Research Note: Integrated gut microbiome and short-chain fatty acids responds to dominance hierarchy in roosters

Effects of Dietary Alfalfa Meal Supplementation on the Growth Performance, Nutrient Apparent Digestibility, Serum Parameters, and Intestinal Microbiota of Raccoon Dogs (Nyctereutes procyonoides)

The raccoon dog (Nyctereutes procyonoides) is a typical omnivore possessing wide dietary adaptability and tolerance to rough feeding, which may be attributed to its intestinal microbiota. The study aimed to investigate the effect of dietary alfalfa meal levels on the growth performance, nutrient apparent digestibility, serum parameters, and intestinal microbiota of raccoon dogs. Sixty raccoon dogs were randomly divided into four dietary treatments containing 0% (AM0), 5% (AM5), 10% (AM10), and 15% (AM15) alfalfa meal for a 60-day experiment. The results showed that compared to raccoon dogs fed the AM0 diet, those fed the AM5 and AM10 diets had no significant difference in growth performance, while those fed the AM15 diet experienced a significant decrease. Raccoon dogs fed the AM5 diet had no significant effect on the nutrient apparent digestibility. Dietary supplementation with alfalfa meal significantly decreased serum urea levels and increased the antioxidant capacity of raccoon dogs. The intestinal microbiome analysis showed that the richness and diversity of colonic microbiota significantly increased in the AM15 group. With the increase in dietary alfalfa meal levels, the relative abundance of fiber-degrading bacteria in the colon of raccoon dogs, such as Treponema, Phascolarctobacterium, and Christensenellaceae R-7 group, increased. However, the relative abundance of pathogenic bacteria, including Anaerobiospirillum, decreased. In conclusion, the inclusion of 5% alfalfa meal in the raccoon dogs' diet had no effect on growth performance, but it exhibited the potential to improve serum antioxidant capacity and intestinal microbiota. This indicates that raccoon dogs have a certain tolerance to the addition of alfalfa meal in their diet.

Versatile, vigilance, and gut microbiome support the priority of high-ranking hens

Dominance hierarchy exists in social animals and shows profound impacts on animals' survival, physical and mental health, and reproductive success. Aggressive interaction, as the main indicator used to calculate social hierarchy, however, is not found in some female animals. In this study, we aimed to figure out the establishment of social hierarchy in hens that almost perform aggressive behaviors and investigated the interactions of social hierarchy with production performance and gut microbiome. Forty 49-day-old Qingyuan hens were randomly divided into four groups. The social hierarchy of hens was calculated by the relative position around the feeder. The rank 1 (R1), R2, R3, R4, R5, R6, R7, R8, R9, and R10 birds were determined in ascending order. Then, R1 and R2 birds (four duplicates, n = 8) were named as the high-ranking hens (HR) group, while R9 and R10 individuals were named as the low-ranking hens (LR) group (four duplicates, n = 8). The heart index (p = 0.01), number of visits per day, daily feed intake, and occupation time per day were higher in the HR group than LR group, but the LR group had a higher feed intake per visit than the HR group. The alpha diversity was significantly lower in the HR group than the LR group (p = 0.05). The relative abundance of phylum Firmicutes was higher while that of phylum Deferribacterota was lower in the HR group than LR group (p < 0.05). At the genus level, the relative abundance of Succinatimonas, Eubacterium hallii group, and Anaerostipes were higher in HR group than in LR group. The relative abundance of Bacteroides, Mucispirillum, Subdoligranulum, and Barnesiellaceae unclassified was higher in the LR group than HR group (p < 0.05). In conclusion, the rank of hens could be calculated by the relative position around the feeder when they compete for food. The dominant hens have a versatile. Moreover, they are more vigilant and have priority when foraging. Low-ranking hens adopt strategies to get enough food to sustain themselves. Hens of high-rank possess beneficial bacteria that use favorable substances to maintain the balance of the gut environment.

Social Hierarchy Dictates Intestinal Radiation Injury in a Gut Microbiota-Dependent Manner

Social hierarchy governs the physiological and biochemical behaviors of animals. Intestinal radiation injuries are common complications connected with radiotherapy. However, it remains unclear whether social hierarchy impacts the development of radiation-induced intestinal toxicity. Dominant mice exhibited more serious intestinal toxicity following total abdominal irradiation compared with their subordinate counterparts, as judged by higher inflammatory status and lower epithelial integrity. Radiation-elicited changes in gut microbiota varied between dominant and subordinate mice, being more overt in mice of higher status. Deletion of gut microbes by using an antibiotic cocktail or restructuring of the gut microecology of dominant mice by using fecal microbiome from their subordinate companions erased the difference in radiogenic intestinal injuries. Lactobacillus murinus and Akkermansia muciniphila were both found to be potential probiotics for use against radiation toxicity in mouse models without social hierarchy. However, only Akkermansia muciniphila showed stable colonization in the digestive tracts of dominant mice, and significantly mitigated their intestinal radiation injuries. Our findings demonstrate that social hierarchy impacts the development of radiation-induced intestinal injuries, in a manner dependent on gut microbiota. The results also suggest that the gut microhabitats of hosts determine the colonization and efficacy of foreign probiotics. Thus, screening suitable microbial preparations based on the gut microecology of patients might be necessary in clinical application.