Abstract:
A measurable quantity of progesterone in a blood or milk sample signifies the presence of luteal tissue in the
ovary. Thus progesterone concentration in blood or milk samples collected at strategic intervals when
interpreted in the light of other information is of diagnostic value in fertility investigations in cattle.
Therefore, a study was conducted using milk progesterone RIA as a tool to monitor the efficiency of AI
services and to identify factors affecting its success rate. Milk samples were collected on days 0 (day of AI),
10-12 and 20-24 from dairy cows bred by AI in five randomly selected VS ranges in wet zone, mid country
region of Sri Lanka. Information relating to the farm, the cow, the bull/semen and the inseminator was
recorded, together with repeat service dates. Pregnancy diagnosis was done by rectal palpation at 60-90
days. Progesterone values on day 0 (n=206) showed that the concentration was high at the time of AI in 17%
of cows, indicating that they could not have been in oestrus. Progesterone values of two samples collected on
day 0 and 10-12 (n=182) showed that only 57.1% of the animals had normal ovulatory cycles while 13.2%
were either in anestrus or had anovulatory oestrus or had short luteal phases. Results of examination of
cows with all three samples (n—110) showed that 61.8% conceived, 10.9% had non-fertilization, embryo
mortality or persistent CL, and 5.5% had been inseminated during pregnancy. The overall CR varied
significantly (p<0.05) between locations from 33.8% to 61.4%. The most significant limiting factor which
influence the success rate of AI appears to be the poor heat detection by the farmers coupled with other
factors such as timing of AI in relation to onset off oestrus, q uality of semen and competency of technicians.
