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Thoroughbred stallions that carry a double-homozygous genotype A/A-A/A for SNPs rs397316122 and rs69101140 in exon 5 of the FKBP6 gene (chr13; EquCab3.0) are uniquely subfertile due to impaired acrosomal exocytosis (IAE). In this study, the sperm proteome in frozen/thawed semen from subfertile Thoroughbred stallions was studied and compared to that of frozen/thawed sperm from fertile Thoroughbred stallions. A total of 2,220 proteins was identified, of which 140 proteins were found to be differentially abundant in sperm from the subfertile stallions compared to that of fertile stallions (83 less and 57 more abundant). Proteins of differential abundance in sperm from the subfertile stallions were mainly overrepresented in the "metabolism" and the "metabolism of lipids" pathways. One of these proteins, arylsulfatase F (ARSF), was studied by immunofluorescence. A lower proportion of sperm displaying ARSF signal at the acrosome region was observed in sperm from subfertile Thoroughbred stallions. In addition, heterologous zona pellucida binding assays revealed that sperm from subfertile Thoroughbred stallions bound at a lower proportion to zonae pellucidae than sperm from fertile Thoroughbred stallions. In conclusion, a group of differential abundance proteins, including some of acrosome origin, were identified in sperm from subfertile stallions with acrosome dysfunction. [ABSTRACT FROM AUTHOR]

Studying animal societies needs detailed observation of many individuals, but technological advances offer new opportunities in this field. Here, we present a state-of-the-art drone observation of a multilevel herd of Przewalski's horses, consisting of harems (one-male, multifemale groups). We track, in high spatio-temporal resolution, the movements of 238 individually identified horses on drone videos, and combine movement analyses with demographic data from two decades of population monitoring. Analysis of collective movements reveals how the structure of the herd's social network is related to kinship and familiarity of individuals. The network centrality of harems is related to their age and how long the harem stallions have kept harems previously. Harems of genetically related stallions are closer to each other in the network, and female exchange is more frequent between closer harems. High movement similarity of females from different harems predicts becoming harem mates in the future. Our results show that only a few minutes of fine-scale movement tracking combined with high throughput data driven analysis can reveal the structure of a society, reconstruct past group dynamics and predict future ones. High resolution tracking is providing new opportunities to understand the social dynamics of wild animals. Here, the authors track individual wild horses with drones and link their movement patterns to long-term population monitoring to reveal the structure of their society. [ABSTRACT FROM AUTHOR]

Przewalski's horses live in stable nonterritorial families (harem) of one or more harem stallions, several mares, and their offspring. The harem stallion typically behaves aggressively towards any male intruder approaching the harem. Play behaviour is frequently observed among the group members in horses. For stallions, the most common, well-known cases of play behaviour are found between members of bachelor groups (groups of young stallions) and between the harem stallion and his offspring. The play between the harem stallion and members of the bachelor groups is, on the other hand, seemingly much rarer as a description of such events in the literature is anecdotal. In this note, we present our observation conducted in the Great Gobi B Strictly Protected Area (Mongolia) and describe the play behaviour between a Przewalski's horse harem stallion and members of a bachelor group. The observation was done as a part of broader research during which selected Przewalski's horses' groups were located by binoculars in daily monitoring routines and filmed from a close distance (from 150 to 800 m). Behavioural Observation Research Interactive Software (BORIS) was used to extract data from the video recordings. The observation described in this note lasted for ∼ 180 min, during which the horses engaged in three separate bouts of play and repeated inter-group association. During the whole study (241.5 h of video recordings), this was the only observation including inter-group interactions. We observed two other events during which two harems approached each other (but never merged). Our observation is the first video recording of such an event and raises the question of how prevalent this behaviour is in the Przewalski's horses' restored natural populations. We conclude that this behaviour is unusual or has not been sufficiently studied in wild or feral harems. Further technological advances may help reveal more information on this topic. [ABSTRACT FROM AUTHOR]

