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Unit 7: Animal Nutrition
Chapters 15-17
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Objectives Basic understand of nutrients, digestibility, evaluation, and composition of feeds Knowledge of digestibility in both the monogastric and ruminant animal Appreciation for nutrient function and requirements for growth, maintenance, reproduction, and lactation Understanding of ration formulation
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Nutrients Any feed that functions to support life
Concentrates and roughages What are they? What are the differences nutritionally? Six basic classes Water Carbohydrates Fats Proteins Minerals Vitamins
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Nutrients Water Difference between water & moisture Dry matter
Most important nutrient! Functions Metabolic reactions Transport nutrients Temperature maintenance Physical shape of the body (cell contents)
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Nutrients Carbohydrates Found in plant & animal tissue
Simple carbohydrates Starch Easily digested High in energy Complex carbohydrates Cellulose, lignin Energy source Present in cell walls
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Nutrients Fats Includes oils A.K.A. lipids
Fats are solid, oils are liquid at room temp. 2.25x more energy/lb. than carbs. >100 fatty acids identified Linoleic, and α-Linolenic are essential in livestock diets Precursor of prostaglandins & cell structure
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Nutrients Proteins Simple Complex
Amino acids Building blocks of the animal’s body Ex. Complex Glycoproteins Lipoproteins Hemeproteins Only nutrient class that contains nitrogen Ave. ~16% 6.25 multiplier %N X 6.25 = %protein
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Nutrients Essential Amino Acids
Must be supplemented in the diet Feed Microbial protein Nonessential Amino Acids are synthesized by the body Various absorption rates Egg Animal Plant
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Nutrients Minerals Chemical elements other than carbon, hydrogen, oxygen, nitrogen Macrominerals Required in larger amounts Ex.? Important for several major bodily functions Micromineral Trace minerals, required in small amounts Important for vitamins, hormone synthesis Usually work together w/ other nutrients Can be harmful in high levels
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Nutrients Vitamins Organic nutrients required for very specific bodily functions 16 vitamins Fat soluble A, D, E, K Water soluble C, B12, B1, Niacin In ruminants, these are synthesized by the microorganisms
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Feed Analysis Proximate Feed Analysis Components measured
Separates feed components into group according to feed value Accuracy of the analysis is dependent upon accuracy of the sample Components measured Water Crude protein Crude Fat Crude Fiber Nitrogen-free extract Ash (minerals)
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Feed Analysis Feed Digestibility Energy Evaluation of Feeds
Determining moisture and/or DM content Feed Digestibility Amount of a feed that is absorbed from the digestive tract Great variance Measuring digestibility Energy Evaluation of Feeds Energy is available in any nutrient with carbon Carbs., protein, fats Driving force in bodily function
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Feed Analysis Measuring energy Calorie (cal) TDN Not as accurate ME
Very accurate NE DE Calorie (cal) Energy required to raise the temp of 1g of water 1 degree C
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Feed Analysis Kilocalorie (kcal) Megacalorie (Mcal)
Energy needed to raise the temp of 1kg water 1 degree C Megacalorie (Mcal) =1,000 kcal or 1,000,000 cal Some energy is lost, and therefore not digested Feces Urine Gases Heat
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Feed Analysis Animal uses energy in two ways Maintenance Production GE
Amount of heat (cal) released from complete burning of a feed (Bomb Calorimeter) ME is what the animal actually has the opportunity to use NE is what is available after energy used for consumption, digestion, metabolism (heat increment)
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Feed Analysis In diet formulation: NEm NEg NEl
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Figure 15.3 Measures of energy and energy utilization.
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Feeds and Feed Consumption
Classification of Feeds Dry roughages & forages Hay Straw Other Range, pasture, green forage
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Feeds and Feed Consumption
Silages Energy Feeds >18% CF, <20%CP Protein supplements >20% CP Mineral supplements Vitamin supplements Nonnutritive additives Antibiotics Coloring Flavors Medicants Etc.
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Feeds and Feed Consumption
Nutrient Composition of Feeds Goal of nutrient analysis is to predict the production capability of a feed Tables are an average, true analysis is much more accurate Composition can vary: 15% in CP 10% in energy 30% in minerals
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Digestion & Feed Absorption
Mechanical Chemical Role is to produce feed particles the can be absorbed and used by the body
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Carnivorous, Omnivorous, & Herbivorous animals
Which is which? Carnivores & Omnivores are monogastric animals One, simple stomach Also some herbivores (horse, rabbit) Herbivores Ruminants Stomach compartments
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The Monogastric Digestive Tract
Mouth Mechanical chewing and swallowing of food Salivary Glands Esophagus Delivery tube from mouth to stomach Valve controls opening Stomach Primary area of reduction in feed particle size
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The Monogastric Digestive Tract
Small intestine Duodenum Jejunum Ileum Split molecules & absorb nutrients Large intestine Cecum Colon Absorb water Forms indigestible waste (Feces)
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Figure 16.1 Digestive tract of the pig as an example of the digestive tract of a monogastric animal.
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Figure 16. 2 Digestive system of the horse
Figure Digestive system of the horse. The posterior view shows the colon or large intestine proportionally larger than the rest of the digestive tract. Note particularly the location of the cecum at the anterior end of the colon.
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Ruminants Rumen Reticulum Fermentation vat Papillae
Bacteria & protozoa Reticulum Aka honeycomb Initiate mixing in rumen
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Ruminants Omasum Abomasum
Many folds (manyplies) Grinding action? Not a lot of digestive responsibility Abomasum True stomach Ruminants can rechew feed already consumed for more thorough breakdown of feed particles (Cud) known as rumination Elimination of gases by eructation
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Figure 16.4 Beef cattle digestive tract.
