This document provides an overview of animal nutrition, including the objectives, basic nutrients, feed analysis, digestion in monogastric and ruminant animals, and nutrient requirements. It discusses the six classes of nutrients - water, carbohydrates, fats, proteins, minerals, and vitamins. It describes the digestive tract of monogastrics and ruminants, and the pathways of energy and protein. The document also covers nutrient requirements for maintenance, growth, fattening, reproduction, lactation, and work. Finally, it discusses ration formulation and diet modification to minimize nitrogen and phosphorus pollution.

1. Animal Nutrition
A Review
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2. 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

3. Nutrients
•
•
Any feed that functions to support life
Concentrates and roughages
– What are they?
– What are the differences nutritionally?
• Six basic classes
1. Water
2. Carbohydrates
3. Fats
4. Proteins
5. Minerals
6. Vitamins

4. 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)

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. Feed Analysis
• Proximate Feed Analysis
– 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)

12. 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

13. 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

14. 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

15. 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)

16. Feed Analysis
•
In diet formulation:
– NEm
– NEg
– NEl

17. Figure 15.3
Measures of energy and energy utilization.

18. Feeds and Feed Consumption
 Classification of Feeds
1. Dry roughages & forages
• Hay
• Straw
• Other
2. Range, pasture, green forage

19. Feeds and Feed Consumption
3. Silages
4. Energy Feeds
• >18% CF, <20%CP
5. Protein supplements
• >20% CP
6. Mineral supplements
7. Vitamin supplements
8. Nonnutritive additives
•
•
•
•
•
Antibiotics
Coloring
Flavors
Medicants
Etc.

20. 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

21. Digestion & Feed Absorption
• Digestion
– Mechanical
– Chemical
– Role is to produce feed particles the can be
absorbed and used by the body

22. Carnivorous, Omnivorous, &
Herbivorous animals
• Which is which?
• Carnivores & Omnivores are monogastric
animals
– One, simple stomach
– Also some herbivores (horse, rabbit)
• Herbivores
– Ruminants
– Stomach compartments

23. 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

24. The Monogastric Digestive Tract
• Small intestine
– Duodenum
– Jejunum
– Ileum
– Split molecules & absorb nutrients
• Large intestine
– Cecum
– Colon
– Absorb water
– Forms indigestible waste (Feces)

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

26. 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.

27. Ruminants
• Rumen
– Fermentation vat
– Papillae
– Bacteria & protozoa
• Reticulum
– Aka honeycomb
– Initiate mixing in rumen

28. 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

29. Figure 16.4
Beef cattle digestive tract.

30. 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.

31. 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.

32. 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

33. 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

34. Digestion in Monogastrics
• Liver function
– Metabolizes feed particles in bloodstream
– Detoxifies harmful substances

35. 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?

36. 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

37. 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

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

39. 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

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

41. Nutrient Requirements for Body
Maintenance
• No gain/loss of weight or production
• High priority for nutrients
1.
2.
3.
4.
Body tissue repair
Temp control
Energy for vital organ function
Water balance maintenance
• Takes ~½ of all ingested feed

42. 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

43. 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

44. 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

46. 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

47. 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

48. 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

49. 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

50. 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?

51. Energy Requirements for Work
– Primary requirement is energy
– Regular exercise schedule is necessary for good
health
• Perspiration removes nitrogenous wastes

52. Ration Formulation
• Objective is to economically match the
animal’s nutrient requirements with available
feeds
• Things to consider:
– Palatability
– Physical form
– Other

53. 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