▪ Abstract Deer have expanded their range and increased dramatically in abundance worldwide in recent decades. They inflict major economic losses in forestry, agriculture, and transportation and contribute to the transmission of several animal and human diseases. Their impact on natural ecosystems is also dramatic but less quantified. By foraging selectively, deer affect the growth and survival of many herb, shrub, and tree species, modifying patterns of relative abundance and vegetation dynamics. Cascading effects on other species extend to insects, birds, and other mammals. In forests, sustained overbrowsing reduces plant cover and diversity, alters nutrient and carbon cycling, and redirects succession to shift future overstory composition. Many of these simplified alternative states appear to be stable and difficult to reverse. Given the influence of deer on other organisms and natural processes, ecologists should actively participate in efforts to understand, monitor, and reduce the impact of deer on ...

https://www.kora.ch/malme/05_library/5_1_publications/C/Cote_et_al_2004_Ecological_impacts_of_deer_overabundance.pdf

Ecological Impacts of Deer Overabundance

The invasion of ecosystems by exotic species is currently viewed as one of the most important sources of biodiversity loss. The largest part of this loss occurs on islands, where indigenous species have often evolved in the absence of strong competition, herbivory, parasitism or predation. As a result, introduced species thrive in those optimal insular ecosystems affecting their plant food, competitors or animal prey. As islands are characterised by a high rate of endemism, the impacted populations often correspond to local subspecies or even unique species. One of the most important taxa concerning biological invasions on islands is mammals. A small number of mammal species is responsible for most of the damage to invaded insular ecosystems: rats, cats, goats, rabbits, pigs and a few others. The effect of alien invasive species may be simple or very complex, especially since a large array of invasive species, mammals and others, can be present simultaneously and interact among themselves as well as with the indigenous species. In most cases, introduced species generally have a strong impact and they often are responsible for the impoverishment of the local flora and fauna. The best response to these effects is almost always to control the alien population, either by regularly reducing their numbers, or better still, by eradicating the population as a whole from the island. Several types of methods are currently used: physical (trapping, shooting), chemical (poisoning) and biological (e.g. directed use of diseases). Each has its own set of advantages and disadvantages, depending on the mammal species targeted. The best strategy is almost always to combine several methods. Whatever the strategy used, its long-term success is critically dependent on solid support from several different areas, including financial support, staff commitment, and public support, to name only a few. In many cases, the elimination of the alien invasive species is followed by a rapid and often spectacular recovery of the impacted local populations. However, in other cases, the removal of the alien is not sufficient for the damaged ecosystem to revert to its former state, and complementary actions, such as species re-introduction, are required. A third situation may be widespread: the sudden removal of the alien species may generate a further disequilibrium, resulting in further or greater damage to the ecosystem. Given the numerous and complex population interactions among island species, it is difficult to predict the outcome of the removal of key species, such as a top predator. This justifies careful pre-control study and preparation prior to initiating the eradication of an alien species, in order to avoid an ecological catastrophe. In addition, long-term monitoring of the post-eradication ecosystem is crucial to assess success and prevent reinvasion.

http://max2.ese.u-psud.fr/epc/conservation/PDFs/BiolReviews.pdf

Mammal invaders on islands: impact, control and control impact

Computer assisted semen analyzers in andrology research and veterinary practice

The measurement of sperm motility and factors affecting sperm quality in cultured fish

The objective of this study was to examine the influence of reactive oxygen species (ROS), generated through the use of the xanthine (X)-xanthine oxidase (XO) system, on equine sperm motility, viability, acrosomal integrity, mitochondrial membrane potential, and membrane lipid peroxidation. Equine spermatozoa were separated from seminal plasma on a discontinuous Percoll gradient, and spermatozoa were incubated with 0.6 mM X and 0.05 U/mL XO for 30 minutes. Catalase (150 U/mL), superoxide dismutase (SOD, 150 U/mL), or glutathione (GSH, 1.5 mM) were evaluated for their ability to preserve sperm function in the presence of the induced oxidative stress. At the end of the 30-minute incubation, sperm motility was determined by computer-assisted semen analysis. Viability and acrosomal integrity were determined by Hoechst-Pisum sativum staining, and mitochondrial membrane potential was determined by staining with JC-1. Incubation with the X-XO system led to a significant (P < .01) increase in hydrogen peroxide production and an associated decrease (P < .01) in motility parameters. Total motility was significantly (P < .01) lower in the presence of X-XO compared with the case of the control (29%+/-9% vs 73%+/-1%, respectively). Catalase, but not SOD, prevented a decline in motility secondary to oxidative stress (71%+/-4% vs 30%+/-3%, respectively). The addition of glutathione had an intermediate effect in preserving sperm motility at the end of the 30-minute incubation (53%+/-3%). No influence of X-XO could be determined on viability, acrosomal integrity, or mitochondrial membrane potential. In order to promote lipid peroxidation, samples were incubated with ferrous sulfate (0.64 mM) and sodium ascorbate (20 mM) for 2 hours after the X-XO incubation. No increase in membrane lipid peroxidation was detected. This study indicates that hydrogen peroxide is the major ROS responsible for damage to equine spermatozoa. The decrease in sperm motility associated with ROS occurs in the absence of any detectable decrease in viability, acrosomal integrity, or mitochondrial membrane potential or of any detectable increase in lipid peroxidation.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.1939-4640.2000.tb03420.x

