Effect of different dietary levels of rosemary (Rosmarinus officinalis) and yarrow (Achillea millefolium) on the growth performance, carcass traits and ileal microbiota of broilers

rosemary and yarrow herb powders on the growth performance, carcass traits and ileal microbiota of broilers was studied. Three hundred and thirty-six one-day-old Ross 308 male chickens were allocated to one of the following treatments (six replicates of 8 birds per treatment): control (basal diet with no rosemary or yarrow herbs added), and basal diet with the addition of either 0.5, 1.0 or 1.5% of rosemary herb, or 0.5, 1.0, or 1.5% of yarrow herb. Significant differences were observed (P<0.05) between treatments in the starting (d 1-21) and growing (d 22-42) periods, and in the average feed intake in the starting period. When the whole experimental period was considered, the best-feed conversion rates (P<0.05) were achieved for the highest rosemary and yarrow supplementation levels. Yarrow supplementation resulted in betterfeed conversion rates (P<0.05) than the control treatment, for all the periods. No significant differences (P>0.05) were found in the final body weight or in most of the carcass traits. The gastrointestinal tract weight, relative to body weight, increased (P<0.05) due to rosemary and yarrow supplementation, compared with the control treatment. At 42 days of age, the rosemary supplementation increased the Lactobacilli counts and decreased the Escherichia coli counts more than the control and yarrow supplemented treatments. In conclusion, under the conditions of the present work, yarrow supplementation mainly improved growth performance, while rosemary supplementation showed the best effects on ileal microbiota, both compared with the control treatment.