Effects of emulsified essential oils blend on performance, blood metabolites, oxidative status and intestinal microflora of suckling calves

Abstract A blend of essential oils (EOs) from four medicinal plants (Thymus kotschyanus, Lavandula angustifolia, Salvia officinalis and Capparis spinosa) were emulsified in water and dissolved in the daily milk allotment of calves to evaluate their effects on growth performance, blood metabolites, oxidative status, and intestinal microflora. Forty 7-day old male Holstein calves were randomly assigned to four dietary treatments (n = 10 calves/group) in a completely randomized design. Treatments were: 1) control group received no EOs (CON), 2) calves received 100 mg of a blend of EOs/d by including 2 mL of the emulsion medium in milk (100E), 3) calves received 200 mg of a blend of EOs/d by including 4 mL of the emulsion medium in milk (200E), and 4) calves received 300 mg of a blend of EOs/d by including 6 mL of the emulsion medium in milk (300E). Data were analyzed as a completely randomized design with repeated measurements in time by using the PROC MIXED of SAS. Feeding calves with a blend of EOs in emulsified form resulted in a linear increase in average daily gain during 14-28 d (P = 0.02) and 28-42 d (P = 0.01). Similarly, increasing doses of the EOs resulted in a linear increase in triglyceride concentration on d 15 (P = 0.01) and d 30 (P = 0.03). On the contrary, blood urea concentration decreased linearly (P = 0.01) on d 15 with increasing doses of the emulsified EOs. Blood level of gamma glutamyl transferase decreased linearly (P = 0.01) on d 15 and 30 with EOs inclusion. Concentrations of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in the blood were not affected by the treatments after 15 days of feeding the emulsified EOs. However, after 30 days, blood ALT (P = 0.03) and AST (P = 0.01) concentrations decreased linearly. Malon di-aldehyde concentration in blood decreased linearly with increasing doses of the emulsified blend of EOs (P =  0.01). Inclusion of EOs resulted in a linear increase (P = 0.01) in total antioxidant status on d 15 of the experiment. Additionally, feeding EOs in emulsified form resulted in a decrease in fecal E. coli count (P =  0.01). Based on the results, feeding EOs in emulsified form could be an effective way to administer EOs to improve the health status of suckling calves.