Nutrient digestibility and nitrogen balance in growing pigs fed a 10% Macadamia integrifolia nut oil cake diet supplemented with exogenous enzymes

Abstract

The study tested a 10% dietary inclusion of Macadamia nut oil cake (MOC) fortified with exogenous enzymes on nutrient digestibility and nitrogen balance in growing pigs. The diets included a commercial maize–soybean pig grower control and a 10% MOC diluted iso-nutrient mix, each with a duplicate supplemented with 500 g/tonne of an enzyme cocktail containing 3000 FTU g^-1 6-phytase (IUB 3e1.3.26), 7270 U g^-1 endo^-1 ,4-beta-xylanase (EC-3.2.1.8), 300 U g^-1 alpha amylase (EC-3.2.1.1), 6000 g^-1 subtilisin protease (EC-3.4.21.62), and 532 U g^-1 endo^-1 ,4-beta-glucanase (IUB 3.2.1.6). Eight male Large White × Landrace 28-day-old weaned piglets were randomly assigned to the four diets in a 2 ×2 factorial experiment within two balanced 4 × 4 Latin squares for cross-over feeding over 8-day periods (3-d adaptation + 5-d feed intake) and total faecal and urine measurement. The digestibility of proximate and detergent fibre components, the nitrogen intake, faecal and urinary excretion; and the calculated total excretion, apparent digestibility, absorption, retention, utilization, and biological value of the dietary protein were evaluated. The 10% inclusion reduced dietary crude protein digestibility and the scaled live (g.kg^-1 live weight) and metabolic (g/day/kg LW^0.75) nitrogen retention. Scaled on live weight, the 10% MOC diet reduced nitrogen retention only when the diets contained exogenous enzymes. Further research is recommended to test the enzymes at a higher dosage or evaluate different enzyme activities.