Dietary duck fat improves meat quality via gut-muscle axis-mediated intramuscular lipid deposition in Cherry Valley duck.

This study investigated the effects of different duck fat (DF) levels on growth performance, intestinal microbiota, and meat quality in Cherry Valley ducks. A total of 120 one-day-old male Cherry Valley ducks (initial body weight 75.00±2.93 g) were randomly allocated to three treatment groups, with 5 replicates per group and 8 ducks per replicate, and fed diets supplemented with 3%, 6%, or 9% DF (DF3, DF6, DF9) respectively for 42 days. Compared with DF3, DF6 increased body weight at 14 d (803.75 vs. 740.00 g; P < 0.05), along with the increase of average daily gain (52.05 vs. 47.50 g/d) and average daily feed intake (65.71 vs. 61.43 g/d) during 1-14 d (P < 0.05). At 42 d, compared with DF3, DF6 and DF9 increased breast muscle intramuscular fat (IMF) content (5.13% and 5.44% vs 3.75%, P < 0.05), accompanied by higher lipogenic gene expression (P < 0.05). Compared with DF6, DF9 increased serum triglyceride, total cholesterol, and low-density lipoprotein cholesterol concentrations, as well as the feed-to-gain ratio during 15-35 d (P < 0.05). Untargeted lipidomics analysis showed that compared with DF3, DF6 and DF9 increased the abundances of selected triglyceride (TG) species in breast muscle (P < 0.05). Furthermore, DF6 and DF9 increased the relative abundance of cecal Lachnospiraceae and butyrate concentration compared with DF3 (P < 0.05), with no significant difference between DF6 and DF9 (P > 0.05). Spearman correlation analyzes showed positive associations among cecal microbial characteristics, butyrate concentration, breast muscle lipid profiles, lipid metabolism-related gene expression, and IMF content. In conclusion, 6% duck fat was the optimum dose which improved early growth and IMF deposition in ducks. Although 9% duck fat increased IMF content, it impaired feed efficiency during 15-35 d and increased serum lipid concentrations. These findings provided new insights into the gut-muscle axis which might regulate intramuscular lipid deposition through mediating cecal microbial characteristics and metabolites in ducks.