This study investigated the effects of recycled poultry bedding (RPB) on performance and protozoa population, microbial enzyme activity and microbial protein synthesis (MPS) in rumen contents of fattening lambs. Thirty-six male Moghani lambs (31.4 ± 3.2 kg body weight) were fed iso-energetic and iso-nitrogenous diets containing 0, 70, 140 or 210 g/kg dry matter (DM) RPB in a balanced randomized design (9 lambs per treatment). Results showed that final body weight, DM intake, average daily gain and feed conversion ratio were unchanged (P > 0.05) by RPB inclusion. Total protozoa population and sub-family of Entoniniinae and Diplodiniiae were linearly decreased by RPB (L, P < 0.05). For rumen fibrolytic enzymes including carboxymethyl-cellulase, microcrystalline-cellulase and filter paper degrading activity, the extra cellular, cellular and total (extra cellular plus cellular fraction) activity were similar (P > 0.05) by feeding the experimental diets. Inclusion of RPB in the diet linearly decreased extra cellular and total α-amylase activity (L, P < 0.05), while cellular activity was unchanged (P > 0.05). The extra cellular activity of proteases tended to increase (L, P = 0.07) and their total and cellular activity increased (P > 0.05) in lambs fed RPB. Incorporation of RPB into the diet had no effect (L, P > 0.05) on urinary purine derivative excretion and MPS. In conclusion, inclusion of RPB up to 210 g/kg DM had no negative impact on performance, ruminal fibrolytic enzyme activity and MPS, while it increased rumen protease activity and decreased protozoa population in fattening Moghani lambs.
Keywords: Enzyme activity; Lamb; Microbial protein; Performance; Recycled poultry bedding.