Nutrient Utilisation in Ram Lambs Fed with Coated Slow Release Non-protein Nitrogen Sources

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Background: Urea is commonly used as source of non protein nitrogen for ruminants. However, the fact that the rate of release of NH3-N must coincide with the rate of digestion of carbohydrates or else lead to toxicity, this has led the industry to seek the development of compounds with a slow release urea (SRU), which have less risk of toxicity in animals. Methods: A study was conducted on 30 ram lambs (1-2 month old; 14.73±0.49 kg body weight) randomly allotted to 5 dietary treatments with 6 animals in each group in a completely randomized design to evaluate the effect of supplementation of SRNPN products on nitrogen balance, plane of nutrition and nutrient utilisation. Five maize stover based complete diets (2190kcal ME/kg and 14.6% CP) were prepared viz. control diet with SBM as major protein source (45% CP) and without any NPN supplement, positive control diet, having urea (46% N) around 1% of dietary DM and in other 3 diets, urea was totally replaced with FCU, CFCU and HMCCU. Result: Supplementation of SRNPN products did not affect the intake of nutrients viz. DM, OM, CP, CF, NFE, NDF, ADF, hemicellulose and cellulose and the digestibilities of DM, OM, NFE and ADF. While, CP digestibility (%) reduced (P less than 0.01) with feeding of urea (78.52) based diet compared to control diet (84.34) and replacement of urea with FCU (85.24) improved the CP digestibility (%) and was comparable to control. Incorporation of urea in the diets decreased (P less than 0.01) the CF and cellulose digestibility compared to control, while incorporation of FCU or CFCU in diets improved (P less than 0.01) CF, NDF and hemicellulose digestibilities. The N intake, excretion and balance (g/d) was though comparable among the dietary groups, the retention in lambs fed urea diets was lower by 14.71% compared to control group, while in FCU, CFCU and HMCCU fed lambs, N retention improved by 18.17, 10.05 and 7.84%, respectively compared to urea diet fed lambs.