Effects of Amino Acid Supplementation in Low-Crude Protein Diets on Growth Performance, Footpad Health, and Economics of Hubbard Broilers Raised in a Deep-Litter System

Authors: Nelson P. Bacawat; Madeline S. Kingan
DOI
10.25125/ijoear-mar-2026-6
DIN
IJOEAR-MAR-2026-6
Abstract

This study evaluated the effects of reduced crude protein (CP) diets supplemented with amino acids on the growth performance and profitability of Hubbard colored broilers. Three isocaloric finisher rations were formulated with 19%, 17%, and 15% CP, with the CP-reduced diets supplemented with methionine, lysine, threonine, and tryptophan. A total of 120 broilers were randomly assigned to these three treatments with four replicates each. Results showed significant differences (p<0.05) in final weight, total weight gain, and average daily gain. Broilers fed reduced CP diets (17% and 15%) exhibited superior growth performance compared to those on the 19% CP control. Furthermore, reduced CP treatments significantly decreased the incidence of footpad dermatitis and increased net profit and return on investment. These findings suggest that lowering CP levels with amino acid supplementation offers a cost-effective and environmentally sustainable strategy for broiler production.

Keywords
Crude Protein Amino Acids Hubbard Broilers Growth Performance Footpad Dermatitis Economics.
Download Options
Download Full PDF
Share Article
Facebook Twitter LinkedIn
Introduction

In the Philippines, poultry production, particularly chicken meat production, continues to grow due to its demand and lower price in the market. The demand for poultry products brought its success in the animal enterprise due to lack of supply and higher cost of pork brought on by the African Swine Fever (ASF) outbreak (Acosta, 2022). In the Cordillera region, backyard raising for livestock and poultry is practiced for consumption and for additional income. Rearing poultry is more likely to increase through the years due to its lower cost in financing compared to livestock such as pigs and ruminants.

Recent industry trends emphasize improving animal welfare, mitigating environmental pollution, and reducing production costs, primarily those associated with feed. The product of metabolism in poultry such as undigested dietary protein and uric acid is excreted into the environment that could become a source of ammonia (Nahm, 2003). According to Poultry World (2019), unused amino acids are changed into nitrogen which results in higher ammonia levels in the poultry house that affects the animal as well as the workers. Generally, production of 1 kg chicken meat generates 1.1 kg CO₂ equivalents and it has also been predicted that it will contribute 7.1% of greenhouse gases (Fiola, 2008).

Current research focuses on mitigating the environmental impact of livestock production, specifically the emission of greenhouse gases. Studies demonstrate that developing reduced-crude protein (CP) diets supplemented with crystalline (non-bound) amino acids significantly lowers gas emissions (Chrystal et al., 2020; Meda et al., 2019). Furthermore, Applegate (2008) identified CP reduction through amino acid supplementation as the most effective strategy for decreasing nitrogen excretion in poultry waste. While formulating reduced-CP diets is an established concept, the modern availability of synthetic amino acids now allows for a substantial reduction in both dietary CP and reliance on soybean meal.

The determination of ideal dietary CP levels has been a subject of debate since the recognition that protein requirements are essentially a requirement for a specific profile of amino acids (Pesti, 2009). Beyond nutritional balance, manipulating these levels serves as an environmental tool; Ferguson et al. (1998) asserted that reducing CP during the grower and finisher phases, supplemented with synthetic amino acids, is the most cost-effective method for controlling ammonia (NH₃) emissions.

High costs of corn and soybean meal often drive up feed prices, prompting producers to seek cost-reduction strategies that maintain flock performance. While Son et al. (2024) observed that reducing dietary CP lowered total feed costs without altering net profit, performance results vary. Consequently, this study aims to validate the performance of Hubbard broilers reared on deep litter when fed CP-reduced diets.

Conclusion

Reducing dietary crude protein (CP) by up to 4% (15% CP) with amino acid supplementation significantly enhances feed intake, final body weight, and average daily gain in Hubbard colored broilers. These improvements in growth parameters resulted in superior feed conversion ratios (FCR) and feed efficiency compared to the 19% CP control. Beyond performance, the reduced-CP diets notably decreased the incidence of footpad dermatitis, suggesting improved welfare and litter quality. While the inclusion of synthetic amino acids increased initial production costs, the 15% and 17% CP treatments yielded a higher net profit, return on investment (ROI), and profit per bird. Consequently, amino acid-supplemented, low-CP diets represent a physiologically superior and more profitable strategy for finisher broiler production.

