Unit 6

Productivity and Nutrition

The objective of this unit of study is to establish a common understanding of some nutrition basics and an appreciation for proper livestock nutrition.  Students are strongly recommended to take additional courses in nutrition for a more complete knowledge of nutitional requirements and techniques used in formulating and balancing rations.  There are six basic classes of nutrients that must be considered in forumulating diets; water, protein, carbohydrates, fats, vitamins and minerals.  In Frank B. Morrison's Feeds & Feeding, a nutrient is defined as "Any feed constituent or group of feed constituents of the same general chemical composition that aids in support of animal life."  

    A number of factors can make an understanding of livestock nutrition very confusing.

  • Many (most) feedstuffs or ingredients in a ration contain more than one of the six basic nutrients.  For instance, a kernel of corn contains all six basic nutrients:

    •       Water -- 13-15% when dried for storage

                                   20-35% field moisture at harvest or if stored as high moisture corn

    •         Protein -- 7-9% crude protein is a typical value

  •         Carbohydrate -- mainly in starch portion of the kernel

  •         Fat -- mainly in the oil portion

  •         Vitamins

  •         Minerals

  • Commonly used feed ingredients may vary considerably in the content of the six basic nutrients.  The example of corn from above demonstrates that the water content can vary widely, as can other perimeters.  Some varieties of corn contain high levels of specific nutrients, such as lysine or oil.

  • The unique physiology and metabolism of different animals enables some to utilize some feed ingredients to their benefit while other animals of a different species cannot.

    • Nonprotein nitrogen sources can be converted to amino acids and from amino acids to protein by ruminants and hindgut fermenters; monogastric animals cannot utilize these feedstuffs.

    • Fiber (roughages - hay, grasses) can be broken down by ruminants and hindgut fermenters to provide an energy source; monogastric animals cannot utilize these feedstuffs.

    • Some feed constituents are essential for certain species, but not for others.  Proline and glycine are essential amino acids and must be added to poultry diets; other species can synthesize them from other amino acids.

  • There are "linkages" or relationships between different basic nutrients. 

    • Selenium (a mineral) is linked to Vitamin E; they share many "duties" in the body and one can often be substituted for the other.

    • Fats, carbohydrates and proteins can all be used to provide energy to the body and can be additive in meeting the energy requirements of an animal.  (Protein will be converted to energy producing subunits if fed in excess of it's basic metabolic needs.)

    • Calcium and Phosphorus must be fed at the appropriate "ratio" for maximal utilization and to prevent interference with other mineral metabolism.

  • No single feed ingredient can supply all 6 basic nutrients an animal needs to survive and be productive.

    • One must "balance" the ratio of different feed ingredients to meet the individual animal's needs.

    • The nutrient needs of an animal varies depending upon the species, age, stage of lifecycle, etc.

  • In addition to meeting an animal's basic nutrient requirements, a diet must also meet the "3 P's" to be useful as a livestock feed.

    • Palatable -- must be edible, accepted, and eaten by the animal

    • Profitable -- if the livestock producer cannot make a profit feeding certain ingredients, he/she won't be in business very long.  Approximately 75% of the out-of-pocket costs in livestock production is feed costs.

    • Productive -- animals eating the diet must be productive.  The least cost ration may just barely meet the animal's nutrient requirements, but not allow the animal to function at it's most productive level.  The optimal ration is athe ration that can be produced for the least cost for the benefit returned in animal performance (growth, productivity, longevity, reproductive performance, etc.)


Six Classes of Nutrients

1. Water

  • The Most Critical Nutrient!
    • Functions in transport, chemical reactions, temperature maintenance, lubrication, etc.
  • Water deprivation ---> dehydration ---> electrolyte imbalance ---> death
  • Requirements vary from one species to another.  For example, the desert rat requires very little, while the dairy cow may require 25-29 gallons/day.
  • Management problems leading to lack of water
    • bad taste (high sulfur content)
    • don’t know how to use or cannot find waterer
    • stray voltage at water source

2. Carbohydrates (CHO)

  • Functions
    • energy source
    • building block for other nutrients
    • dietary excess stored as fat
  • Two main components of carbohydrates
    • Crude fiber (cellulose mainly)
    • Nitrogen-free extract (soluable sugars, starches)
  • Differences between monogastric, hindgut fermenter and ruminant
    • Ruminants and hindgut fermenters have microorganisms in the rumen or hindgut that can break down crude fiber (cellulose) into useable products; monogastrics cannot utilize most crude fiber.
    • All livestock are capable of breaking down the soluable sugars and starches.
  • Management Problems
    • poor quality feedstuffs
    • improper ration balancing

3. Fats (lipids)

  • Functions
  • Energy (stored at higher conc./g than CHO)
  • Source of heat, insulation, body protection (cushioning)
  • Essential fatty acids (immune function, CLA-anticancer link?)
  • Sources
    • Oils (soybean oil, corn oil, fish oil)
    • By product fats (lard or tallow from livestock rendering)
      • provides cheap energy source
      • reduces dust in feed manufacturing and animal feeding
      • increases feed palatability

4. Proteins

  • Most expensive ingredient in ration, need decreases as animal matures
  • Source of Essential Amino Acids (number, type and level of amino acids required varies with animal species)
    • Functions -- basic structural unit, needed in metabolism, hormone, antibody and DNA production
  • When fed in exess, converted to energy, fat
  • Monogastric vs. ruminant
    • True protein is composed of amino acids
    • Crude protein contains both true protein and other nitrogenous products (non-protein nitrogen)
    • Non-protein nitrogen can be converted by rumen bacteria to true protein (cheaper source of protein for the ruminant animal)

5. Minerals

  • Two classes
    • Major minerals -- Ca, P, Na, Cl, Mg, K, S
    • Minor (Trace minerals) -- Co, Cu, F, I, Fe, Mn, Mo, Se, Zn
      • The need for supplementation of minor minerals such as Se and F varies with the region
  • Functions -- skeleton, protein synthesis, oxygen transport, fluid and acid-base balance in body, enzyme reactions
  • Mineral/mineral and vitamin/mineral interactions
    • Ca - Vitamin D
    • P - Vitamin D
    • Co - Vitamin B12
    • Se - Vitamin E
  • Both deficiencies and excesses can lead to disease

6. Vitamins

  • Two classes
  • Water soluble -- B & C
  • Fat soluble -- A, D, E, K
  • Functions -- most vitamins have multiple functions in body involving metabolism, enzyme reactions, etc.
  • Requirements increase with age
  • Both deficiencies and excesses lead to disease

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