The transition dairy cows are challenged by various stresses such as decreased dry matter intake, liver dysfunction, increased inflammation, and oxidative stress, particularly in subtropical regions. These might increase the requirement for vitamin E and trace elements. To examine whether supplementation of vitamin E, selenium or copper, zinc, and manganese complex would help transition dairy cows to achieve greater reproduction performance by overcoming the immune function and postpartum disorders in subtropical Taiwan. A total of 24 Holstein Friesian dairy cows were enrolled in this study and divided into three groups (n = 8 cows/group): treatment 1 supplemented with organic selenium and vitamin E (SeE), treatment 2 supplemented with organic copper, zinc, and manganese complex (CZM) and control (CON). The results showed SeE supplementation improved immune function, reproductive performance, and milk yield, but not negative energy balance status. Supplementation of CZM improved milk yield and energy regulation through antioxidative capacity and immune function, but had no influence on reproductive performance.

This study aimed to investigate the effect of supplementation with a mixture of molasses and condensed molasses fermentation solubles (M-CMS) in different synchronization diets formulated with different forage sources in an attempt to improve the fermentation efficiency of diets by M-CMS. In the first experiment, three levels of M-CMS (N: 0%; L: 1.75%; and H: 3.50%) were supplied to diets with or without corn silage to evaluate the supplementation effect on the diet with a synchrony index (SI) of 0.80. In the second experiment, diets containing different corn silage levels (60 or 30% of the forage source) were used to evaluate the effects of M-CMS supplementation on higher SI (at 0.88). The in vitro digestibility, fermentation products, microbial crude protein (MCP), and gas kinetic parameters were determined after 48 h of fermentation. The results demonstrated that M-CMS supplementation improved MCP synthesis in both diets with low and high SI, but did not enhance digestibility. M-CMS supplementation was beneficial to the fermentation stability and extent. It also affected the gas kinetic parameters of the fast- and slow-degradation fractions during fermentation. M-CMS supplementation improved MCP synthesis in diets containing less corn silage. The forage source and degradation rate of individual ingredients should be considered simultaneously to enhance the rumen fermentation efficiency. M-CMS provided a practical choice to further improve MCP synthesis and fermentation stability, even in a diet with high SI.