Nutrient utilization and growth performance of defaunated and faunated lambs maintained on complete diets containing varying proportion of roughage and concentrate

Nutrient utilization, feed conversion efficiency and growth performance of defaunated and faunated growing lambs maintained on complete diets containing different proportion of roughage and concentrate were evaluated in a 90-day experiment. Sixty Malpura weaner (90 days) lambs with average body weight of 13.2 kg were randomly divided into six equal groups (G1, G2, G3, G4, G5 and G6) of 10 lambs each. All lambs were defaunated by administration of sodium lauryl sulfate at the rate of 8 g/100 kg body weight as a 10% aqueous solution, infused directly into the rumen by stomach tube for two consecutive days. Six days after defaunation, all the lambs of G4, G5 and G6 groups were refaunated by inoculation of 100 ml per lamb rumen content drawn from normal faunated and fistulated rams. The lambs of G1 and G4, G2 and G5, and G3 and G6 groups were maintained on three complete diets in which the roughage and concentrate ratio were 50:50, 65:35 and 80:20, respectively. The digestibility of cell wall constituents was poor in defaunated lambs while daily intakes of digestible crude protein (DCP) and digestible energy (DE) were similar in defaunated and faunated lambs. Irrespective of the presence or absence of rumen protozoa, digestibility of dry matter (DM), organic matter (OM), crude protein (CP) and energy increased, while digestibility of cell and cell wall constituents decreased with increase in dietary proportion of concentrate resulting in their higher daily intake of DCP and DE. Even with similar DM, DCP and DE intake during the experiment, nitrogen retention, total body weight gain, average daily gain and feed conversion efficiency were better in defaunated than faunated lambs. With decreased dietary proportion of concentrate the body weight gain and feed conversion efficiency decreased both in defaunated and faunated lambs. concluded from the study that with similar intake of DM, DE and DCP, the growth performance and feed conversion efficiency were better in defaunated than in faunated lambs.