Antibiotics
Antibiotics are
chemical substances which are produced by living organisms, for example mold
bacteria or green plant, which have bacteriostical or bacteriacidal properties.
Commercially
produced antibiotics are through of as substances produced by mold – like organisms
grown in nutrient solution in large steel tanks. Hundreds of antibiotics are
known including commercially produced. Bacitracin (zinc bactracin)
Chlortetracyline (Aureomycine) Crythromycin, Hydromycin, Neomycin,
Oleandromycin, Oxytetracyclin (Terramycin Penicillin, Streptomycin and tylosin).
The role of antibiotics
- They stimulate certain enzyme system.
- They stimulate appetite and have a nutrient sparing effect.
- They reduce the incidence of subclinical level of bacterial infections in the digestive and respiratory tracks.
Hormones
Most stock
men are familiar with, or have used one or more of the hormones or hormone – like
product. In 1954, stilbestrol, a synthetic female hormone, that are not
nutrient was approved by the feed and drug administration for use in cattle
finishing ration. And two years later (1956), the feed and drug administration
approach the use of stilbestrol implants for steer. Soon, the race was on, and
other hormones and hormone – like product then followed.
The following
that is presently available and approved product have been shown to improve
gain and/or feed efficiency of feed lot cattle and calbes, dietry stilbestrol,
oral or implanted; melangestrol acetate, use orally for heifer, zeranol (ralgro)
implanted; and rapid gain implanted. Most of these products appear to work well
for lambs. Although much of lower dosage are required.
Hormones and
hormone – like products are receiving considerable attention as to their
relation safety to livestock and man. Hence some of this product may eventually
be removed from the approved drug list of feed and administration. Conversely,
in the future more of this type of product may be approved for use in livestock
production.
In ruminants,
the hormones result in the increase of feed intake and increase nitrogen
retention. The usual result is an increase in growth rate and feed efficiency and
less finished when animals are fed to the same weight as untreated animals. Hormones
have not showed any consistent benefit for swine.
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