Animal nutrition / [Thomas Barlow Wood].

  • Thomas Barlow Wood
Date:
1924
Catalogue details

Licence: In copyright

Credit: Animal nutrition / [Thomas Barlow Wood]. Source: Wellcome Collection.

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    feeding stuff. Skim milk, for instance, is rich in protein though it contains only a low percentage. Richness in pro¬ tein should be measured relatively to the percentage of other ingredients. The usual way to express this relative richness in protein is by means of what is known as the albuminoid or nutritive ratio, which is the ratio of the protein to the non-protein constituents. In calculating this ratio it must be remembered that weight for weight fat gives out 2'3 times as much heat as carbohydrates. The formula for calculating the nutritive ratio therefore is :— digestible fat X 23 + digestible carbohydrates and fibre digestible protein Thus the nutritive ratio of linseed cake of normal composi¬ tion is:— 87 X 2-3 + 28 5 + 4-5 _ 53’0 _ 0 , 25 3 25 3 ~ “ ' This means that for every lb. of digestible protein in linseed cake there are 2T lb. of digestible nonprotein reckoned as carbohydrate. The ratio of protein to non¬ protein is 1 : 2'1. This is what is called a narrow ratio, and implies that the linseed cake is comparatively rich in protein. Approximate nutritive ratios are given for many feeding stuffs in Tables I. to IY. and in Rations for Live How toUs0 Stock. They are quite useful in showing at a Ratios. glance the relative richness of feeding stuffs in protein. It has been customary for many years to use nutritive ratios in the computation of rations, and this custom has given rise to many very serious mistakes. A few instances will suffice to show the pitfalls which beset the amateur, or even in some cases the expert, who tries to com¬ pute rations by this method. Thus, to calculate the propor¬ tions in which barley and fish meal should be mixed iii order to provide a ration for pigs, with a nutritive ratio of 1:7, the following method has been recommended. The nutritive
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