Effect of level and source of energy during the periparturient period on reproductive performance

The financial loss due to poor reproductive performance is substantial. Poor energy nutrition during the transition period will predispose dairy cattle to poor reproductive performance later in lactation when it is critical for them to become pregnant to optimize financial returns. Dairy cattle should consume diets higher in energy than recommended by NRC (1989) during the late dry period to stimulate dry matter intake (DMI) and to offset decreases in energy intake due to decreasing DMI. Care must be taken to avoid over feeding energy throughout the dry period because this can result in fat cows and poor postpartum reproductive performance. Propylene glycol can be added to transition cow diets to increase plasma insulin and glucose concentrations and perhaps improve reproductive performance. Dietary fat appears to improve reproductive performance independent of energy status in many studies when fed for several months during early lactation. However, it is not recommended for use during the transition period because of concerns regarding decreased DMI and the long-term management of body condition in high producing cows, which hasn't been studied in cows fed fat during consecutive dry periods.