Utilisation of monosodium glutamate fermentation by-product as an alternative protein source in broiler diets: effects on growth performance, meat quality and estimated feed supply-chain carbon footprint

Rising feed prices and increasing attention to the environmental sustainability of poultry production motivate the evaluation of non-conventional protein sources for broiler diets. The present study examined monosodium glutamate fermentation by-product (MSG-BP) as a partial replacement for soybean meal, with emphasis on broiler performance, physiological status, carcase characteristics, meat quality, and feed-related greenhouse gas emissions. One hundred and eighty male Ross 308 broilers were assigned to a control diet or diets containing 3% or 5% MSG-BP and reared for 32 days, with experimental diets offered from days 15 to 32. Growth performance, including body weight, feed intake, and feed conversion ratio, was not affected by dietary treatment. In contrast, broilers receiving MSG-BP exhibited higher red blood cell counts, haemoglobin concentrations, and haematocrit values (p ≤ 0.001), whereas leukocyte profiles, heterophil-to-lymphocyte ratio, serum biochemical variables, and antibody titres against Newcastle disease and infectious bronchitis were unchanged. Inclusion of MSG-BP at 5% increased breast yield and reduced breast fat content, without adverse effects on technological meat quality traits. The life cycle assessment showed a decrease in the carbon footprint of the feed, dropping from 0.536 to 0.505 kg CO2e/kg feed when 5% MSG-BP was included. The results demonstrate that MSG-BP can partially substitute soybean meal in broiler finisher diets, preserving performance and product quality while modestly enhancing feed-related environmental sustainability.