Composition of rabbit caecal microbiota and the effects of dietary quercetin supplementation and sex thereupon

Abstract

The purpose of this study was to add to the current understanding of rabbit caecal microbiota. This involved describing its microbial composition and linking this to live performance parameters, as well as determining the effects of dietary quercetin (Qrc) supplementation (2 g/kg feed) and sex on the microbial population. The weight gain and feed conversion ratio of twelve New Zealand White rabbits was measured from 5 to 12 wk old, blood was sampled at 11 wk old for the determination of serum hormone levels, and the rabbits were slaughtered and caecal samples collected at 13 wk old. Ion 16S<sup>TM</sup> metagenome sequencing was used to determine the microbiota profile. The dominance of <em>Firmicutes</em> (72.01±1.14% of mapped reads), <em>Lachnospiraceae</em> (23.94±1.01%) and <em>Ruminococcaceae</em> (19.71±1.07%) concurred with previous reports, but variation both between studies and individual rabbits was apparent beyond this. Significant correlations between microbial families and live performance parameters were found, suggesting that further research into the mechanisms of these associations could be useful. Negative correlations with the caecal flavonoid content were found, but the latter was not affected by diet, and the effects of quercetin supplementation on the microbiota were very limited, possibly due to the absorption of the quercetin-aglycone from the gastrointestinal tract prior to the caecum. Nonetheless, <em>Clostridiales Family XIII. Incertae Sedis</em> was more abundant in the quercetin-supplemented rabbits (Control: 0.003±0.003%; Qrc: 0.020±0.000; <em>P</em>=0.005), as was the genus <em>Anaerofustis</em> (Control: 0.000±0.002; Qrc: 0.010±0.002; <em>P</em>=0.003). Serum cortisol levels were higher in females, and several microbial families differed between the sexes. Most were more abundant in female rabbits, including the most abundant, the family <em>Eubacteriaceae</em> (Male: 2.93±0.40; Female: 4.73±0.40; <em>P</em>=0.01).

Antimicrobial Effects of Black Soldier Fly and Yellow Mealworm Fats and Their Impact on Gut Microbiota of Growing Rabbits

“…These findings could be the reason for its overrepresentation in cecum where it is supposed to play an active role [52,57]. A previous study reported that the presence of this taxa was positively correlated with the feed conversion rate [58].…”

Breeding farm, level of feeding and presence of antibiotics in the feed influence rabbit cecal microbiota

“…A potential pro-inflammatory role has been proposed for this genus [ 42 ] what could be related to a reduced incidence of enteric disorders when feed restriction is applied. It is worth mentioning that family Peptococcaceae , which encompasses genus rc4–4 , is strongly related to total rabbit weight gain from weaning to 12-week old [ 43 ]. Although in our study this genus was prevalent in animals fed AL, its association with weight gain is not clear since the greater growth exhibited by these animals was consequence of higher feed intake.…”

Effects of Gut Microbiome and Short-Chain Fatty Acids (SCFAs) on Finishing Weight of Meat Rabbits

“…Wang Q. et al (2019) found that Coprococcus and Ruminococcaceae_UCG-004 may hinder the production of pro-inflammatory factors that exert beneficial effects on the finishing weight of rabbits. Moreover, North et al (2019) indicated that rabbits with greater abundances of Eubacteriaceae, Natranaerobiaceae, Peptococcaceae, and Syntrophomonadaceae in the gut microbial communities tended to gain more weight at finishing. Nevertheless, these investigations are based on 16S rRNA gene sequencing analysis, which cannot determine species and functional capacities that affect finishing weight.…”