Gut–brain bidirectional determination in regulating the residual feed intake of small-sized meat ducks
Hao Bai, Dandan Geng, Fuguang Xue, Xiaofan Li, Chenxiao Wang, Chenyu Wang, Qixin Guo, Yong Jiang, Zhixiu Wang, Yulin Bi, Guohong Chen, Guobin Chang
Abstract
The gut-brain axis is essential in maintaining the homeostasis of neuronal system, endocrine system, and intestinal microbiota in both the afferent and efferent directions. This axis is considered to be a key mechanism that regulates feed efficiency ( FE ). This study aimed to investigate the regulatory mechanisms of gut–brain axis-related genes on the residual feed intake ( RFI ) in H-strain small-sized meat ducks. A total of 500 ducks with similar initial BW (635.2 ± 15.1 g) were selected and reared in the same experimental facility until slaughter at 42 d of age. RFI was calculated from the average daily gain ( ADG ), average daily feed intake ( ADFI ), and metabolic body weight ( MBW 0.75 ). Thirty high-RFI ( H-RFI ) and 30 low-RFI ( L-RFI ) birds were selected for further evaluation of growth performance, carcass characteristics, and blood biochemical parameter measurements. Six L-RFI and 6 H-RFI birds were then subjected to hypothalamic transcriptomic and cecal microbial sequencing analyses. Results indicated that L-RFI birds exhibited lower production performance (ADFI, FCR, and RFI) and blood biochemical indices (total cholesterol and ghrelin content) compared with H-RFI birds ( P < 0.05). Gene expression differed significantly between the L-RFI and H-RFI birds, with 70 upregulated and 50 downregulated genes. The bacterial communities of L-RFI birds showed higher abundances of Bacteroides, Bifidobacterium , and Lactococcus, and lower abundances of Erysipelatoclostridium, Parasutterella, Fournierella , and Blautia compared with H-RFI birds ( P < 0.05). Interactive analysis revealed bacterial communities associated with FE were significantly correlated with hypothalamic genes ( P < 0.05), for example, Bacteroides was positively correlated with DGKH and LIPT2 , while negatively correlated with CAPN9, GABRD , and PDE1A. Bifidobacterium showed significant correlations with ATP2A3, CALHM6 , and TMEM121B . Overall, RFI was a crucial indicator of FE, regulated by interactions between brain gene expression and gut microbiota through cAMP signaling, neuroactive ligand-receptor interaction, and calcium signaling pathways. Notably, increased expression of hypothalamic genes and abundance of carbohydrate-utilization microbiota in L-RFI meat ducks improved FE by enhancing energy metabolism and volatile fatty acids absorption.