The effect of heat treatment on the microbial count and chemical composition of broiler litter

This research was carried out to study the effect of heat treatment on microbial count and nutritive value of broiler litter in 2009. For this purpose, samples of broiler litter (containing wood shaving) collected and divided into 2 portions (treatment 1, 2) with four replications. Treatment 1 considered as control (un-autoclaved litter) and treatments 2 was autoclaved at 121°C under steam pressure of 1.5 atmosphere for three periods of time including: 4, 8 and 12 minutes, then they were studied for total microbial count. Results showed that no colony was found in samples obtained after autoclaving for 12 minutes. Therefore, at the next stage, the nutritive value of control samples and also treatment samples (autoclaved litter at 121°C for 12 min) were determined and compared together, according to a completely randomized design. According to results, NDF contents for Control (39.5%) and autoclaved litter (42%) were significantly different (p<0.05). However, no significant differences were observed in DM, CP, Ash, OM, ADF, NFC, TDN, ME, Ca, P and Cu contents between the treatments. The rapidly soluble fraction (a) of DM and CP were 27.93 and 66.20 for control but 13.95 and 50.30 for autoclaved treatment respectively (p<0.05). Heating of broiler litter decreased rapidly soluble fraction of DM and CP (p<0.05) and increased the insoluble fraction (b) of DM and CP (p<0.05). Rumen effective degradability of DM and CP of broiler litter (k = 0.02, 0.05 and 0.08 h-1) were significantly decreased by autoclaving (p<0.05). This study demonstrates that moist heat treatment is an effective method to decrease the microbial count and to increase the rumen escape protein value of broiler litter.