Social environment modulates investment in sex trait versus lifespan: red deer produce bigger antlers when facing more rivalry.

Theory predicts that the plastic expression of sex-traits should be modulated not only by their production costs but also by the benefits derived from the presence of rivals and mates, yet there is a paucity of evidence for an adaptive response of sex-trait expression to social environment. We studied antler size, a costly and plastic sex trait, and tooth wear, a trait related to food intake and longevity, in over 4,000 male Iberian red deer (Cervus elaphus hispanicus) from 56 wild populations characterized by two contrasting management practices that affect male age structure and adult sex-ratio. As a consequence, these populations exhibit high and low levels of male-male competition for mating opportunities. We hypothesized that males under conditions of low intra-sexual competition would develop smaller antlers, after controlling for body size and age, than males under conditions of high intra-sexual competition, thus reducing energy demands (i.e. reducing intake and food comminution), and as a consequence, leading to less tooth wear and a concomitant longer potential lifespan. Our results supported these predictions. To reject possible uncontrolled factors that may have occurred in the wild populations, we carried out an experimental design on red deer in captivity, placing males in separate plots with females or with rival males during the period of antler growth. Males living with rivals grew larger antlers than males living in a female environment, which corroborates the results found in the wild populations. As far as we know, these results show, for the first time, the modulation of a sexual trait and its costs on longevity conditional upon the level of intra-sexual competition.

Vaccination with BM86, subolesin and akirin protective antigens for the control of tick infestations in white tailed deer and red deer.

Red deer (Cervus elaphus) and white-tailed deer (Odocoileus virginianus) are hosts for different tick species and tick-borne pathogens and play a role in tick dispersal and maintenance in some regions. These factors stress the importance of controlling tick infestations in deer and several methods such as culling and acaricide treatment have been used. Tick vaccines are a cost-effective alternative for tick control that reduced cattle tick infestations and tick-borne pathogens prevalence while reducing the use of acaricides. Our hypothesis is that vaccination with vector protective antigens can be used for the control of tick infestations in deer. Herein, three experiments were conducted to characterize (1) the antibody response in red deer immunized with recombinant BM86, the antigen included in commercial tick vaccines, (2) the antibody response and control of cattle tick infestations in white-tailed deer immunized with recombinant BM86 or tick subolesin (SUB) and experimentally infested with Rhipicephalus (Boophilus) microplus, and (3) the antibody response and control of Hyalomma spp. and Rhipicephalus spp. field tick infestations in red deer immunized with mosquito akirin (AKR), the SUB ortholog and candidate protective antigen against different tick species and other ectoparasites. The results showed that deer produced an antibody response that correlated with the reduction in tick infestations and was similar to other hosts vaccinated previously with these antigens. The overall vaccine efficacy was similar between BM86 (E=76%) and SUB (E=83%) for the control of R. microplus infestations in white-tailed deer. The field trial in red deer showed a 25-33% (18-40% when only infested deer were considered) reduction in tick infestations, 14-20 weeks after the first immunization. These results demonstrated that vaccination with vector protective antigens could be used as an alternative method for the control of tick infestations in deer to reduce tick populations and dispersal in regions where deer are relevant hosts for these ectoparasites.

Should legislation regarding maximum Pb and Cd levels in human food also cover large game meat?

Game meat may be contaminated with metals and metalloids if animals reside in anthropogenically polluted areas, or if ammunition used to kill the game contaminates the meat. Muscle tissue from red deer and wild boar shot in Ciudad Real province (Spain) in 2005-06 was analysed for As, Pb, Cu, Zn, Se and Cd. Samples were collected from hunting estates within and outside an area that has been historically used for mining, smelting and refining various metals and metalloids. Meat destined for human consumption, contained more Pb, As and Se (red deer) and Pb (boar) when harvested from animals that had resided in mined areas. Age related accumulation of Cd, Zn and As (in deer) and Cd, Cu and Se (in boar) was also observed. Two boar meat samples contained high Pb, at 352 and 2408 µg/g d.w., and these were likely to have been contaminated by Pb ammunition. Likewise, 19-84% of all samples (depending on species and sampling area) had Pb levels > 0.1 µg/g w.w., the EU maximum residue level (MRL) for farm reared meat. Between 9 and 43% of samples exceeded comparable Cd limits. Such data highlight a discrepancy between what is considered safe for human consumption in popular farmed meat (chicken, beef, lamb), and what in game may often exist. A risk assessment is presented which describes the number of meals required to exceed current tolerable weekly intakes (PTWIs) for Pb and Cd, and the potential contribution of large game consumption to such intake limit criteria.

Changes in fatty acid profiles in testis and spermatozoa of red deer exposed to metal pollution.

