Effect of Supplementing Mixed Plant Essential Oils on Milk Yield and Composition, Ruminal Fermentation, and Candidate Blood Parameters of Holstein Lactating Dairy Cows

Abstract

Aim: There is little regarding the effect of mixture of supplemental dietary thyme, mint, and savory essential oil components on dry matter intake (DMI), milk yield, milk composition, rumen fermentation characteristics, and the various blood parameters of Holstein lactating dairy cows. Materials and methods: In a randomized complete design arrangement with six replications, 18 Holstein lactating dairy cows with 660 ± 50 kg initial body weight and 210 ± 30 days in milk were used for 28 days throughout the experiment. Treatments were as follows: control (COD, no essential oil supplement), mixture of thyme, mint, and savory at the rate of 1: 1: 1 for two levels of 5 (EOD5) and 10 ml (EOD10) per day per cow. Dry matter intake and milk production recorded daily and body weight was measured at the beginning and the end of the study. Results: Dry matter intake and milk yield were influenced by diets containing essential oils (P< 0.05). Dry matter intake was higher for cows fed EOD>10 than EOD5 (P< 0.05). However, there was no difference in the milk yield of cows fed essential oils of the two levels (P> 0.05). No significant difference was observed for milk fat, protein, lactose, total solid, and milk urea nitrogen concentrations among the treatments, yet milk protein tended to increase in animals fed EOD10 (P = 0.10). Cows fed EOD10 had a higher rumen pH value than those given other treatments. Conclusion: Overall, the results demonstrate that the addition of a mixture of essential oils to the diet influenced feed palatability and increased dry matter intake of Holstein lactating dairy cows.