Factors Affecting the Fertility of Ewes after Intrauterine Insemination with Frozen-Thawed Semen During the Non-Breeding Season

Abstract

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.

Factors influencing the pregnancy rate in indigenous ewes following AI using frozen semen

“…However, the pregnancy rate was nonsignificantly higher after LAPAI (75.0 vs. 60.0%) than after TCAI with cervical relaxation treatment. LAPAI bypasses the cervix and deposits semen directly into uterine horn (Fukui et al, 2010). These findings conform to the study of Hiwas et al…”

Management Factors Affecting Fertility in Sheep

“…In this sense, in highly prolific ewes like D'Man breed, higher levels of nutrition prior to and during mating were associated with improved reproductive performance, but in low prolific breeds such as Queue Fine de l'Ouest, neither ovulation rate nor lambing rate were affected by the dietary treatment. In a recent work by Fukui et al (2010) body weight did not significantly affect fertility. Body condition score (BCS) has proved useful as a management tool for subjectively assessing the nutritional status of ewes.…”

“…With the aim of improving its efficiency, this paper focuses on identifying the main management effects affecting AI results when this technology is applied. Paulenz et al (2007), observed that the age of the ewes had a significant effect on the nonreturn rate, but not on lambing rate, whereas in Fukui et al (2010), both the pregnancy and lambing rates in the ewes significantly declined as age increased. The detrimental effect of increased fertility age could be explained by the fact that aged ewes have increased risks of reproductive disorders and decreased ovulation rates with quality ovulated oocytes compared with younger ewes.…”

“…The importance of BCS in fertility has been also reported in Spanish Manchega breed (Montoro, 1995). Fukui et al (2010), , concluded that body nutritional condition is an important factor, next to ewe age, influencing the fertility of ewes after AI regardless of body weight. Nulliparous ewes less than 3 years old and with a BCS of more than 3.0 are expected to have higher fertility than other types of ewes.…”

Traversing the ovine cervix – a challenge for cryopreserved semen and creative science

“…The inability to manipulate the ewe cervix per rectum, in the same way as in the cow, is a further difficulty. Thus, the application of MOET programmes, and indeed the use of frozen-thawed semen, which requires deposition within the uterus for successful fertilisation, still relies on laparoscopic penetration of the abdomen in ewes (Cognie, 1999;Cognie et al, 2003;Menchaca et al, 2009;Fukui et al, 2010).…”