The Functional Role of Oxytocin in the Induction of Oocyte Meiotic Resumption in Cattle

The aim of the present study was to examine the role of oxytocin (OT) in the progesterone (P4) and prostaglandins (PGs) pathway to induce oocyte meiotic resumption. Cumulus–oocyte complexes were co‐cultured with follicular hemisections for 15 h to determine the effects of different doses of OT or atosiban (ATO; oxytocin receptor antagonist) on oocyte meiotic resumption. In another experiment, we examined the effect of the interaction between P4, OT and PGs on the regulatory cascade of the oocyte meiotic resumption. Oxytocin at 1 μm was effective in inducing meiotic resumption in oocytes co‐cultured with follicular cells (84.0%), not differing from the positive control group (74.4%). Atosiban inhibited in a dose‐dependent manner the positive effect of OT on the meiotic resumption (27.6% metaphase I with 10 μm of ATO, which did not differ from the 25.5% of the negative control group). Furthermore, a third experiment showed that P4 was able to induce oocyte meiotic resumption, which was inhibited by ATO. However, the OT positive effect was not blocked by mifepristone (P4 antagonist), but was inhibited by indomethacin (a non‐selective PTGS2 inhibitor). Collectively, these data suggest a sequential role of P4, OT and PGs in the induction of oocyte meiotic resumption.     

Effects of Hypo‐ and Hyperthyroidism on Proliferation,Angiogenesis, Apoptosis and Expression of COX‐2 in the Corpus Luteum of Female Rats

Although thyroid dysfunction occurs frequently in humans and some animal species, the mechanisms by which hypo‐ and hyperthyroidism affect the corpus luteum have not been thoroughly elucidated. This study evaluated the levels of proliferative activity, angiogenesis, apoptosis and expression of cyclooxygenase‐2 in the corpus luteum of female rats with thyroid dysfunction. These processes may be important in understanding the reproductive changes caused by thyroid dysfunction. A total of 18 adult female rats were divided into three groups (control, hypothyroid and hyperthyroid) with six animals per group. Three months after treatment to induce thyroid dysfunction, the rats were euthanized in the dioestrus phase. The ovaries were collected and immunohistochemically analysed for expression of the cell proliferation marker CDC‐47, vascular endothelial growth factor (VEGF), VEGF receptor Flk‐1 and cyclooxygenase‐2 (COX‐2). Apoptosis was evaluated using the TUNEL assay. Hypothyroidism reduced the intensity and area of COX‐2 expression in the corpus luteum (p < 0.05), while hyperthyroidism did not alter COX‐2 expression in the dioestrus phase. Hypothyroidism significantly reduced the expression of CDC‐47 in endothelial cells and pericytes in the corpus luteum, whereas hyperthyroidism did not induce a detectable change in CDC‐47 expression (p > 0.05). Hypothyroidism reduced the level of apoptosis in luteal cells (p < 0.05) and increased VEGF expression in the corpus luteum. In contrast, hyperthyroidism increased the level of apoptosis in the corpus luteum (p < 0.05). In conclusion, thyroid dysfunction differentially affects the levels of proliferative activity, angiogenesis and apoptosis and COX‐2 expression in the corpus luteum of female rats.     

Tortoises and tourists in the Western Indian ocean: The curieuse experiment

A colony of giant tortoises Geochelone gigantea from Aldabra Atoll was established in 1978 on the island of Curieuse in the granitic Seychelles, where tortoises have long been extinct. Ninety-five were landed in April 1978 and 78 in April 1980. The animals have shown considerable increases in wieght, and the first hatchling was found n February 1980. The main purpose of the colony is to provide a tourist attraction within easy reach of Mahé and deflect tourist pressure from Aldabra: at the same time the colony has considerable scientific potential. The environment and history of Curieuse are reviewed in the light of criteria initially established for the choice of an island for the project, and the future of the experiment is discussed.     

