The effect of bacterial protein grown on natural gas on growth performance and sensory quality of broiler chickens

Bacterial protein meal (BPM) produced from natural gas by Methylococcus capsulatus (Bath), Alcaligenes acidovorans, Bacillus brevis and Bacillus firmus was studied as a protein source for broiler chickens. Three experiments from day-old to slaughter at 35 d were carried out. In exp. 1, BPM was fed at 0, 20, 40, 60, 80 and 100 g kg -1 diet (as fed) replacing soybean meal protein. Levels of BPM up to 60 g kg -1 had no effect on 0-5 wk gain, while the 80 and 100 g kg -1 levels significantly reduced gain, especially in the 0–2 wk period. In exp. 2, chickens were fed diets containing 0, 30, 60 and 90 g kg -1 BPM and two protein levels, 23 and 21 g kg -1 . The highest level of BPM significantly reduced growth, independent of protein level, whereas growth responses to lower levels of BPM were similar to the control diet. In exp. 3, 90 g kg -1 BPM in diets containing 23 g kg -1 protein had no negative effect on growth, but significantly reduced the abdominal fat pad. Overall, substitution of soybean meal protein with increasing levels of BPM significantly lowered feed-to-gain ratio during the last part of the feeding period. Sensory analysis of thigh meat after 2 mo of frozen storage (exp. 1) showed that meat from 35-d-old chickens fed 60 and 100 g kg -1 BPM had less odor intensity and less rancid flavor than meat from control animals fed no BPM. Other sensory attributes were not affected by treatment. Key words: Bacterial protein meal, chicken, growth performance, feed:gain ratio, feed conversion, sensory quality