THE NUTRITIVE VALUES OF SOME FORAGE CROPS OF PUERTO RICO 1. Grasses

Abstract

1. Twenty metabolic experiments with grasses cut at different periods, between August 1936 and May 1937, are reported. 2. The biological values were determined for these grasses; the highest recorded values belonging to Para grass and the lowest values to elephant grass. 3. The coefficients of apparent digestibility for Yaragua and malojillo grasses of second cutting are quite low. 4. All the grasses tend to give wide nutritive ratios, but Yaragua and malojillo, second cutting grasses, give exceptionally wide ones. 5. Yaragua grasses show a higher fiber content than any of the other grasses investigated. 6. Guinea grass yields, on analysis, significantly high values for calcium; Guatemala grass yielding the lowest values for this element in all the grasses studied. 7. First cuttings of grasses usually yield higher percentages of protein than second cuttings. The same is true of the fat. The nitrogen- free extract, on the contrary, is lower in first cutting than in second cutting grasses. 8. The addition of phosphorus to the fertilizer does not seem to influence to any great extent the nutritive indexes of the grasses studied. 9. The vitamin A activity of the leaves of the grasses has been determined.