Ovarian function and pregnancy outcome in pony mares following immunocontraception with native and recombinant porcine zona pellucida vaccines

Reasons for performing study: Few studies have investigated ovarian function in the mare undergoing porcine zona pellucida (pZP) immunocontraception despite reported ovarian dysfunction in other species. Objectives: This study aimed to describe ovarian function and oestrous cyclicity in pony mares following treatment with either the conventional pZP vaccine or a novel recombinant form of the vaccine derived from porcine ZP3 and ZP4 (reZP). In addition, the contraceptive efficacy of pZP versus reZP was assessed. Study Design: Mares (n=21) were randomized into three groups of seven: Group I received the conventional pZP vaccine, with a booster five weeks later; Group II received the reZP vaccine, with a booster five weeks later; and Group III (controls) received two treatments, five weeks apart, of saline and adjuvant alone. Data were collected over a 24 week period coinciding with the physiological breeding season, with treatments commencing in week four. Methods: Mares underwent weekly monitoring via trans-rectal palpation and ultrasound examination of the reproductive tract, with daily monitoring during oestrus. Serum samples were obtained for antibody titres and ovarian steroid level analyses at seven day intervals. Cycling mares were bred via fresh semen artificial inseminations, over a maximum of two consecutive oestrous cycles that commenced five weeks post booster vaccination. Results: Control mares cycled throughout the trial. Post-treatment, six of seven pZP mares (86%) and one reZP mare (14%) had extended anoestrus that correlated with basal serum oestradiol and progesterone levels. All mares resumed cyclicity by ten months post treatment. Pregnancies were diagnosed in all controls, four reZP- (57%) and none of the pZP- immunized mares. Conclusions: The current study demonstrates the reversible suppression of ovarian function in pony mares following treatment with pZP. The effect of the reZP vaccine on pregnancy outcome requires further investigation

Consistency test of general relativity from large scale structure of the Universe

We construct a consistency test of General Relativity (GR) on cosmological scales. This test enables us to distinguish between the two alternatives to explain the late-time accelerated expansion of the universe, that is, dark energy models based on GR and modified gravity models without dark energy. We derive the consistency relation in GR which is written only in terms of observables - the Hubble parameter, the density perturbations, the peculiar velocities and the lensing potential. The breakdown of this consistency relation implies that the Newton constant which governs large-scale structure is different from that in the background cosmology, which is a typical feature in modified gravity models. We propose a method to perform this test by reconstructing the weak lensing spectrum from measured density perturbations and peculiar velocities. This reconstruction relies on Poisson's equation in GR to convert the density perturbations to the lensing potential. Hence any inconsistency between the reconstructed lensing spectrum and the measured lensing spectrum indicates the failure of GR on cosmological scales. The difficulties in performing this test using actual observations are discussed.Comment: 7 pages, 1 figur

Controlling wildlife reproduction : reversible suppression of reproductive function or sex-related behaviour in wildlife species

