The effects of superovulation on Brucella abortus infection in the bovine uterus

Uterine flushings were collected three times at predetermined intervals from 11 mixed-breed beef cows and cultured for Brucella abortus . Prior to sampling, all cows had aborted fetuses from which brucellae had been isolated. Initial collections were made between 21 and 34 days following abortion. The second flushing was conducted at the onset of injections used for inducing superovulation and the third flushing was conducted 6 to 8 days after the ensuing estrus. The latter two flushes were conducted between 60 and 120 days following abortion. Brucellae were isolated from uterine flushings collected from 6 of the 11 cows on the initial round of sampling. Cultures of all subsequent uterine flushings collected before and after injections for superovulation were negative. It was concluded that the superovulatory treatment is not likely to reactivate the release of brucellae into the uterine lumen during the period when embryos are normally collected.     

Effects of hormone-induced superovulation on latent infectious bovine rhinotracheitis virus in cattle

Twelve nulliparous, sexually mature heifers free of antibodies to infectious bovine rhinotracheitis (IBR) virus were exposed intranasally to Colorado strain IBR virus. After 3 mos, when the postexposure antibody titers had stabilized, the heifers were divided into three groups. Individuals in each group were treated with either saline, dexamethasone or follicle stimulating hormone (FSH) for five consecutive days. Blood samples were taken at predetermined intervals for isolation of virus, and for determination of serum cortisol levels. No changes occurred in the saline-treated group, except that one heifer had a slightly elevated serum neutralizing antibody titer. Recrudescense of typical clinical lesions was observed in the dexamethasone-treated group, and the IBR virus was isolated from nasal swab samples taken from all heifers. In the FSH-treated group, no changes occurred, with the exception of slightly reduced serum cortisol levels. Results indicate that FSH-induced superovulation does not cause reactivation of IBR virus in heifers previously infected by the intranasal route, and has no effect on serum neutralizing anti-IBR virus antibody titers.     

The effect of a GnRH antagonist pre-treatment,in the superovulation of goats

The effect of a short pre-treatment with a GnRH antagonist (Cetrorelix acetate) and the induced superovulation response was evaluated in goats. A total of 16 nanny goats were allocated to two groups. The goats in the antagonist treatment group (n = 8) received 6 doses of the GnRH antagonist, once daily, as a pre-treatment to superovulation. The does in the control group were provided with saline only. Natural mating was implemented using three fertile bucks. Large follicles on the ovaries were detected via ultrasound at 3.5 MHz. All goats were laparotomized and the CL's and cystic follicles visually recorded. Embryos were recovered via flushing and recorded 6 days after sponge removal. The number of large follicles induced and embryos produced were significantly increased by treatment. However, no differences were noted regarding the numbers of cystic follicles, indicating a lack of negative side-effects following the use of GnRH. In general, the number of large follicles and embryos were significantly (P < 0.05) higher in the treated group. It was demonstrated that a GnRH antagonist treatment can improve the superovulatory response by 64% and embryo recovery rate by 90% in goats.     

Polymorphisms of the bovine luteinizing hormone/choriogonadotropin receptor (LHCGR) gene and its association with superovulation traits

The major limitation to the development of embryo transfer technique in cattle is the highly variable between individuals in ovulatory response to FSH-induced superovulation. The objective of this study was to identify a predictor to forecast superovulation response on the basis of associations between superovulation performance and gene polymorphism, variation in the bovine luteinizing hormone/choriogonadotropin receptor (LHCGR) gene was investigated using PCR-single-strand conformational (PCR-SSCP) and DNA sequencing. Four single nucleotide polymorphisms (SNPs) of G51656T, A51703G, A51726G and G51737A were identified at the intron 9 of the LHCGR gene in 171 Chinese Holstein cows treated for superovulation, and evaluated its associations with superovulatory response. Association analysis showed that these four SNPs had significant effects on the total number of ova (TNO) (P < 0.05). Moreover, the A51703G and A51726G polymorphisms significantly associated with the number of transferable embryos (NTE) (P < 0.05). In addition, significant additive effect on TNO was detected in polymorphisms of G51656T (P < 0.05) and A51703G (P < 0.01), and the A51703G polymorphism also had significant additive effects on NTE (P < 0.01). These results indicate that LHCGR gene is a potential marker for superovulation response and can be used to predict the most appropriate dose of FSH for superovulation in Chinese Holstein cows.     

