Seasonal ovulatory activity exists in tropical Creole female goats and Black Belly ewes subjected to a temperate photoperiod

Table 2 Mean durations in days ± S.E.M. of anovulatory and ovulatory seasons in Creole goats maintained under two different photoperiodic conditions.

	1^st anovulatory season (1990)	2^nd anovulatory season (1991)	2^nd breeding season (90–91)	3^rd breeding season (91–92)
Temperate regimen	173.0 ± 8.0	79.6 ± 9.5	194.5 ± 9.5	301.8 ± 7.8
Tropical regimen	65.0*** ± 8.4	81.6 ± 21.6*	304.3*** ± 10.8	265.5 ± 31.3***

Two groups of Creole female goats were maintained in light-proof rooms and subjected to either simulated temperate photoperiodic conditions (TE, 16 goats, 8 to 16 hours of light per day from winter to summer solstice), or simulated tropical photoperiodic conditions (TR, 17 goats, 11 to 13 hours of light per day from winter to summer solstice) for 33 months. Ovulatory activity was assessed by determinations of plasma progesterone by radioimmunoassay. Means and variances were compared between groups within each column. Significant differences between means and between variances are indicated by asterisks (*:p < 0.05, ***: P < 0.001).

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