Effect of time of artificial insemination on fertility of progestagen and PMSG treated indigenous Greek ewes, during non-breeding season.

A total of 2567 indigenous Greek ewes (Chios, Vlachiki and VlachikixChios breeds) were used to determine the optimum time for insemination, following synchronization of oestrus with MAP-impregnated intravaginal sponges and PMSG during non-breeding season. Within each breed group, the ewes were divided into three subgroups and submitted to a double blind cervical artificial insemination 48 and 60h (subgroup I), 60 and 72h (subgroup II) and 48 and 72h (subgroup III) after sponge withdrawal. From the results of the present investigation it can be concluded that the conception rate in the Chios island breed is better than that in the VlachikixChios breed, with the latter being better than that in the Vlachiki breed. Using fixed time for AI, a better conception rate is obtained when applied 48 and 72h after sponge withdrawal for Chios and ChiosxVlachiki breeds, while for Vlachiki breed a better conception rate is obtained when fixed AI is applied 48 and 60h after sponge withdrawal.

Characteristics and seasonal variations in the semen of Alpine, Saanen and Damascus goat bucks born and raised in Greece.

Twenty-three purebred Alpine (n=8), Saanen (n=7) and Damascus (n=8) goat bucks raised at the Institute of Reproduction and Artificial Insemination in Thessaloniki, Greece (40 degrees 37 minutes N, 22 degrees 58 minutes E and altitude 32 m above sea level), were used to study the effect of photoperiod on semen production. Samples were collected with an artificial vagina and examined immediately after collection. In spite of the variation in nearly all semen characteristics studied among the 3 breeds of bucks, there was significant seasonal variation in both semen quantity (volume, concentration and total number of spermatozoa per ejaculate) and quality (percentage of motile spermatozoa, percentage of abnormal spermatozoa and rate of progressive motility). The best semen was produced during the breeding season (late summer and autumn). However, the magnitude of these seasonal effects was not sufficient to prevent bucks from being used for breeding throughout the year. Nevertheless, individual differences in the semen quantity and quality among bucks within a breed make individual evaluation of semen necessary to select the most fertile males for breeding.

Seasonal variation in semen characteristics of Chios and Friesian rams in Greece.

Five Chios and five Friesian rams were used to study the effect of season on semen production. Semen samples were collected with an artificial vagina. In spite of the large variation of most of the semen characteristics among rams of the two breeds, seasonal variation in semen quantity (volume, concentration and total number of spermatozoa per ejaculate) and quality (percentage of motile spermatozoa, sperm progressive motility and percentage of abnormal spermatozoa) were significant (P<0.05). The best semen was produced mainly during autumn and the worst during spring (semen volume: 1.47ml in Chios and 1.48ml in Friesian rams versus 1.24ml in Chios and 1.07ml in Friesian rams; percentage of abnormal sperm: 5.66% in Chios and 5.42% in Friesian rams versus 8.22% in Chios and 7.75% in Friesian rams; total sperm/ejaculate (x10(9)): 7.05 in Chios and 6.74 in Friesian rams versus 4.09 in Chios and 4.05 in Friesian rams). The magnitude of these seasonal effects was not sufficient to prevent rams from being used for breeding throughout the year. However, the existence of differences among rams within each breed in semen quality and quantity makes it necessary to perform a semen evaluation on individual basis in order to select the best males before they are used for breeding.

Ram seminal plasma and fertility: results from an ongoing field study.

The effects of partial replacement of ram semen diluent with ram seminal plasma on the fertility of ewes were studied. Crossbred Chios ewes (n = 152) were assigned to six groups. The oestrous cycles of the ewes were synchronised at the peak (Groups A, B, C and D) and at the end (Groups E and F) of the breeding season by means of intravaginal sponges impregnated with fluorogestone acetate (FGA) for 14 days. Four hundred IU of PMSG were injected intramuscularly at the time of sponge removal. Ewes of Groups A, C and E were artificially inseminated with ram semen diluted with skim milk extender, while those of Groups B, D and F with ram semen diluted with 50% skim milk and 50% ram seminal plasma. The addition of ram seminal plasma induced a significant increase (P < 0.05) in litter size in Groups B and D when compared with that of Groups A and C (1.85 and 1.88 vs. 1.39 and 1.52, respectively). This increase was not significant when insemination was performed at the end of the breeding season (2.0 vs. 1.4). These results indicate that the addition of seminal plasma can influence the fertility of ewes or the fertilising capacity of extended ram semen to some extent.

Fertility of fresh and frozen-thawed goat semen during the nonbreeding season.

A total of 4109 does of a local Greek breed (Capra prisca) were synchronized with intravaginal MPA-sponges and PMSG, and 24 bucks of Alpine (n = 8), Saanen (n = 8) and Damascus (n = 8) breeds were used for studying the fertility of nonfrozen and frozen-thawed semen during the nonbreeding season (June to August). Artificial insemination (AI) was performed once (50 to 55 h after sponge withdrawal) or twice (36 and 60 h after sponge withdrawals with fresh semen (collected during the nonbreeding season, stored at 16 degrees C and inseminated within 6 h) or frozen semen (prepared from the same bucks during the preceding breeding season). The induction of estrus was successful, varying between 91.0 and 95.0%. The form of semen (fresh or frozen-thawed used for inseminating the synchronized does affected their fertility: the overall kidding rate with fresh semen (65.5%) was higher (P < 0.05) than that with frozen-thawed semen (53.4%). The fertility level was also affected by the number of inseminations performed: the overall kidding rate was significantly higher (P < 0.001) in the does inseminated twice with fresh or frozen-thawed semen (70.4 and 59. 1%, respectively) than in those inseminated only once (48.9 and 44.9%, respectively). Finally, the breed of the buck used for preparing the fresh or the frozen-thawed semen affected the fertility level of the does. The kidding rate was higher in does inseminated with fresh semen prepared from bucks of the Damascus breed than from bucks of Saanen or Alpine breed. However, when frozen-thawed semen was used the kidding rate was lower in does inseminated with semen prepared from bucks of the Damascus breed than from bucks of the Alpine or Saanen breed. It is concluded that the fresh semen of Alpine, Saanen and Damascus breed bucks, born and raised under the climate conditions prevailing in Greece (34 degrees to 41 degrees N), can be used successfully during the nonbreeding season (June to August) for inseminating does.