The value of certain agricultural, marine and industrial products and by‐products in livestock feeding. II. —Non‐ruminants

Abstract

FEW new energy sources have proved to be worth exploiting for the feeding of non-ruminants.Cereals and root crops remain the main sources of energy, with fibrous materials, whether in their native or processed state, playing a very small part. However, American feeders have recently begun to use low-grade fats, inedible by man, in poultry feeding.With protein concentrates more attention is being given to improving the methods of processing to obtain materials of higher nutritive value than to developing new products. Since many materials at the onset of processing have a high intrinsic nutritive value, the problem is to devise methods of processing that will minimize loss of this value in the by-product destined for animal feeding. In some cases, as in the production of white iish meal and soya-bean meal, processing requirements are well understood. In other cases little is known, or obstacles stand in the way of adopting superior processing methods.One of the commonest and most informative is the biological value (BV), essentially a measure of the nutritive value of absorbed nitrogen. Another is the gross protein value (GPV), which is a measure of the value of the protein in a concentrate for supplementing the proteins in mixtures of cereals and miller's offals.In Table I1 (p. 243) are set out the GPV ratings of a number of concentrates, most of which * Part I:

Fish products as protein supplements to cereals

“…These corresponded generally to the findings of other workers for the better commercial meals, made from either white or 'oily' fish (cf. review by Duckworth, 1955), and the figures obtained here for the two white-fish meal samples (H and I) are of the same order. It is clear also that the value of fish meals prepared less carefully can be much lower, but our first interest was to obtain an estimate of how far the best commercial product still fell short of an 'ideal' material in G.P.V.…”

Nitrogen Solubility as a Means of Estimating the Gross Protein Value of Rapeseed Meal

“…On the average, however, the G.P.Vs. of the prepress-solvent and solvent processed rapeseed meals were close to that of soybean meal (Duckworth, 1955). …”

A comparison of Barley meal, meat meal, and dried buttermilk, fed alone and in various combinations, as supplements to whey for fattening pigs

“…There is the further possibility that at least some of the observed differences between the supplements containing buttermilk and those containing meat meal were due to the protein of the meat meal being of relatively low nutritive value. Work reviewed by Duckworth (1955) has revealed considerable variation between different samples of meat meals in this respect.…”