On-farm lambing outcomes after transfer of vitrified and slow frozen embryos.

The aim of the present study was to determine the most suitable embryonic stage and embryo freezing technique for commercial implementation of frozen embryo trading by small-scale sheep producers. There was a 2 × 2 factorial design utilized for conducting the study consisting of two embryo stages (2-8 cells or morula/blastocyst) and two cryopreservation protocols (vitrification or slow-freezing). For the in vivo produced embryos, there were treatments of crossbred donor ewes to induce superovulation. Embryos were recovered surgically on either Day 2 or 5.5 after estrous onset. The embryos were cryopreserved using either a vitrification or slow-freezing method before there was transfer to recipients. Ovarian response, embryo survival and lambing outcomes were analyzed. There were no differences in number of recovered and fertilized embryos at the two embryonic developmental stages. There were no effects of embryonic stages and cryopreservation methods on pregnancy rate, twinning rate, fetal birth weights and lamb weight at 1 month of age. When there was use of vitrified embryos for transfers, there was a greater lamb weight at 2 months of age (8.38 ± 0.20 compared with 7.78 ± 0.21 kg; P = 0.044) than when there was transfer of embryos cryopreserved using slow freezing procedures. Considering economic and practical benefits to small-scale sheep farms, morula/blastocyst stage-embryo collection and transfer into the uterus is more efficacious than transferring 2-8 cells embryos into the oviduct. Results of this study may contribute to the genetic improvement in the flocks of small-scale sheep producers.

Comparison of the ovarian and uterine reproductive parameters, and the ovarian mRNA and protein expression of LHR and FSHR between the prepubertal and adult female cats.

This study aimed to evaluate and compare the ovarian and uterine characteristics along with the ovarian mRNA and protein expression of LHR and FSHR between the pre-pubertal and adult female cats. The uterine horns and ovaries were collected from pre-pubertal and adult female cats at their follicular, luteal and interoestrous stages of the oestrous cycle (n = 6/group). Endometrial and myometrial thickness, uterine gland diameter, ovarian weight and type of follicles were analysed. The mRNA and protein expression of LHR and FSHR was analysed by IHC and qPCR, respectively. The ovarian weight of pre-pubertal cats was significantly lower than that of adult cats. No differences were recorded in the numbers of primordial and primary follicles between the study groups, while adult luteal cats had significantly lower numbers of antral follicles compared to pre-pubertal cats. No differences in the ovarian expression of FSHR mRNA, LHR protein or mRNA were found between the pre-pubertal and adult cats, but significantly lower FSHR protein expression was found in pre-pubertal cats compared to adult luteal cats.

GnRH-agonist implants suppress reproductive function and affects ovarian LHR and FSHR expression in prepubertal female cats.

Effect of a GnRH-agonist (deslorelin) was studied on reproductive function and ovarian luteinizing hormone receptor (LHR) and follicle stimulating hormone receptor (FSHR) expression in prepubertal female cats that were either implanted with 4.7-mg deslorelin (implanted: n = 6) or not (controls: n = 18) or ovariohysterectomized at prepubertal age (prepubertal OVH: n = 6). Body weights, fecal estradiol, and sexual behavior of implanted and control cats were monitored for 48 weeks followed by collection of ovaries and uteri. Ovaries and uteri were collected from control cats at follicular, luteal, and inactive stage (n = 6/group) and from prepubertal OVH cats at prepubertal age. Ovaries and uteri were analyzed for anatomical/histological characteristics. Ovaries were also analyzed for LHR and FSHR expression. Statistical analysis showed higher (P ≤ 0.05) body weight in control than implanted cats only during 22nd to 26th weeks of the study. Estrus was observed in control cats only. Deslorelin reduced (P ≤ 0.05) ovarian weight and number of antral follicles but did not affect endometrial thickness and gland diameter. However, myometrial thickness of implanted cats was significantly lower than control cats at follicular and luteal stage. Ovarian LHR mRNA expression was lower (P ≤ 0.05) in implanted cats than control cats at follicular stage. FSHR mRNA and LHR protein expression did not differ among the three groups. FSHR protein expression was lower (P ≤ 0.05) in prepubertal OVH cats and was not affected by deslorelin. In conclusion, deslorelin suppresses reproductive function in prepubertal female cats for at least 48 weeks possibly through a change in the ovarian mRNA expression of LHR.

GnRH-agonist implantation of prepubertal male cats affects their reproductive performance and testicular LH receptor and FSH receptor expression.

This study was conducted to investigate the effect of GnRH-agonist implantation in prepubertal tomcats on sexual behavior, reproductive performance, and expression of testicular LH receptor (LHR) and FSH receptor (FSHR) and also to compare the testicular characteristics, LHR and FSHR expression between prepubertal and adult tomcats. In experiment 1, 3-month-old tomcats (n = 6/group) were either treated with or left without 4.7 mg deslorelin implants. Semen collection and evaluation were performed just before castration at 48 weeks after treatment; removed testes were analyzed for mRNA and protein expression of LHR and FSHR. We were able to collect semen from six non-treated cats, whereas in treated cats, semen was uncollectable. The results revealed that sexual behavior was absent in the implanted cats throughout the study period. Testicular volume was found to decrease from 30 weeks after treatment onward in the implanted cats compared to the controls (P < 0.05). Semen production was found only in non-implanted cats. Testicular tissue score, seminiferous tubule diameter, and LHR protein expression were found lower in the implanted cats (P < 0.05), but no differences were observed in mRNA expression of LHR and protein expression of FSHR between groups. The mRNA expression of FSHR was higher in the implanted (P < 0.05) compared to control cats. In experiment 2, testes from prepubertal (n = 6) and adult (n = 6) male cats were collected after castration and analyzed for mRNA and protein expression of LHR and FSHR. No differences were observed in the protein expression of LHR and FSHR between the two groups, whereas mRNA expression of FSHR was higher in prepubertal cats (P < 0.05). Testicular and epididymal weight, diameter of seminiferous tubules, and the testicular grade were higher in the adult compared to prepubertal cats (P < 0.05). In conclusion, deslorelin implants suppressed protein expression of LHR and enhanced mRNA expression of FSHR along with suppression of reproductive function without any adverse effects for at least 48 weeks in male cats.

A review of advances in the use of the GnRH agonist deslorelin in control of reproduction.

The prevention of breeding in animals using GnRH analogues has been the object of research over many years. Recently, a new drug delivery formulation was developed which enabled the development of products that could be commercialised for veterinary use. The formulation has now been approved in certain countries for use in male dogs, and applications are being expanded to cover repeat usage, extended duration, use in females, other indications and other animal species. With respect to repeat usage, dogs have been re-implanted for four consecutive doses and monitored until they returned to normal steroidogenesis. All dogs returned to normal steroidogenesis following cessation of treatment. In females, it was previously shown that implanted bitches with progesterone < 5 ng/mL at the time of implantation had an induced estrus. In a new study at Chulalongkorn University, implanting female pups at around 4 mo prevented this occurrence, whereas implantation at 7 mo did not.