Effect of Varying Levels of Dietary Ruminal Undegradable Protein on Feed Consumption and Growth Performance of Growing Kajli Lambs

The present experiment was conducted to evaluate the effect of different levels of ruminal undegradable protein (RUP) on feed consumption, digestibility and growth performance of growing Kajli lambs. In this 70 days trial, 36 growing Kajli male lambs (average weight of 20 +/- 2 kg) were used. Lambs were randomly divided into 4 groups (9 lambs per group). Four iso-caloric and iso-nitrogenous diets but varying in RUP were formulated. The control diet had 25% bypass protein and was termed as RUP25 diet. The RUP35, RUP45 and RUP55 diets contained 35, 45 and 55% RUP, respectively. The dry matter (DM), CP, neutral detergent fiber (NDF) and acid detergent fiber (ADF) intakes were higher (P<0.05) in lambs fed RUP55 diet than those fed RUP45 diet, however, remained unchanged (P>0.05) in animals fed RUP35 and RUP25 diets. The DM and CP digestibility by lambs fed RUP25 (63.61 and 76.03%) and RUP35 (63.96 and 78.30%) diets were higher (P<0.05) than those fed RUP45 (60.11 and 73.60%) and RUP55 (59.80 and 72.80%) diets. However, NDF and ADF digestibility remained unaltered (P>0.05) across all treatments. The nitrogen balance in lambs fed RUP55 diet was 8.05 gram (g) and was higher (P<0.05) than those fed RUP45 (5.14 g) diet but it remained unchanged (P>0.05) in animals fed RUP35 (3.58 g) and RUP25 (3.63 g) diets. The blood urea nitrogen (BUN) and creatinine were higher (P<0.05) in lambs fed RUP25 and RUP35 diets than those fed RUP45 and RUP55 diets. The daily live weight gain was 170, 201, 222 and 245 g in lambs fed RUP25, RUP35, RUP45 and RUP55 diets, respectively. The feed conversion ratios in lambs fed RUP25, RUP35, RUP45 and RUP55 diets were 4.94, 4.22, 4.05 and 4.08, respectively. The best feed conversion values (P<0.05) were noticed in lambs fed RUP45 and RUP55 diets compared to those fed RUP25 and RUP35 diets. In conclusion, increasing dietary RUP concentration not only increased Kajli lamb's growth but it also improved feed efficiency. (C) 2016 Friends Science Publishers