[The optimal service period in bitches].
The fertile period in bitches as estimated from the findings reported in the literature is discussed. Fertile periods of oocytes and spermatozoa are examined extensively. The period of ovulation is found to be more closely associated with hormonal changes than it is with symptoms of oestrus. This period occurs when the concentration of progesterone in the blood increases to a level higher than (16 nmol/l). Service one and a half days after the ovulation period results in high pregnancy rates.