Effects of emulsified essential oils of a medicinal herbs mix on performance, nutrient digestibility, blood metabolites and immunity of suckling calves

Abstract

First Experiment: The purpose of this experiment was to investigate the effect of different levels of an emulsified essential oils blend on blood metabolites and the immune system of sucking calves. At first experiment, 40 suckling calves with an average body weight of 40.4±3 kg from the age of 7 days were used in a completely randomized design with 4 treatments and 10 replications. The experimental groups were: 1) control group, 2) calves receiving 100 mg of a blend of essential oil per day as emulsified form via milk, 3) calves receiving 200 mg of a blend of essential oil per day as emulsified form via milk, 4) Calves receiving 300 mg of a blend of essential oil per day as emulsified form via milk. Four medicinal plants including Thymus kotschyanus, Lavandula angustifolia, Capparis spinosa and Salvia officinalis were used to prepare the essential oils blend.The results showed that the experimental treatments did not affect dry matter intake and feed conversion ratio. Weight gain of 1-14 days and the whole period were not affected by feeding different levels of emulsified essential oils, but weight gain of 14-28 days and 28-43 days increased linearly (P<0.01). Blood concentrations of glucose, cholesterol and beta-hydroxybutyrate were not affected by a mixture of plant essential oils, but the concentrations of triglycerides and urea nitrogen in the blood increased and decreased linearly, respectively (P<0.05). Feeding the emulsified essential oil blend caused a significant linear decrease in blood concentrations of liver enzymes including aspartate aminotransferase and alanine aminotransferase at 30 days and gamma-glutamyl transferase at 15 and 30 days (P<0.05). The concentrations of superoxide dismutase and glutathione peroxidase were not affected by the experimental treatments, whereas the blood concentration of malondialdehyde decreased and the blood antioxidant activity increased linearly by increasing essential oil levels (P<0.05). Feeding the micellar mixture of plant essential oil reduced linearly the excretion of lactobacilli and E. coli in the feces (P <0.01). Based on the results, the positive effects of the emulsified essential oil on improving the growth and health of sucking calves were observed and the level of 300 mg per day had the best results. At second experiment, 50 male Holstein calves were used from the 7 th day after birth (mean body weight 39.6 ±3.6 kg) to evaluating the effect of feeding a blend of plant essential oils, vitamin C and vitamin E on their performance, blood metabolites and the immune system. The experimental groups were: 1) control group (CON), 2) calves receiving 300 mg essential oil mixture per day as emulsified form, 3) calves receiving 600 mg vitamin C per day as emulsified form, 4) calves receiving 500 IU vitamin E per day as emulsified form and 5) calves receiving 300 mg essential oil blend with 600 mg vitamin C and 500 IU vitamin E per day as emulsified form. Feed intake, daily weight gain and conversion ratio were not affected by experimental treatments. Blood glucose and albumin concentrations were significantly affected by experimental treatments (P<0.01). Calves receiving vitamin E had higher glucose level and blood urea nitrogen concentration was significantly lower in calves receiving essential oil (P<0.01). The highest blood level of beta-hydroxybutyrate was observed in calves receiving essential oil with vitamins E and C (P<0.05). Blood levels of liver enzymes including aspartate aminotransferase, alanine aminotransferase and gamma-glutamyl transferase decreased at 30 days by experimental treatments (P <0.01). Glutathione peroxidase concentration was affected by experimental treatments at 15 and 30 days (P <0.01). The lowest concentration of malondialdehyde and the highest blood antioxidant status were observed in calves receiving plant essential oil, vitamin E and vitamin C. According to the results, the use of the emulsified form of plant essential oil, vitamin C and vitamin E were effective in improving blood parameters related to health and oxidative status.