Effect of bacterial protein meal on protein and energy metabolism in growing chickens

Abstract

This experiment investigates the effect of increasing the dietary content of bacterial protein meal (BPM) on the protein and energy metabolism, and carcass chemical composition of growing chickens. Seventy-two Ross male chickens were allocated to four diets, each in three replicates with 0% (D0), 2% (D2), 4% (D4), and 6% BPM (D6), BPM providing up to 20% of total dietary N. Five balance experiments were conducted when the chickens were 3 – 7, 10 – 14, 17 – 21, 23 – 27, and 30 – 34 days old. During the same periods, 22-h respiration experiments (indirect calorimetry) were performed with groups of 6 chickens (period 1), 5 chickens (period 2), and one chicken (periods 3 – 5). After each balance period, one chicken in each cage was killed and the carcass weight was recorded. Chemical analyses were performed on the carcasses from periods 1, 3, and 5. Weight gain, feed intake, and feed conversion rate were found to be similar for all diets. Chickens on D0 retained 1.59 g N · kg^−0.75 · d⁻¹, significantly more than chickens on D2, D4, and D6, which retained 1.44 g, 1.52 g, and 1.50 g N · kg^−0.75 · d⁻¹, respectively. This was probably caused by the higher nitrogen content of D0. Neither the HE (p = 0.92) nor the retention of energy (p = 0.88) were affected by diet. Carcass composition was similar between diets, in line with the values for protein and energy retention found in the balance and respiration experiments. It was concluded that the overall protein and energy metabolism as well as carcass composition were not influenced by a dietary content of up to 6% BPM corresponding to 20% of dietary N.

Keywords:

• Chickens
• bacterial protein meal
• protein metabolism
• energy metabolism
• nucleic acids
• carcass composition

Acknowledgements

This experiment was part of the strategic research program, “Protein produced from natural gas: a new feed resource for fish and domestic animals.” We gratefully acknowledge the financial support of the Research Council of Norway (grant no. 143196/140) for this program. Skilful technical assistance with chemical analyses was provided by Merethe Stubgaard, Lotte Ørbæk, and Ebba de Nedergaard Harrison, and with the operation of the respiration unit by Abdalla Ali, assistance for which the authors wish to express their sincere gratitude.