Lowered sperm quality associated with reduced superoxide dismutase activity in testis and spermatozoa has been observed in red deer from a mined area in South-central Spain. Here we present fatty acid profiles for testis and spermatozoa of deer from this mined area (n=29) and a control area (n=33). Despite elevated Pb in liver and bone of red deer from this area, concentrations in testis and sperm were not significantly higher than in control areas; however, Cu in testis was lower in mined areas. Testis from mined areas also contained higher percentages of linoleic acid (18:2n-6) and dihomo-gamma-linolenic acid (20:3n-6), but lower arachidonic acid (20:4n-6). The percentage of 20:4n-6 was also lower in spermatozoa of deer from the mined area. Copper levels in testis correlated positively with the percentage of 20:4n-6. The imbalance in Cu homeostasis caused by metal pollution may have caused the observed effects on deer sperm.

Reduced sperm quality in relation to oxidative stress in red deer from a lead mining area.

We studied the effects of elevated heavy metal uptake on the sperm quality and the antioxidant mechanisms of sperm and testis of red deer from a Pb mining area in Spain. Testis, liver and bone of red deer from mining (n = 21) and control (n = 20) areas were obtained from hunters and analyzed for Pb, Zn, Cu, Cd, As and Se. Testes were weighed and measured. Motility, acrosome integrity and viability and functionality of membrane were evaluated in epididymal spermatozoa. Lipid peroxidation, total glutathione, glutathione peroxidase (GPX) and superoxide dismutase (SOD) were studied in testis and spermatozoa. Deer from mined areas showed less Cu in testis, a higher testis mass and size and reduced spermatozoa membrane viability and acrosome integrity. Effects on sperm quality were associated to decreased Cu and increased Se in testis, and to decreases in the activity of SOD and GPX in testis and spermatozoa.

Heavy metal exposure in large game from a lead mining area: effects on oxidative stress and fatty acid composition in liver.

The Pb mining area of the valley of Alcudia and the Sierra Madrona mountains (S. Spain) has been exploited intermittently for over 2100 years, since Roman occupation and up until the late 1900s. Red deer (n=168) and wild boar (n=58) liver and bone (metacarpus) were analyzed for Pb, Zn, Cu, Cd, As and Se. Lipid peroxidation, total and oxidized glutathione (GSH), superoxide dismutase (SOD), GSH peroxidase (GPX) and fatty acid composition were studied in liver of red deer. The concentrations of Pb in liver and bone of red deer and wild boar were higher in the mining area than in the control area, and higher in the wild boar than red deer, but well below the level associated with clinical signs of Pb poisoning. Liver levels of Cu, Cd and Se were also higher in red deer from the mining area. Red deer from the mining area had 39% less total GSH than in the control area. The percentage of docosahexaenoic acid in liver of red deer from the mining area was 16% lower than in the control area.

Bovine tuberculosis in Doñana Biosphere Reserve: the role of wild ungulates as disease reservoirs in the last Iberian lynx strongholds.

Doñana National Park (DNP) in southern Spain is a UNESCO Biosphere Reserve where commercial hunting and wildlife artificial feeding do not take place and traditional cattle husbandry still exists. Herein, we hypothesized that Mycobacterium bovis infection prevalence in wild ungulates will depend on host ecology and that variation in prevalence will reflect variation in the interaction between hosts and environmental risk factors. Cattle bTB reactor rates increased in DNP despite compulsory testing and culling of infected animals. In this study, 124 European wild boar, 95 red deer, and 97 fallow deer were sampled from April 2006 to April 2007 and analyzed for M. bovis infection. Modelling and GIS were used to identify risk factors and intra and inter-species relationships. Infection with M. bovis was confirmed in 65 (52.4%) wild boar, 26 (27.4%) red deer and 18 (18.5%) fallow deer. In the absence of cattle, wild boar M. bovis prevalence reached 92.3% in the northern third of DNP. Wild boar showed more than twice prevalence than that in deer (p<0.001). Modelling revealed that M. bovis prevalence decreased from North to South in wild boar (p<0.001) and red deer (p<0.01), whereas no spatial pattern was evidenced for fallow deer. Infection risk in wild boar was dependent on wild boar M. bovis prevalence in the buffer area containing interacting individuals (p<0.01). The prevalence recorded in this study is among the highest reported in wildlife. Remarkably, this high prevalence occurs in the absence of wildlife artificial feeding, suggesting that a feeding ban alone would have a limited effect on wildlife M. bovis prevalence. In DNP, M. bovis transmission may occur predominantly at the intra-species level due to ecological, behavioural and epidemiological factors. The results of this study allow inferring conclusions on epidemiological bTB risk factors in Mediterranean habitats that are not managed for hunting purposes. Our results support the need to consider wildlife species for the control of bTB in cattle and strongly suggest that bTB may affect animal welfare and conservation.