Abstract
Under the dual influence of antibiotic restriction policies in animal husbandry, marine-derived Enterococcus durans YQ-6 has been considered a promising alternative feed additive. A total of 180 one-day-old male Leizhou black ducks were randomly allocated into five groups: a blank control, three YQ-6 dose groups (1 × 10(7), 1 × 10(8), 1 × 10(9) CFU/kg), and a Lactobacillus acidophilus control group, with six replicates per group. The trial lasted 42 days. The results showed that YQ-6 could significantly increase the body weight and average daily gain of Leizhou black ducks (P < 0.05) and reduce the feed conversion ratio. The high dose group (M3) significantly increased the dressing percentage, breast muscle rate and leg muscle rate (P < 0.05), decreased the sheer force and b value of breast muscle and optimized the amino acid composition of muscle, the contents of l-aspartic Acid, alanine and l-Phenylalanine were significantly increased (P < 0.05). In addition, YQ-6 could improve intestinal morphology, increase the ratio of villus height to crypt depth, enhance digestion and absorption capacity and regulate the structure of intestinal flora, such as increasing the relative abundance and proportion of Firmicutes and Bacteroides. In conclusion, dietary YQ-6 supplementation, especially at a dose of 1 × 10(9) CFU/kg, can effectively promote the growth, improve meat quality and enhance intestinal health of Leizhou black ducks.