The aim of this study was to compare the fertility parameters in response to pregnant mare serum gonadotropin (conventional treatment) or gonadotrophin-releasing hormone (alternative treatment) in Romanov sheep subjected to a 7-d short-term protocol during non-breeding season. All sheep (n:57) were subjected to short-term synchronization protocol. Intravaginal sponge impregnated with 20 mg fluorogestone acetate was inserted for 7 days and all sheep received 125 µg cloprostenol at sponge removal. Sheep were randomly assigned to receive no additional treatment (CON, n:16), 240 IU pregnant mare serum gonadotropin (PMSG, n:24) at sponge removal or 10 µg buserelin acetate (GnRH, n:17) at 30 h after sponge removal. Natural mating was performed following detection of estrous with fertile eight Romanov rams. Estrous response, pregnancy rate, lambing rate, and litter size were compared among groups. Estrous response and pregnancy rate were 86% and 75.4% in all sheep, respectively. Estrous response was numerically higher about 7% (p>0.05) in treatment groups (PMSG, 87.5%; GnRH, 88.2%) than CON (81.2%). However, pregnancy rate was numerically higher (p>0.05) in PMSG (83.3%) than GnRH (70.6%) and CON (68.7%). Similarly, lambing rate in the PMSG (79.1%) was approximately 15% numerically greater (p>0.05) than in GnRH (64.7%) and CON (62.5%). In addition, litter size in PMSG (2.1) was also numerically higher (p>0.05) than GnRH (1.9) and CON (1.9).The use of GnRH provided similar estrous response compared to use of PMSG in Romanov sheep synchronized with short-term protocol. However, use of PMSG provided numerically higher pregnancy rate, lambing rate, and litter size than use of GnRH. Considering the serious ethical concerns and animal welfare for the production of PMSG, it is necessary to use alternative gonadotropins. Comprehensive studies are needed to compare the fertility parameters between application of PMSG and GnRH in Romanov sheep.

Foi estudada a resposta reprodutiva (taxa de parição e tamanho de leitigada) das ovelhas inseminadas artificiosamente após o tratamento de sincronização do estro em relação à carneiros, dose de PMSG e número de inseminações artificiales. Ovelhas adultas Merino em estação reprodutiva (primavera), foram tratadas com esponjas intravaginais impregnadas com 60 mg acetato de medroxiprogesterona (MAP) para sincronização do estro. As esponjas foram retiradas após 14 dias e foram administradas i.m. 375 ou 400 UI gonadotrofina da égua pregnhe (PMSG). Utilizaram-se carneiros vasectomizados para a detecção do cio. As ovelhas que apresentaram cio foram inseminadas artificiosamente com sêmen fresco diluido de carneiros, uma ou duas vezes. A taxa de parição não foi afectada pelos carneiros ou pelo número de inseminações. A taxa de parição foi maior nas ovelhas tratadas com 400 UI PMSG que aquêlas tratadas com 375 UI (76.47% v 54.32%; p<0.01). O tamanho de leitigada não sofreu influência das variáveis estudadas. | The experiment was conducted to determine the reproductive performance (lambing rate and litter size) of sheep artificially inseminated at a synchronized estrus in relation to rams, dose of PMSG and number of artificial inseminations performed. During spring cyclic Merino adult ewes were treated with intravaginal sponges impregnated with 60 mg medroxyprogesterone acetate (MAP). After 14 days sponges were removed and the females received an intramuscular injection of either 375 or 400 IU pregnant mare serum gonadotropin (PMSG). Estrus detection was performed with vasectomized rams. Females in estrus were cervically inseminated with fresh diluted semen from different rams either once or twice. Data on lambing rate and litter size were recorded. Lambing rate was not affected by rams or number of inseminations. A higher proportion of ewes that received 400 IU PMSG lambed compared with those receiving 375 IU PMSG (76.47% v 54.32%; p<0.01). Litter size was not affected by any of the variables under study.

