Effect of feeding sweet potato and/or high-oleic peanuts to laying hens on ileal nutrient digestibility

Authors: HARDING, KARI - North Carolina State University; MALHEIROS, DIMITRI - North Carolina State University; Vu, Thien; WYSOCKY, REBECCA - North Carolina State University; MALHEIROS, RAMON - North Carolina State University; ANDERSON, KENNETH - North Carolina State University; Toomer, Ondulla

Submitted to: International Journal of Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/13/2022
Publication Date: 10/1/2022
Citation: Harding, K.L., Malheiros, D.M., Vu, T.C., Wysocky, R., Malheiros, R.M., Anderson, K.E., Toomer, O.T. 2022. Effect of feeding sweet potato and/or high-oleic peanuts to laying hens on ileal nutrient digestibility. International Journal of Poultry Science. 21(4):174-180. https://doi.org/10.3923/ijps.2022.174.180.
DOI: https://doi.org/10.3923/ijps.2022.174.180

Interpretive Summary: Scientists are searching for different feed ingredients that can be fed to poultry without decreasing growth and the production of meat or eggs. However, it is important to understand how birds digest these feed ingredients to reach their maximum potential. There are very few studies examining the nutrient digestibility of peanuts and/or sweetpotato by-products. Hence, in this study we aimed to determine the nutrient digestibility of high-oleic peanuts and sweetpotato by-products by determining the metabolizable energy, the dietary nitrogen retention, the protein digestibility, and the fat digestibility. We fed four experimental diets formulated to be nutritionally complete to hens for six weeks. Each diet had the inclusion of an indigestible marker to determine the nutrient digestibility of feeding an 8% inclusion of high-oleic peanuts (HOPN), a 4% inclusion of sweetpotato by-products (SWP), or a 4% inclusion of sweetpotato by-products + 4% inclusion of high-oleic peanuts (SWP + HOPN) as well as a control corn and soybean meal diet. The control diet as well as the HOPN had better apparent metabolizable energy compared to the SWP and the SWP + HOPN diets, suggesting that these birds had better access to high energy feed ingredients in the control and HOPN diets allowing them to digest and utilize the energy for production. The apparent nitrogen retention was the same for all dietary treatments, with the lowest dietary nitrogen (protein) retention in the SWP treatment group. Birds fed the SWP + HOPN diet had the highest fat digestibility percentages when compared to the other diets and the control had the lowest fat digestibility percentage. The SWP experimental diet had the highest protein digestibility when compared to the other treatment groups. To summarize, this study demonstrates that feeding high-oleic peanuts or sweetpotato by-products separately have similar or improved fat and/or protein digestibilities as compared to conventional feed ingredients and could possibly be used as alternative feed ingredients for laying hens. However, feeding a combination of sweetpotato by-products and high-oleic peanuts in hen diets may require the supplementation of additional dietary energy and protein. The impact of this study is the validation of sweetpotato by-products as a value-added alternative feed ingredient for egg-producing hens and sustainable utilization of a considerable agricultural waste by-product.

Technical Abstract: Objective: The study’s goal was to compare, apparent metabolizable energy corrected for nitrogen, apparent nitrogen retention, apparent fat digestibility and apparent protein digestibility (APD). Materials and Methods: Four isocaloric and isonitrogenous diets were fed to 80 Shaver hens for six weeks. Diets had a 2% inclusion of Celite indigestible marker. The four diets were (1) Conventional corn-soybean control, (2) 8% inclusion of high oleic peanut, (3) 4% inclusion of sweet potato by-product and (4) 4% sweet potato by-product +4% high-oleic peanut inclusion. Results: Control and birds fed a high-oleic peanut containing diet had greater apparent metabolizable energy values than other treatments, while diets containing sweet potatoes and high oleic peanuts had the least (p<0.0001). Apparent nitrogen retention for hens fed a diet containing sweet potatoes was significantly lower (p<0.0001) than other treatments. The diet containing both sweet potatoes and high oleic peanuts had highest apparent fat digestibility (p<0.0001) than other treatments. Control had the lowest apparent fat digestibility with the high oleic containing diet being slightly higher. The apparent protein digestibility of the diet containing sweet potatoes was higher than all treatments (p<0.0001). Control and the birds fed a diet containing high oleic peanuts were lower than the birds fed a diet with sweet potatoes included. Conclusion: This study implicated that diets containing sweet potato are a reasonable alternative feed ingredient for layers and sustainable utilization of a considerable agricultural waste by-product.