Agriculture Journal IJOEAR Call for Papers

References
  1. Acosta, A. (2022, December 12). Update of the Philippine broiler industry. Veterinaria Digital. Retrieved May 24, 2024, from https://www.veterinariadigital.com/en/articulos/update-of-the-philippine-broiler-industry/
  2. Nahm, K. H. (2003). Evaluation of the nitrogen content in poultry manure. World's Poultry Science Journal, 59(1), 77–88.
  3. Poultry World. (2019). More performance with reduced protein. Retrieved July 6, 2024, from https://www.poultryworld.net/health-nutrition/nutrition/more-performance-with-reduced-protein/
  4. Fiola, N. (2008). Meeting the demand: An estimation of potential future greenhouse gas emissions from meat production. Ecological Economics, 67(3), 412–419.
  5. Chrystal, P. V., Moss, A. F., Khodammi, A., Naranjo, V. D., Selle, P. H., & Liu, S. Y. (2020). Effects of crude-protein levels, dietary electrolyte balance, and energy density on the performance of broiler chickens offered maize-based diets with evaluations of starch, protein, and amino acid metabolism. Poultry Science, 99(3), 1421–1431.
  6. Meda, B., Hassouna, M., Aubert, C., Robin, P., & Dourmad, J. Y. (2011). Influence of rearing conditions and manure management practices on ammonia and greenhouse gas emissions from poultry houses. World's Poultry Science Journal, 67(3), 441–456.
  7. Applegate, T. J. (2008). Protein and amino acid requirements for poultry. Retrieved July 6, 2024, from https://s3.wp.wsu.edu/uploads/sites/346/2014/11/Protein-and-amino-acid-for-poultry-final.pdf
  8. Pesti, G. M. (2009). Impact of dietary amino acid and crude protein levels in broiler feeds on biological performance. Journal of Applied Poultry Research, 18(3), 477–486.
  9. Ferguson, N. S., Gates, R. S., Taraba, J. L., Cantor, A. H., Pescatore, A. J., Ford, M. J., & Burnham, D. J. (1998). The effect of dietary crude protein on growth, ammonia concentration, and litter composition in broilers. Poultry Science, 77(10), 1481–1487.
  10. Son, J., Lee, W., Kim, C., Kim, H., Hong, E., & Kim, H. (2024). Effect of dietary crude protein reduction levels on performance, nutrient digestibility, nitrogen utilization, blood parameters, meat quality, and welfare index of broilers in welfare-friendly environments. Animals, 14(21), Article 3106.
  11. WINMIX SOFT. (2014). Hubbard broiler management guide. Retrieved July 9, 2024, from https://www.winmixsoft.com/en/blog/item/hubbard-eng
  12. Hubbard. (2023). Broiler performance guide: JA787. Retrieved November 16, 2025, from https://www.pouletanglais.co.uk/wp-content/uploads/go-x/u/2d422738-a2f0-40ae-9e44-91c4b54a480f/Broiler_Leaflet_PREMIUM-JA787_EN_20230802.pdf
  13. Sterling, K. G., Vedenov, D. V., Pesti, G. M., & Bakalli, R. I. (2005). Economically optimal dietary crude protein and lysine levels for starting broiler chicks. Poultry Science, 84(1), 29–36.
  14. Kidd, M. T., McDaniel, C. D., Branton, S. L., Miller, E. R., Boren, B. B., & Fancher, B. I. (2004). Increasing amino acid density improves live performance and carcass yields of commercial broilers. Journal of Applied Poultry Research, 13(4), 593–604.
  15. Van Harn, J., Dijkslag, M. A., & Van Krimpen, M. M. (2019). Effect of low protein diets supplemented with free amino acids on growth performance, slaughter yield, litter quality, and footpad lesions of male broilers. Poultry Science, 98(10), 4868–4877.
  16. Belloir, P., Méda, B., Lambert, W., Corrent, E., Juin, H., Lessire, M., & Tesseraud, S. (2017). Reducing the CP content in broiler feeds: Impact on animal performance, meat quality and nitrogen utilization. Animal, 11(11), 1881–1889.
  17. Khan, S. A., Ujjan, N. A., Ahmed, G., Rind, M. I., Fazlani, S. A., Syed, S. F., Pirzado, S. A., Arain, M. A., Jammu, A., & Kashmir, P. (2011). Effect of low protein diet supplemented with or without amino acids on the production of broiler. African Journal of Biotechnology, 10(49), 10058–10065.
