A Study of Infertility in Scottish Blackface Sheep in Colombia, South America

SUMMARY The reproductive performance of a flock of 226 Scottish Blackface (SB) ewes in Colombia, lat. 5°N, alt. 3200 m, showed that 96·0% were keel marked and 42·4% lambed. Of the 56·7% served once, 66·7% lambed. Of the 43·3% returning to service only 14·9% lambed. More detailed investigations were carried out on a representative sub-group of 19 Blackface ewes and on 10 ewes of the local Criolla breed. Progesterone profiles indicated that barrenness in SB sub-group ewes was due to relapse into anoestrum following an ineffective service or termination of pregnancy before day 60.