Relationships between the Physico-Chemical Characteristics of Hays and their Nutritive Value1

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Abstract
Data from 54 male sheep were used to determine voluntary intake and nutrient digestibility of nine hays. Chemical and physical characteristics of hays were measured and related to daily intakes, digestibility coefficients and digestible nutrient intakes by means of simple correlation analyses. Characteristics highly correlated to dry matter (DM) intake per kg.75 were percentage DM solubility in water (r = .91) and percentage cell walls (r = −.89). Highly significant correlations were found between lignin and apparent cell wall digestibility (r = −.94), between logarithm (lignin × 100/acid detergent fiber) and apparent cell wall digestibility (r = −.96), and between crude protein and apparent protein digestibility (r = .95). Nutritive value of hays was defined as digestible energy intake (DEI), digestible protein intake (DPI) and total digestible nutrient intake (TDNI). Multiple regression equations were developed to predict daily DEI (kcal/kg.75) from percentage DM solubility and percentage crude fiber (r = .92), daily DPI (g/kg.75) from percentage crude protein and percentage cell walls (r = .99), and daily TDNI (g/kg.75) from percentage DM solubility and percentage crude fiber (r = .99) as independent variables. This study demonstrates that the nutritive value of hays can be accurately predicted from laboratory analyses of DM solubility, crude fiber, crude protein and cell walls. The precision of the equations could be improved by testing a larger number of forages at different stages of growth. Nutritive value Measured as daily TDN ingested varied from 33.6 g/kg.75 for Champ timothy,a medium quality hay, to 49.6 g/kg.75 for iroquois alfalfa, a good quality hay. Copyright © 1982. American Society of Animal Science . Copyright 1982 by American Society of Animal Science