Ileal microbial composition in genetically distinct chicken lines reared under normal or high ambient temperatures

Authors: EMAMI, NIMA - University Of Arkansas; Schreier, Lori; GREENE, ELIZABETH - University Of Arkansas; TABLER, TRAVIS - University Of Arkansas; ORLOWSKI, SARA - University Of Arkansas; ANTHONY, NICHOLAS - University Of Arkansas; Proszkowiec-Weglarz, Monika; DRIDI, SAMI - University Of Arkansas

Submitted to: BMC Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/6/2022
Publication Date: 4/21/2022
Citation: Emami, N.K., Schreier, L.L., Greene, E., Tabler, T., Orlowski, S.K., Anthony, N.B., Proszkowiec-Wegla, M.K., Dridi, S. 2022. Ileal microbial composition in genetically distinct chicken lines reared under normal or high ambient temperatures. BMC Microbiology. https://doi.org/10.1186/s42523-022-00183-y.
DOI: https://doi.org/10.1186/s42523-022-00183-y

Interpretive Summary: Heat stress has very negative effect on poultry production, health and welfare. Negative effects of heat stress results in huge economic losses for the producers. Meat-type chickens (broilers) are very susceptible to heat stress because of their high metabolic rate, rapid growth and lack of sweat glands to regulate the body temperature. Little is known about the effects of heat stress on microbiota in genetically different broiler chickens. Microbiota plays an important role in health, nutrition, growth and development of the animal’s gastrointestinal tract and can be influenced by many physiological, environmental and dietary factors. Therefore, the aim of the present study was to investigate changes in the ileal (part of the small intestine) microbiota in four different chicken lines during heat stress. Giant Jungle Fowl (ancestor of chickens), Athens Canadian Random bred (broiler chicken raised in 1950s), 1995 Random Bred (broiler chickens raised in 1995) and Modern Random bread (broiler chickens from 2015) were used for this study. Birds were raised under normal temperature until day 28 and then were subjected to daily heat stress (36 °C for 8h) until day 56. Microbiota samples were collected on day 56 and analyzed. We have determined that 1) ileal microbiota was affected by heat stress 2) the genetic background affected the microbiota, 3) there was difference in the response to heat stress between microbiota in the digesta vs. microbiota attached to the epithelial cells of the small intestine, and 4) predicted function of the microbiota was not affected by the heat stress.

Technical Abstract: Background: Heat stress (HS) has negative effects on poultry productivity, health and welfare resulting in economic losses. Broiler chickens are particularly susceptible to HS due to their high metabolic rate, rapid growth, and lack of sweat glands. The commensal intestinal bacterial populations have an important physiological role in the host and could ameliorate the negative effect of HS on the host. Thus, the aim of this study was to compare changes in the ileal (IL) microbiota in four different broiler lines during HS. Results: Day-old broiler chicks from Giant Jungle Fowl (JF), Athens Canadian Random Bred (ACRB), 1995 Random Bred (L1995), and Modern Random Bred (L2015) lines were raised under thermoneutral (TN) conditions until day (d) 28. On d 29 birds were subjected to TN (24°C) or chronic cyclic HS (8 h/d, 36°C) condition till d 56. On d 56 two birds per pen were euthanized, and IL luminal content (IL-L) and mucosal scrapings (IL-M) were collected for bacterial DNA isolation. Libraries were constructed using V3-V4 16S rRNA primers and sequenced using MiSeq. DNA sequences were analyzed using QIIME2 platform and SILVA 132 database for alpha and beta diversity, and taxonomic composition, respectively. Functional property of microbiota was predicted using the PICRUSt 2 pipeline and illustrated with STAMP software. Shannon index was significantly elevated in IL-M under HS. ß-diversity PCoA plots revealed separation of microbial community of L2015-TN from JF-TN, JF-HS, ACRB-TN, and ACRB-HS in the IL-M. PERMANOVA analysis showed a significant difference between microbial community of L1995-HS compared to ACRB-HS and JF-TN, L1995-TN compared to ACRB-HS and JF-TN, L2015-HS compared to ACRB-HS and ACRB-TN, L2015-HS compared to JF-TN, L2015-TN compared to ACRB-HS and JF-TN, and ACRB-HS compared to JF-TN in the IL-L. The impact of HS on microbial composition of IL-M was more prominent compared to IL-L with 12 and 2 taxa showing significantly different relative abundance, respectively. Furthermore, differences in microbiota due to the genetic line were more prominent in IL-M than IL-L with 18 and 8 taxa showing significantly different relative abundance, respectively. Unlike taxonomy, predicted function of microbiota was not affected by HS. Comparison of L2015 with JF or ACRB showed significant changes in predicted function of microbiota in both, IL-M and IL-L. Differences were most prominent between L2015 and JF; while there was no difference between L2015 and L1995. Conclusions: These data indicate the genetic line ' temperature effect on the diversity and composition of IL microbiota. Moreover, the data showcase the effect of host genetics on the composition of IL microbiota and their predicted function. These data are of critical importance for devising nutritional strategies to maintain GIT microbial balance and alleviate the negative effects of HS on broiler chickens’ performance and health.