2014 Volume 2 Issue 1 Pages 45-50
We conducted two experiments to investigate the relationships among starch intake, feces starch and fecal pH in fattening Japanese Black steers. In experiment 1, 18 steers were observed at the ages of 12 and 15 months. The steers were fed 5.2, 7.8 kg of concentrate and 3.1, 1.5 kg of roughage on a dry matter basis at the age of 12, 15months, respectively. In experiment 2, 15 steers were observed at the ages of 25 and 28 months. The steers were divided into three groups; six steers were fed 5.1, 5.3 kg of concentrate A (consisting of 50% ground corn grain) and 5.4-4.8 kg of corn silage (ConA･CS group), six steers were fed 4.8, 5.1 kg of concentrate B (consisting of 40% ground brown rice) and 5.7, 4.9 kg of corn silage (ConB･CS group), and three steers were fed 8.5, 8.8 kg of concentrate A and 1.6, 1.3 kg of wheat straw (control group) at each observation period, respectively. In experiment 1, the ratios of starch intake to dry matter intake (DMI) for steers at the ages of 12 and 15 months were 28.8 and 36.8%, respectively. However, feces starch and fecal pH did not differ at the two ages. In experiment 2, the ratios of starch intake to DMI were 41.3, 38.3 and 38.8%, the feces starch levels were 10.9, 14.1 and 6.8% and the fecal pH were 6.09, 5.81 and 6.31, respectively, in the ConA･CS group, the Con B･CS group and the control group. The correlation coefficients between fecal pH and feces starch, and between fecal pH and the dry matter ratio of feces, were -0.44 and -0.47, respectively (p<0.01). These results indicate that lower fecal pH is correlated with higher feces starch, and suggest that excessive flow of starch from the small intestine increase hindgut fermentation and feces pH decrease.
