Mentha piperita (peppermint) in growing Japanese quails diet: Performance, carcass attributes, morphology and microbial populations of intestine

• Mentha piperita did not improve quail performance.
• Mentha piperita increased the lactic acid bacteria in the ileum.
• Mentha piperita decreased the Escherichia coli in the ileum.
• Mentha piperita increased the absorption surface area in the ileum.

An experiment was conducted to evaluate the effect of dietary Mentha piperita L. (MP, peppermint) on growth performance, carcass characteristics, ileal morphology and intestinal bacterial populations of growing Japanese quails. A total of 360, 7-day-old quail chicks were fed six experimental diets (with 5 replicates and 12 birds each) including a basal diet with no antibiotics (negative control), the basal diet with subtherapeutic amount of flavophospholipol (positive control), MPI (basal diet + 10 g/kg peppermint), MPII (basal diet + 20 g/kg peppermint), MPIII (basal diet + 30 g/kg peppermint), and MPIV (basal diet + 40 g/kg peppermint) for 5 weeks. Dietary treatments did not affect bird performance, however, feed intake (P = 0.09) and feed conversion ratio (P = 0.06) in peppermint groups showed an incremental trends from 7 to 35 days of age. Inclusion of peppermint in the diet linearly increased the length of small intestine, villus height, villus width, crypt depth, and villus area (P < 0.001). Regression analysis showed that the maximum villus area and CFU of LAB may be obtained with 28.9 (R2 = 0.82) and 28.9 g/kg of dietary peppermint (R2 = 0.93), respectively. However, the minimum CFU of coliforms may be achieved with 22.0 g/kg of dietary peppermint (R2 = 0.50). From the results of present study, it can be concluded that peppermint at the rate of 20–30 g/kg of diet could be a promising alternative to antibiotics in order to improve intestinal bacterial populations and absorption surface area in growing Japanese quails.