| |
1st breeding season 1998–1999
|
2nd breeding season 1999–2000
|
3rd breeding season 2000–2001
|
|---|
| |
onset
|
end
|
onset
|
end
|
onset
|
end
|
|---|
|
Temperate regimen
|
NA
|
22/04 ± 7
|
15/09 ± 3
|
25/04 ± 12
|
22/09 ± 5
|
NA
|
|
Tropical regimen
|
NA
|
09/04 ± 4
|
05/08*** ± 5*
|
22/04 ± 4*
|
13/09 ± 3
|
NA
|
- Two groups of Black-Belly ewes were maintained in light-proof rooms and subjected to either simulated temperate photoperiodic conditions (TE, 12 ewes, 8 to 16 hours of light per day from winter to summer solstice) or simulated tropical photoperiodic conditions (TR, 12 ewes, 11 to 13 hours of light per day from winter to summer solstice) for 25 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). NA: not available.
