Linking norepinephrine production and performance to diet-induced low-grade, chronic inflammation in the intestine of broilers

Authors: Kogut, Michael - Mike; Byrd Ii, James - Allen; Genovese, Kenneth - Ken; Swaggerty, Christina - Christi; DANIELS, KARRIE - Iowa State University; LYTE, MARK - Iowa State University

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/28/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: Until recently, poultry producers have relied on antibiotics to compensate for potential poor husbandry and management issues. However, with the removal of growth-promoting antimicrobials in poultry feed, intestinal inflammation has become more of an issue worldwide. For the poultry producer, chronic low-grade intestinal inflammation has a negative impact on the productivity of the poultry operation by impairing the ability of the birds to absorb nutrients and reach 100% of growth and genetic potential. We developed a baby chick model that mimics this inflammation by using a diet that has rice bran in it. This rice diet irritated the guts of the chicks so they did not eat as much feed as would normally be expected and which also resulted in a smaller weight gain. We looked further at what could be causing this affect on the birds appetites, and found increased production of a specific stress hormone call norepinephrine. This is important for chicken growers because without the growth promoters in the diet, dietary stress results in birds that do not gain weight normally, and may be more susceptible to germs that cause infections in the bird and in humans who eat chicken products.

Technical Abstract: Maintenance of intestinal health is critical to successful poultry production and one of the goals of the poultry production industry. For decades the poultry industry has relied upon the inclusion of antibiotic growth promoters (AGPs) to achieve this goal and improve growth performance. With the removal of AGPs, the emergence of chronic, low-level gut inflammation has come to the forefront of concern in the poultry industry with the diet being the primary source of inflammatory triggers. We have developed a dietary model of low-grade, chronic intestinal inflammation in broilers that employs feeding a high non-starch polysaccharides (NSP) diet composed of 30% rice bran to study the effects of this inflammation on bird performance and physiology. For the present studies, we hypothesize that the low-grade chronic inflammation causes neurons in the intestinal enteric nervous system to secrete neurochemicals that activate immune cells that drive the inflammation and negatively affect bird performance. To test our hypothesis, one-day-old broiler chickens were weighed and divided into two dietary regimes: a control corn-soybean diet and a group fed a high NSP diet (30% rice bran). At 7-, 14-, 21-, and 28-days post-hatch (PH), birds were weighed, fecal material collected, and 5 birds were sacrificed and sections of duodenal and cecal tissues excised, and duodenal and cecal contents collected for ultra-high performance liquid chromatography analyses (UHPLC). UHPLC revealed 1000s-fold increase in the concentration of norepinephrine (NE) in birds fed the high NSP diet compared to the control fed birds. Further, the fecal concentrations of NE were also found to be significantly elevated in the birds on the NSP diet throughout all time points. There were no differences in weight gain nor feed conversion from 1-14 days PH, but birds fed the high NSP diet had significantly reduced weight gain and feed conversion from 14-28 days PH. The results revealed that a dietary-induced low-grade chronic inflammatory response increased NE production in the gut which negatively affected bird performance. This study suggests that neuroimmune pathways may serve as a mechanistic target for the development of new interventions to decrease the incidence of chronic inflammation and thereby benefit performance.