Prepubertal plasma FSH concentrations and their relationship with reproductive performance in three Greek breeds of sheep

Plasma FSH concentrations were studied in three Greek sheep breeds; the pro lific Chios, the medium prolific Karagouniki and the less prolific Florina breeds. Correlation between plasma FSH concentrations and reproductive perf ormance were estimated. FSH concentrations were greater in Chios than Flori na ewe lambs at 10, 11 and 12 weeks of age (p < 0.05). No differences were observed in FSH concentrations between Florina and Karagouniki ewe lambs du ring the period of 6-12 weeks of age. Chios ewe lambs had elevated FSH leve ls compared with Karagouniki ewe lambs, but the differences were non-signif icant during the above-mentioned period. No relationship was observed betwe en prepubertal plasma FSH and age at puberty. Significant correlations were observed between FSH concentration at 11 weeks of age and ovulation rate a t puberty in the Chios breed and also between FSH concentration at 12 weeks of age and litter size of the first lambing. No relationships were observe d between prepubertal plasma FSH levels and ovulation rate at puberty for t he Florina and Karagouniki breeds. Likewise, prepubertal plasma FSH levels appeared unrelated to litter size at first, second and third lambings for F lorina and Karagouniki breeds. It was concluded that the plasma FSH concent rations during the period from 6-12 weeks of age of ewe lambs could be a su itable criterion for an early selection of litter size of adult Chios ewes, but not for Karagouniki and Florina ewes. (C) 1999 Elsevier Science B.V, A ll rights reserved.