In vitro performance and in vivo fertility of antibiotic-free preserved boar semen stored at 5℃

Background: Hypothermic preservation of boar semen is considered a potential method for omitting antibiotics from insemination doses, thereby contributing to the global antibiotic resistance defence strategy. The main challenges are chilling injury to spermatozoa and bacterial growth during semen storage leading to reduced fertility.Objectives: To examine chilling injury and the number and type of bacteria in boar semen stored at 5 ℃ in the absence of antibiotics, and to assess the applicability of hypothermic semen storage under field conditions.Material and methods: Boar ejaculates were extended with AndroStar~? Premium, stored at 17 ℃ with and at 5 ℃ without antibiotics and tested for functional sperm parameters by flow cytometry. Raw semen and extended samples were investigated bacteriologically. Fertility was evaluated after once-daily inseminations of 194 sows in a field study.Results: Lethal sperm damage assessed by motility and membrane integrity was low throughout storage in both experimental groups. Sublethal chilling effects based on the decrease of viable spermatozoa with low membrane fluidity were higher(P < 0.05) up until 72 h in sperm stored at 5 ℃ compared to 17 ℃ but did not differ after 144 h.After 72 h, incubation in capacitating medium for 60 min induced a similar decrease in viable sperm with high mitochondria membrane potential and low cytosolic calcium in both groups. In semen stored at 5 ℃, bacteria counts were below 103 CFU/mL and the bacteria spectrum was similar to that of raw semen. In 88% of 34 boars,cooled semen fulfilled the requirements for insemination. Fertility was high and did not differ(P > 0.05) between sow groups inseminated with semen stored antibiotic-free at 5 ℃ and semen stored at 17 ℃ with antibiotics.Conclusion: Despite subtle chilling effects and low bacterial numbers, antibiotic-free hypothermic storage of boar semen offers the possibility to reduce the use of antibiotics in pig insemination. However, strict sanitary guidelines must be maintained and further evidence of efficiency under field conditions is considered desirable.

The sperm-interacting proteome in the bovine isthmus and ampulla during the periovulatory period

Background Spermatozoa interact with oviduct secretions before fertilization in vivo but the molecular players of this dialog and underlying dynamics remain largely unknown.Our objectives were to identify an exhaustive list of sperm-interacting proteins(SIPs)in the bovine oviduct fluid and to evaluate the impact of the oviduct anatomical region(isthmus vs.ampulla)and time relative to ovulation(pre-ovulatory vs.post-ovulatory)on SIPs number and abundance.Methods Pools of oviduct fluid(OF)from the pre-ovulatory ampulla,pre-ovulatory isthmus,post-ovulatory ampulla,and post-ovulatory isthmus in the side of ovulation were collected from the slaughterhouse.Frozen-thawed bull sperm were incubated with OF or phosphate-buffered saline(control)for 60 min at 38.5℃.After protein extraction and digestion,sperm and OF samples were analyzed by nanoLC-MS/MS and label-free protein quantification.Results A quantitative comparison between proteins identified in sperm and OF samples(2333 and 2471 proteins,respectively)allowed for the identification of 245 SIPs.The highest number(187)were found in the pre-ovulatory isthmus,i.e.,time and place of the sperm reservoir.In total,41 SIPs(17%)were differentially abundant between stages in a given region or between regions at a given stage and 76 SIPs(31%)were identified in only one region×stage condition.Functional analysis of SIPs predicted roles in cell response to stress,regulation of cell motility,fertilization,and early embryo development.Conclusion This study provides a comprehensive list of SIPs in the bovine oviduct and evidences dynamic spatiotemporal changes in sperm-oviduct interactions around ovulation time.Moreover,these data provide protein candidates to improve sperm conservation and in vitro fertilization media.

Landscape and scale-dependent spatial niches of bats foraging above intensively used arable fields

