[Energy requirements of pregnant and lactating sows]

The energy requirement of pregnant and lactating sows is derived on the basis of extensive experimental studies of the energy metabolism (indirect calorimetry, slaughtering) according to the factorial method. For the first reproduction cycle (RC) 0.41 MJ metabolizable energy (ME) or 0.29 MJ net energy fat, pig (NEFpig) resp. were necessary for energy maintenance requirement for pregnant and lactating sows and, depending on age, 0.44 MJ ME or 0.31 MJNEFpig in the second or third RC and 0.47 MJ ME/kg LW0.75.d or 0.33 MJ NEFpig/kg LW0.75.d in the 4th-8th RC. A linear increase of up to 6% of the energy requirement caused by pregnancy between the 85th and 115th day of pregnancy is taken into consideration. Energy requirement per 1 MJ retention both in pregnancy and lactation is 1.45 MJ ME or 1.03 MJ NEFpig, per 1 MJ milk yield it is 1.33 MJ ME or 0.91 MJ NEFpig. 1 MJ body energy for milk yield corresponds to 1.20 MJ ME or 0.82 MJ NEFpig. Equations describing energy retention in the products of conception, uterus and udder are established as well as equations characterizing the connections between live weight gain or loss and energy content of the gain or loss.