Feed Passage Time, Apparent Metabolisable Energy and Apparent Ileal Amino Acid Digestibility of Pretreated Anchovy Waste in Quails

Abstract

This study investigated the effects of pretreatment methods on the digestive utilisation of anchovy waste (Engraulidae) in Japanese quail (Coturnix japonica), evaluating feed passage kinetics, apparent Metabolisable energy (AME), and apparent ileal amino acid digestibility (AIAAD). Anchovy waste was subjected to desalting (DAW) by soaking in distilled water (1:3 w/v for 2 h) or Lactiplantibacillus plantarum fermentation (FAW) (5% inoculum, 10% molasses, 37°C for 48 h) and compared against untreated anchovy (UAW) and commercial fish meal (FM) as a reference. One-day-old quail chicks (n=140) were fed basal or experimental diets containing untreated, desalted, or fermented anchovy or commercial fish meal at 25% inclusion, with 0.5% TiO₂ as a marker. Rate of passage (T₅₀ and MRT), AME, and ileal crude protein and amino acid digestibility were determined using the difference and direct methods, with data analysed by one-way ANOVA (Tukey's HSD, p<0.05). Fermentation increased crude protein to 58.90% and reduced sodium by 60.8% compared to UAW (57,473 mg/kg DM). Desalting increased sodium concentration on a dry matter basis to 71,137 mg/kg DM whereby the apparent increase attributable to concentration of mineral residues following removal of water and soluble fractions as well as increased calcium to 61,627 mg/kg DM. UAW produced the shortest T50 (2.313 h) but longest mean retention time (4.945 h), associated with its high-ash, high-mineral composition. Fermentation normalised passage kinetics. Desalted anchovy achieved the highest energy values at both the diet (2,870 kcal/kg) and ingredient (5,521 kcal/kg) levels, surpassing FM, attributable to compositional enrichment of energy-yielding fractions following aqueous washing. UAW showed the highest amino acid digestibility, matching or exceeding FM, while fermentation reduced digestibility. These findings indicate that anchovy waste represents a viable alternative protein ingredient for poultry, and that pretreatment selection should be guided by whether energy optimisation or amino acid availability is the primary nutritional objective.