Productive Performance, Egg Quality, Nutrients Digestibility, and Physiological Response of Bovans Brown Hens Fed Various Dietary Inclusion Levels of Peppermint Oil: Short title: Peppermint Oil for Laying Hens
• Supplementation of peppermint oil at different levels was tested in the laying hens for 12 weeks.
• Peppermint oil supplementation improved egg production, egg weight, egg mass, feed intake, feed conversion ratio, Haugh unit, eggshell quality and decreased serum cholesterol.
• Inclusion of peppermint oil to laying hens diet increased the digestibility of crude protein, ether extract, and phosphorus.
Herbal plants and their extracts are commonly used as feed supplements to improve the performance and physiology of poultry. This study was conducted to determine the effects of supplementation of peppermint oil in laying hens’ diets on laying performance, egg quality, nutrients digestibility, and serum metabolic profile. A total of two hundred Bovans brown laying hens (32 weeks old) were assigned to five treatment diets including peppermint oil at 0, 74, 148, 222, and 296 mg/kg, respectively, for 12 weeks. Each treatment had eight replicates with five hens each. The results revealed that the incremental dietary peppermint oil linearly increased (P < 0.001) egg weight, egg production, egg mass, and feed intake from 32 to 38, 38 to 44, and 32 to 44 weeks of age. Moreover, feed conversion ratio significantly improved (linear, P < 0.001) following the increase of levels of peppermint oil in laying hens’ diet. Haugh unit and eggshell thickness and percentages were improved (P < 0.01) with the increase of levels of peppermint oil at 38 and 44 weeks of age. However, peppermint oil supplementation did not influence other egg quality characteristics like albumen and yolk percentages. Digestibility of crude protein, ether extract, and phosphorus linearly increased (P < 0.001) with the increase of levels of supplementation. Notably, serum total proteins increased (P < 0.01) while serum cholesterol significantly decreased (P < 0.001) with the increase of levels of peppermint oil. In conclusion, although all inclusion levels of peppermint oil improved egg production and quality, feed conversion ratio, digestibility of nutrients, and increased serum total proteins and decreased cholesterol levels of laying hens; however, better results were observed at higher levels of supplementation.