The termite gut contains different kinds of lignin and lignocellulose degrading microbes. This study was conducted to isolate and identify termite gut symbiotic bacteria with lignocellulose-degrading potential, and evaluate their effects on the chemical composition and in vitro digestibility of wheat straw and date leaves. Termite gut contents were extracted and cultured in 9 different culture media containing lignin and lignocellulosic materials that had been prepared from water-extracted sawdust and wheat straw. Three superior bacteria capable of growing on all media, and with higher lignin peroxidase activity, were selected and subjected to molecular identification.Following this, wheat straw and date leaves were incubated with the isolated bacteria in liquid medium for 6 weeks. 16S rRNA sequence analysis showed that these isolates possessed 97, 99 and 97% similarity with Bacillus licheniformis, Ochrobactrum intermedium and Microbacterium paludicola, respectively. The highest (P<0.05) dry matter (DM) loss in wheat straw and date leaves was observed following treatment with B. licheniformis. In the case of wheat straw, the organic matter (OM) and neutral detergent fibre (NDF), and for date leaves OM, NDF and acid detergent lignin (ADL) contents were not influenced by the treatments (P>0.05). The greatest and lowest (P<0.05) ADF content of wheat straw was observed as a result of treatment with B. licheniformis and O. intermedium, respectively. However, bacterial treatments decreased (P<0.05) ADF content of date leaves when compared to the control. Acid detergent lignin content of wheat straw was decreased (P<0.05) by bacterial treatments in comparisons to the control. For wheat straw, the highest and lowest (P<0.05) value of crude protein (CP) was observed in the case of M. paludicola and O. intermedium treatments, respectively. For date leaves, the CP content of the control treatment was 3 highest (P<0.05) among treatments. For wheat straw, bacterial treatments enhanced (P<0.05) DM, OM and ADF digestibility when compared to the control. However, highest and lowest (P<0.05) CP digestibility was observed using O. intermedium and M. paludicola, respectively. For date leaves, treatment with B. licheniformis significantly increased (P<0.05) digestibility of DM, OM and NDF when compared to the others.However, CP and ADF digestibility was not different (P>0.05) between experimental groups. Overall, the results of this study showed that the isolated bacteria partially changed the chemical composition of wheat straw and date leaves while, they improved digestibility of nutrients. These bacteria are suitable candidates for increasing nutritive value of by-products for ruminants.

This study was conducted to assess the effect of feeding corn steep liquor (CSL) on in vivo digestibility, ruminal pH, ammonia and hydrolytic enzyme activities, blood metabolites, feed intake (FI) and growth performance in fattening lambs. The CSL is a by-product of wet milling process of maize starch industry. The crude protein (CP), rumen-degradable protein (RDP), lactic acid and metabolisable energy contents of this by-product were 420, 324, 200 g/kg dry matter (DM) and 12.6 MJ/kg DM respectively. Twenty-seven male Moghani lambs were assigned randomly into three groups of nine lambs each in a completely randomised design. Three iso-energetic and iso-nitrogenous diets containing different levels (0, 50 or 100 g/kg dry matter) of CSL were offered ad libitum three times a day. Forage to concentrate ratio of the diets was 30:70. With inclusion of CSL in diet, the contents of canola meal, fish meal, wheat bran, corn grain and sugar beet pulp were decreased. The contents of DM, ash-free neutral detergent fibre (NDFom), ether extract, starch, Ca and S were numerically lower, but soluble protein, RDP and non-fibre carbohydrates were greater in the diets containing CSL in comparison with the control diet. The lambs fed with the diets containing CSL had lower [linear (L), p < 0.06] digestibility coefficients of DM and NDFom as compared to those fed with the diet free of CSL. Ruminal ammonia-N concentration increased (L, p < 0.05), but pH decreased (L, p < 0.05) with raising CSL level in diet. Carboxymethyl cellulase and filter paper-degrading activities decreased (L, p < 0.05), while proteases activity increased (L, p < 0.05) as dietary rates of CSL increased. Microcrystalline cellulase and ɑ-amylase activities were similar among the treatments. Within blood metabolites, only urea-N concentration increased (L, p < 0.05) in the lambs receiving CSL as compared to those fed with diet without CSL. Dietary inclusion of CSL resulted in linear decreases (L, p < 0.05) in the intakes of DM, organic matter, CP, NDFom and ash-free acid detergent fibre, and average daily gain. However, the feed conversion ratio was similar among the experimental animals. Overall, feeding CSL up to 100 g/kg diet DM in lamb resulted in reductions of rumen fibrolytic microbial enzyme activities, in vivo digestibility, FI and growth performance, but rumen proteases activity increased.

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