The last 3 weeks each of pregnancy and early lactation are very critical for the dairy animals because of the challenges posed by metabolic and hormonal changes in the body. The dry matter intake of these animals starts declining during advanced pregnancy and gets reduced up to 30% just 3 weeks before parturition.  Most of the energy is utilized for the production of colostrum and milk after parturition due to which the animal faces negative energy balance.  The animal also loses its body condition score due to the utilization of its body fat to meet energy requirements that lead to an increase in non-esterified fatty acids in the blood.  The animals are prone to metabolic disorders and decreased production of milk when its body fats are depleted. The energy requirements of such animals could be met by increasing the energy density of their diet.  There is an increase in rumen acidosis if more quantity of concentrate is offered to such animals.  Acidosis leads to the poor digestion of fibers in the rumen. There is increased production of propionate in comparison to acetate which is responsible for less percentage of fat in the milk of these animals. The ill effects of negative energy balance may be eliminated if these animals are offered bypass fat in their diet.  The cellulose digesting bacteria stay unharmed due to bypass fat where as ordinary fat may harm these bacteria if more than 1% of its dry matter intake is fed. Therefore, it is advisable to offer bypass or prilled fat to the animals during transition period.