Can protein utilisation from pasture be improved?
M.J. Ulyatt
AgResearch Grasslands Research Centre, Palmerston North, New
Zealand.
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Proceedings of the New Zealand Society of Animal Production. 1997,
57: 4-8
Although temperate pasture plants usually contain sufficient
protein to potentially support most types of animal production, this
protein is utilised for ruminant production with relatively low
efficiency because of the losses that occur via microbial deamination in
the rumen. These processes are well understood, yet procedures that
should theoretically improve protein capture, such as the addition of
soluble carbohydrate or protected protein to the diet, are frequently
not effective. The paper considers reasons for this situation. It also
examines several additional reasons why plant protein utilisation may be
impaired, such as: high rumen degradability, hepatic detoxification of
absorbed ammonia and its associated costs in terms of amino acid
catabolism, and the relationship between amino acid supply to the
duodenum and tissue amino acid requirements.
The paper evaluates whether an enhanced supply of individual amino
acids, or mixtures of amino acids, to the tissues might increase the
production of meat, milk and wool. It also considers whether we have
enough information to be able to assess the likelihood of using specific
enhanced amino acid supply or novel combinations to manipulate product
quality.
The efficacy of various mathematical models of protein digestion and
metabolism are evaluated in relation to our current knowledge of the
subject.
Keywords: NZSAPAB;
pasture protein utilisation; production response; product
quality.
Last Updated 12-09-1998
