Growth performance and gut health of broilers fed graded inclusion levels of soyhulls in low-protein soybean meal diets and challenged with mixed Eimeria spp.

Authors: KASIREDDY, BHARGAVI - University Of Georgia; OLUSEYIFUNMI, IYABO - University Of Georgia; Shanmugasundaram, Revathi; Oladeinde, Adelumola; OLUKOSI, OLUYINKA - University Of Georgia

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/7/2026
Publication Date: 7/8/2026
Citation: Kasireddy, B., Oluseyifunmi, I.W., Shanmugasundaram, R., Oladeinde, A.A., Olukosi, O.A. 2026. Growth performance and gut health of broilers fed graded inclusion levels of soyhulls in low-protein soybean meal diets and challenged with mixed Eimeria spp.. Poultry Science. https://doi.org/10.1016/j.psj.2026.107410.
DOI: https://doi.org/10.1016/j.psj.2026.107410

Interpretive Summary: Coccidiosis is a common intestinal disease that slows growth and reduces feed efficiency in chickens, costing U.S. poultry producers millions of dollars each year. At the same time, feed costs continue to rise, and poultry companies are exploring whether lower-protein soybean meal blends that include soy hulls can reduce feed costs without harming bird health or performance. However, it is not known how these modified soybean meal ingredients affect chickens during an intestinal disease challenge. This study evaluated how different levels of soy hulls blended into soybean meal affected the growth, gut health, and immune response of broiler chickens exposed to a controlled coccidiosis infection. Hence, chickens were raised on low, moderate, or high amounts of soy hulls and then exposed to a mild intestinal infection to test whether these feed changes affected growth or health. This study found that chickens fed a moderate level of soy hulls grew just as well as those fed regular soybean meal, even during infection. This moderate inclusion also helped reduce excessive inflammation during the peak of illness. In contrast, high soy hull levels reduced growth and nutrient use in sick birds. This research shows that a moderate amount of soy hulls can replace part of the protein in soybean meal without harming performance, even when birds face intestinal disease. By using moderate soy hull inclusion, poultry producers may be able to lower feed costs, reduce dependence on higher-protein soybean meal, and maintain bird health during enteric stress. This contributes to more sustainable feed formulation and provides science-based guidance to nutritionists and the poultry industry. These findings also help scientists better understand how fiber-rich ingredients influence gut health and immunity in modern broiler production.

Technical Abstract: A 42-d study was conducted to investigate the effects of standard soybean meal (SSBM, 464 g/kg crude protein (CP)) or three low-protein SBM (LPSBM) produced by adding soyhulls (SH) at 27, 55, or 86 g/kg (yielding 449, 437, and 417 g/kg crude protein, respectively; LPSBM 1-3) on growth performance, nutrient digestibility, gut integrity, short-chain fatty acids, jejunal gene expression, histomorphology, spleen and cecal tonsils relative inflammatory cytokine gene expression, T- cell ratio, in broilers challenged with mixed Eimeria spp. A total of 1,056 male broilers were allocated to eight treatments in a 4 × 2 factorial arrangement, consisting of four corn-based diets with (CH) or without challenge (NCH). All diets were balanced for metabolizable energy, CP, and standardized digestible amino acids. Birds were challenged with Eimeria spp. on d14 and performance was recorded on 0, 10, 14, 17, 21, 28, and 42 d of age. During the acute phase (d 17-21) CH group had shown decreased BWG and FI and increased FCR compared with NCH birds (P = 0.001). CH birds fed SPSBM or LPSBM1 had higher BWG and final body weight than those fed LPSBM2 or LPSBM3 (p< 0.05). A significant interaction effect for FCR was observed with FCR increasing linearly in CH birds fed LPSBM2 and LPSBM3 (P = 0.049). Eimeria challenge increased the intestinal permeability in CH group compared to those in NCH group (P < 0.05). Amino acid digestibility did not differ among diets on d14; however on d20, digestibility of N, Tyr, Met, Lys, and Arg decreased linearly with decreasing dietary CP in CH group (P < 0.05). The CH group had higher concentration of isobutyrate, isovalerate, and valerate, and lower relative mRNA expression of PepT1, BO+AT, EAAT3, and OCLDN (P < 0.05) compared to NCH group. A significant interaction effect was observed for VH: CD, with NCH birds receiving LPSBM2 had a higher ratio compared to birds in SSBM (P = 0.05). On d21, CH birds fed SSBM had higher relative expression of IL-1 and IFN-' in the cecal tonsil, which were further reduced by LPSBM1 and increased again with LPSBM2 and LPSBM3 (P < 0.05). In conclusion, Eimeria challenge impaired growth performance, gut integrity, and nutrient utilization in broilers. Moderate inclusion level of SH (LPSBM1) enhanced growth performance metrics and modulated immune responses under challenge conditions, whereas higher SH inclusion levels negatively affected growth performance, particularly in CH birds.