- -  AGRICULTURE CORE CURRICULUM  - -

(CLF3000)  Advanced Core Cluster:  ANIMAL SCIENCE

  (CLF3150)  Unit Title:  NUTRITION AND FEEDS

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  (CLF3153)  Topic:  HORMONES                   Time:             Year(s) 
                                                1 hour            3 / 4   
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          Topic Objectives:  Upon completion of this lesson, the student
                             will be able to:

          Learning Outcome #:

            (B-3)  -  Explain how hormones are used as growth regulators and
                      list the animals on which those hormones are used.

          Special Materials and Equipment:  Implant gun and pellets of 
                      Ralgro or any other hormone samples for examples.
         
          References: Gillespie, James R. (1981). MODERN LIVESTOCK AND
                        POULTRY PRODUCTION.  New York:  Delmar Publishers.
                      Maynard, Leonard A. (1979). ANIMAL NUTRITION (7th 
                        ed.). New York:  McGraw-Hill Book Co.

          Evaluation: Quiz by instructor


TOPIC PRESENTATION:  HORMONES

(Note:  For additional introductory material on hormones and their affects on 
growth and development, see the Basic Core Lesson Plans CLF229 and CLF246).

A.  Definition

    1.  Hormones are organic materials secreted by certain body tissues 
        which act at sites some distance away from the tissue of origin.

        a.  Hormones are naturally produced by the organs in the endocrine
            system such as the pituitary gland, testes, ovaries, and the 
            thyroid gland,

        b.  Synthetic hormones have been used extensively in the meat animal
            industry to improve efficiency (rate of gain and conversion of 
            feed to body mass).


B.  Types of Hormones

    1.  Thyroxine:

        a.  This hormone has been tested to determine its effect on growth,
            milk, and wool production.

        b.  Because this hormone has proven to increase milk production in 
            dairy cattle up to 25 percent in favorable situations, the dairy
            industry has expressed interest in potential applications for 
            herd production improvement.

    2.  Iodinated casein (protomone): 

        a.  is a product related to thyroxine that is used for commercial 
            applications.

        b.  Unfortunately, this has side effects including loss of body 
            tissue and increased body temperature.

    3.  BST (bovine somatotropin):

        a.  is a bovine growth hormone which may produce a 5-40 percent 
            increase in milk production.

        b.  has been shown to have minimal side effects.

        c.  use is currently being questioned (both economically and 
            politically) in the dairy industry.  (The controversy centers 
            around the use of hormones in general to increase production and 
            the possible residues in the milk which are ingested by the 
            consumer -- i.e., you and me.)

    4.  Biological and Synthetic Hormones:

        a.  Examples are - estrogens, androgens (testosterone), and
            progestrogens.  (Ralgro and Synovex are examples of trade
            names.)

        b.  These hormones have been used as ear implants successfully on
            ruminant animals only.  Swine do not respond to these hormones.

        c.  Effects of synthetic hormones

            1)  Growth and metabolism:

                a)  Less feed is needed per unit of gain.

                b)  Up to 12 percent faster daily gains have been noted.

            2)  Side effects:

                a)  Pelvic changes in cattle.

                b)  Vaginal or rectal prolapse.

                c)  Difficulty in urination and changes in the urogenital 
                    system of lambs.

        d.  Regulations for Use

            1)  both Ralgro and Synovex must be implanted in the ear.

            2)  both have a withdrawal period (before slaughter) that must 
                be followed.


          ___________________________________________________________
          ACTIVITY:

          1.  Show students an implant gun, demonstrate its use, and 
              allow practice use it if possible.
                        
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5/2/90sg


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