PUBERTY AND SERUM CONCENTRATIONS OF OVARIAN-STEROIDS DURING PREPUBERAL PERIOD IN FRIESIAN HEIFERS ARTIFICIALLY INFECTED WITH FASCIOLA-HEPATICA

An experiment was conducted to study the effect of fascioliasis on pub erty in 13 Friesian heifers divided into a control group (n = 7) and a n infected group (n = 6). At 4 mo of age each infected heifer received 600 metacercariae of F. hepatica. Blood samples were taken twice a we ek, at which time permanent heat mount detectors were checked, from 8 mo of age until 2 estruses were detected in all heifers. Serum concent rations of progesterone (P-4) and estradiol-17 beta (E-2) were assayed by ELISA and RIA, respectively. There was a significant delay in the onset of puberty in infected heifers compared with controls. All anima ls reached puberty at similar body weights but at different ages. Firs t estrus was delayed by 39 d in infected compared with control animals . Serum concentrations of E-2 were significantly higher in the infecte d group than the control group, while P-4 concentrations were lower. F ascioliasis alters the serum concentration of E-2, which in turn resul ts in an abnormally low concentration of P-4, probably due to underdev eloped or absent corpora lutea (C) 1998 by Elsevier Science Inc.