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M. TISCHNER

Investigations carried out on the transport and resorption of the unejaculated spermatozoa have failed to determine conclusively the percentage of the spermatozoa being produced which are expelled into the urethra. Among numerous authors dealing with the fate of the unejaculated spermatozoa, only Lino, Braden & Turnbull (1967) recorded a figure as high as 88% of the total number of spermatozoa being produced which were voided in the urine. Experiments in which we applied the method for urine collection described by Lino et al. (1967) demonstrated that rams were masturbating by rubbing the penis against a rubber funnel fastened under the prepuce. After masturbation had been prevented by tying the tunica albuginea of the penis to the skin, only small numbers of spermatozoa were found in the urine.

The urine was collected

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M. Tischner and A. Bielański

Summary. Observations were made on 14 mares which were non-surgically flushed on one or more occasions for recovery of embryos on Days 7–9 after ovulation. Flushing alone shortened the oestrous cycle by about 2·7 days but increased the number of mares failing to ovulate. Flushing followed by an injection of a prostaglandin analogue shortened the cycle by about 4·5 days and hence increased the frequency of ovulations. From a total of 70 flushings performed, 27 embryos were recovered and of 12 mares inseminated during the first oestrus after embryo collection, 6 conceived and foaled. The other 7 mares were used again as donors during the next season. They underwent a total of 21 non-surgical embryo collections and yielded 15 embryos. It is concluded that non-surgical embryo recovery and transfer provides a practical means of increasing the fecundity of valuable donor mares without depressing their fertility.

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M. TISCHNER, K. KOSINIAK and W. BIELAŃSKI

Summary.

The emission of stallion semen was studied with the aid of an `open' Kraków-72 Model artificial vagina. The pattern of mating behaviour was constant in all copulations observed : a mean number of seven intravaginal thrusts was required to elicit ejaculation. The pressure within the vestibule of the artificial vagina averaged 66 mmHg at the beginning of copulation, 142 mmHg just before ejaculation, and 70 mmHg during the emission of semen. Emission appeared to be a more variable process. Five to ten jets were observed; the mean number was eight. The early jets occurred under high pressure in a stream with characteristic spatter. The later jets, accompanied by declining erection and withdrawal of the penis from the vagina, were associated with low pressure. Of the total time of ejaculation, 24% involved actual emission of semen; the rest comprised intervals between successive seminal jets. The first three jets contained 80 % of the ejaculated spermatozoa. The total number of spermatozoa, and the ergothioneine content, gradually decreased in successive jets. No bacterial growth was found when the sperm-rich fraction was inoculated on solid media.

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W. R. Allen, Francesca Stewart, A. O. Trounson, M. Tischner and W. Bielański

Agricultural Research Council Unit of Reproductive Physiology and Biochemistry, Animal Research Station, Cambridge, U.K. and Academy of Agriculture, Institute of Applied Animal Physiology, 30-059 Krakow 2, al. Mickiewicza 24128, Poland

Sheep and cattle embryos continue to develop normally in the ligated oviducts of rabbits (Adams, Moor & Rowson, 1968) and retain viability when transferred to ewes or cows, provided they are removed from the rabbit within 3-4 days (Lawson, Adams & Rowson, 1972; Lawson, Rowson & Adams, 1972). The rabbit genital tract was first used for long-distance transport of embryos by Hunter, Bishop, Adams & Rowson (1962), who obtained normal lambs after transfer to recipient ewes. In this paper, we describe the development and viability of horse embryos after long-distance transport in rabbits.

Methods

Seven maiden 2- and 3-year-old Welsh Mountain Pony mares maintained in Cambridge were used as embryo donors and six mixed-breed mares aged 2 to 8 years