The effect of reactive oxygen species on equine sperm motility, viability, acrosomal integrity, mitochondrial membrane potential, and membrane lipid peroxidation.

Reducing fertility among free-roaming feral horses (Equus caballus) has been the goal of numerous studies over the past 16 years (Kirkpatrick et al. 1982, Goodloe et al. 1988, Plotka et al. 1989). Initial experiments by Kirkpatrick et al. (1982) and Turner and Kirkpatrick (1982) resulted in an 83% decrease in foaling among feral mares bred by stallions which were first immobilized and then treated with injectable microencapsulated testosterone propionate (mTP). Although the treatment decreased sperm count and motility, the high costs and the stress caused by immobilization or capture made it clear that the contraceptive agent needed to be delivered remotely. In a second study Kirkpatrick and Turner (unpublished data) demonstrated the pharmacological effectiveness of mTP in stallions, but difficulty was encountered in remotely delivering a sufficient mass of the steroid. Recently, attention has turned to contraception in the feral mare. Experiments with ethinylestradiol-progesterone Silastic? implants (Vevea et al. 1987, Plotka et al. 1988, Plotka et al. 1989) showed pharmacological promise, but the technique required capture, restraint, and field surgery to place the implants intraperitoneally. An alternative to steroid-induced fertility control is immunocontraception. A conjugated form of luteinizing hormone releasing hormone (LHRH) has been used successfully to raise antibodies in captive feral mares (Goodloe et al. 1988), and solubilized porcine zonae pellucidae (PZP) injections inhibited fertility in 13 of 14 domestic and captive feral mares (Liu et al. 1989). The success of the PZP vaccine in suppressing fertility is based on its ability to inhibit fertilization or possibly implantation (Sacco et al. 1984). The porcine zona pellucida consists of 3 glycoproteins. One of those, ZP3, is the receptor molecule for sperm surface molecules (Florman and Wassarman 1985). Equine antibodies raised against PZP are thought to block the sperm receptor sites on the equine ovum, thereby preventing fertilization (Liu et al. 1989). To date, PZP has been used to successfully inhibit fertility in a number of mammals, including 5 species of nonhuman primates and in vitro fertilization in humans (Sacco 1987). The objectives of this study were to (a) determine the effectiveness of remote delivery, (b) test the contraceptive effectiveness of a PZP vaccine in free-roaming feral mares, (c) determine the contraceptive effectiveness of the vaccine in pregnant and nonpregnant mares, and (d) evaluate the safety of the vaccine for use in pregnant mares.

Remotely-delivered immunocontraception in feral horses.

The electrical myometrial activity of three mares with a documented increased susceptibility to chronic uterine infection (CUI) and three mares considered to be resistant to CUI was investigated. Electrodes were surgically implanted in the myometrium of the mares and electrical activity was monitored by a Grass polygraph. Oestrus was determined by transrectal ultrasonography of the reproductive tract and teasing of the mares with a stallion. Findings were confirmed by blood progesterone concentrations 35 mm was detected, the uterus was infused with a genital strain of 5 \m=x\10 Streptococcus zooepidemicus. Myometrial electrical activity was monitored for 1\p=n-\4h before the bacterial infusion and continued until a visual stabilization of the activity occurred. No statistically significant differences in electrical myometrial activity were detected between susceptible and resistant mares before the infusion of bacteria into the uterus. A visible increase in myometrial electrical activity was seen in all mares following the bacterial infusion. However, the myometrial response of susceptible and resistant mares was different. Resistant mares demonstrated a greater myometrial activity (P < 0.001) than did susceptible mares. These differences were observed in frequency (P < 0.005) as well as duration (P < 0.001) and intensity (P < 0.001) of the uterine activity. Differences were most marked between 10 and 20 h after the intrauterine inoculation of bacteria. It was concluded from this study that myometrial activity is an important part of the uterine defence mechanism in mares. Mares susceptible to CUI appear to have an impaired electrical myometrial activity in response to an intrauterine bacterial challenge.

