| Resumo: |
Previously, the concept of a gestation period of sheep shorter than 121 days was unheard of in the field of sheep biology. Our findings during a farmers’ survey in the Lotkho area of Chitral, Pakistan, revealed that the sheep native to the region, locally called “Kari”, gestates for a period of only three months. This duration is 25-40% short of the usual gestation length and is shorter than ever recorded for the species. The mean and mode gestation length (GL) was 110 and 92 days respectively and was concentrated in three distinct clusters: day 87-95, 120-123 and 151-153, accounting for 52% of all observations. GL was influenced by location, season of conception and lambing and the interaction of location with season; had an estimated repeatability of zero. The mean lambing interval was 224.7 ±5.24 days, ranging between 109 and 467 days. During a trial conducted in a controlled environment, only three out of the 27 copulated ewes conceived, and gestated in 113, 125 and 145 days respectively. Gestation length during the trial supported field findings. The results suggest that GL in Kari sheep is unusual as many ewes gestated in three months, with variations of up to 5 months. Genotype by environment interaction is a possibility. However, reasons for the findings are still not clear and further controlled studies should be carried out to establish and further explore the factor(s) responsible for this unusual and unique manifestation of the Kari with regards to its gestation length.
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