[Detection of estrus and determination of the optimal time for insemination in polar foxes (Alopex lagopus)].

Oestrus cycles were investigated in seven polar foxes: the investigation consisted of evaluation of clinical symptoms of heat (vulva enlargement), measurement of vaginal mucus electrical resistance and determination of progesterone concentrations in the blood plasma of foxes; the objective was to determine optimum insemination time. The females were inseminated with fresh semen intravaginally by means of a pseudopenis, a day following the record of maximum electrical resistance of vaginal mucus and at the minimum progesterone concentration in blood plasma of 30 ng.ml-1.

[Collection of sperm from foxes using electroejaculation under halothane anesthesia].

A method has been developed for the collection of ejaculate from anaesthesized dog foxes. General anaesthesia was produced by inhaling 3 to 5% narcotan mixed with oxygen, the inhalation rate being two litres per minute. An electroejaculator with a bipolar electrode, introduced in the rectum, was used for the electrostimulation of ejaculation.

[Fertilizing capacity of the ejaculate of nutria (Myocastor coypus) after the removal of the seminal vesicles as evaluated by the penetration test and natural mating].

The fertility of male coypu sperm following seminal vesicle extirpation was investigated using the penetration test into the egg of Syrian golden hamster (Mesocricetus auratus). Ejaculates were obtained from five males by means of electro-ejaculation under halothane narcosis. The results of the zona-free hamster eggs (ZFHE) penetration test showed that the ejaculates of all the surgically treated coypu males were fertile and that ZFHE value fluctuated from 54 to 76.

[Fluctuations in the level of progesterone in the peripheral blood of nutria during pregnancy].

The fluctuations in the concentrations of progesterone in peripheral blood of three intact coypus and three coypus after natural mating were investigated for the period of four months. Immediately after mating the concentrations of progesterone are low (1.5-2.