Effect of cutting interval on nutritive value of guineagrass and setaria

Abstract

Effect of cutting interval on nutritive value of guineagrass and setaria was investigated, and appropriate cutting interval from the viewpoint of nutritive yield of both species was discussed. Annual mean nitrogen concentration and in vitro dry matter digestibility of both species decreased linearly with increasing cutting interval (p<0.05). Nitrogen concentration of all treatments decreased in summer season. Though the seasonal change in in vitro dry matter digestibility was relatively small, increasing cutting interval in summer caused marked decrease in in vitro dry matter digestibility. The significant multiple regressions were obtained with nutritive values (nitrogen concentration and in vitro dry matter digestibility) as criterion variables and with cutting interval and climatic conditions (temperature and precipitation) as explanatory variables (p<0.01). Standard partial regression coefficients indicated that cutting interval was the major factor to affect the nutritive value. Total nitrogen yield decreased with increasing cutting interval, although dry matter yield increased with extending cutting interval. Since total digestible dry matter yield was maximized at 30 to 40 days of interval in guineagrass and at 50 days of interval in setaria, an extension of cutting interval above these intervals caused decrease in digestible dry matter yield. From results of this experiment, it is shown that extending cutting interval led to decrease in nutritive value, which was especially marked in summer season. Therefore, appropriate cutting interval in summer season should be within 40 days for maintaining high nutritive value of both species.