EFFECT OF PROTEIN SUPPLY DURING PREGNANCY AND LACTATION ON BODY-COMPOSITION OF SOWS DURING 3 REPRODUCTIVE-CYCLES

Changes in chemical body composition during three reproductive cycles were investigated in a study involving two levels of nitrogen during p regnancy (diet C or L) and lactation (diet C or H). N contents in the diets C, L and H were 28.5, 19.3 and 32.8 g N . kg DM(-1), respectivel y. Tested combinations of pregnancy treatment (first character) and la ctation treatment (second character) were: CC, CH, LC and LH. Treatmen ts had no effect on litter gain during lactation nor on the amount of body protein after three reproductive cycles. After the third weaning, the water/protein ratio was higher on pregnancy treatment L_ than on C_ and the amounts of fat, dry matter and energy in the body were lowe r on lactation treatment _H than on _C. Equations to predict body comp osition of sows using live weight and backfat thickness (P2) were used to assess body composition during three reproductive cycles. The lowe r retention of protein during the first reproductive cycle on pregnanc y treatment L was not completely compensated in the next two cycles. A feeding level of about 440 kg . sow(-1) per reproductive cycle (pregn ancy+lactation) increased live weight and the amounts of protein, wate r and energy in the body and decreased backfat thickness. The amount o f fat hardly changed.