Feed and feeding quality of imported grass hays as evaluated by newly proposed grades

Abstract

AbstractIn conjunction with investigating the quality of imported grass hays, the present study set out to develop an evaluation standard. A total of 123 hay samples were tested: 70 of timothy hay, 23 of sudangrass hay, 20 of oat hay and 10 of bermudagrass hay. Crude protein content, nitrogen cell wall free extract (NCWFE) content, Oa (organic a fraction in cell wall, non‐lignified portion of cell wall) content and Ob (organic b fraction in cell wall, lignified portion of cell wall) content were measured for each sample, and the values of these were used as the basis for the determination of digestible carbohydrate content and dry matter intake (DMI). The variation in crude protein, NCWFE, Oa and Ob content within each grass species was large. The coefficients of variation for the chemical composition of all 123 samples were 24.9% for crude protein, 37.4% for NCWFE, 30.7% for Oa and 11.0% for Ob. Because variation in composition was large, variations in digestible carbohydrate content and DMI within each species were also large. On the basis of the mean values of chemical composition, it was determined that the harvesting period was after the flowering stage. Evaluation standards were set using a five‐point scale (5, excellent; 4, good; 3, medium; 2, low; 1, poor), based on the 123 samples tested in the present study, using the mean values and standard deviations of chemical parameters, digestible carbohydrate content and DMI. Consequently, in assessing DMI (per bodyweight of 600 kg), a grade of 5 was given for values of 14.3 kg or higher, 4 for values between 11.5 and 14.3 kg, 3 for values between 8.7 and 11.5 kg, 2 for values between 5.9 and 8.7 kg, and 1 for values lower than 5.9 kg.