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

Table 1 Mean dates ± S.E.M. in days, for onset and end of ovulatory activity in Creole goats maintained under two different photoperiodic conditions.

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 < 0.01, ***: P < 0.001). NA: not available.

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