Attempted immunisation of cats against feline infectious peritonitis using canine coronavirus

Specific pathogen free kittens were vaccinated with an unattenuated field isolate of canine coronavirus (CCV) either by aerosol or subcutaneously, and received boosting vaccinations four weeks later. Aerosolisation elicited a homologous virus-neutralising (VN) antibody response that increased steadily over a four-week period and levelled off one to two weeks after revaccination. The initial aerosolised dose produced an asymptomatic infection with excretion of CCV from the oropharynx up to eight days after vaccination; virus shedding was not detected, however, after the second inoculation. Cats vaccinated subcutaneously developed low VN antibody titres after the first CCV dose and experienced a strong anamnestic response after the second dose. Neutralising antibody titres then levelled off one to two weeks after revaccination at mean values somewhat lower than in cats vaccinated by aerosol. CCV was not isolated from the oropharynx after either subcutaneous dose. Four weeks after CCV boosting inoculations, vaccinated cats and sham-vaccinated control cats were divided into three subgroups and challenged by aerosol with the virulent UCD1 strain of feline infectious peritonitis virus (FIPV UCD1) at three different dosage levels. Five of six cats (including sham-vaccinated controls) given the lowest challenge dose showed no signs of disease, while all other cats developed lesions typical of feline infectious peritonitis (FIP). The five surviving cats developed FIP after subsequent challenge with a fivefold higher dose of FIPV. Thus heterotypic vaccination of cats with CCV did not provide effective protection against FIPV challenge.     

Administration of hCG 5 days after Breeding and Reproductive Performance in Nulliparous Dairy Goats

The objective of this study was to investigate the effect of hCG administration 5 days after breeding on plasma progesterone (P4) concentration and reproductive performance of oestrous-induced nulliparous dairy goats. A total of 59 nulliparous goats (36 Alpine and 23 Saanen) received intravaginal sponges with 60 mg medroxyprogesterone acetate for 9 days plus 200 IU equine chorionic gonadotrophin (eCG) and 22.5 microg d-cloprostenol 24 h before sponge removal. After detection of oestrus (day of oestrus = day 0) and breeding, 49 females were randomly assigned, according to the breed, into two treatments (T1 and T2). In T1 (n = 25) and T2 (n = 24), animals received intramuscular injection of 1 ml of saline solution (control) or 250 IU hCG, respectively, 5 days after breeding. Plasma P4 concentration (ng/ml) was determined from blood sampled on days 0, 5, 7, 13, 17, 21, 28 and 45 after breeding. Animals were scanned by transrectal ultrasound (5 MHz probe) on days 35 and 70 after breeding for detection of pregnancy. Plasma P4 concentration did not differ (p > 0.05) between treatments in all days, but it was increased (p < 0.05) in Saanen than in Alpine goats from days 13 to 45. Pregnancy and parturition rates, litter size and gestation period were similar (p > 0.05) to treatments and breeds. Results of this study indicate that human chorionic gonadotrophin (hCG) administration 5 days after breeding did not significantly alter reproductive performance in dairy nulliparous goats and that plasma P4 differed between Saanen and Alpine goats.     

Elimination of bovine viral diarrhoea virus in New Zealand: a review of research progress and future directions

The major impacts of bovine viral diarrhoea (BVD) on cattle health and production have prompted many countries to embark on national elimination programmes. These programmes typically involve identifying and removing persistently infected (PI) cattle in infected herds and implementing biosecurity measures, such as pre- or post-movement testing. In order to design a systematic national control programme to eliminate BVD in New Zealand, which achieves the greatest benefits to the industries at the lowest cost to individual farmers, an accurate understanding is necessary of the epidemiology, economics and social motivation for BVD control in New Zealand. In this article we briefly review the pathogenesis of BVD, transmission and diagnosis of BVD virus infection, and effectiveness of vaccination. We summarise the current state of knowledge of the prevalence, risk factors for transmission, and financial impacts of BVD in New Zealand. We describe control programmes in Europe and then discuss the challenges that must be addressed to design a cost-effective national control programme to eliminate BVD in New Zealand.     