  18. Corzo, A., Dozier, W. A., & Kidd, M. T. (2006). Dietary lysine needs of late-developing heavy broilers. Poultry Science, 85(3), 457–461.
  19. Baxter, M., Greene, E. S., Kidd, M. T., Tellez-Isaias, G., Orlowski, S., & Dridi, S. (2020). Water amino acid-chelated trace mineral supplementation decreases circulating and intestinal HSP70 and proinflammatory cytokine gene expression in heat-stressed broiler chickens. Journal of Animal Science, 98(3), skaa049.
  20. Lisnahan, C. V., Wihandoyo, Zuprizal, Z., & Harimurti, S. (2017). Growth performance of native chickens in the grower phase fed methionine and lysine-supplemented cafeteria standard feed. Pakistan Journal of Nutrition, 16(12), 940–944.
  21. Songuine, T., Feteke, L., Kpomasse, C. C., Yarkoa, T., Parobali, T., Karou, S. D., & Pitala, W. (2025). Effects of methionine-supplemented low-protein diets on production efficiency, heat resilience, and welfare of broilers in tropical climates. Veterinary Medicine and Science, 11(5), e70242.
  22. Hossain, M. A., Zulkifli, I., & Soleimani, A. F. (2017). Effect of high protein supplementation on growth and nutrient digestibility of broiler. Bangladesh Journal of Animal Science, 46(1), 44–50.
  23. Liu, N., Wang, J. Q., Gu, K. T., Deng, Q. Q., & Wang, J. P. (2017). Effects of dietary protein levels and multienzyme supplementation on growth performance and markers of gut health of broilers fed a miscellaneous meal based diet. Animal Feed Science and Technology, 234, 110–117.
  24. Apajalahti, J., & Vienola, K. (2016). Interaction between chicken intestinal microbiota and protein digestion. Animal Feed Science and Technology, 221, 323–330.
  25. Qaisrani, S. N., Van Krimpen, M. M., Kwakkel, R. P., Verstegen, M. W. A., & Hendriks, W. H. (2015). Dietary factors affecting hindgut protein fermentation in broilers: A review. World's Poultry Science Journal, 71(1), 139–160.
  26. Buwjoom, T., Yamauchi, K., Erikawa, T., & Goto, H. (2010). Histological intestinal alterations in chickens fed low protein diet. Journal of Animal Physiology and Animal Nutrition, 94(3), 354–361.
  27. Macelline, S. P., Wickramasuriya, S. S., Cho, H. M., Kim, E., Shin, T. K., Hong, J. S., Kim, J. C., Pluske, J. R., Choi, H. J., Hong, Y. G., & Heo, J. M. (2020). Broilers fed a low protein diet supplemented with synthetic amino acids maintained growth performance and retained intestinal integrity while reducing nitrogen excretion when raised under poor sanitary conditions. Poultry Science, 99(2), 949–958.
  28. Wang, J. X., & Peng, K. M. (2008). Developmental morphology of the small intestine of African ostrich chicks. Poultry Science, 87(12), 2629–2635.
  29. Srivastava, S. (2022). Heat stress in chicken. Acta Scientific Veterinary Sciences, 4(5), 59–61.
  30. Nagaraj, M., Wilson, C. A. P., Hess, J. B., & Bilgili, S. F. (2007). Effect of high-protein and all-vegetable diets on the incidence and severity of pododermatitis in broiler chickens. Journal of Applied Poultry Research, 16(3), 304–312.
  31. Alfonso-Avila, A., Cirot, O., Lambert, W., & Létourneau-Montminy, M. (2022). Effect of low-protein corn and soybean meal-based diets on nitrogen utilization, litter quality, and water consumption in broiler chicken production: Insight from meta-analysis. Animal, 16(3), Article 100458.
  32. Lemme, A., Hiller, P., Klahsen, M., Taube, V., Stegemann, J., & Simon, I. (2019). Reduction of dietary protein in broiler diets not only reduces n-emissions but is also accompanied by several further benefits. Journal of Applied Poultry Research, 28(4), 867–880.
  33. Swiatkiewicz, S., Arczewska-Wlosek, A., & Jozefiak, D. (2017). The nutrition of poultry as a factor affecting litter quality and footpad dermatitis – An updated review. Journal of Animal Physiology and Animal Nutrition, 101(5), e14–e20.
Article Preview
Quick Actions
Download PDF View References
Article Info
Pages
34-44