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 pregnancy (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), respectively. Tested combinations of pregnancy treatment (first character) and lactation treatment (second character) were: CC, CH, LC and LH. Treatments 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 lower on lactation treatment _H than on _C. Equations to predict body composition of sows using live weight and backfat thickness (P2) were used to assess body composition during three reproductive cycles. The lower retention of protein during the first reproductive cycle on pregnancy treatment L was not completely compensated in the next two cycles. A feeding level of about 440 kg . sow(-1) per reproductive cycle (pregnancy+lactation) increased live weight and the amounts of protein, water and energy in the body and decreased backfat thickness. The amount of fat hardly changed.