Effect of Diets Differing in Rate of Gas Production on Intake, Digestibility and Nitrogen Metabolism in Crossbred Lactating Cows Sudha S.K., Krishnamoorthy U.*, Bhaskaran R., Robinson P.H.1 Department of Livestock Production and Management, Veterinary College, Karnataka Veterinary, Animal & Fisheries Sciences University, Bangalore- 560 024, India. *Corresponding author: Dr. U. Krishnamoorthy, E-mail: ukmthy@yahoo.com
1Department of Animal Science, University of California, Davis, USA. Abstract Effects of diets (finger millet straw (FMS) and concentrate supplement (CS) differing in their in vitro determined rate of fermentation (k) on total DM intake, nutrient digestibility and nitrogen metabolism were studied in crossbred dairy cows. The two diets, viz high k (0.081/h) and low k (0.065/h), were formulated to be iso-energetic and iso-nitrogenous. Six crossbred cows were divided into two groups of three based on body weight, milk yield and days in lactation. Diets consisted of ad libitum access to finger millet straw and concentrate. The experiment was completed in two periods in a switch-over design, with each period lasting 6 weeks with a 6 day metabolism trial at the end of each period. Intake (kg/d) of DM, organic matter (OM) and CP for the two groups did not differ, and the digestibility (g/kg DM consumed) of OM and CP for the two groups also did not differ. The N retained in both groups were similar (8.0 g/d), and urinary allantoin excretion (mmol/d) in the High k diet was 170.0 vs. 131.0 in the Low k diet (P=0.05). Calculated microbial N supply to the duodenum (g/d) was also higher (P=0.05) in the High k (136) vs. Low k (112) diet. These findings suggest that the higher in vitro measured k, tends to increase rumen microbial growth efficiency. Top Keywords Partitioning factor, Microbial efficiency, Rate of fermentation, Allantoin. Top |