A recent study was conducted to determine the effects of supplementation of dried peppermint (Mentha piperita L.) leaves in laying hen diets on laying performance, egg quality, and serum metabolic profile. A total of one hundred and fifty Hy-Line Brown laying hens (64 week old), were assigned to five treatment diets including dry peppermint leaves at 0, 5, 10, 15 or 20 g/kg, respectively, for 12 weeks. Each treatment had six replicates with five hens each.
Results indicated that over the course of the trial incremental levels of dietary peppermint leaves significantly increased (linear, P<0.001) egg weight, egg production and egg mass. They also increased feed intake from 64 to 76 weeks of age. Moreover, feed conversion ratio was linearly decreased (P<0.001, a positive result) with increasing levels of peppermint leaves in laying hens diet. The inclusion of 20 g/kg peppermint leaves resulted in overall best performance.
In terms of eggshell quality, the eggshell percentage, thickness and Haugh unit of eggs from hens fed diets supplemented with peppermint leaves were greater (P<0.01) than that of hens fed the control diet. Peppermint supplementation did not influence any other egg quality characteristics like albumen, yolk percentage or albumen height. Notably, serum cholesterol significantly decreased (P<0.001), but serum total proteins increased (P=0.015), with increasing levels of peppermint leaves.
Effective feed additive
It can be concluded that peppermint leaves can be used as an effective feed additive to improve performance of laying hens during the late laying period and that up to 2 percent can be used with safety. Regarding future research, feeding higher levels should be tested. Also, feeding this ingredient at earlier stages would also be of interest.
Certainly, from a commercial point of view, we need to investigate which ingredient in peppermint leaves conferred these beneficial results. Also, the global availability of this ingredient merits investigation. All in all, a very interesting piece of innovative research thinking.