These feeding programs, called "accelerated calf growth" programs, use milk replacers not all that different from formulas fed to human babies. The milk replacers have very high crude protein content, some up to 26 percent. Such high-protein diets have been shown to increase feed use efficiency by more than 50 percent, Lambert said.
All proteins are composed of chemically linked amino acids. All creatures require proteins for growth and good health. Some of these amino acids can be synthesized by an animals metabloism; others cannot.
The ones that cannot be synthesized are called "essential" amino acids. For humans and other non-ruminants swine, for example the required amino acids are known with certainty. In humans, for example, nine amino acids are considered essential. Two of these nine, lysine and tryptophan, are either not present or found only in small amounts in plant protein. This is why strict vegetarians must pay careful attention that their diet contains these two amino acids.
For multi-stomach animals such as dairy cows, the situation is more complicated. The first two stomachs host bacterial that can synthesize protein from plant fiber. There is a limit, however, to how much protein these rumen-based bacteria can supply. Also, it is not clearly known by dairy nutritionists which of the amino acids are "limiting" factors: which ones need to be increased by what amount to provide complete protein for the growing dairy calf, Lambert said.
"There are no current National Research Council recommendations for the essential amino acid requirements of young growing dairy calves," he said.
So the current formulas take the "shotgun approach" increasing all 21 essential amino acids, Lambert said. The result is as planned: increased calf growth and feed efficiency but there's also more waste in terms of
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2-Mar-2005