Introduction:Bats are threatened by agricultural intensification,and although bat ecology in agricultural landscapes is in the focus of current research,the effects of interacting spatiotemporal factors on species-specific bat activity above farmland remain understudied.Our aim was to identify spatiotemporal factors and their interactions relevant for the activity of bat species above conventionally managed arable fields.Methods:We repeatedly monitored relative bat activity above open arable fields in Germany using acoustic monitoring.We used site-related biotic and abiotic factors and landscape characteristics across five spatial scales,their combinations,and interactions to identify those factors which best explain variation in bat activity.Results:Numerous interactions between landscape characteristics and the insect abundance affected bat activity above fields.For instance,Pipistrellus pipistrellus became more active with increasing insect abundance,but only above fields with a low proportion of woody vegetation cover in the surroundings.Additionally,the level of bat activity in summer depended on landscape characteristics.For example,the activity of Pipistrellus nathusii was relatively low in summer above fields that were surrounded by vegetation patches with a high degree of edge complexity(e.g.,hedgerow).However,the activity remained at a relatively high level and did not differ between seasons above fields that were surrounded by vegetation patches with a low degree of edge complexity(e.g.,roundly shaped forest patch).Conclusions:Our results revealed that landscape characteristics and their interactions with insect abundance affected bat activity above conventionally managed fields and highlighted the opportunistic foraging behavior of bats.To improve the conditions for bats in agricultural landscapes,we recommend re-establishing landscape heterogeneity to protect aquatic habitats and to increase arthropod availability.

Global parasite and Rattus rodent invasions: The consequences for rodent-borne diseases

We summarize the current knowledge on parasitism-related invasion processes of the globally invasive Rattus lineages,originating from Asia,and how these invasions have impacted the local epidemiology of rodent-borne diseases.Parasites play an important role in the invasion processes and successes of their hosts through multiple biological mechanisms such as“parasite release,”“immunocompetence advantage,”“biotic resistance”and“novel weapon.”Parasites may also greatly increase the impact of invasions by spillover of parasites and other pathogens,introduced with invasive hosts,into new hosts,potentially leading to novel emerging diseases.Another potential impact is the ability of the invader to amplify local parasites by spillback.In both cases,local fauna and humans may be exposed to new health risks,which may decrease biodiversity and potentially cause increases in human morbidity and mortality.Here we review the current knowledge on these processes and propose some research priorities.

Penis size and sperm quality,are all bats grey in the dark?

Penises play a key role in sperm transport and in stimulating female genitals.This should impact post-copulatory competition,and expose penis characteristics to sexual selective pressures.Studies of male genitalia have repeatedly reported negative static allometries,which mean that,within species,large males have disproportionally small genitals when compared with smaller individuals.Males of some sperm-storing bat species may stand as an exception to such a pattern by arousing from hibernation to copulate with torpid females.The selection for large penises might take place,if a long organ provides advantages during post-copulatory competition and/or if females have evolved mechanisms allowing the choice of sire,relying on characters other than pre-copulatory traits(e.g.,penis size).In this study,we measured dimensions of the erected penis in 4 sperm-storing bat species.Furthermore,we collected sperm and evaluated the link between penis dimensions and sperm velocity.Our results revealed steep allometric slopes of the erected penis length in Barbastella barbastellus and an inverse allometry of penis head width in Myotis nattereri.More detailed studies of copulatory behavior are urgently needed to explain the range of observed scaling relations.Furthermore,penis head width correlates with sperm velocity in Plecotus auritus.For this last species,we propose that penis shape might act as a marker of male fertility.

Effects of social and climatic factors on birth sex ratio in Macaca mulatta in Mount Taihangshan area

Sex allocation theory predicts the optimal investment to male and female offspring.However,a biased sex ratio requires explanations as to why the deviation occurs.Rhesus macaque(Macaca mulatta)is the most widely distributed nonhuman primate species and the Taihangshan macaque(Macaca mulatta tcheliensis)occupies the northern limit of all rhesus macaque natural populations worldwide.We observed one macaque troop(Wangwu-1[WW-1])inhabiting Taihangshan Macaque National Nature Reserve and recorded all birth events and the sex of newborn macaques from 2004 to 2013.Our aim was to apply the Trivers–Willard hypothesis to this free-ranging rhesus macaque troop,and to understand the relationship between climatic parameters(precipitation and temperature)and birth sex ratio.We found that the total newborn macaques showed a female-biased sex ratio at birth in the WW-1 troop,but there were no significant biased birth sex ratios in all matriarchs and in high-ranking and middle-ranking matrilineal units.However,the low-ranking macaque matrilineal unit was significantly female-biased.Moreover,we found that the annual precipitation of the previous year was positively associated with the birth sex ratio,and there was an interactive effect of troop size and current winter temperature on the birth sex ratio.The underlying mechanisms for the effects of social and climatic factors on birth sex ratio could be complex,and we discuss several plausible explanations.

