Limited vertical transmission of gut bacteria in commercial chickens

Abstract

Background: Efficient vertical transmission of commensal gut microbes is important for the host in order to promote gut microbiota functions such as protection from gut pathogens, and for gut microbes considering microbial competition over limited niche space. While the role of direct contact with parents in transmission is well established, conflicting reports exist regarding transmission in commercial settings where chicks are raised separated from adults, including the utilization of the chicken egg as a transmission mechanism. This question is also relevant to other vertebrates which leave their eggs after laying. Results: We compared the fecal microbiota of poultry chicks hatched and grown separately, with the microbiota of their mothers over three rounds of egg incubation and chick growth. We found that most bacterial strains identified in the hens did not appear at all in chicks up to two weeks of age. Furthermore, most of the strains common with the hens which did appear in chicks had a low incidence among the chicks. Thus, the gut microbiota of hens does not efficiently transmit to chicks when there is no contact with adults. That been said, a few bacterial strains common with the hens were good colonizers of chicks; these included members of Lactobacillales and Enterobacteriales. Finally, we performed two interventions in an attempt to disrupt transmission. In round two, we sprayed a disinfectant on half of the eggs. In round three, we treated half of the hens with an antibiotic cocktail which decimated their cecum and fecal microbiota. Both interventions resulted in a reduction in chick colonization. Interestingly, both interventions affected strains shared with the hens as well as strains not identified in hen samples, implying many ‘environmental’ opportunistic strains reach the chicks through the egg. Conclusions: To conclude, vertical transmission in commercial poultry grown separately from hens likely exists but is not efficient, possibly resulting in impairment of microbiota function as evidenced by sensitivity of chicks to gut pathogens. These results also imply that artificial exposure to adult hen bacterial strains might result in improved microbiota functioning.

Differences in gut bacterial community composition between modern and slower-growing broiler breeder lines: Implications of growth selection on microbiome composition

“…To determine the presence of Akkermansia in other broilers, four more sources of modern broilers and broiler breeders were sampled. Broiler source #1—ceca of six Ross breed broilers were sampled from a commercial farm at age 32 days; Broiler source #2—ceca of five Ross breed broilers were sampled from a commercial farm at age 34 days; Broiler breeders source #1—ceca of five Ross breed broiler breeders were sampled from the experimental farm in the Hebrew University of Jerusalem’s Faculty of Agriculture at age 55 weeks ( Shterzer et al, 2022 ); Broiler breeders source #2—ceca of five Ross breed broiler breeders were sampled from a commercial farm at age 56 weeks. All ceca were sampled as mentioned above.…”

Colonization of the Gastrointestinal Tract of Chicks with Different Bacterial Microbiota Profiles

“…Kubasova et al identified 13 genera whose abundance in chick’s caecal microbiota increased between 8- and 120-fold and five genera whose abundance decreased between 5- and 45-fold in chicks reared in the presence of an adult hen [ 51 ]. Furthermore, the lack of microorganism vertical transmission from the hen, cloacal, and nest onto eggs in industrial systems might predispose to colonization by environmental bacteria [ 52 ]. As such, the conventionally raised donor’s microbiota was likely acquired from the environment, explaining why the Control or Conventional group converged towards a similar microbiota composition and structure.…”