Effect of supplementing sulphate-reducing bacteria along with sulphur on growth performance, nutrient utilization and...

A competitive relationship exists between sulphate-reducing bacteria and methanogens in the anaerobic environment including rumen for hydrogen where sulphate is not limiting growth and consequently inhibit enteric methane emission as thermodynamically energetic sulphate reduction (∆G^o =  - 21.1 kJ/mole of H₂) is more favourable than methanogenesis (∆G^o =  - 16.9 kJ/mole H₂). To validate this hypothesis, a study was designed to investigate the effect of supplementation of sulphate-reducing bacteria (SRB) identified as Streptococcus caviae RM296 as microbial feed additives alone or along with sulphur (as sodium sulphate) on methane production, live weight gain, feed intake, nutrient digestibility and energy metabolism in goats. The experiment was conducted on growing kids (n = 36, 5-6 months of age) with average body weight of 10.08 ± 0.21 kg, divided into six groups (n = 6). The duration of the feeding trial was of 150 days. The six treatments were control fed a basal diet (T1), SRB 0.5 ml/kg BW (T2), sulphur (as sodium sulphate) 0.095% of DMI (total sulphur level in the diet 1.5 times the requirement) (T3), sulphur (as sodium sulphate) 0.095% of DMI + SRB 0.5 ml/kg BW (T4), sulphur (as sodium sulphate) 0.19% of DMI (total sulphur level in the diet 2 times the requirement) (T5) and sulphur (as sodium sulphate) 0.19% of DMI + SRB 0.5 ml/kg BW (T6). Duration of study was 150 days and goats were fed as per ICAR (2013) feeding standard. Methane (CH₄) production (l/kg DMI) was reduced by 11.8% (P = 0.052) in T6 where sulphur (0.19% DMI) was supplemented along with SRB4 (at the rate 0.5 ml/kg BW) as compared to T1 (un-supplemented group). However, the dry matter intake (DM), total weight gain (TG), average daily gain (ADG), feed conversion ratio (FCR), excretion of purine derivatives (allantoin, uric acid, xanthine and hypoxanthine) and digestibility of organic matter (OM), dry matter (DM), ether extract (EE), crude protein (CP), acid detergent fibre (ADF) and neutral detergent fibre (NDF) were similar (P > 0.05) among all the groups. The experimental data revealed that feeding of SRB as a microbial feed additive along with sulphur (as sodium sulphate) is capable of reducing enteric CH₄ emission without any adverse effect on rumen fermentation and digestibility of the nutrients.