At the ProHealth seminar at VIV Europe 2018 last month, Ivan Rychlik from the Veterinary Research Institute in Brno in the Czech Republic, presented the results of studies carried out by his lab on the transfer of gut microbiota from the adult hen to the chick, and also the results from trials where the team inoculated newly hatched chicks with pure cultures of selected gut anaerobes from the caecal content of the adult hen.
Rychlik and his team showed that the differences in gut microbiota between commercially hatched and raised chickens and chickens in contact with adult hens are quite extensive, and that natural contact between an adult hen and a chick results in rapid and efficient microbiota transfer between the hen and offspring.
Chickens evolved for millions of years to be hatched in a nest in a contact with an adult hen. However, current commercial production of chickens is based on hatching of chickens in clean environment of hatcheries in the absence of adult hens, with colonization of commercially hatched chickens thus exclusively dependent on environmental sources.
In terms of the development of chicken gut microbiota, Rychlik suggests that the prototype and reference model should be the one from chicks hatched in a nest in a contact with an adult hen.
The bacterial isolates used in the inoculation of chicks, as part of the Czech team’s research work, also proved to be efficient gut colonizers, he said. However, the researchers saw that it is Gram negative bacteria that are effective at colonizing a chicken gut, not gram positive bacteria.
Rychlik told us: “We have done a lot of research in this area. We can now point to particular bacterial species or isolates in our laboratory collection that do have a positive effect on chicken gut health.”
Typically, next steps following such findings might include moving to commercialization phase and seeking approval from various authorities to use a product based on those isolates on a large scale.
“Right now I would prefer to wait [at least] one more year and get additional results and data to produce a product of even better performance,” he said.
A report on the team’s research findings for publication in a peer reviewed journal is near completion, added the researcher.
Prior to this work, detailed studies focused on the microbiota transfer between hens and offspring chicks were absent. It was not known whether all microbiota members or only a certain subset of microbiota is effectively transferred from hens to chickens. It was also not known how rapid the transfer of microbiota between the hen and chickens. Hence the reason for Czech team’s line of research.
They set about addressing the issue of microbiota transfer and development in newly hatched chickens. The researchers conducted three experiments with chickens raised in the presence or absence of an adult contact hen.
The findings showed extensive differences in the composition of caecal microbiota in control and contact chickens, reported Rychlik.
The microbiota of control chickens raised in the absence of a hen was dominated by Gram positive representatives of phylum Firmicutes. However, 50% of caecal microbiota of the ‘contact’ chickens was formed by Gram negative representatives of phylum Bacteroidetes. Adult hens also acted as donors of Actinobacteria, he said.
The results also showed how rapid and efficient the microbiota transfer between hen and chickens by a natural contact is.
“We found out that a mere 24-hour-long contact between a hen and newly hatched chickens is long enough for nearly complete transfer of hen gut microbiota to chickens.”
Rychlik said the team then tested whether the hen can be replaced, in other words, whether the accelerated microbiota development seen through natural contact could be achieved by administration of bacterial washes from WCHA and YCFA agars obtained by anaerobic subculture of caecal samples from the adult hen.
Both the use of commercial product - Aviguard - and the microbiota grown on two different nutrient agars resulted in similar findings as in the trials on microbiota colonization in chicks in contact with the adult hen, he said.
The team saw that microbiota of chickens inoculated with Aviguard or bacterial washes from WCHA and YCFA agars differed from control non-inoculated chicks and was enriched for Bacteroidetes and Actinobacteria. Bacteroidetes in these chicks formed around 70% of total microbiota, i.e. even more than in the chicks raised with contact hens, according to the findings.
Protection against S. Enteritidis infection
Their research also showed accelerated development of the chicken gut microbiota significantly increased the chicken’s resistance to S. Enteritidis infection, added Rychlik.
Resistance to caecum colonization by S. Enteritidis increased more than 5 logs in contact chickens compared to controls, around 2 logs in Aviguard treated chickens, but around 6 logs in the chickens inoculated with bacterial washes from WCHA or YCFA agars, they reported.
Most of Bacteroidetes, Actinobacteria, Selenomonadales and Faecalibacterium were efficiently transferred from donor hens to chickens. However, the team never recorded transfer of Lactobacilli or Clostridiales.
“These conclusions should be considered when designing [the] next generation of probiotics.”