Effect of Dietary Levels of Oxalic Acid on Calcium and Phosphorus Assimilation in Crossbred Bulls

Sixteen crossbred (Local x Jersey) bulls of about 3 years age were randomly divided into four equal groups. The animals were fed four levels of oxalic acid in wheat and paddy straws diet with concentrate mixture. The total oxalate content of concentrate mixture, untreated wheat straw, 0.5 percent (w/w) oxalate treated wheat straw, untreated paddy straw and 0.5 percent (w/w) oxalate treated paddy straw were determined as 0.31, 0.17, 0.70, 1.54 and 2.01 percent on DM basis, respectively. The total oxalate intake in groups were 0.21, 0.58, 1.19 and 1.54 percent of the total DM intake respectively during the experimental period of 30 days. The intake of oxalic acid not influences the digestibility of different nutrients. The calcium balances in the Tl, T2, T3 and T4 were +1.21, 0.37, -1.79 and -2.03 and +2.49 +2.46, +2.44 & +2.42 g/animal/day, respectively. The calcium balance phosphorus balances were between the treatments was significantly lower (p<0.01) in T3 and T4 groups. The levels of oxalate intakes were negatively correlated (r=0.96) with calcium balance. Though soluble oxalates constituted about 73 percent of total oxalate of paddy straw but the same was not found in the faeces of all the animals indicating thereby the break down of soluble oxalates in the rumen whereas the insoluble oxalates were broken down up to 50 percent levell It can be concluded that the total oxalate intake at the level of 0.58 percent of the DM intake may be harmless with the calcium intake of 7 8g/100kg body weight.