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Title: Targeted gene panels and microbiota analysis provide insight into the effects of effects of alternative production diet formulations on channel catfish nutritional physiology

Author
item Schroeter, Julie - Southern Illinois University
item Peterson, Brian
item Bledsoe, Jacob - University Of Idaho
item Small, Brian - University Of Idaho

Submitted to: Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/23/2018
Publication Date: 3/1/2018
Citation: Schroeter, J., Peterson, B.C., Bledsoe, J., Small, B. 2018. Targeted gene panels and microbiota analysis provide insight into the effects of effects of alternative production diet formulations on channel catfish nutritional physiology. Aquaculture. 489:46-55.

Interpretive Summary: Research evaluated targeted gene panels and microbiota analysis to provide greater insight into the effects of alternatively-sourced dietary ingredients on production indices, gut health, changes in the gut microbiota and genes involved in the regulation of appetite, growth, metabolism, and intestinal inflammation. Four dietary formulations were based primarily on distinguishing protein sources: (1) fishmeal (control), (2) porcine meat and bone meal, (3) soybean meal, and (4) corn germ meal/cottonseed meal, respectively, and fed to channel catfish for 12 weeks. Differences in feed conversion ratio (FCR), specific growth rate, feed intake, body condition, weight gain, proximal intestine histology, intestinal microbiome composition and quantitative gene expression were analyzed. FCR was increased in Diets 2 - 4 relative to Diet 1; however, other production indices were unaffected by treatment. Dietary treatment also had no effect on intestinal histology. Diets 2, 3, and 4 caused diet specific differences in the expression of neuropeptide Y, peptide YY, a-amylase, insulin receptor-a, glucose-6-phosphate-dehydrogenase, glucocorticoid receptor 1, and glucocorticoid receptor 2, relative to the control (Diet 1). These changes likely relate to differences in diet-mediated regulation of appetite and glucose metabolism, and perhaps gut passage rate. By evaluating the molecular regulation of these pathways, as well as the gut-associated microbiota, effects not detectable in short term feeding trials may be elucidated and may explain subtle differences in performance, such as FCR, as observed in the present study.

Technical Abstract: The present research evaluated targeted gene panels and microbiota analysis to provide greater insight into the effects of alternatively-sourced dietary ingredients on production indices, gut health, changes in the gut microbiota and genes involved in the regulation of appetite, growth, metabolism, and intestinal inflammation. Four dietary formulations were based primarily on distinguishing protein sources: (1) fishmeal (control), (2) porcine meat and bone meal, (3) soybean meal, and (4) corn germ meal/cottonseed meal, respectively, and fed to channel catfish for 12 weeks. Differences in feed conversion ratio (FCR), specific growth rate, feed intake, body condition, weight gain, proximal intestine histology, intestinal microbiome composition and quantitative gene expression were analyzed. FCR was significantly (P<0.05) increased in Diets 2 - 4 relative to Diet 1; however, other production indices were unaffected by treatment. Dietary treatment also had no effect on intestinal histology (P<0.05). Diets 2, 3, and 4 caused diet specific differences (P<0.05) in the expression of neuropeptide Y, peptide YY, a-amylase, insulin receptor-a, glucose-6-phosphate-dehydrogenase, glucocorticoid receptor 1, and glucocorticoid receptor 2, relative to the control (Diet 1). These changes likely relate to differences in diet-mediated regulation of appetite and glucose metabolism, and perhaps the modulation of gut passage rate. By evaluating the molecular regulation of these pathways, as well as surveying the gut-associated microbiota, effects not detectable in short term feeding trials may be elucidated which affect fish well-being and may explain subtle differences in performance, such as FCR, as observed in the present study.