FEEDS AND FEED ADDITIVES

I.        Labeling

A.     Required for all commercial feed products and serves the following purpose

1.      Identify the product

2.      Information about nature and purpose of the product

3.      provide instructions

4.      provide precautions

II.     Feed Additives

A.     Manufactures must demonstrate safety of new additives before FDA will approve

1.      The Delaney Clause – 1958 – Zero tolerance (carcinogenic to animals or humans)

B.     Growth Promotion and Feed Efficiency (No longer used without prescription)

1.      Antibiotics – (Ex. = chlortetracycline, oxytetracycline) substances produced by living organisms and have bacteriostatic properties. In general, they are fed to reduce the incidence of sub-clinical levels of bacterial infections of the digestive and respiratory tracts.  In young, growing  animals monensin & lasalocid – 1st approved as cocidiostats in poultry.  (­ propionic acid; ¯ methane)

2.      Chemotherapeutic Agents – inorganic or organic compounds which will inhibit the growth of organisms – not produced by living organism (1o­ ADG and(or) feed efficiency)

C.     Medicinal Uses

1.      Coccidiostats – prevent and treat coccidiosis in chickens (intestinal infection of protozoa) – monensin & lasalocid

2.      Anthelmintic Agents – deworming agents – intestinal parasites (1o).  Ivermectin; fenbendazol = Safe guard; levamisol = Tramisol; Pyrantel Palmitate = Banminth; thibendazol

3.      Miscellaneous

a)      Liver abcesses in cattle – chlortetracycline (oxytetracycline some also)

b)      Bloat prevention – poloxalene (Bloat Guard)

c)      Foot Rot – chlortetracycline

d)      Stress – chlortetracycline & oxytetracycline

 

NATURAL TOXICANTS IN FEEDS

I.        General

A.     Everything is toxic if given in a large enough dose

B.     For almost every animal organ, tissue, and system there is (in the plant kingdom) a chemical which is antagonistic to it.

C.     Animals have developed defenses: Rumen, liver enzymes

II.     Toxicants/Livestock

A.     Many plant/feed toxicant problems are of less concern today because of:

1.      recognition of the cause

2.      changes in agronomic practices

3.      plant breeding

4.      feed processing

III.    Examples

A.     Ergot – general name for fungi that grow on rye and barley and dallisgrass and bahiagrass (dallisgrass is the most common in U.S.)

1.      General Effects

a)      Vasoconstriction à gangrene

b)      ­ blood pressure

2.      removal is only effective treatment

B.     Fescue = cool season grass.  We are on the very southern end of the “Fescue Belt”

1.      Endophytic fungus = inside the plant – can not see

2.      Symptoms

a)      Hoof sloughs off (tail tips) (¯ blood flow to extremities)

b)      Abortion (horses)

c)      ¯ milk production (agalactia) (horses)

d)      ¯ ADG

e)      ¯ Feed intake

f)        ­ Body Temperature (¯ blood flow) è standing in water

3.      Prevention??

a)      Get fungus free fescue – fungus makes fescue hardy

b)      Seed is where most concentrated è graze to ¯ seed head production

c)      Drugs = don’t really work; metachlopramide & cimetidine; domperidone

d)      Dilute (clover, ryegrass, etc.)

e)      Genetically engineer plant (ultimate answer = Max Q)