Effect of essential oils and distillation residues blends on growth performance and blood metabolites of Holstein calves weaned gradually or abruptly
This project is completed at 2015 in a commercial dairy farm in Isfahan Iran.
The objective of this study was to investigate preweaning calf performance responses and
initial postweaning profile of some blood metabolites to dietary supplementation of calf
starter with essential oils or distillated residues blend (Rosmarinus officinalis L., Zataria
multiflora Boiss, and Mentha pulegium L.). Sixty Holstein calves, were randomly assigned to
three dietary treatment groups: (1) starter with no additive (CON), (2) starter with essential
oils blend (EOB, 300 mg/kg starter), and (3) starter with distillation residues blend (DRB, 50
g/kg starter). The blend was prepared by mixing the essential oils or the distillation residues
(1:1:1) and then was added to the starter diet. Each group of calves was weaned based on two
different methods: (1) gradual weaning during 4 days [G], and (2) abrupt weaning [A].
Results of DPPH test showed that radical scavenging activity of EOB was higher than DRB
(81.4 vs. 15.4%) (P<0.05). Supplementation of the starter diets with essential oils and/or
distillation residues increased (P<0.05) feed intake and average daily weight gain of calves.
These calves had about 3 days lower age (P<0.05) and higher body weight (BW) at the
weaning time. Calves fed EOB had higher (P<0.05) insulin concentrations during the weaning
period, especially in abrupt weaned group compared to the group CON-A. The weaning
method and treatment had no effect on total serum protein (TSP), serum albumin and
globulin. It is concluded that supplementation of starter diets with a mixture of essential oils
or distillation residues had a beneficial effect on the growing performance of suckling calves
and may change some of blood metabolites.