Experimental manipulation of reproductive tactics in Seba’s short-tailed bats:consequences on sperm quality and oxidative status

To reproduce,males have to fertilize the female’s eggs,sometimes in competition with ejaculates of other males.In species where males display alternative reproductive tactics,whereby territorial males secure mating and non-territorial males have to sneak copulations,the latter might be expected to invest relatively more resources towards sperm quality compared with the territorial males.Sperm cells are especially vulnerable to oxidative stress,which reduces male fertility.Therefore,antioxidant resources are expected to modulate sperm quality,and might be allocated differently between reproductive tactics.To test the link between reproductive tactics,redox profile and sperm quality,we experimentally induced changes in the reproductive tactics of 39 captive males Seba's short-tailed bats Carollia perspicillata.We monitored the blood and ejaculate oxidative balance,and the sperm quality before,7 days and 21 days after the manipulation of reproductive tactic.Although ejaculates'oxidative damage was negatively related to sperm velocity,males exhibited similar blood and ejaculates redox profiles and similar sperm quality,regardless of their reproductive tactic.Possibly,these results arise as a consequence of some constraints having been lifted during the experiment.Our results also suggest that,in Seba's short-tailed bats,the expression of alternative reproductive tactics is not subjected to strong oxidative constraints.Furthermore,our results could reflect an absence of trade-off between pre-and post-copulatory traits in harem males,as they could be selected to invest both in female attraction and sperm quality,as a consequence of their inability to fully monopolize females.

Sex and season explain spleen weight variation in the Egyptian mongoose

The Egyptia n mon goose (Herpestes ichneumon Linn aeus, 1758) is a medium-sized car nivore that experienced remarkable geographic expansion over the last 3 decades in the Iberian Peninsula. In this study, we investigated the association of species-related and abiotic factors with spleen weight (as a proxy for immunocompete nee) in the species. We assessed the relationship of body con dition, sex, age, seas on, and envir onmental conditi ons with splee n weight established for 508 hunted specimens. Our results indicate that the effects of sex and season outweigh those of all other variables, including body condition. Spleen weight is higher in males than in females, and heavier spleens are more likely to be found in spring, coinciding with the highest period of investment in reproduction due to mating, gestation, birth, and lactation. Coupled with the absence of an effect of body condition, our findi ngs suggest that splee n weight variation in this species is mostly influe need by lifehistory traits linked to reproduction, rather than overall energy availability, winter immunoenhancement, or energy partitioning effects, and prompt further research focusing on this topic.

Responding to the weather:energy budgeting by a small mammal in the wild

Energy conservation is paramount for small mammals because of their small size,large surface area to volume ratio,and the resultant high heat loss to the environment.To survive on limited food resources and to fuel their expensive metabolism during activity,many small mammals employ daily torpor to reduce energy expenditure during the rest phase.We hypothesized that a small terrestrial semelparous marsupial,the brown antechinus Antechinus stuartii,would maximize activity when foraging conditions were favorable to gain fat reserves before their intense breeding period,but would increase torpor use when conditions were poor to conserve these fat reserves.Female antechinus were trapped and implanted with small temperature-sensitive radio transmitters to record body temperature and to quantify torpor expression and activity patterns in the wild.Most antechinus used torpor at least once per day over the entire study period.Total daily torpor use increased and mean daily body temperature decreased significantly with a reduction in minimum ambient temperature.Interestingly,antechinus employed less torpor on days with more rain and decreasing barometric pressure.In contrast to torpor expression,activity was directly related to ambient temperature and inversely related to barometric pressure.Our results reveal that antechinus use a flexible combination of physiology and behavior that can be adjusted to manage their energy budget according to weather variables.

Migratory flight imposes oxidative stress in bats

Many animal species migrate over long distances, but the physiological challenges of migration are poorly understood. It has recently been suggested that increased molecular oxidative damage might be one important challenge for migratory animals. We tested the hypothesis that autumn migration imposes an oxidative challenge to bats by comparing values of 4 blood-based markers of oxidative status (oxidative damage and both enzymatic and nonenzymatic antioxidants) between Nathusius' bats Pipistrellus nathusii that were caught during migration flights with those measured in conspecifics after resting for 18 or 24 h. Experiments were carried out at Pape Ornithological Station in Pape (Latvia) in 2016 and 2017. Our results show that flying bats have a blood oxidative status different from that of resting bats due to higher oxidative damage and different expression of both non enzymatic and enzymatic antioxidants (glutathione peroxidase). The differences in oxidative status markers varied betwee n sampli ng years and were in depende nt from in dividual body con dition or sex. Our work provides evidence that migratory flight might impose acute oxidative stress to bats and that resting helps animals to recover from oxidative damage accrued en route. Our data suggest that migrating bats and birds might share similar strategies of mitigating and recovering from oxidative stress.