The objectives of this study were: 1) to determine estrus presentation and distribution following a conventional method of estrus synchronization (progestagen-PMSG treatment) in an ewe herd and 2) to analyze estrus presentation and distribution in adult ewes and ewe lambs. During spring a total of 300 cyclic Merino ewes, including 231 adult ewes and 69 ewe lambs were treated with intravaginal sponges impregnated with 60 mg medroxyprogesterone acetate (MAP). After 14 days sponges were removed and 375 IU pregnant mare serum gonadotropin (PMSG) were administered i.m. Estrus detection was performed with vasectomized rams. Ewes were inspected for the presence of marks at 4-hours intervals. Sponge losses, estrus synchronization and distribution were analyzed for adult ewes and ewe lambs. It was detected 1% (3/300) of sponge losses. Estrus synchronization rate was 92.93% (276/297) for the ewe herd, being 93.48% (215/230) for adults and 91.04% (61/67) for lambs (p>;0.10). Estrus onset was detected from 28 to 68 hours following treatment in both classes of females. The interval between sponge removal and estrus onset was 46.88 ± 11.78 hours for the ewe herd, being 46.99 ± 12.22 hours for adult ewes and 47.31 ± 10.94 hours for ewe lambs (p>;0.10). Statistical differences were found only for the intervals 34-38 (p<0.10) and 50-54 hours (p<0.05) between adult ewes and ewe lambs. It was concluded that the treatment used was effective for estrus synchronization in ewes. | Os objetivos deste trabalho foram: 1) determinar a apresentação e a distribuição do estro através do método convencional de sincronização do estro (tratamento progestágeno-PMSG) num rebanho de ovelhas; e 2) analisar a apresentação e a distribuição do estro em ovelhas adultas e borregas. Um total de 300 ovelhas Merino em período reprodutivo (primavera), incluindo-se 231 ovelhas adultas e 69 borregas, foram tratadas com esponjas intravaginais impregnadas com 60 mg de acetato de medroxiprogesterona (MAP). As esponjas foram retiradas após 14 dias e foram administradas 375 UI IM de gonadotrofina de égua prenhe (PMSG). Utilizaram-se carneiros vasectomizados para a detecção do cio. As ovelhas foram observadas para a presença das marcas a intervalos de 4 horas. Analisaram-se perdas das esponjas, sincronização e distribuição dos cios nas ovelhas adultas e borregas. Detectou-se 1% (3/300) de perda das esponjas. A taxa de sincronização do estro no rebanho de ovelhas foi de 92,93% (276/297), sendo 93,48% (215/230) nas adultas e 91,04% (61/67) nas borregas (p>;0,10). Detectou-se a apresentação do cio desde 28 até 68 horas após o tratamento nas duas classes de fêmeas. O intervalo entre a extração das esponjas e a apresentação do cio foi de 46,88 ± 11,78 horas no rebanho de ovelhas, sendo 46,99 ± 12,22 nas adultas e 47,31 ± 10,94 nas borregas (p>;0,10). Encontraram-se somente diferenças significativas entre adultas e borregas nos intervalos 34-38 (p<0,10) e 50-54 horas (p<0,05). Conclui-se que o tratamento utilizado foi efetivo na sincronização do estro nas ovelhas.

The authors tried to evaluate the effect of environmental factors on the embryo transfer of 21 Holstein cows, in a 30 months period, submitted to 37 superovulatory treatments with 3.000 I.U. of PMSG. The results were analyzed considering two seasons: wet period (October to March) with an average maximum temperature = 30.0 ± 0.8ºC and an average absolute precipitation = 153.1 ± 78.8 mm³ and dry period (April to September) with an average maximum temperature = 26.5 ± 1.6ºC and an average absolute precipitation = 59.2 ± 53.8 mm³. Climatic differences between seasons were demonstrated (P<0.05), but there were no significant differences between seasons in the average number of structures per superovulation: 5.4 ± 2.63 and 4.3 ± 4.00; in the viable embryos percentage: 50.0% and 57.6% and the pregnancy rates in the recipients: 44.4% and 35.2%, respectively. Then, the climatic variations between wet and dry periods did not appear to adversely affect the embryo transfer performance in superovulated Holstein cows with PMSG. | Estudou-se a influência de fatores sazonais na performance de 21 vacas da raça Holandesa submetidas a 37 superovulações com 3.000 U.I. de PMSG. Os resultados das transferências de embriões foram analisados segundo o efeito da época do ano: chuvosa (outubro a março) com temperatura máxima média = 30,0 ± 0,8ºC e precipitação pluviométrica mensal = 153,1 ± 78,8 mm³ e seca (abril a setembro) com temperatura máxima média = 26,5 ± 1,6ºC e precipitação pluviométrica mensal = 59,2 ± 53,8 mm³. Registrou-se variação climática entre as estações (P<0,05), mas não houve diferença significativa (P>;0,05) entre épocas do ano quando foi comparado o número médio de estruturas por superovulação (5,4 ± 2,63 e 4,3 ± 4,00), o percentual de embriões viáveis (50,0% e 57,6%) e o percentual de prenhezes obtidas: 44,4% e 35,2%, respectivamente. Concluiu-se, portanto, que as diferentes condições climáticas das épocas do ano não influíram nas transferências de embriões em vacas holandesas superovuladas com PMSG.