Fertility control represents a proactive approach to population management for various mammalian wildlife species. In large predators, deslorelin implants have proven to be useful contraceptives in species such as lions, tigers and cheetahs. Although female lions and tigers responded well to various doses of deslorelin, the 9.4 mg implants at 48-month intervals are recommended for treatment of these species. In cheetahs both sexes could be effectively down-regulated using annual 4.7 mg implants. It does however, appear that certain species, like the African wild dog, are more difficult to down-regulate than others. Whether this relates to differences in peripheral deslorelin concentrations achieved or to actual concentrations at the effector site is unknown. Determining peripheral deslorelin concentrations in species like the lion, cheetah and wild dog may provide some answers. LH response to GnRH stimulation at various intervals after deslorelin treatment may also be informative. Additionally, the ability to deliver the implants remotely would make this method of contraception much more appealing to reserve managers. Immunocontraception of free-ranging African elephant cows with the porcine zona pellucida (pZP) vaccine has been shown to be 100% effective in small to medium populations. The protocol followed was three vaccinations (400 μg pZP with Freund’s complete modified adjuvant; 200μg and 200 μg with Freund’s incomplete adjuvants) at 4 to 6-week intervals during the first year followed by a single annual booster (200 μg with Freund’s incomplete adjuvant) thereafter. The vaccine was delivered remotely with darts and thus capture was not required for treatment of the cows. Of the 108 cows treated 62 (57.4%) were pregnant at the time of primary vaccination and calved during Years 1 and 2 of the program. Once these cows had calved, no more calves were born. The method was shown to be safe to use in pregnant cows. A small number of cows developed minor temporary swellings at the dart site. Future research should concentrate on development of slow-release vaccine-formulations that would reduce implementation costs and enable use on larger populations. Although studies are ongoing, there is also a need to expand behavioural studies on treated populations. A GnRH vaccine produced promising results for the down-regulation of androgen-related behaviour in elephant bulls. The bulls were given a primary and two to three booster vaccinations (4 to 7 week intervals) while behaviour and faecal androgen metabolite concentrations were monitored. More intensive studies on animals (African and Asian elephant bulls) of various ages are required to determine whether the treatment is capable of suppressing the annual musth cycles and to establish the effects of GnRH vaccination on male fertilit

Non-invasive assessment of the reproductive cycle in free-ranging female African elephants (Loxodonta africana) treated with a gonadotropin-releasing hormone (GnRH) vaccine for inducing anoestrus

Background In southern Africa, various options to manage elephant populations are being considered. Immunocontraception is considered to be the most ethically acceptable and logistically feasible method for control of smaller and confined populations. In this regard, the use of gonadotropin-releasing hormone (GnRH) vaccine has not been investigated in female elephants, although it has been reported to be safe and effective in several domestic and wildlife species. The aims of this study were to monitor the oestrous cycles of free-ranging African elephant cows using faecal progestagen metabolites and to evaluate the efficacy of a GnRH vaccine to induce anoestrus in treated cows. Methods Between May 2009 - June 2010, luteal activity of 12 elephant cows was monitored non-invasively using an enzyme immunoassay detecting faecal 5alpha-reduced pregnanes (faecal progestagen metabolites, FPM) on a private game reserve in South Africa. No bulls of breeding age were present on the reserve prior to and for the duration of the study. After a 3-month control period, 8 randomly-selected females were treated twice with 600 micrograms of GnRH vaccine (Improvac®, Pfizer Animal Health, Sandton, South Africa) 5-7 weeks apart. Four of these females had been treated previously with the porcine zona pellucida (pZP) vaccine for four years (2004-2007). Results All 12 monitored females (8 treated and 4 controls) showed signs of luteal activity as evidenced by FPM concentrations exceeding individual baseline values more than once. A total of 16 oestrous cycles could be identified in 8 cows with four of these within the 13 to 17 weeks range previously reported for captive African elephants. According to the FPM concentrations the GnRH vaccine was unable to induce anoestrus in the treated cows. Overall FPM levels in samples collected during the wet season (mean 4.03 micrograms/gram dry faeces) were significantly higher (P<0.002) than the dry season (mean 2.59 micrograms/gram dry faeces). Conclusions The GnRH vaccination protocol failed to induce anoestrus in the treated female elephants. These results indicate that irregular oestrous cycles occur amongst free-ranging elephants and are not restricted to elephants in captivity. The relationship between ecological conditions and endocrine activity were confirmed. Free-ranging female elephants were observed to not cycle continuously throughout the year in the absence of adult bulls

Collection of preputial material by scraping and aspiration for the diagnosis of Tritrichomonas foetus in bulls

