Peripubrtal Plasma Progesterone Patterns in Ethiopian Menz Ewe Lambs

Abstract

Muksa -Mugenua, E. and Mutiga, E. R. 1993. Penpubertal plasma pmgestemnepatterns in Ethiopian Menz ewe lain bs. J Appl. Anim. Res., 3 : 31-38 Plasma progesterone concentrations were determined every 10 days for 38 grazing Menz ewe lambs from weaning (93 * 7 d) until conception. Lambs wereeither fed extrasupplementary concentrates and / or drenched for endoparasites. Inadequate nutrition delayed puberty onset by 4 to 5 months (PCO.05). Progesterone concentrations, determined by the ELISA technique, were basal (S 1.0 ng/ml) before puberty. Subsequently, 63% lambs exhibited a 'silent ovulation' prior to first behavioural oestrus but, transient rises ofprogesterone were not observed in 45% of lambs conceiving at first mating. Further, first oestrus was unovulatory (non-pubertal) in 21.1% of animals which may bias estimates of puberty onset based only on first oestmus behaviour. 5% of lumbs exhibited a gestational oestrus.