Effect of stage of follicular growth during superovulation on developmental competence of bovine oocytes

The final steps of oocyte capacitation and maturation are critical for embryonic development but detailed information is scarce on how the oocyte is affected during this period. In this study, 2033 oocytes were collected from 106 superovulated cattle at four different time points before ovulation. Follicular characteristics were measured and oocyte quality was assessed by morphology, mRNA expression of eight marker genes or developmental ability after in vitro/in vivo maturation and subsequent in vitro fertilization and culture. Approaching ovulation, expected increases in follicular size and cumulus expansion suggested progression of oocyte maturation. No differences were found in the expression patterns of analyzed genes, except for heat-shock-protein (Hsp) that was lower in in vivo matured oocytes collected shortly before ovulation. Oocytes collected at this time also had higher developmental ability measured as blastocyst rates (57.6%) after in vitro production while no differences were found between oocytes recovered earlier at the first three time points (39.3-41.5%). We conclude that oocytes recovered late in the preovulatory period are more developmentally competent than oocytes recovered at the pre-capacitation and the capacitation period, probably due to the former having matured in vivo. However, a precisely defined time for aspirating immature oocytes for subsequent in vitro development seems not to be crucial.     

Factors affecting superovulation in heifers treated with PMSG

In this study we determined 1) if the immunoneutralization of PMSG affected the ovulatory response, the number of large follicles and embryo yield compared with that of PMSG alone or pFSH, and 2) whether the stage of the estrous cycle at which PMSG was injected affected the ovulatory response and yield of embryos in superovulated heifers. Estrus was synchronized in 99 (Experiment 1) and 71 (Experiment 2) heifers using prostaglandin F2alpha (PG) analogue, cloprostenol, given 11 d apart in replicate experiments over 2 yr. In Experiments 1 and 2, heifers were randomly allocated to 1 of 3 treatments (initiated at mid-cycle): Treatment 1--24 mg of pFSH (Folltropin) given twice daily for 4 d; Treatment 2--a single injection of 2000 IU PMSG; Treatment 3--2000 IU PMSG followed by 2000 IU of Neutra-PMSG at the time of first insemination. In Experiment 3, 116 heifers were given 2000 IU PMSG on Day 2 (n = 28), Day 3 (n = 27), Day 10 (n = 41) or Day 16 (n = 20) of the estrous cycle. The PG was given at 48 h (500 microg cloprostenol) and 60 h (250 microg cloprostenol) after the first gonadotropin treatment. Heifers were inseminated twice during estrus, and embryos were recovered on Day 7, following slaughter and graded for quality. The numbers of ovulations and large follicles (> or =10 mm) were also counted. There was no effect of treatment on ovulation rate in Experiment 1, but in Experiment 2 it was greater (P < 0.002) in heifers given PMSG (14.7 +/- 1.5) than pFSH (7.5 +/- 1.4) or PMSG-neutra-PMSG (8.7 +/- 1.5). The number of large follicles was higher following PMSG than pFSH treatment in Experiment 1, and it was higher (P < 0.004) in heifers given PMSG (5.5 +/- 0.8) than pFSH (1.12 +/- 0.7) or PMSG-neutra-PMSG (2.7 +/- 0.8) in Experiment 2. The use of Neutra-PMSG did not affect the numbers of embryos recovered or numbers of Grade 1 or 2 embryos, but it did decrease the number of Grade 3 embryos in both experiments. In Experiment 3, the ovulation rate decreased (P < 0.004) when PMSG was given on Day 3 (5.7 +/- 1.46) of the cycle rather than on Day 2 (12.3 +/- 1.64), Day 10 (13.4 +/- 1.45) or Day 16 (12.5 +/- 1.87). There was no effect of day of treatment on the numbers of large follicles. The mean numbers of embryos recovered were lower (P < 0.01) in heifers treated on Day 3 (2.1 +/- 0.67) than on Day 2 (6.8 +/- 1.0), Day 10 (6.4 +/- 0.86) or Day 16 (7.8 +/- 1.87). It is concluded that Neutra-PMSG given to heifers treated with PMSG did not improve embryo yield or quality and that treatment with PMSG early in the cycle can result in acceptable embryo yields provided sufficient time elapses between treatment and luteolysis.     

