Effects of the number of spermatozoa and volume of diluted semen on fertility in the ewe

Progestagen-impregnated vaginal sponges + PMSG were used to synchronize oestrus in crossbred adult ewes which were inseminated 56 h after sponge removal with 0.5 ml diluted semen containing 400, 200, 100, 50 or 25 x 10(6) spermatozoa per insemination. The diluent was skim milk-citrate or pooled seminal plasma. There was no difference in reproductive performance due to the insemination medium. Fertility (no. of ewes lambing) after insemination of 400 or 200 x 10(6) spermatozoa was 68% and was similar to that observed after natural service at progestagen-induced oestrus. When less than or equal to 100 x 10(6) spermatozoa were inseminated, fertility fell markedly and the number of lambs per ewe inseminated decreased. A decrease in litter size also occurred. The data indicate that insemination of 200 x 10(6) spermatozoa, i.e. less than 10% of the number in a single ram ejaculate, allows normal conception rates in progestagen-treated ewes.

Section: Resultsmentioning

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Influence of sperm number and seminal plasma on fertility of progestagen-treated sheep in confinement

Langford¹,

Marcus²

1982

“…(Fig. 3) (Dunlop & Tallis, 1964;Mattner & Braden, 1967;Entwistle & Martin, 1972 (1970) and Robinson (1967Robinson ( , 1982 has emphasized that neither phenomenon may be normal under hormone treatment. Nevertheless, if in our experiment ovulation occurred near to 24 h after the start of oestrus then the results of Dziuk (1970) would be conformable with those obtained in our more natural conditions.…”

Section: Bi-paternal Twinsmentioning

confidence: 99%

Multiple mating and siring success during natural oestrus in the ewe

Jewell¹,

Hall²,

Rosenberg³

1986

Summary. Ewes were each mated on four separate occasions, at 3, 9, 15 and 21 h after the start of oestrus and at each time by a different ram. The progeny were assigned to sires by blood typing, supplemented by resemblance between lambs and rams. The paternity of 64 lambs, born to 41 ewes, was established: 2 were conceived at a 3-h mating, 27 at 9 h, 23 at 15 h and 12 at 21 h. The optimum time for a ram to inseminate, when in competition with others, is therefore 9\p=n-\15h after onset of oestrus, and this finding accords with behavioural observations. Ewes tended to lamb during the same half of the day as that when they had come into oestrus.

“…Jones, Martin & Lapwood (1969) and Entwistle & Martin (1972) studied the effect of restricted sperm doses (100 \ m=x\ 106 and 50 \ m=x\ 106 spermatozoa) and, by relating the results to vaginal mucus score, found that the highest conception rate occurred in ewes with a copious, clear or cloudy mucus at the time of insemination. On the other hand, in recent work in this laboratory , it was shown that with the use of 300 to 500 \ m=x\106 freshly ejaculated spermatozoa, single inseminations of ewes were of uniform and high efficiency almost throughout oestrus.…”

mentioning

confidence: 99%

The Conception Rate of Ewes in Relation to Sperm Dose and Time of Insemination

Schindler¹,

Amir²

1973

The effect of different sperm doses on the conception rate has been studied by Salamon (1962), Gancev (1963) and Kareta, Osikowski & Wierzbowski (1966), but without relation to a possible effect of time of insemination. Jones, Martin & Lapwood (1969) and Entwistle & Martin (1972) studied the effect of restricted sperm doses (100 \ m=x\ 106 and 50 \ m=x\ 106 spermatozoa) and, by relating the results to vaginal mucus score, found that the highest conception rate occurred in ewes with a copious, clear or cloudy mucus at the time of insemination. On the other hand, in recent work in this laboratory , it was shown that with the use of 300 to 500 \ m=x\106 freshly ejaculated spermatozoa, single inseminations of ewes were of uniform and high efficiency almost throughout oestrus. The present study was undertaken in order to investigate the possibility that the time range for obtaining maximal results may be more limited with reduced sperm numbers. The stages of oestrus were defined in terms of time intervals after its onset or before its end, since the mucus score was only a rough guide for the determination of the stage of oestrus .In the first experiment, a total of 206 cycling, non-lactating Awassi and German Mutton Merino ewes were inseminated. The onset and duration of standing heat were determined by teasing with aproned rams in small groups for 30 min at 8-hr intervals, under the close supervision of the herdsman. Ewes in oestrus were immediately withdrawn and teasing was continued at 8-hr intervals until after the end of heat, when they were returned to the flock. This procedure ensured equal exposure of all ewes to the rams and also made it possible to relate the insemination results to the end of oestrus. Semen was collected with an artificial vagina from fourteen rams in a random sequence. Only ejaculates with strong wave motion and a minimum con¬ centration of 3-5 x 109 spermatozoa/ml were used. The semen was immediately diluted at 30°C with reconstituted skimmed milk according to the method of Colas, Dauzier, Courot, Ortavant & Signoret (1968). The dilution ratio was adjusted for each ejaculate so as to provide 800 IO6 spermatozoa/ml. The diluted semen was kept at 25 to 30°C until insemination, which was carried out within 1 hr of ejaculation.