CHAPTERS 15-17

Unit 7: Animal Nutrition

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

Nutrients

Any feed that functions to support life Concentrates and roughages

What are they? What are the differences nutritionally?

Six basic classes1. Water2. Carbohydrates3. Fats4. Proteins5. Minerals6. Vitamins

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)

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

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

Nutrients

Proteins Simple

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

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

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 Ex.? Important for vitamins, hormone synthesis

Usually work together w/ other nutrients Can be harmful in high levels

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

Feed Analysis

Proximate Feed Analysis Separates feed components into group according to

feed value Accuracy of the analysis is dependent upon accuracy

of the sampleComponents measured

Water Crude protein Crude Fat Crude Fiber Nitrogen-free extract Ash (minerals)

Feed Analysis

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

Feed Analysis

Measuring energy TDN

Not as accurate ME

Very accurate NE DE

Calorie (cal) Energy required to raise the temp of 1g of water 1

degree C

Feed Analysis

Kilocalorie (kcal) 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

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)

Feed Analysis

In diet formulation: NEm NEg NEl

Figure 15.3 Measures of energy and energy utilization.

Feeds and Feed Consumption

Classification of Feeds1. Dry roughages & forages

• Hay• Straw• Other

2. Range, pasture, green forage

Feeds and Feed Consumption

3. Silages4. Energy Feeds

• >18% CF, <20%CP

5. Protein supplements• >20% CP

6. Mineral supplements7. Vitamin supplements8. Nonnutritive additives

• Antibiotics• Coloring• Flavors• Medicants• Etc.

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

Digestion & Feed Absorption

Digestion Mechanical Chemical Role is to produce feed particles the can be absorbed

and used by the body

Carnivorous, Omnivorous, & Herbivorous animals

Which is which?Carnivores & Omnivores are monogastric

animals One, simple stomach Also some herbivores (horse, rabbit)

Herbivores Ruminants Stomach compartments

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

The Monogastric Digestive Tract

Small intestine Duodenum Jejunum Ileum Split molecules & absorb nutrients

Large intestine Cecum Colon Absorb water Forms indigestible waste (Feces)

Figure 16.1 Digestive tract of the pig as an example of the digestive tract of a monogastric animal.

Figure 16.2 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.

Ruminants

Rumen Fermentation vat Papillae Bacteria & protozoa

Reticulum Aka honeycomb Initiate mixing in rumen

Ruminants

Omasum 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

Figure 16.4 Beef cattle digestive tract.

Figure 16.5 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.

Figure 16.7 The esophageal groove, with its location relative to the esophagus, reticulum, and rumen. Courtesy of N. J. Benevenga et al., 1969. Preparation of the ruminant stomach for classroom demonstration. J. Dairy Sci. 52:1294.

Digestion in Monogastrics

Begins in the mouthEnzymatic reactions

Organic catalyst that speeds a chemical reaction without being altered by the reaction

Stomach secretions HCl Mucus Pepsin Gastrin

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

Digestion in Monogastrics

Liver function Metabolizes feed particles in bloodstream Detoxifies harmful substances

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?

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

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

Figure 16.8 Energy pathways in the ruminant. Source: J. Bryant and B. R. Moss, Montana State University.

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

Figure 16.9 Protein pathways in the ruminant. Source: J. Bryant and B. R. Moss, Montana State University.

Nutrient Requirements for Body Maintenance

No gain/loss of weight or production High priority for nutrients

1. Body tissue repair2. Temp control3. Energy for vital organ function4. Water balance maintenance

• Takes ~½ of all ingested feed

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

Nutrient Requirements for Growth

Occurs when: Protein synthesis is > protein breakdown Cells increase in number & size Both

Building of muscle, bone, connective tissueNutrients needed for growth

Energy, protein, minerals, vitamins

Muscle growth is due to protein

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

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

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

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

Nutrient Requirements for Lactation

Requires protein, minerals, vitamins, energyProtein is greatest

>3% protein in milk Body protein can be mobilized in deficient times

Ca & P are critical Hypocalcemia

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?

Energy Requirements for Work

Primary requirement is energy Regular exercise schedule is necessary for good

health Perspiration removes nitrogenous wastes

Ration Formulation

Objective is to economically match the animal’s nutrient requirements with available feeds

Things to consider: Palatability Physical form Other

Diet Modification to Minimize N & P Pollution

Impacts air & water qualityN

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