In this study, two successive field trials were conducted during the non-breeding season to investigate various factors affecting on fertility of Suffolk ewes after intrauterine insemination with frozen-thawed semen. In the first year (Experiment 1), three sperm numbers per insemination dose (0.25, 0.5 and 1 million sperm) and five sheep farms were used, and in the second year (Experiment 2), parity, age, body weight, body condition score (BCS) and postpartum days were investigated to compare pregnancy and lambing rates. High pregnancy and lambing rates (70.6 and 70.6%, respectively) were obtained with 0.25 million sperm per dose. There were no significant differences in the pregnancy and lambing rates among the five farms, but there was a tendency for one farm to have higher pregnancy (75.8%, P=0.065) and lambing (72.7%, P=0.077) rates than those (46.7-53.3% and 45.2-53.3% for the pregnancy and lambing rates, respectively) of the other farms. In Experiment 2, ewe age significantly affected both the pregnancy and lambing rates. Nulliparous ewes had a higher lambing rate (72.0%) than that (44.2%) of multiparous ewes, but a significant difference was not revealed. Regardless of body weight, BCS tended to be an important factor influencing on fertility of ewes. Body weight and the postpartum days did not affect the fertility of ewes. It was concluded from these results that the fertility of Suffolk ewes after intrauterine insemination with frozen semen was significantly influenced by sperm number per dose and ewe age. Nulliparous ewes at less than three years of age and with a BCS of more than 3.0 are expected to have higher fertility than other ewes.

Abstract. The aim of this study was to investigate the effects of the presence and the numbers of corpora lutea (CL) in porcine ovaries on in vitro oocyte maturation and embryonic development following intracytoplasmic sperm injection (ICSI). At oocyte collection, the ovaries of non-delivered and delivered pigs were classified into four groups by CL presence. The effect of the number of CL was also investigated following re-division of the non-delivered groups into four groups. In addition, the progesterone (P4) concentrations in follicular fluid (FF) of all the groups were measured to confirm the relationship between the presence and numbers of CL. Throughout the present study, the oocytes recovered from the CL-holding ovaries showed high (P<0.05) oocyte maturation rates, blastocyst rates and P4 concentrations in FF. Furthermore, in the non-delivered groups, the blastocyst rates and P4 concentrations in FF seemed to coincide with the CL numbers in each ovary. From these findings, we concluded that the presence and number of CL in the ovary can be used as an indicator for estimation of the developmental competence of porcine oocytes. Additionally, the present study suggests that P4 in FF influences in vitro oocyte maturation and embryonic development in porcine in vitro production. Key words: Corpus luteum, Embryonic development after ICSI, Oocyte maturation, Pig, Progesterone (J. Reprod. Dev. 55: [655][656][657][658][659][660] 2009) o date, in vitro production (IVP) of embryos has been attempted in many species including pigs [1][2][3][4][5][6][7][8][9][10][11], cattle [12][13][14][15] and sheep [16,17]. In these trials, the oocytes used for IVP were obtained from animals in various stages of growth, e.g., sexual maturity. The usage of younger oocyte donors enables reduction of the generation interval and rapid expansion of a valuable genotype. In many cases, however, the oocytes obtained from prepubertal animals have had a lower developmental competence than those of postpubertal or aged animals [1,6,8,[14][15][16][17][18]. The low quality of oocytes recovered from prepubertal animals is the principal problem for IVP.In IVP of porcine embryos, prepubertal pigs without corpora lutea (CL) in their ovaries are commonly utilized as oocyte donors. The prepubertal individuals are characterized by the fact that they have not completed maturation or ovulated yet. Ovulation produces morphological and physiological changes in the ovaries. CL are formed after ovulation and secrete progesterone (P4), which seems to be transferred to follicular fluid (FF), leading to a change of the hormonal balance in the FF. Therefore, the preovulatory oocytes of prepubertal pigs without CL are exposed in FF with a lower P4 concentration than those of adult pigs [1].Supplementation of the culture media with P4 accelerates the meiosis resumption in porcine oocytes [19]. Thus, P4 might be a key molecule in oocyte maturation and subsequent development. Pigs are multi-ovulatory animals. Therefore, it is likely that under the presence of a...

Uterine artery embolization influenced reproductive ability in sheep and UAE with GP could lead to intrauterine growth retardation.

The mid-term influence of UAE on reproductive ability in sheep was minimal.