[The energy and nitrogen metabolism of pregnant and lactating sows and suckling piglets. 1. Experimental plan and results concerning the live weight development of pregnant, non-pregnant and lactating sows and the reproductive performance during gestation and lactation].

The aim of the experiments was to work out new results for a factorial derivation of energy and protein requirement. The experiments were carried out according to a 3 x 3 factorial experimental plan with 3 variants of litter number (1, 2 and 4, age of sows) and 3 variants of energy supply (120, 100 and 80% of the norm of pregnancy, continued in lactation with 80, 100 and 120%). Methods of the indirect calorimetry and the slaughtering technique were used. The mean cumulative live weight changes of the sows for the 9 experimental variants amounted from 13.1 to 63.2 kg for the 115 days of pregnancy and from -17.0 to 6.8 kg for the first 26 days of lactation. The chosen variation of energy supply of pregnant and lactating sows had no relevant effect on the reproductive performances, measured by litter size, weight of conception products, litter weight at birth and the quantity of milk per sow and day respectively. In comparison with the sows of litter number 1 the sows of litter number 2 and 4 had higher litter weights at birth and higher milk quantities.