Impact of Feeding Growing Japanese Quail on Low Protein Diets Supplemented with Protease Enzyme

Mohammed, zeinab G.; Ibrahim, Mohamed T.; samy, hayam M.; Yusuf, Mohamed S.

doi:10.21608/scvmj.2025.380619.1202

	Impact of Feeding Growing Japanese Quail on Low Protein Diets Supplemented with Protease Enzyme
Suez Canal Veterinary Medical Journal. SCVMJ
Article 13, Volume 30, Issue 1, June 2025, Page 169-186 PDF (902.18 K)
Document Type: Original Article
DOI: 10.21608/scvmj.2025.380619.1202
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Authors
zeinab G. Mohammed ¹; Mohamed T. Ibrahim ²; hayam M. samy³; Mohamed S. Yusuf⁴^{, 5}
¹Nutrition and Clinical Nutrition Department, Faculty of Veterinary Medicine, Suez Canal University, Ismailia, Egypt
²Nutrition and Clinical Nutrition Department, Suez Canal University, Faculty of Veterinary Medicine, Egypt
³Nutrition and Clinical Nutrition Department, Suez Canal University, Faculty of Veterinary Medicine, Egypt.
⁴Faculty of Veterinary Medicine, King Salman International University, South Sinai, Egypt
⁵Department of Nutrition and Clinical Nutrition, Faculty of Veterinary Medicine, Suez Canal University, Ismailia, Egypt.
Abstract
Background: The rising cost of protein-rich feedstuffs poses a significant challenge in poultry production, particularly in developing countries. Feed additives like protease can improve protein digestibility. This could reduce crude protein levels while maintaining the performance of poultry, making it a promising solution to improve feed efficiency and reduce cost. Aim: This study evaluated the effects of low-protein diets with or without protease supplementation on the growth performance, carcass traits, immunity, antioxidant indices, and blood metabolites of grower Japanese quail. Methods: A total of 294 one-week-old Japanese quail chicks (15.73 ± 0.18 g) were randomly distributed into seven groups with three replicates per group. Birds were fed diets containing different crude protein (CP) levels: G1 control, 24% CP (diet 1), G2 22.8% CP, (diet 2), G3 (diet 2 + 1.4g protease /kg diet), G4 21.6% CP (diet 3), G5 (diet 3 + 1.4g protease /kg diet), G6 20.4% CP (diet 4), and G7 (diet 4 + 1.4g protease /kg diet). Results: A linear decline in body weight and body weight gain was observed as dietary protein decreased, while protease supplementation numerically improved body weight and body weight gain but had no significant effect within the same protein levels. Higher protein levels increased feed intake and improved feed conversion ratio (FCR), though protease effects were inconsistent. Carcass traits remained unaffected, except for increased liver weight in lower-protein groups. Liver function markers, such as alanine aminotransferase (ALT) and aspartate aminotransferase (AST), were highest in severely protein-restricted groups, indicating potential stress. Protease improved antioxidant status and reduced corticosterone levels but did not influence immune parameters. Economic efficiency was highest at 21.6% CP, particularly without protease, while the 24% CP diet had the lowest efficiency. Conclusion: Protease improved antioxidant status and stress mitigation but had a limited impact on growth and immunity. The dietary CP (22.8%) maintained the final body weight and body weight gain similar to 24% CP, but with the advantage of 12.23% more economical efficiency.
Keywords
grower Japanese quail; protein level; protease; growth performance; blood parameters; antioxidant; carcass traits


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