Feeding of groundnut haulms containing rumen degradable nitrogen on microbial protein supply and growth in lambs

The present study was carried out to find out the optimum rumen degradable nitrogen (RDN) g/kg digestible organic matter in dry matter (DOMD) in groundnut haulms (GNH)-based rations in male lambs. Four experimental diets were formulated using GNH + molasses (R₁) and GNH + concentrates (60: 40) containing 14.29, 17.26 and 20.64 RDN (g/kg DOMD), in R2 to R 4 respectively. Twenty four Nellore Jodipi lambs (3–4 months age, 15.2± 0.5 kg) were allotted at random to the four treatments in a growth trial of 90 days. The digestibility of organic matter, crude protein, acid detergent fibre and cellulose was higher in R₂ to R₄, although significant difference (P<0.01) was observed only for neutral detergent fibre digestibility. The nitrogen intake, nitrogen voided through urine and total nitrogen voided (g/d) increased (P<0.01) in R ₂ to R ₄ treatments as compared to R and the nitrogen retention was not significantly different among treatments. The microbial protein supply (g/kg DOMD) was higher (P<0.01) in R₂ and R₄ than in R₁ lambs. The average daily gain and feed efficiency were significantly higher (P<0.01) in R₂ to R₄ fed lambs than in R₁. The feed cost/kg gain was lower (P<0.01) in lambs fed R₂ (Rs. 86.00) than in R₁ (Rs. 93.10), R₃ (Rs. 96.0) and R₄ (Rs. 89.60). In conclusion, this study indicated that a total mixed ration with 10.40% crude protein and 15.45 g RDN/kg DOMD was optimum for efficient microbial protein synthesis and economic production of lambs on groundnut haulms-based diets.