[Orienting study on the treatment of cattle with human chorionic gonadotropin on the day of insemination].

A report on two experimental studies in which 1,500 I.U. of HCG were administered to dairy cows on the day of insemination. The first experimental studies were done in 113 subfertile animals in which clinical examination did not reveal any clinically perceptible changes. HCG was injected intravenously in the animals of the experimental group, 0.9 per cent sodium chloride being injected intravenously in the controls. The pregnancy rates were 47 (sixty-one animals) and 30 per cent (fifty-two animals) in the experimental group and in the controls respectively. This difference was significant (P = 0.047). The ultimate pregnancy rates were 66 and 58 per cent (P = 0.32) respectively. The other experimental studies were done on a single dairy herd. The animals to be inseminated all were alternately assigned to an experimental group and a group of controls, regardless of the sequence of insemination. The pregnancy rates in the experimental group and the group of controls were 40 (ninety-eight inseminations) and 43 per cent (ninety-six inseminations) respectively. In concluding, it can be stated that routine administration of HCG to cattle with a view to increasing the pregnancy rate of the first or second insemination cannot be expected to be effective. Treatment with HCG may possibly be successful in a particular group of cattle which have difficulty in becoming pregnant.