Is there an appropriate energy level in the diet during the cow transition period? A systematic review and...

A systematic review and meta-analysis was undertaken to predict the effect of prepartum energy level on postpartum energy metabolism and milk production in dairy cows. In this systematic review, the criteria of PRISMA guidelines were followed: in vivo experimental evaluation of diets with different prepartum energy levels; presentation of initial, final, and/or total results; statement of treatment period including the last 21 days of the prepartum of period; and description of dry matter intake (DMI), milk production, blood parameters and feed efficiency data. A descriptive analysis was performed for better visualization of the data, and Pearson's correlation was used between the collected variables and the prepartum energy intake. The acquired data were subsequently analysed, employing a link function in a polynomial regression model. Prepartum energy intake does not influence DMI or energy balance in the postpartum phase. A higher-energy diet prepartum increased feed efficiency postpartum, accompanied by an increase in blood levels of BHB and NEFA. However, it also resulted in a decrease in milk production and blood glucose.