Extracted and Characterized Humic Substances as Feed Supplement in Rabbit Feeding: Effects on Performance, Blood Metabolites and Caecal Fermentation Activity

This study aimed to evaluate the effect of dietary humic acid (HA) supplementation on the growth performance, nutrient digestibility, carcass characteristics, blood metabolites, and caecal fermentation activity in growing rabbits. Six-week-old New Zealand White (NZW) rabbits (n = 63) with an initial body weight of 726.32 ± 42.85 g, were randomly allocated to three groups of 21 rabbits each. Rabbits were fed on the basal diet with 0 (HA0, control), 5 (HA5) and 10 (HA10) gram/kilogram diet for 70 days in a completely randomised experimental design. A significant heavier (P