Effect of feeding various forms of oxalate on the rumen metabolism and the fate of calcium in buffalo (Bubalus bubalis) calves

The degradation of 45Ca oxalate in the rumen and the absorption of 45Ca released (experiment 2), the production of bicarbonates and TVFA in the rumen, and the rumen pH value (experiment 1) were studied in male buffalo calves consuming paddy straw (group 1), wheat straw supplemented with calcium oxalate (group 2) and wheat straw supplemented with calcium oxalate plus potassium oxalate (group 3). The radioactivity 1n the blood appeared with 1 hr in all the animals. Maximum 45Ca specific activity in the blood was observed at 18,24 and 36 hr in groups 1 to 3, respectively, after intraruminal infusion of 15 mCi 45Ca oxalate. Paddy-straw feeding caused polyurea. In all the animals the very first micturition showed the presence of radioactivity, and maximum 45Ca specific activity in the urine and feaces was obtained around 31 and 25 hr, respectively, after infusion. However, during the following 5 days, the decline in 45Ca specific activity in the feaces was sharper in group 1 than in the other groups indicating less absorption of calcium in group 1. Higher bicarbonates contents and pH of the rumen fluid were observed in group 3. The results indicated a slow and continuous release of oxalates from paddy straw. The ruminal TVFA concentration was lower and pH was relatively higher in group 3. Group 1 showed uniformly higher amounts of TVFA. (auth.)