No abstract

-Fifty-six lactations, 23 from primiparous Large White x Landrace sows and 33 from I I multiparous sows were controlled. Milk yield was estimated by weighing the piglets before and after sucklings throughout a 12-h period on days 7,14, 21, 28, 35 and 42 of lactation. Total milk yield and milk production per weaned piglet during a 6-week lactation period were 170.0 ± 48.8 kg and 29.4 ± 7.3 kg respectively for primiparous sows and 210.9 ± 33.6 kg and 26.9 ± 5.1 kg respectively for multiparous sows. In both groups, the peak of lactation was reached in the 3rd week and the lowest amount of milk was yielded during the 6th week (33.5 ± 14.3 kg and 23.3 ± 9.9 kg in primiparous sows and 43.3 ± 11.1 kg and 28.0 9.8 kg in multiparous sows). Milk production curve was fitted to a gamma function (R'-= 0.86 in primiparous and R 2 = 0.91 in multiparous sows). The season of farrowing had no significant influence (P > 0.05) on total milk yield and milk production per weaned piglet in primiparous sows. However, total milk yield was increased (P < 0.001) as a result of increased litter size. For each additional weaned piglet, total milk production increased 25 kg, whereas milk production per weaned piglet non-signiticantly decreased by 1.O1 kg (P < 0.2). For multiparous sows, total milk yield and milk production per weaned piglet were significantly affected (P < 0.05) by sow and by parity. In the lactation 4 the milk output was higher than in the lactation 2 and 3. Litter size at weaning did not affect the total milk yield; it affected the milk production per weaned piglet (P <