Influence of pelleting and β-mannanase on nutrient digestibility and metabolizable energy of DDGS, copra meal, palm kernel meal, and jatropha meal in precision-fed Single Comb White Leghorn roosters.

This study evaluated the effects of pelleting and β-mannanase supplementation on nutrient digestibility and metabolizable energy of four alternative feed ingredients distillers dried grains with solubles (DDGS), copra meal, palm kernel meal (PKM), and jatropha meal (JM) using precision-fed Single Comb White Leghorn roosters. Two independent precision-fed rooster assays were conducted. In Experiment 1, each ingredient was offered in mash form or as pellets produced under controlled conditions (<65 °C) to minimize heat-induced nutrient damage. In Experiment 2, mash samples were supplemented with β-mannanase (0.25% as-fed basis). Apparent dry matter digestibility, nitrogen retention, and metabolizable energy values, including apparent metabolizable energy (AME), nitrogen-corrected AME (AMEn), true metabolizable energy (TME), and nitrogen-corrected TME (TMEn), were determined. Pelleting improved dry matter digestibility, nitrogen retention, and all metabolizable energy parameters across ingredients (p < 0.05), with more pronounced responses observed in DDGS and jatropha meal. β-mannanase supplementation also enhanced nutrient utilization and energy utilization, particularly in copra meal and palm kernel meal, which are rich in β-mannan-containing non-starch polysaccharides. Overall, the results demonstrate that both pelleting and β-mannanase supplementation can improve the nutritional value of fibrous alternative feed ingredients, thereby supporting their more efficient use in poultry diets.