Blood parameters in growing pigs fed increasing levels of bacterial protein meal

Bacterial protein meal (BPM) is a new protein source fermented on natural gas, ammonia, and oxygen by Methylococcus capsulatus (Bath) (>90%), Ralstonia sp., Brevibacillus agri, and Aneurinibacillus sp. The protein content of BPM is 65–70% and the amino acid composition is comparable to those of fish meal and soybean meal [1]. Rapidly growing bacteria may contain up to 25% nucleic acids on a dry matter basis [2]. The nucleic acid (i.e., ribonucleic acid (RNA) and deoxyribonucleic acid (DNA)) content of BPM is approximately 10%, which is similar to that of yeast [3,4] but much higher than that of soybean meal or fish meal [5,6].In pig production experiments in which 40–50% of the nitrogen (N) was derived from BPM, slightly improved growth performance in the piglet period was recorded in one experiment [7], whereas another experiment found a reduction in weight gain with increasing BPM level, probably due to suboptimal lysine levels [1]. In growing-finishing pigs, high levels of BPM, replacing soybean meal, could be fed without affecting growth performance [1,7], no clinical health problems related to inclusion of dietary BPM being encountered in any of these studies. Heat production, nitrogen retention, and energy retention were not affected in pigs receiving up to 50% of their dietary N from BPM [8].Adenine and guanine levels are higher in diets containing BPM than in diets containing fish meal or soybean meal, and the excretion of uric acid has been demonstrated to increase with increasing dietary BPM [9]. Although pigs display uricase activity, and purine bases ought to be completely decomposed to allantoin, this might indicate that the uricase activity is insufficient to metabolize all uric acid to allantoin. This could lead to increased plasma levels of uric acid, and possibly the accumulation of uric acid in joints and kidneys [10].Investigations in mink, rats and chickens [11-13] have shown that liver cell integrity, purine base metabolism, protein metabolism a