Non-fertility in cows: treatment with PGF and investigation of uterine biopsies.

Experiments with seventeen 'repeat breeders' confirmed that the carbohydrate composition, the hormonal pattern, the cholesterol content and the occurrence of indole metabolites, such as blue fluorescing protein, in cervical mucus can be used as parameters for the fertilizing capacity of these cows. After careful rectal examination 25 mg PGF2 alpha was administered to thirteen 'repeat breeders' on that day of the luteal phase when next to the corpus luteum no follicle was palpable; ten of them became pregnant or were fertilized. Uterine biopsies were taken from eight 'normal' cows and from eight 'repeat breeders', simultaneously with cervical mucus samples. The biochemical composition of the biopsies was comparable to that of the mucus samples. The taking of two biopsies produced injurious consequences for the animals, perceptible in oestrous behaviour. Investigation of cervical mucus samples is therefore preferred to uterine biopsies for the examination of sterility in cows.