After calving, high yielding dairy cows should meet the challenge of producing quickly high milk quantity, despite a slow evolution of their appetite and the low capacity of their rumen ecosystem to adjust quickly to important ration changes. The cows are capable to compensate, partly, the difference between energy ration contributions and feed needs by using body reserves. The fact that the animal gives priority to milk production in this period, could lead to a lack of nutriments for tissues (not for the udder), or to an excessive mobilization of body reserves resulting in possible metabolic disease. The major digestive and metabolic risks after calving are acidophilus, hypocalcemia and Ketosis. This last disorder is the cause of an energy deficiency that leads to a huge weight loss of the animals. Ketosis is the result of blood accumulation of cetonic corps and / or an accumulation of fat in the liver (steatose). Sub-clinic conditions of these diseases go together with a diminution of production and protein content, with a slower resumption of ovary activity, and with a decrease of immunity defense.

Prevention of this cetose-steatose consists in a good management of energy sources and the body condition of the cows at the beginning of the lactation. Additives can also help to reduce the risks. Glucose precursors like propylene-glycol work on glucose deficiency at the beginning of fat mobilization. Other type of substances is the so called hepato-protectors, who increase the circulation of hepatic fats in the blood: this process is reinforced by choline and methonine, which supplements can only reach the liver when they have resisted the ruminal degradation.

Finally, other additives like niacine or carnitine can modulate the metabolism of fats in the adipose tissue or the liver.