Statistical research on the digestibility in the cow. II. Nitrogen and ether extract

Abstract

SUMMARY: The results obtained for nitrogen and ether extract digestibility with 116 different rations fed to 242 non-pregnant dry cows and 96 lactating cows were studied.A hyperbolic relation exists between nitrogen digestibility (Y) and crude protein content (X), with the equation:Y = 88·6–(301/X)(r = – 0·928^**, RSD = 4·78).Digestible protein content ( Y) is linearly related to crude protein content(X):Y = 0·90X-3·10 (r = 0·982^**, RSD = 0·823).From dry-matter intake and crude protein content it is possible to estimate accurately the amount of digestible nitrogen. With all the experimental rations the mean metabolic faecal nitrogen was 496 mg/100 g of ingested dry matter, and the true nitrogen digestibility was conspicuously constant up to 90%.Digestibility of ether extract depends on the nature of the feeds. When the concentrate percentage of the ration is high, the digestibility of ether extract obeys the same laws as that of nitrogen.