Abstract
BackgroundHost genotype plays a crucial role in microbial composition of laying hens, which may lead to dissimilar odor gas production. The objective of this study was to investigate the relationship among layer breed, microbial structure and odor production.ResultsThirty Hy-Line Gray and thirty Lohmann Pink laying hens were used in this study to determine the impact of cecal microbial structure on odor production of laying hens. The hens were managed under the same husbandry and dietary regimes. Results of in vivo experiments showed a lower hydrogen sulfide (H2S) production from Hy-Line hens and a lower concentration of soluble sulfide (S2−) but a higher concentration of butyrate in the cecal content of the Hy-Line hens compared to Lohmann Pink hens (P < 0.05), which was consistent with the in vitro experiments (P < 0.05). However, ammonia (NH3) production was not different between genotypes (P > 0.05). Significant microbial structural differences existed between the two breed groups. The relative abundance of some butyrate producers (including Butyricicoccus, Butyricimonas and Roseburia) and sulfate-reducing bacteria (including Mailhella and Lawsonia) were found to be significantly correlated with odor production and were shown to be different in the 16S rRNA and PCR data between two breed groups. Furthermore, some bacterial metabolism pathways associated with energy extraction and carbohydrate utilization (oxidative phosphorylation, pyruvate metabolism, energy metabolism, two component system and secretion system) were overrepresented in the Hy-Line hens, while several amino acid metabolism-associated pathways (amino acid related enzymes, arginine and proline metabolism, and alanine-aspartate and glutamate metabolism) were more prevalent in the Lohmann hens.ConclusionThe results of this study suggest that genotype of laying hens influence cecal microbiota, which in turn modulates their odor production. Our study provides references for breeding and enteric manipulation for defined microbiota to reduce odor gas emission.
Highlights
Host genotype plays a crucial role in microbial composition of laying hens, which may lead to dissimilar odor gas production
Previous studies found that an active carbohydrate fermentation by gut acid-producing bacteria could result in the suppression of protein fermentation and partly inhibit the production of odor gas [16, 17]
A lower Hydrogen sulfide (H2S) production and lower concentration of soluble sulfide in the cecal content were shown in Hy-Line hens compared to those of Lohmann hens (Figs. 1 and 2a), these findings were in agreement with a previous report that the concentrations of gut soluble sulfide and sulfate radical are positively correlated with the release of hydrogen sulfide [33]
Summary
Host genotype plays a crucial role in microbial composition of laying hens, which may lead to dissimilar odor gas production. Large quantities and diverse microorganisms inhabit in the cecum of laying hens, which prolongs the retention time of digesta to approximately 12–20 h. This latter process is known as microbial-based metabolism [3,4,5]. The degradation of undigested feed components (mainly undigested carbohydrates and proteins) and uric acid produce various bacterial metabolites. Previous studies found that an active carbohydrate fermentation (adequate production of VFAs) by gut acid-producing bacteria could result in the suppression of protein fermentation and partly inhibit the production of odor gas [16, 17]
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