/pdf/multiple-site-electromyography-recordings-of-uterine-vguk2mfpjp.pdf

Multiple site electromyography recordings of uterine activity following an intrauterine bacterial challenge in mares susceptible and resistant to chronic uterine infection.

Ten fertile feral mares and 6 domestic horses (4 fertile mares, 1 infertile mare, 1 gelding) were immunized with heat-solubilized pig zonae pellucidae by 4 injections equivalent to 2000 or 5000 zonae each at 2-4-week intervals and a booster injection of 20,000 zonae 6-10 months after the last of the initial inoculations. The immune response was reflected by high antibody levels as measured by an enzyme-linked immunosorbent assay (ELISA) using immobilized pig zona antigen. In-vivo inhibition of fertility occurred in 12 (86%) of the 14 fertile mares studied and persisted for a minimum of 7 months. Repeated mating of the fertile domestic mares resulted in conception when anti-pig zona antibody concentrations had decreased from initial peak absorbance ratios (greater than 1.0) to relatively lower levels (0.64 or less with one exception). An indirect immunofluorescence assay, revealed a considerably lower cross-reactive antibody titre with horse oocytes as compared to pig oocytes. Clinical, endocrinological and histological analyses of the ovaries and their function following regained fertility after immunization revealed no abnormalities. One mare remained infertile.

/pdf/contraception-in-mares-heteroimmunized-with-pig-zonae-2ymb25eqel.pdf

Contraception in mares heteroimmunized with pig zonae pellucidae

Mammalian sperm that have completed capacitation are capable of undergoing the acrosome reaction in response to a number of biological and chemical stimuli. In the present report, we have investigated the ability of progesterone to stimulate acrosome reactions of stallion sperm capacitated in vitro. Motile sperm were selected by a two-layer Percoll gradient centrifugation and were incubated in TALP medium modified by the 1:1 (v/v) addition of TEST-yolk medium for 5 hours at 39 degrees C, under 5% CO2 in humidified air. Sperm incubated in vitro in TALP-TEST medium had a higher percentage of acrosome reactions following the addition of progesterone (3.18 mumol/L) compared to controls (P < 0.05). Furthermore, sperm from stallions classified as fertile on the basis of breeding history had higher percentages of progesterone-induced acrosome reactions in comparison with stallions classified as subfertile (P < 0.05). Acrosome reactions were assessed routinely by fluoresceinated lectin binding, but the physiological appearance of induced acrosome reactions was confirmed at the ultrastructural level by transmission electron microscopy. We conclude that 1) TALP-TEST medium supports stallion sperm capacitation in vitro, 2) progesterone-induced acrosome reactions are physiological, and 3) sperm from fertile stallions may be more responsive to progesterone-induced acrosome reactions than those of subfertile stallions. This is the first report in a nonhuman species that differences exist between the sperm of fertile and subfertile males in the ability to capacitate and acrosome react in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Capacitation In Vitro of Stallion Spermatozoa: Comparison of Progesterone‐Induced Acrosome Reactions in Fertile and Subfertile Males

Behavioral and reproductive consequences of porcine zona pellucida (PZP) immunocontraception were examined in a herd of white-tailed deer (Odocoileus virginianus; n = 30) from September 1992 to September 1994. Does were captured from a wild population and placed within either of 2 large (32-ha total) wooded enclosures. Does were administered either: (1) a single injection containing PZP-emulsified in Freund's complete adjuvent (FCA) and microsphere-encapsulated PZP; (2) 2 injections of PZP-emulsified in FCA and Freund's incomplete adjuvant (FIA), 4 weeks apart; or (3) no treatment. Mature, spermic bucks (n = 5) were added to each pasture 4 weeks after the final PZP treatment, and reproductive behaviors and fawn production were observed for 2 years. Immunocontracepted females exhibited increased activity compared to non-treated females, presumably reflecting an increased number of estrus intervals. Similarly, enclosure bucks exhibited an extended breeding season compared to males in the surrounding wild population. The 2-injection PZP regimen provided effective contraception during both years of the study. The 1-injection PZP regime provided effective contraception only during the second year, following administration of a PZP booster. Histological evaluations of ovaries failed to reveal among-group differences in ovarian architecture. Contracepted-nonpregnant does gained significantly more weight than control females during the study.

Irwin K. M. Liu

Papers

Remotely-delivered immunocontraception in feral horses.

Multiple site electromyography recordings of uterine activity following an intrauterine bacterial challenge in mares susceptible and resistant to chronic uterine infection.

Contraception in mares heteroimmunized with pig zonae pellucidae

Capacitation In Vitro of Stallion Spermatozoa: Comparison of Progesterone‐Induced Acrosome Reactions in Fertile and Subfertile Males

The effect of immunocontraception on the behavior and reproduction of white-tailed deer