Oladimeji, B.S., Osinowo, O.A., Alawa, J.P., and Hambolu, J.O. (2001) Seasonal effects on oestrus patterns and progesterone profiles of Yankasa ewes of different age-groups in the sub-humid tropics. Nigerian Journal of Animal Production, 28 (2). pp. 211-216.

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Abstract

Oestrus patterns and serum progesterone profiles of 10 adult and 10 yearling Yankasa ewes were investigated in the late hot-dry and late-wet seasons in the subhumid tropical climate of Zaria, Nigeria. The proportions of ewes which came on heat once, twice or thrice within the experimental periods in the late hot-dry and late-wet seasons were 25, 15 and 0%, and 5, 10 and 85% respectively, while mean oestrous cycle length was significantly longer (P<0.001) in the hot-dry season than in the fate-wet .season (30.9 vs 18.4 days) due to the higher incidence of anoestrus in the former. However, the mean duration of oestrus was not affected by season. Mean serum progesterone levels were significantly (P<0.05) higher in the late-wet season than in the late hot-dry season (l.57 vs 0.52 ng/ml). However, there was a highly significant (P<0.001) interaction between season and age group in mean serum progesterone levels due to a relatively greater depression in progesterone levels in yearling ewes during the hot-dry season compared with adult ewes. The observed disruptions in the oestrus cycle and serum progesterone levels of the ewes in the hot-dry season confirm the adverse effect of heat stress on the reproductive behaviour of ewes.

Item ID:	35660
Item Type:	Article (Research - C1)
ISSN:	0331-2062
Date Deposited:	04 Aug 2015 03:01
FoR Codes:	07 AGRICULTURAL AND VETERINARY SCIENCES > 0702 Animal Production > 070206 Animal Reproduction @ 100%
SEO Codes:	83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8303 Livestock Raising > 830310 Sheep - Meat @ 100%
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