Milk Allantoin Content as an Indicator to Assess Rumen Microbial Protein Synthesis

Deshpande, K.Y., Mehra, U.R., Singh, P. and Verma, A.K. 2012. Milk allantoin secretion as an indicator to assess nutrient utilization in daily cows. Animal Nutrition and Feed Technology, 12: 229-239. Response parameters were studied in thirty dairy cows (Bos taurus x Bos indicus; 348.67 +/- 10.77kg mean body weight and 10.00 +/- 0.63kg/d average milk yield) divided into three groups, and fed on the diets having mixed green roughages and concentrate mixtures containing varying metabolisable energy (ME) i.e. 28, 30 and 32 Mcal/day. The experimental feeding was continued for 90days and a digestion trial was conducted at the end. The dietary DCP levels ranged from 16.0 to 16.9 g/kg W-0.75. Digestibility of DM and OM was similar among three groups. The digestibility of NDF and ether extract increased significantly in group III. However, ADF digestibility was significantly higher in groups II and III. Urinary excretion of allantoin (mmol/L), purine derivatives : creatinine (PD: C) ratio and PDC index increased significantly with the increase in dietary energy levels. Milk composition was comparable among three groups throughout the study. The concentration of allantoin, uric acid and total PD (mmol/L) in plasma and milk increased significantly in groups II and III. The correlation coefficient (r) between digestible dry matter intake (kg/d) and milk allantoin (mmol/L) was 0.67 (P < 0.05). It is concluded that PD assay in milk may be used as an alternate indicator to assess nutrient utilization and microbial protein supply in dairy cows.