Assessing the age of puberty of Djallonke gimmers born in rainy or dry season using progesterone measurements

2018

English

A study was carried out to determine the age of puberty of 20 Djallonke gimmers born under the two major seasons in the northern Guinea Savannah Zone of Ghana, the rainy season (n=10) and the dry season (n=10). Peripheral blood progesterone (P4) measurements were used to establish the age at which gimmers first showed ovarian activity. The age at first oestrus, age at first lambing, lambing intervals, placenta weights and lamb birth weights were also assessed. The effect of season on these reproductive parameters was determined. The Djallonke gimmers started to show ovarian activity (rise of P4) at the age of 221± 9 days, at 55.6% of adult weight, with rainy season lambed gimmers (RSLG) showing ovarian activity significantly earlier (202 ± 11 v 239 ±13 days) compared to the dry season lambed gimmers (DSLG) (P<0.05). The RSLG also went on to lamb earlier than DSLG (425± 11 v 496± 31 days) (P<0.05) and produced heavier lambs as well (1.77 ± 0.08 v 1.40± 0.13 kg). It is suggested that timing lambing to occur in the rainy season may provide a better nutritional environment for lactating ewes to nourish their lambs and for gimmers to grow faster and attain puberty earlier.

Salifu, S.; Osei, S. A.; Hagan, B. A.; Allegye-Cudjoe, E.; Avornyo, F. K.