Effect of Peppermint Leaves Powder (Mentha Piperita L.) and L-Menthol Crystal on Nutrients Digestibility, Performance, Digestive Enzymes, Thyroid Hormone, Immunity, Antioxidant Indices and Microbial Population of Laying Quail

Abstract

The current experiment aimed to study impacts of feeding on peppermint leaves powder (PLP) and its respective L-menthol crystal (LMC) supplementations on performance, plasma biochemistry, antioxidant, impregnability, microbial content, digestibility and digestive enzymes in laying Japanese quail. A total of 504 birds were randomly assigned to seven test groups, each one with 6 replicates and 12 birds. First group received a standard diet, whereas treatments from second to four obtained standard diet plus PLP at 1.5, 2.0, and 2.5%, respectively. While, five to seven groups received control diet plus LMC at levels being 17, 22 and 27 ppm, respectively. Birds fed diets that contain 27 ppm had the highest DC (p ≤ 0.001) of dry matter, organic matter, nitrogen free extract and protein retention, while the group fed with LMC at a level of 22 and 17 ppm recorded the higher digestibility coefficients (DC) of ether extract and crude fiber, respectively. Quail fed diets supplemented with PLP 2.0 % followed by LMC 27 ppm and PLP 2.5 %, respectively showed significantly (p ≤ 0.001) higher trypsin enzyme. All performance traits except feed intake (FI) were significantly influenced by PLP 2.5% followed by LMC 27 and 22 ppm, respectively compared to the standard treatment. Berds fed LMC 27 ppm had dramatically lower lipid, liver enzymes, Salmonella and Escherichia coli population (p ≤ 0.001) with the better thyroid function, antioxidant measures, Lactobacilli population amount, immune and best fertility and hatchability percentage. Finally, adding 27 ppm LMC followed by 2.5% PLP to the standard diet enhanced digestibility of nutrients, digestive enzymes, performance, antioxidant properties, plasma biochemical, immune, and microbial count in the gut in laying Japanese quails. With economical point of view, the diet with 2.5% PLP was the best.