Colour‐Doppler ultrasound imaging as a laparoscopy substitute to count corpora lutea in superovulated sheep

This study evaluated colour‐Doppler ultrasound imaging (UI) as a substitute for laparoscopy to count the corpora lutea (CL) in superovulated sheep. Twenty‐five Santa Ines ewes were superovulated three times at 21‐day intervals. Corpora lutea were counted by colour‐Doppler UI (CL_DOPPLER) 6 days after each superovulation and confirmed by laparoscopy (CL_LAP) 12 hr later. The mean number of CL was similar for both techniques (2.1 ± 2.5 vs. 2.1 ± 2.7 for CL_DOPPLER and CL_LAP, respectively) with a significant positive correlation (r = .94; r²=.89). Colour‐Doppler UI effectively evaluated the ovarian response in superovulated ewes and efficiently identified animals that did not respond to superovulation.     

Pre‐Selection Test to Identify High Responder Donor Goats

The aim of the study was to evaluate the feasibility of pre‐selection of high or low responder does prior to the superovulatory protocols. Twenty Saanen does received 800 IU of equine chorionic gonadotropin (eCG) at the end of long‐term progestogen treatment. Fourteen days later, a second progestogen protocol associated with a multiple‐dose follicle stimulation hormone (FSH) treatment (5 IU/kg of FSH, in six decreasing doses between days 4 to 6 of the protocol) was administered. Transrectal ultrasound was used to assess the follicular status at the beginning of superovulatory treatments, at the oestrous onset and on the seventh day of the oestrous cycle for counting corpora lutea (CL). A significant lower number of CL was obtained in eCG‐treated in comparision with FSH‐treated does (p < 0.05). A quartic regression was able to explain the relationship between the number of CL in response to both treatments (r²=0.50; p < 0.05). Seventy per cent (14 of 20) of does maintained the same ovulatory response (high or low) after treatments. The Kappa (κ = 0.40; p < 0.05) and Spearman (rs = 0.39; p = 0.08) coefficients were able to show a relationship between treatments. Regarding the follicular status, there is a significant relationship between the number of small follicles (r = 0.71; r²=0.47; p < 0.01) and total follicles (r = 0.60; p < 0.01) at eCG and first FSH dose with the number of CL. Moreover, it was found a negative relationship between the presence of large follicles and the number of CL in response to eCG treatment (r = ?0.44; p < 0.05), but not from FSH (p > 0.05). In conclusion, the screening test with eCG has the potential to identify Saanen does that will better respond to the superovulatory protocol with FSH. In addition, it highlighted the importance of an ultrasound evaluation prior to the beginning of superovulatory treatments with FSH to characterize the follicular status and identify the potential donors of high ovulatory response in MOET programmes in goats.     

Abortion in goats by Caprine alphaherpesvirus 1 in Spain

An abortion outbreak occurred in a goat herd of Murciano‐Granadina breed in Almeria Region in Spain where 80 pregnant females aborted. All bacteriological and parasitological examinations resulted negative, whereas virological investigations and real‐time PCR assay showed the presence of Caprine alphaherpesvirus 1 DNA in the pathological specimens from aborted foetuses. Nucleotide sequence analysis revealed that the DNA was highly close related to the Swiss strain E‐CH (99.7%) and a little less extent to the Italian BA.1 strain (99.4%). Histopathological examination revealed multifocal, well‐circumscribed, 50‐ to 200‐μm‐diameter foci of coagulative necrosis in the liver, lungs and kidneys of three foetuses. In the periphery of the necrosis, there were frequently epithelial cells with the chromatin emarginated by large, round, amphophilic intranuclear viral inclusion bodies. The source of the infection in the herd could not clearly find out even some hypothesis were formulated. This seems to be the first report of an abortion outbreak due to Caprine alphaherpesvirus 1 in a goat herd in Spain.