Effect of pFSH dose reduction on in vivo embryo production in Dorper ewes

Abstract

To evaluate the effect of pFSH dose on the in vivo embryo production of Dorper ewes in the semi-arid northeast of Brazil, 40 sheep females were distributed into two groups of 20 animals that received intravaginal CIDR for 14 days, and two days before device removal, they received one of the following treatments: in the FSH200 group, the ewes received 200 mg of pFSH; and in the FSH128 group, the ewes received a total of 128 mg in decreasing doses every 12 h. Beginning 12 h after the conclusion of the treatments, estrus detection was performed every four hours using two Dorper rams of proven fertility. The ewes were mated at estrus onset and 24 hours later. Seven days after intravaginal device removal, the superovulatory response was evaluated, and embryo collection was performed using the laparotomy method. The recovered flushings were subjected to embryo searches under a stereomicroscope and classified according to their qualities. Analyses of variance (ANOVAs) and LSD tests were used to compare the different parameters. The data expressed as percentages were analysed by chi-square test. The ovulation rate was higher in the FSH200 group, which had 16.3 ± 0.3 corpora lutea (CL), than in the FSH128 group, which had 11.3 ± 0.3 CL (P<0.05). However, higher fertilization rate (83.6% vs. 62.4%) and higher transferable (86.0% vs. 71.6%) and freezable (67.9% vs. 40.8%) embryo rates were observed in the FSH 128 group compared with the group that received 200 mg. Furthermore, no significant differences in the remaining parameters were observed between the experimental groups (P>0.05), demonstrating that pFSH dose reduction promoted a greater production of freezable and transferable embryos in Dorper ewes subjected to MOET. ResumoCom o objetivo de avaliar o efeito da redução de pFSH na produção in vivo de embriões de ovelhas da raça Dorper exploradas no semiárido do Nordeste do Brasil, 40 fêmeas ovinas foram distribuídas em dois grupos com 20 animais, os quais receberam um CIDR intravaginal por 14 dias e dois dias antes da remoção do dispositivo receberam um tratamento superovulatório proposto: grupo FSH200 onde as ovelhas receberam 200 mg de pFSH, enquanto o grupo FSH128 totalizou 128 mg em doses decrescentes intervaladas por 12 horas. Doze horas após o final do tratamento, foi realizada a detecção de estro, a cada quatro horas, utilizando dois carneiros Dorper, de fertilidade comprovada. As ovelhas foram cobertas no início do estro e 24 horas depois. Sete dias após a retirada do dispositivo intravaginal, foi realizada a avaliação da resposta superovulatória e a colheita de embriões pelo método de laparotomia. O lavado recuperado foi submetido à procura de embriões em estereomicroscópio e classificados de acordo com sua qualidade. Para comparação dos diversos parâmetros, foi utilizada a Análise de Variância (ANOVA), seguida da realização do teste LSD. Os dados expressos em porcentagem foram submetidos ao Teste de Qui-quadrado. A taxa de ovulação foi superior no grupo FSH200 com 16,3 ± 0,3 corpos lúteos (CL) quand...

Early luteal development in Santa Inês ewes superovulated with reduced doses of porcine follicle‐stimulating hormone

“…The gradual increase of CLs diameter during the early luteal phase observed in animals from G100 and G133 indicates adequate development of these structures based on the information brought by some authors (Gonzalez de Bulnes et al, ; Kraisoon et al, ), who described progressive increasing of luteal area and CL weight, respectively, until mid‐luteal phase in sheep. Conversely, animals which received 200 mg of pFSH presented an increase in the diameter of CLs only between Days 11–13 and then, reduction on Days 14 and 15.…”

“…From these findings, it can be expected that the production of embryos can be favoured when the lowest dose of pFSH is used. Although more studies are needed to confirm our hypothesis, the number of ovulations is decisive for the embryo yields as well as the luteal dynamic, especially the adequate progesterone concentrations until embryo collection day are beneficial to the uterine environment and embryonic development in donor females (Connell et al, ; Kraisoon et al, ). Brasil et al () observed a similar number of CLs to that obtained in this study using 133 mg of total dose of pFSH in Santa Inês ewes.…”

“…In small ruminants superovulatory protocols, the total doses of pFSH (Folltropin®, Bioniche, Canada) more frequently used are 256 mg (Oliveira et al, ), 215 mg (Sánchez‐Dávila et al, ) or 200 mg (Loiola Filho et al, ; Oliveira et al, ) while in cows good results are achieved with lower doses (100–133 mg) (Baruselli et al, ). Therefore, studies addressing the efficacy of lower doses of FSH in sheep are needed.…”

“…Therefore, studies addressing the efficacy of lower doses of FSH in sheep are needed. Because, high doses of FSH may induce changes in ovarian and/or endocrine dynamics (Kafi & McGowan, ) and on LH pulses, increasing the incidence of PRCL (Bevers, Dieleman, Blankestein, Tol, & Broek, ; Oliveira et al, ) besides being more expensive (Loiola Filho et al, ). Furthermore, higher doses may maintain the stimulus of the luteinized anovulatory follicles for longer periods, so these follicles are still producing oestrogen in the early luteal phase, causing persistence of high concentrations of this hormone, providing the early release of PGF2α and thus premature luteal regression (Okada et al, ).…”

“…Although the mechanisms determining the PRCL are not yet fully understood, the gonadotrophin used, commercial product, manufacturing batch, FSH:LH ratio of the preparation, protocol of injection and/or use of high exogenous FSH doses may influence on this incidence (Kafi & McGowan, ; Quan et al, ). There are few reports in the literature regarding studies with lower doses of FSH in sheep (Loiola Filho et al, ; Sánchez‐Dávila et al, ; Wu et al, ), moreover there is no disclosure of results concerning the effects on luteal development dynamics, as well as about the occurrence of PRCL. We hypothesized that the incidence of PRCL decreases when lower doses of exogenous pFSH are used in embryo donor sheep.…”