effect of mentha piperita and melissa officinalis powder on performance and digestibility of fat and protein of broilers subjected to heat stress

this study was conducted to investigate the effect of mentha piperita (pp) and melissa officinalis (mp)powder on performance, apparent digestibility of fat and protein and blood parametersof broiler chicks subjected to heat stress. 200-day-old male ross broiler chicks were assigned to a completely randomized design with five dietary treatments and four replicates. the experimental treatments were: 1. control group (diet without feed additive), 2. diet supplemented with 0.5 percent pp, 3. diet supplemented with 1 percent pp, 4. diet supplemented with 0.2 percent mp and 5. group supplemented with 0.4 percent mp. the experimental diets were offered to the chicks from 25 to 42 day of age. during the experiment, the birds were kept at 34°c ± 2 for 8 hours (9.00 to 17.00). the diets supplemented by mentha piperita and melissa officinalis powder had not significant effect on feed intake, but higher body weight gain (bwg) and lower feed conversion ratio (fcr) observed in the birds fed diet supplemented with one percent of pp. apparent digestibility of dry matter and crude fat were not affected by the dietary treatments, but the digestibility of protein was increased (p