219. Influence of Maillard Reaction Compounds Formation and Biogenic Amines in Raw Materials on Protein Utilization Efficiency in Dogs.

Abstract Considering that protein sources with biogenic amines (BA) and Maillard compounds (MC) formed during thermal processing may interfere in protein utilization, this study evaluated the body balance of MC and BA and their relationship with protein utilization efficiency (PUE) and protein turnover (PT) in dogs fed extruded diets containing poultry by-products. Diets formulated with increasing substitution of conventional poultry by-product meal (PBM) by hydrolysed poultry by-product meal (HPM; 0, 50, and 100%) were processed under two levels of specific mechanical energy (SME; low: 10 kWh/t, mass temperature 100 °C; high: 25 kWh/t, 150 °C). MC evaluated included furosine, lysine–alanine, carboxymethyl-lysine, and hydroxymethylfurfural (HMF), while BA included putrescine, cadaverine, histamine, serotonin, spermidine, and spermine (Ethics approval 003799/23). MC were quantified in diets, feces, urine, and plasma, and BA in diets and feces to estimate intake, excretion, and metabolic retention. PUE and PT were determined using the indicator amino acid oxidation (IAAO) technique applied only to diets containing 100% PBM or 100% HPM processed under both SME levels in six dogs. To apply IAAO six crude protein levels (6, 8, 10, 12, 14, and 16% on a dry matter basis) were obtained through a dilution technique using a low-protein diet. High SME increased HMF formation in diets (303±8 vs 2,067±31 mg/kg; P < 0.01), with corresponding increases in plasma concentrations (P < 0.05). HMF intake reflected dietary concentration and was primarily excreted in urine (46±0.3%; P < 0.01), while body retention averaged 43±2% (P < 0.01). Fecal excretion of HMF increased only under high SME (P < 0.01). MC concentrations showed negative correlations with both PUE and PT (ρ = −0.58 and −0.51; P < 0.01), indicating that greater MC formation is associated with reduced PUE and PT. The inclusion of HPM increased total dietary BA concentrations (114.5±1.4 vs 259.6±3.1 vs 379.6±4.8 mg/kg; P < 0.01), resulting in higher intake (1.2–6.5 mg/kg0.75; P < 0.01) without affecting fecal excretion (P > 0.05). BA balance was negative for putrescine and positive for the remaining amines (P < 0.05), with serotonin shifting from a negative to a positive balance (−0.10±0.01 mg/kg0.75 vs 0.21±0.03 mg/kg0.75) in HPM diets (P < 0.01). Despite the increased BA intake associated with HPM inclusion, no negative effects on PUE or PT were observed, with no correlation with crude protein levels (P > 0.05) and positive overall correlations with PUE and PT (ρ = 0.64 and ρ = 0.77; P < 0.05). In conclusion, higher SME during extrusion increases the formation and retention of MC, particularly HMF, which is associated with reduced PUE and PT in dogs. In contrast, although HPM inclusion increases dietary BA concentrations and intake, these compounds do not impair PUE or PT, indicating that BA alone are not reliable indicators of low dietary protein quality or reduced PUE and PT in dogs.