Feeding during lactation has been shown to effect physiology of reproduction in sows. A study was conducted to define the hormonal patterns of FSH and LH in lactation (21 days), the development of uterus and follicles after weaning in primiparous sows fed restricted (RE) or ad libitum (AL). 14 sows were used; 7 in each group AL and in group RE (≈70% of the diet of AL-sows). An intravenous catheter was inserted on day 6/7 post partum (pp). Blood samples were collected on days 12, 15 and 18 pp. FSH and LH were analysed by RIA. Daily ultrasonography of the ovaries between day 8 and 20/21 pp was used on a few animals per group to monitor follicular growth. All sows were slaughtered either 1 or 7 days after weaning. Mean daily feed intake during lactation was 3.9 kg in AL- and 2.7 kg in RE-sows. FSH concentrations were similar in AL- and RE-sows on day 12 pp, but higher in AL-sows on day 15 and day 18 pp (P<0,05). Generally LH concentrations were higher in AL- than in RE-sows (P<0.05). The results demonstrate that lactating AL-sows had higher both LH and FSH concentrations during lactation than RE-sows. An association to simultaneously observed differences in follicular growth is assumed. The weights of uterus were higher 24 hours and 7 days after weaning, in AL-sows (399/478g) than in RE-sows (335/392g). Generally the follicular status of ALsows was more developed than in RE-sows.Pokazalo se da hranidba za vrijeme laktacije djeluje na fiziologiju reprodukcije u krmača. Istraživanje je provedeno da se u krmača prvopraskinja, hranjenih ograničenim obrocima (RE) ili ad libitum (AL), odredi hormonalna struktura FSH i LH u laktaciji (21 dan) te razvoj uterusa i folikula nakon odbića prasadi. Istraživanje je provedeno na 14 krmača, 7 iz skupine AL i 7 iz skupine RE (=70% obroka AL krmača). Intravenozni kateter je umetnut 6/7 dan post partum (pp). Uzorci krvi uzimani su 12.,15. i 18. dan pp. FSH i LH su analizirani pomoću RIA. Dnevna ultrasonografija jajnika primijenjena je između 8. i 20/21. dana pp na nekoliko životinja po skupini radi praćenja folikularnog rasta. Sve su krmače žrtvovane 1. ili 7. dana poslije odbića. Prosječni dnevni unos hrane za vrijeme laktacije bio je 3.9 kg u AL krmača i 2.7 kg u RE krmača. Koncentracije FSH bile su slične u AL i RE krmača 12. dana pp ali više u AL krmača 15. i 18. dana pp (P<0.05). Općenito su LH koncentracije bile više u AL krmača nego u RE krmača (P<0.05). Rezultati pokazuju da su koncentracije LH i FSH u laktaciji bile više u AL nego u RE krmača. Povezanost s istovremeno primijećenim razlikama u folikularnom rastu utvrđena je 24 sata i 7 dana poslije odbića. Težine uterusa bile su više u AL krmača (399/478) nego u RE krmača (335/392). Općenito je folikularno stanje AL krmača bilo razvijenije nego u RE krmača
