Effects of adding Thyme and Peppermint essential oils in calf starter diet on performance of Holstein calves

This experiment was conducted to evaluate the effects of feeding thyme or peppermint essential oils in calf starter diet on growth performance, fecal score, nutrient digestibility, dry matter intake and weaning age of Holstein calves. Thirty-six Holstein calves were allocated to each of dietary treatments (Twelve calves (six females and six males) per treatment as: Control, (starter without additive), Mint, (starter supplemented with 0.2% peppermint essential oil) and Thyme, (starter supplemented with 0.2% Zataria multiflora essential oil). Calves were housed in individual hutches, and fed whole milk at 10% of the initial body weight daily and had free access to starter and water. Calves were weaned when they had consumed one kg of starter for two consecutive days. The experiment was ended two weeks after weaning of the calves. Feed intake was measured daily. Body weight was measured at birth, at monthly throughout the study, at weaning and at the end of study. Thyme and mint diets resulted in higher daily weight gain and feed efficiency. No significant difference showed in growth performance between calves after weaning (P>0.05). Essential oils were resulted in higher economical profit at weaning. Results of this study showed that supplementing calf starter diet with thyme and peppermint essential oils guaranty higher calf performance.