The role of nutritional supplementation on the outcome of superovulation in cattle

Since the 1990s nutritional supplements including protein, fatty acids, vitamins, and minerals have been used to try and improve the superovulatory response of embryo donors in cattle. However, the accumulated information indicates that nutritional supplementation with protein, fatty acids, or minerals does not increase the number of viable embryos from superovulated cattle. Most of the evidence has shown that vitamin supplementation may increase the mean production of transferable embryos, but only in cows, as a detrimental effect on embryo viability has been reported in young heifers. Nevertheless, vitamin supplementation seems to be effective only when compared with control cows displaying a poor mean embryo production (i.e. less than four viable embryos), questioning the economical significance of such approach. Detrimental effects on embryo development have been reported in superovulated cattle supplemented with protein or fatty acids as well. New approaches to investigate the role of nutritional supplementation on superovulatory outcome in cattle are suggested in the present review. Overall, the available evidence indicates that nutritional supplementation strategies tested are not an effective approach to enhance the superovulatory outcome of well-fed cattle donors.     

Recent advances in the superovulation in cattle

The variability in the superovulatory response continues to be one of the most frustrating problems with embryo transfer in cattle. The removal of LH from pituitary extracts has tended to reduce the variability in response, and several studies involving the use of the purified porcine pituitary extract. Folltropin-V are reviewed. The major source of variability in the superovulatory response in cattle is the status of ovarian follicles at the time of initiation of gonadotrophin treatments. Data support the benefits of initiating gonadotrophin treatments at the time of emergence of a follicular wave. Incorporation of techniques designed to control follicular wave dynamics, such as follicular ablation, or treatment with estradiol/progesterone, have reduced the variability caused by treating cows at different stages of follicular development, and at the same time improved response by taking advantage of endogenous recruitment and selection mechanisms. New protocols offer the convenience of being able to initiate gonadotrophin treatments quickly and at a self-appointed time, without the necessity of estrus detection and without sacrificing response. Methods can be used for repeated superstimulation of donor animals at 25 to 30 day intervals, without regard to estrus detection or stage of the estrous cycle, and without compromising embryo production.     

The formulation of a national strategy for biological control of possums and bovine Tb

Abstract

The Government has designated the control of possums and bovine Tb a National Science Strategy (NSS) research area. An NSS Committee has been appointed by the Ministry of Research Science and Technology, commissioned to “identify, coordinate and promote national priorities for possum and tuberculosis (Mycobacterium bovis) related research in order that threats both to New Zealand's export markets and to conservation values can be eliminated”.     

Ovarian responses and FSH profiles at superovulation with a single epidural administration of gonadotropin in the Thai-Holstein crossbreed

The conventional method of ovarian superstimulation requires multiple injections of gonadotropins which is time-consuming and may be stressful for the cows. This study was designed to determine whether a single epidural injection of FSH (EI group) would induce the superovulatory response in the Thai-Holstein crossbreed and evaluate FSH plasma hormone concentrations. Eight cows (replication = 3; n=24) were assigned to one of 2 treatments in switch back design. Control group (n=12): cows were received 400 mg FSH twice daily by intramuscularly for 4 days (80, 80, 60, 60, 40, 40, 20 and 20 mg), EI group (n=12): cows were received 400 mg FSH by single epidural injection. Data were collected in term of ovarian follicle responses, superovulatory responses, ova/embryo collection. FSH concentrations were examined using ELISA. The total follicular responses during oestrus were not different between treatments; however, the large follicles were less frequent (P < 0.01) while the medium follicle sizes were higher (P < 0.05) in the EI group. The plasma concentration of FSH in EI was dramatically increased within 2 hours before decreasing sharply thereafter (P < 0.01) and did not remain above baseline after 10 hours of administration. The embryo quality was better in the control than the EI groups (P < 0.05). Interestingly, the number of ovulation cysts in the EI group was 50%. The ovarian responses and embryo quality in the cows with cysts were worse compared with the non-cyst groups (P < 0.05). In conclusion, alternative protocols decreased the superovulatory response and increased poor embryo quality in Thai-Holstein crossbred. Also, the incidence of ovarian follicular cysts is higher in the EI group.     

