Research note: Impacts on turkey health when fed titrating reduced energy diets with an energy sparing feed additive

Authors: WILSON, BROOKE - Iowa State University; Kerr, Brian; RAMIREZ, BRETT - Iowa State University; KOLTES, DAWN - Iowa State University

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/11/2025
Publication Date: 12/15/2025
Citation: Wilson, B.A., Kerr, B.J., Ramirez, B.C., Koltes, D.A. 2025. Impacts of an energy sparing feed additive on health indicators in turkeys fed titrating reduced energy diets. Poultry Science. https://doi.org/10.1016/j.psj.2025.106257.
DOI: https://doi.org/10.1016/j.psj.2025.106257

Interpretive Summary: The cost of feed represents approximately 70% of the total expenses involved in raising a turkey to market weight. Main sources of energy in the diet include corn, soybean meal, and lipids. An energy-sparing feed additive composed of calcium propionate, propylene glycol, DL-methionine, and vitamin B12 was evaluated on its ability to modulate immune and gastrointestinal function of growing turkeys. Results of this study suggest that inclusion of an energy-sparing feed additive in a mild energy-reduced diet did not impact key indicators of turkey health; however, further investigation is needed to determine its impact on the immune system. This information is important for nutritionists at universities, feed companies, and turkey production facilities to formulate diets to meet the energy needs for growing turkeys without affecting their overall health. Reducing the energy concentration in a turkey diet while maintaining performance and health would be economically beneficial to turkey producers.

Technical Abstract: The source of energy in turkey diets is one of the highest costs to turkey producers, with the increasing feed consumption occurring as birds age. Reducing the cost by reducing energy concentration in a turkey diet while maintaining performance and health would economically benefit turkey producers. The reduction of energy, however, may impact immune competency, metabolism, and bone structure by diverting energy away from those areas in order to sustain growth. This study evaluated the effects of the addition of a commercial fat replacement product (Enercore®, Biosen) at 1 kg/tonne in the energy sparing feed additive (ESFA) dietary treatments that included a control diet (CON) and 3 experimental diets with reduced calories to equal a 50 kcal/kg deficit (ESFA 1), 70 kcal/kg deficit (ESFA 2), and 100 kcal/kg deficit (ESFA 3). At hatch, 1,800 turkey poults were evenly placed across treatments with (n=8 pens per treatment). Toms were placed on experimental diets from placement through 18 weeks of age, with body weights and feed measurements taken every 5 weeks and before loadout. At 17 weeks of age, one tom from each pen was weighed and euthanized to determine health indicator status which included right thigh bone for bone ash, spleen weight to examine possible immune status, measuring ketone body concentrations, liver weight and liver score, and small intestine for morphology. Live weights (P = 0.937), liver score (P = 0.248), ketone body concentration (P = 0.997) and bone ash (P = 0.156) were similar across dietary treatments. In contrast, relative spleen weight was altered by dietary treatment (P = 0.044) with ESFA 3 spleen yielding significantly less than CON (P = 0.005). Small intestine morphology of villus height (VH), crypt depth (CD), and villus height to crypt depth ratio (VH:CD) were not affected by dietary treatment (P > 0.120). In conclusion, the removal of 50 and 70 Kcal/kg of energy in turkey diets supplemented with an energy sparing feed additive did not significantly alter body weight or metabolic traits.