Pregnancy diagnosis in Thai native goats

Pregnancy status was determined in two groups of native Thai goats, mated in either October (n = 116) or March (n = 37), by assay of the progesterone level in four plasma samples taken at 7 day intervals after the completion of mating. The progesterone level (P) in each sample was determined using facilities in a local hospital, and a commercial assay kit with human serum-based standards was used. The distribution of log(10) P yielded a discriminatory value of 2 ng/ml; any value below this level was assumed to indicate a follicular phase. Pregnancy diagnoses based on this criterion were 96.2% accurate. Diagnoses based on returns to service were not accurate, as 36.5% of pregnant does were recorded as returning. Real-time ultrasonic imaging of the March mated group was 100% accurate for pregnancies, but detection of twins was poor. The progesterone technique described here is useful in field studies where mating dates are not known, and where there is no access to an animal assay laboratory.