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Figure Lining of the four compartments of the ruminant stomach (goat). (A) Compartments intact. (B) Compartments separated. Courtesy of George F. W. Haenlein. University of Delaware.
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Figure The esophageal groove, with its location relative to the esophagus, reticulum, and rumen. Courtesy of N. J. Benevenga et al., Preparation of the ruminant stomach for classroom demonstration. J. Dairy Sci. 52:1294.
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Digestion in Monogastrics
Begins in the mouth Enzymatic reactions Organic catalyst that speeds a chemical reaction without being altered by the reaction Stomach secretions HCl Mucus Pepsin Gastrin
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Digestion in Monogastrics
Mixture and some digestion occurs, resulting in Chyme Amino acids, fatty acids, and monosaccharides are available for absorption Two methods of absorption Passive Molecules diffuse from high concentration area to low concentration Active Engulf molecules in villi, and transport them to bloodstream or lymph
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Digestion in Monogastrics
Liver function Metabolizes feed particles in bloodstream Detoxifies harmful substances
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Digestion in Ruminants
Fermentation in rumen & reticulum Microorganisms number in the billions Excess are removed with feed movement and killed by acid in the abomasum Mutually beneficial relationship Digestion is the same after feed reaches the abomasum Microorganisms use starch and sugar for their growth and development Robs the animal of valuable energy sources Produce Volatile Fatty Acids (VFA) which the animal absorbs and converts to energy Acetic Propionic Butyric Methane gas is released through eructation What if this action fails?
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Digestion in Ruminants
Esophageal groove Pathway directing milk to abomasum Complete function of digestive tract is not complete until: Sheep ~2 mos. Cattle ~3-4 mos. Influenced by feed type Energy Pathways End products of glucose and fatty acids supply body tissues with energy, and become milk fat and lactose in the lactating ruminant
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Digestion in Ruminants
Primary organs and tissues in energy metabolism Rumen Abomasum Small intestine Liver Blood vessels Mammary gland Body tissue Undigested energy products Complex carbos. (lignin) and other (ex. Ketone bodies) Excreted through large intestine or kidneys
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Figure 16. 8 Energy pathways in the ruminant. Source: J. Bryant and B
Figure Energy pathways in the ruminant. Source: J. Bryant and B. R. Moss, Montana State University.
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Digestion in Ruminants
Protein Pathways End products of protein and NPN: Amino acids Ammonia Excess formed into urea in liver and excreted in the urine Some is returned to the rumen Synthesized amino acids
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Figure 16. 9 Protein pathways in the ruminant. Source: J. Bryant and B
Figure Protein pathways in the ruminant. Source: J. Bryant and B. R. Moss, Montana State University.
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Nutrient Requirements for Body Maintenance
No gain/loss of weight or production High priority for nutrients Body tissue repair Temp control Energy for vital organ function Water balance maintenance Takes ~½ of all ingested feed
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Nutrient Requirements for Body Maintenance
Examples Feedlot steers ~30-40% for maintenance Breeding animals ~90% 100# dairy cow eat 4-5x their daily maintenance requirement Body size & Maintenance Increased body size means increased nutrient requirement But, not at a linear rate
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Nutrient Requirements for Growth
Occurs when: Protein synthesis is > protein breakdown Cells increase in number & size Both Building of muscle, bone, connective tissue Nutrients needed for growth Energy, protein, minerals, vitamins Muscle growth is due to protein
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Nutrient Requirements for Growth
Ca, P, & NaCl Ca usually plentiful in legume forage P plentiful in grain I & Se Deficiency in I results in goiter Se deficiency-white muscle disease
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Nutrient Requirements for Growth
Vitamin D Needed for proper use of Ca & P Can get from sunshine (conversion of cholesterol in the skin), unless raised inside Vitamin A Can be lost during drying in the sun, or extended dry storage
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Nutrient Requirements for Fattening
Storing surplus feed in and around body tissue Desirable for quality meat production and energy storage 2.25x more energy to produce 1# fat as opposed to 1# protein Due to excess: carbos, fats, protein
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Nutrient Requirements for Reproduction
2 categories Gamete production Nothing above normal maintenance Body condition affects fertility Fetal growth Greatest in last trimester of pregnancy Requirements of the fetus are the same as those after it is born Healthy females can withdraw nutrients from their body for the fetus
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Nutrient Requirements for Lactation
Requires protein, minerals, vitamins, energy Protein is greatest >3% protein in milk Body protein can be mobilized in deficient times Ca & P are critical Hypocalcemia
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Nutrient Requirements for Lactation
Energy Based on amount of milk produced Production can be limited by intake High producing dairy cow may need 3-4x the energy of non-lactating cow of same size Why do some cows continue to lose weight? What is the ideal forage to concentrate ratio in dairy cows?
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Energy Requirements for Work
Primary requirement is energy Regular exercise schedule is necessary for good health Perspiration removes nitrogenous wastes
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Ration Formulation Objective is to economically match the animal’s nutrient requirements with available feeds Things to consider: Palatability Physical form Other
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Diet Modification to Minimize N & P Pollution
Impacts air & water quality N By-product of protein digestion What does it affect? P Mineral nutrient Will be excreted if fed in excess Two concerns Volatility of N in the form of ammonia Distribution of manure nutrients P contaminates surface water N contaminates groundwater
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