Animal Nutrition: Basic Terms

Basic Terms in Animal Nutrition

• Nutrients are chemical substances in feed needed for growth, maintenance, production, and health, including carbohydrates, proteins, lipids, minerals, and vitamins.
• Feed can be any naturally occurring ingredient or combinations given to animals for nourishment.
• A Ration is the amount of feed an animal gets over 24 hours.
• Feedstuff refers to any ingredient in a diet (ration) that serves a useful purpose.
• As-fed refers to feed as it is normally provided to animals, moisture included.
• Dry matter is the total weight of feed, not including the water.
• Total Digestible Nutrients (TDN) measures the energy value available in a feedstuff.
• Feed Conversion Ratio (FCR) measures the rate at which an animal converts feed into meat.
• Feed Conversion Efficiency (FCE) measures an animal's ability to convert feed into flesh.
• Digestibility is quantifying the digestion process.
• Digestibility is the extent that ingested food and its nutrient components are digested and absorbed.
• Digestibility is measured by feed intake minus faeces output.
• Gross Energy (GE) is the total energy within a feed.
• Gross Energy is accounted for before any losses from digestive, metabolic, or productive functions.
• Digestible Energy (DE) is the energy available for use by an animal.
• Digestible Energy is estimated by subtracting energy loss in faeces from gross energy intake.
• Metabolizable Energy (ME) is the gross feed energy minus the energy lost in faeces, urine, and gaseous products.
• Net Energy (NE) is the amount of energy in feed that is available for maintenance, growth, and production.
• Net Energy is the proportion of ME remaining after energy expended in body heat, NE = ME – heat increment of feeding.

Classes of Feedstuff

• Dry roughages: bulky feeds with low weight per unit volume and high crude fiber content.
• Dry roughages have generally low protein and fat digestibility.
• Dry roughages are classified as roughage if it has over 18% crude fiber and 70% total digestible nutrients.
• Dry roughage examples include hay, straw & chaff, sugarcane bagasse, corn cobs, and cottonseed hulls.
• Succulent roughages include pasture grasses natural and cultivated, legumes fresh, tree leaves, roots, and tubers.
• Silages and haylages are fermented high-moisture feeds made from plant material.
• Silage contains 20% to 45% DM, while haylage contains 50% to 75% DM.
• High-energy concentrates include cereal grains, milling by-products of cereal grains, molasses, and animal & vegetable fat.
• Protein concentrates/supplements contain more than 20% Crude Protein (CP).
• Protein supplements include oil seeds and their meals, animal/avian/marine sources, milk and by-products, brewery/distillery by-products, urea, and ammonia.
• Vitamins & Mineral Supplements, animals must be able to absorb.
• Vitamin concentrations in plant and animal tissues varies.
• Plant vitamin concentrations are affected by harvesting, processing, and storing.
• Animal livers and kidneys are good sources of vitamins.
• Feed Additives are non-nutritive ingredients that stimulate growth or improve the efficiency of feed.
• Feed additives are added in very small quantities.
• Feed additives include antibiotics, antifungals, antimicrobials, probiotics, buffers, colors, flavors, hormones, and enzymes.