Hormonal control of estrous cyclicity and attempted superovulation in wood bison (Bison bison athabascae)

The wood bison (Bison bison athabascae) is a threatened Canadian species that has faced extinction twice in the last 100 yr. Development of assisted reproductive technologies could help ensure the long-term propagation and genetic management of this species. The objectives of this study were to refine estrus synchronization techniques and evaluate superovulatory responses after FSH or eCG administration. In Experiment 1, females were fitted with Syncro-mate B (SMB) implants for 9 d and received an injection of either estradiol valerate (E2V; n = 9) or cloprostenol (PGF; n = 9) at implant insertion (Day-9). In Experiment 2, estrus was synchronized with SMB implants and a PGF injection of Day-9, and superovulation was attempted on Day-2 with either 2500 IU eCG (n = 5) or 400 mg Folltropin-V (n = 5). In each experiment, biosin were examined daily for estrual behavior. Ultrasonography was used during the luteal phase to detect ovulation and assess ovarian status; feces were analyzed by ELISA for immunoreactive progestogens (P) to study ovarian endocrine responses. In Experiment 1, a closer synchrony of estrus was observed between Days 2 to 4 among the PGF-treated (77.8%) than the E2V-treated (66.7%) females. Corpora lutea (CL) were detected in 55% of E2V- and PGF-treated females. In Experiment 2, neither treatment successfully induced superovulation, with only a single female per treatment producing > or = 1 CL. In both experiments, progestogen profiles were similar for each treatment (P < 0.05).     

The day of the estrous cycle that FSH is started and superovulation in cattle

A total of 993 commercial donor cows were superovulated with 28 mg FSH-P. The first injection of FSH-P was administered on one of days 9 through 13 of the donor's estrous cycle. The day that FSH was started did not affect total embryos collected, the number of transferable embryos or the percent transferable. These results did not support the current hypothesis that because the population of antral and preantral follicles in the ovaries on days 9 and 10 is higher, best embryo production should be achieved by starting donor cows on day 9 or 10 of the estrous cycle.     

Involvement of prostaglandins in LH-induced superovulation in the cyclic hamster

Osmotic minipumps containing 400 micrograms ovine LH were inserted subcutaneously (sc) on day 1 (estrus) at 09:00-10:00h of the cycle in the hamster. This treatment induced increased ovarian blood flow by day 3 and superovulation of 30.0 +/- 1.4 ova at the next estrus compared to controls (16.5 +/- 0.8 ova). The continuous infusion of LH throughout the cycle increased prostaglandin F (PGF) and decreased prostaglandin E (PGE) in the growing follicles destined to ovulate and suppressed a day 3 increase in PGF concentrations in the nonluteal ovarian remnant devoid of the larger follicles. Indomethacin, a cyclooxygenase inhibitor, given sc (2 or 4 mg regimens) at 12:00-14:00h on days 1 and 2, at 09:00h and 17:00h on day 3 and at 09:00h on day 4 of the cycle to LH-infused and saline treated animals suppressed ovarian prostaglandin levels, prevented the superovulation and prevented the increased ovarian blood flow. Exogenous PGF2 alpha or PGE2 restored the superovulatory effect of LH infusion in the presence of indomethacin. The results suggest that the superovulation in response to continuous LH infusion may be mediated in part by prostaglandins via altered ovarian blood flow.