SENSORY EVALUATION OF THE FEEDING VALUE OF HAY
A system for rating the quality of hay by sight, touch and smell was designed and tested. Seven sensory criteria were defined and rated independently on a scale from one to nine in direct relation to their assumed nutritional merit. Hays of different quality were obtained from four grasses and two alfalfas, each harvested at six maturity stages. Each hay was rated independently by five judges. The ratings did not differ (P < 0.05) between judges, but significant differences and interactions occurred between crops, maturity stages, and sensory criteria.Each hay was fed to sheep, and its nutritional value was determined as the voluntary consumption of digestible organic matter (grams consumed daily per kg of metabolic size—weight0.75). The correlation between voluntary consumption and the ratings of the sensory criteria in each hay was generally significant (P < 0.01) for composition, growth stage, color and texture, but not for freshness, odor and cleanness. The three last criteria varied little in the hays studied; therefore, it could not be concluded that they were unimportant in sensory evaluation of hay in general.The variability in voluntary intake "accounted for" by ratings of the seven sensory criteria ranged from 59 to 90% in the different kinds of hay, and 65% when the hays were pooled. When the hays were rated by composition and color only, these criteria "accounted for" 48 to 77% of the variability in intake, but only 38% when the hays were pooled. Coefficients of variation from regression for the pooled ratings were 23% for the seven sensory criteria, 30% for composition and color alone, and 38% from the mean for all seven criteria.