Abstract
Seasonal variations of chemical compositions and feeding value of orchard grass hay by the usual methods of hay making in Tokachi district were investigated. The results may be summarized as follows: 1) Evaluating hay quality be based on percentage of leafiness and green coloration, the quality of the 1st cutting hay was a lower grade than that of the 2nd and 3rd cutting hay. 2) In the case of 1st cutting hay, contents of NDF, ADF, lignin and silicic acid were low. The significant negative correlation was observed between content of TDN and contents of ADF, lignin and silicic acid. There were significant correlation between the DDM value calculated with the regression equation showed by Van Soest and the DDM value obtained by digestion trial with sheep, whereas non-significant correlation between the TDN value calculated with the regression equation showed by Adams and the TDN value obtained by the practical digestion trial with sheep was recoginized. 3) In comparison with the 1st cutting hay, the TDN content and DE concentrate of both 2nd and 3rd cuttings hay were low. The DCP content was kept almost constant throughout the 1st, 2nd and 3rd cutting hay were, DCP ; 10.3, 9.9 and 9.8%, TDN ; 65.1, 57.8 and 57.5%, and DE ; 2.96, 2.59 and 2.57kcal/g DM, respectively. 4) In comparison with the 1st cutting hay, digestibility of DM, crude fat, NFE and energy of both 2nd and 3rd cutting hay were low and crude fiber digestibility had a tendency to decreased in the 2nd and 3rd cutting hay. The decreased TDN content of 2nd and 3rd cutting hay was due to decreased digestible NFE content in both hay. 5) In the case of 2nd and 3rd cutting hay, content of crude protein was higher than that of the 1st cutting hay, whereas digestibility of crude protein of the 2nd and 3rd cutting hay had a tendency to decreased. This suggests that, in order to increased nitrogen level in CWC, as is analogized from high value of nitrogen in NDF/total nitrogen in the 2nd and 3rd cutting hay, a large amount of undigestible nitrogen may be excreted in feces. 6) It was found that, in order to make comparison of feeding value of 1st cutting hay with that of after-math growth hay, Van Soest method was very proper method compared to the other method.
