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Results
of research conducted by Texas A&M University prove that PVM
stimulates the efficiency of forage utilization. Most of our research
was conducted on yearlings - the reason being, it is more difficult
for a yearling to convert forage than a mature adult animal. The
following is only a small portion of the article published in 1990
by W.C. Ellis, F.M. Rouquette and D.P. Hutchinson - Texas A&M
University - College Station, Texas.
When
grazing forage, and especially warm season pastures, growing calves
do not achieve their genetic potential for growth. For example,
a 400 pound, medium frame, weaned calf is genetically capable of
gaining more than 2.5 pounds per day. However this calf will typically
only gain 1.25 pounds to 1.5 pounds per day when grazing warm season
pastures such as bermudagrass even under the best of pasture management.
Results
of current research suggest that a nutritional deficiency of protein
may be a major factor limiting growth of calves grazing growing
pasture; pasture which, based on protein content of the forage,
would appear to contain adequate protein.
The
occurrence of a nutritional protein deficiency in calves when grazing
growing forage appears to be the result of inefficient digestive
utilization of forage proteins, especially in growing forages containing
more than 8 to 12 percent crude protein.
Typically,
80 percent or more of the protein of freshly grazed forage may be
degraded by fermentation in the rumen of cattle. This fermentative
degradation is essential to provide the protein required for growth
of rumen microorganisms and digestion of forage fiber. However,
fermentative degradation of forage protein in excess of that required
by rumen microorganisms (8 to 12 percent crude protein) is of no
nutritional benefit to the calf.
Presumably,
increased deficiency of forage utilization was the result of the
supplement correcting a nutrition deficiency in the forage, a deficiency
which otherwise either limits forage intake and/or the efficiency
of digestion or metabolizing forage nutrients. Regardless of the
way efficiency was improved, it is clear that low intakes of supplement
provide a desirable, supplementary effect.
As
daily intake of supplement increases, or the supplement fails to
provide deficient nutrients, the supplement may fail to have the
desired supplementary effect. In contrast to a supplementary effect,
supplements may have a substitutive effect if supplement intake
substitutes for forage in the animals diet. Clearly, the objective
of supplementation should be to maximize utilization of the usually
less expensive forage with a minimal amount of the usually more
expensive supplement.
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