Effects of dietary essential oil and live yeast supplementation on dairy performance, milk quality and fatty acid composition of dairy cows

This study aimed to determine the effects of live yeast (LY) and essential oil (EO) on dairy cattle diets on performance and milk composition traits. A total of 120 multiparous (in 2nd and 3rd lactations) Holstein dairy cows were used and 30 animals were allocated to each treatment group. Treatment groups were as follows: 1) control, (C, without any supplementation), 2) herbal essential oil mixture addition (EO, 10 g/day/cattle) 3) live yeast, (LY, Saccharomyces cerevisiae, 10 g/day/cattle, 4x109 CFU/g) 4) EO+LY (10 g/day/cattle+10 g/day/cattle). Experiments were performed for 16 weeks. Bodyweight, milk yield, and feed conversion ratio were not influenced by the treatments. Milk fat increased with EO addition. Milk protein content decreased in the LY+EO group. Somatic cell counts (SCC) decreased significantly with EO addition. Milk lactose, casein, and density were not significantly influenced by the treatments. Milk urea concentration increased in the LY group. Milk-free fatty acids significantly increased in the EO group. Milk citric acid content increased in the LY group. The control (C) group had greater pentadecanoic acid (C15: 0) content than the other groups. The myristic acid ratio (C14: 0) of the C and EO groups was greater than the myristic acid ratio of the LY and LY+EO groups. Based on present findings, EO mixture supplementation to dairy cattle diets had positive effects on milk fat content and SCC.