Supplementing low protein diets with methionine or threonine during mixed Eimeria challenge

Authors: TAYLOR, JAMES - Agri-Food And Biosciences Institute; MERCIER, YVES - Adisseo France Sas; OLUKOSI, OLUYINKA - University Of Georgia; KIM, WOO - University Of Georgia; SELVARAJ, RAMESH - University Of Georgia; APPLEGATE, TODD - University Of Georgia; Shanmugasundaram, Revathi; BALL, ELIZABETH - Agri-Food And Biosciences Institute; KYRIAZAKIS, ILIAS - Queen'S University - Ireland

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/30/2024
Publication Date: 3/31/2024
Citation: Taylor, J., Mercier, Y., Olukosi, O., Kim, W.K., Selvaraj, R., Applegate, T., Shanmugasundaram, R., Ball, E., Kyriazakis, I. 2024. Supplementing low protein diets with methionine or threonine during mixed Eimeria challenge. Poultry Science. 103: (6); 103714. https://doi.org/10.1016/j.psj.2024.103714.
DOI: https://doi.org/10.1016/j.psj.2024.103714

Interpretive Summary: This study focused on identifying a solution for the parasite Eimeria, which causes coccidiosis in chickens. When chickens contract this infection, they eat less and grow more slowly, impacting their overall health and productivity. Coccidiosis is a widespread issue that results in billions of dollars in losses for the poultry industry. This study aimed to determine whether adding specific amino acids (such as methionine or threonine) to the chickens’ low-protein diets could enhance their performance during an Eimeria infection. These amino acids are essential for the chickens’ diet and can positively influence their growth and immune system. While directly supplementing threonine or methionine didn’t significantly affect the severity of Eimeria infection itself, it did boost the chickens’ immune response. This discovery provides valuable insights for developing better feeding strategies to keep chickens healthy and productive. Understanding how specific nutrients impact chickens’ ability to fight infections contributes to more effective and sustainable practices in poultry farming. Ultimately, this research helps maintain healthier and sustainable chicken production, which is critical for the poultry industry.

Technical Abstract: We investigated the effects of supplementing low protein diets with methionine (Met) or threonine (Thr) during a mixed Eimeria challenge in broilers. All birds were fed the same starter diet (d1-9) and finisher diet (d28-35) which met Cobb 500 nutrient specifications. Birds were allocated to 1 of 4 dietary treatments from d9-28: a basal diet (19% CP); a low protein diet (16% CP); or the low protein diet supplemented with Met or Thr at 50% above recommendations. On d14, half of the birds were challenged, and half of the birds were unchallenged. From d14-28, feed intake was recorded daily and BW every 3 or 4 days. Oocyst excretion was measured daily from d18-27. On d21 and 28, 3 birds per pen were euthanized to assess nutrient digestibility, cytokine expression and intestinal histology. During the acute stage of the challenge, challenged birds reduced ADFI and ADG (P < 0.05). In the pre-patent and recovery stages, birds given the 16% CP diets increased ADFI (P < 0.05), meanwhile there were no differences in ADG in these stages (P > 0.05). Nutrient digestibility was reduced in challenged birds in the acute stage (P < 0.05) but tended to be greater than in unchallenged birds during the recovery stage. There was no significant effect of diet on oocyst excretion or intestinal histology (P > 0.05). Interactions were observed between diet and challenge on IL10 and IL21 expression in the caecal tonsils during the acute stage of the challenge (P < 0.05), due to reduced IL10 expression in challenged Thr birds and greater IL21 expression in challenged Met birds. Supplementation with Thr or Met had limited effects on the outcomes of a mixed Eimeria challenge but provides benefits to the host by enhancing their immune response. Key words: Anorexia; Broilers; Methionine; Threonine; Eimeria