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A Formula for Evaluating Feeds on the Basis of Digestible Nutrients

1932; Elsevier BV; Volume: 15; Issue: 4 Linguagem: Inglês

10.3168/jds.s0022-0302(32)93416-x

1529-9066

WM.E. Petersen,

Agriculture Sustainability and Environmental Impact

The nutritive value is an important consideration in the selection of a feed, although not the only consideration.The modern feeding standards prescribe the requirements of the cow in terms of digestible crude protein and total digestible nutrients and intelligent feeders appreciate the necessity of supplying the minimum amounts of the two groups of nutrients for good results.It is common knowledge that feeds vary greatly in composition and in price.It is also factual that high protein feeds as a rule are higher priced than lower protein feeds and that the difference varies from year to year.In the purchase of a feed, therefore, two questions must be answered : First, does it supply the required nutrients, and second, is it a reasonably cheap source of these nutrients?The problem of economical source of nutrients has long been recognized and attempts have been made to indicate relative cheapness of nutrients in different feeds.One of the most familiar is to charge the entire cost of the feed to either the protein or the total digestible nutrients and express the results in cost per pound.The fallacy of this method is apparent as high protein feeds contain nonprotein nutrients for which it should have credit even though purchased chiefly for its protein content.Likewise feeds purchased chiefly for total digestible nutrients have protein for which they should be credited.The chief objection to this method, however, comes in evaluating medium protein foods where both protein and total digestible nutrient costs become relatively high.H a y d e n of Ohio proposed a more accurate, though cumbersome, method for evaluating feeds.It consisted of establishing a value per pound of nutrients in corn by dividing the cost by the total nutrients.Then the value of protein was calculated by: 1. Determining the "excess p r o t e i n " in linseed oilmeal by calculating all nonprotein nutrients plus sufficient protein to give the same composition as corn.The remaining protein was designated as "excess protein."2. Crediting linseed oilmeal with its corn equivalent by multiplying the number of pounds by the price established per pound of nutrients in corn.