Two trials were carried out to assess the diagnostic sensitivity and practicability of preputial scraping as a method of collecting preputial material from bulls infected with Tritrichomonas foetus. In the 1st trial, preputial material was collected by simultaneous scraping and aspiration from 3 infected and 1 uninfected bull 10 times over a 5-week period. In the 2nd trial, samples from 5 infected bulls were collected by both sheath washing and scraping on 6 occasions, while 8 uninfected animals were sampled 3 times. Samples were cultured using a modified Trichomonas culture medium (Oxoid). In the first trial, 29 of 30 samples from infected bulls were found to be positive. In the second trial, 83 % of samples collected by both methods tested positive. In neither trial were any samples from the control bulls found to be positive. Scraping was found to be quick and safe, and offered advantages over preputial washing in that urine contamination was easily avoided, samples were smaller and more concentrated and contamination was reduced. It may, however, be subject to greater operator variability than sheath washing. It is concluded that preputial scraping is as effective as washing and represents a suitable alternative for the collection of material for direct examination and culture of Tritrichomonas foetus

Evaluation of oestrus observation and conception rates in suckling beef cows using whole milk progesterone concentration

A 2-sample regime was used to measure whole milk progesterone concentration on the day of oestrus and insemination (Day 0) and 6 days later (Day 6) in a sample of 50 primiparous and 100 multiparous suckling beef cows. Exposure to teaser bulls and observation by cattlemen identified the occurrence of oestrus. Three sets of criteria used to define ovulatory oestrus were compared : a) milk progesterone concentration less than 6 nmol / l on Day 0 ; b) milk progesterone less than 6 nmol / l on Day 0 and rising to greater than 6 nmol / l on Day 6; c) milk progesterone less than 6 nmol / l on Day 0 and rising to greater than 6 nmol / l on Day 6, or cow diagnosed pregnant to 1st insemination. Using only a single milk sample on Day 0 (criterion a) would have resulted in the positive predictive value of heat detection being estimated at 98.7%. Using a paired measurement (criterion b) resulted in a significantly lower estimate of 84.7%. The inclusion of cows that conceived despite not showing a marked rise in milk progesterone concentration (criterion c) resulted in a more accurate estimate of 89.3%. Use of a 2-sample regime also allowed calculation of conception rates while eliminating the effect of heat detection errors. In the cows sampled, of those in ovulatory oestrus that were inseminated, 73.1% conceived to the 1st insemination. These results demonstrate that artificial insemination within a limited breeding season can be successful if nutrition is optimal and management is intensive. The use of a 2-sample milk progesterone test may be a valuable tool in investigating heat detection and conception problems in beef herds in which artificial insemination is used

Ovarian suppression following pZP vaccination in pony mares and donkey jennies

Immunocontraceptive vaccines target one or more selected proteins essential to a critical step in fertility. Examples include anti-gonadotrophin release hormone (GnRH) and native porcine zona pellucida (pZP) vaccines. The successful application of pZP vaccines over several decades for population management in feral horse populations in the USA is well described. The currently-hypothesised mechanism responsible for this vaccine’s contraceptive effect is the prevention of sperm-zona binding, sperm penetration of the zona and thus fertilisation of the oocyte, which is prevented for as long as antibody titres are sufficiently high whilst treated females continue to cycle normally. Our group’s recent research projects investigated pZP vaccination of pony mares in South Africa and donkey jennies in the Caribbean. These trials included intensive clinical and laboratory monitoring and clearly showed that the majority (85.7%) of both mares and jennies treated with the vaccine formulated with either Freund’s complete modified (primary) or Freund’s incomplete (booster) adjuvants developed small inactive ovaries. This was accompanied by baseline serum progesterone concentrations typical of anoestrus. All mares resumed normal cyclic activity after approximately 7-8 months during the following physiological breeding season. We additionally measured the concentrations of anti-Müllerian hormone (AMH) at strategic times during the mare study to better define the mechanism of ovarian shut-down. Notably, AMH, which is reportedly well correlated with small antral follicle counts in the mare, was not detectable during the intervals of ovarian suppression. Of further interest was an AMH rebound observed coincident with the recovery of ovarian cyclicity. As normal ovarian function was re-established in all mares, an inflammatory process (with or without cellular invasion) seems an unlikely explanation for this ovarian response. These results showed vaccination was followed by a period of ovarian suppression related to the loss or malfunction of small antral follicles and suggested that prevention of fertilisation was not the only potential mechanism responsible for infertility in pZP-immunocontracepted mares