onset? Partial vs. complete? Is there fever?

  • Oral Examination: Checking for tooth abscesses, foreign bodies, or mandibular fractures.

  • Systemic Signs: Jaundice, dehydration, or anemia.

  • Vitamin B Deficiency: A major cause of anorexia in cats, whose requirements are $8$ times greater than a dog's.

• Appetite Stimulation Strategies

  • Cats: Prefer meats, fat flavors (fat-coated foods), and acidic rations. Stimulate licking by putting food on paws/lips. Use wide, shallow bowls (to avoid whisker contact). Reduce stress and use petting.

  • Dogs: Attracted to protein, fat, sweets, and strong odors. Warming food increases the enticing aroma.

  • Conditioned Aversion: Dogs associate food with nausea/cramping; do not feed immediately after administering medications that cause vomiting.