Horses are seasonal polyoestrous animals, and the photoperiod is the main factor modulating their reproductive activity. There is no consensus on the andrological and biochemical factors that influence breeding seasonality. To assess the involvement of climate in reproduction, Mangalarga Marchador stallions were monitored over 1 year regarding semen quality and seminal plasma proteome. Here, we show that kallikrein (KLKs) proteoforms in seminal plasma are involved in climate conditioning of reproduction. During the breeding season, greater abundance and different types of KLKs occurred simultaneously to lower sperm motility, greater semen volumes and higher concentrations of glucose and cholesterol. Considering that vasodilation due to activation of the kallikrein-kinin system and the consequent inhibition of the renin-angiotensin system may be associated with lower sperm motility, unravelling the involvement of KLK proteoforms in reproductive seasonality is a priority in horse breeding. [ABSTRACT FROM AUTHOR]

Seminal plasma (SP) of donkey stallions was evaluated using various oxidative stress parameters as well as protease and protease inhibitor activities. SP was obtained by nine donkey stallions. In addition, one donkey stallion with non-obstructive azoospermia was enrolled in this study. Free radical scavenging activity (FRSA), the ferric reducing ability of plasma (FRAP), total antioxidant capacity (TAC), and total thiol level (TTL) were highly correlated with each other and with the protease inhibitor activity. However, only FRAP, TAC, and the nitrate/nitrite concentration (NOx) were significantly correlated with sperm concentration, production, and kinetics. Protease inhibitor activity was highly correlated with sperm concentration and production; however, it did not correlate with sperm kinetics. The azoospermic stallion produced a lower amount of semen than the normospermic stallions and its SP showed a lower antioxidant activity when evaluated with FRAP, TAC, and TTL as well as a higher NOx and a lower protease inhibitor activity. In conclusion, the evaluation of SP oxidative profile by FRAP, TAC, and NOx may provide reliable information on donkey sperm quality whereas protease inhibitor activity may play a role as a marker of the sperm concentration in this species. [ABSTRACT FROM AUTHOR]

Purpose: To define the effect of sperm agglutination, associated with incubation under capacitating conditions, on accuracy of membrane assessment via flow cytometry and to develop methods to mitigate that effect. Methods: Sperm motility was measured by CASA. Sperm were stained with PI-PSA or a novel method, LD-PSA, using fixable live/dead stain and cell dissociation treatment, before flow-cytometric analysis. Using LD-PSA, acrosome reaction and plasma membrane status were determined in equine sperm treated with 10 μm A23187 for 10 min, followed by 0, 1, or 2 h incubation in capacitating conditions. Results: Using PI-PSA, measured membrane integrity (MI; live sperm) was dramatically lower than was total motility (TMOT), indicating spurious results ("zombie sperm"). Sperm aggregates were largely of motile sperm. Loss of motility after A23187 treatment was associated with disaggregation and increased MI. On disaggregation using LD-PSA, MI rose, and MI then corresponded with TMOT. In equine sperm incubated after A23187 treatment, as the percentage of live acrosome-reacted sperm increased, TMOT decreased to near 0. Conclusion: Flow cytometry assesses only individualized sperm; thus, agglutination of viable sperm alters recorded membrane integrity. As viable sperm become immotile, they individualize; therefore, factors that decrease motility, such as A23187, result in increased measured MI. Disaggregation before assessment allows more accurate determination of sperm membrane status; in this case we documented a mismatch between motility and live acrosome-reacted equine sperm that may relate to the poor repeatability of A23187 treatment for equine IVF. These findings are of profound value to future studies on sperm capacitation. [ABSTRACT FROM AUTHOR]

Exercise is a beneficial practice to the body and can constitute a challenge when taken to the extreme especially in competitive sports. Haematological parameters play a very important role in exercise and are usually good indicators of the effects of exercise on the body. In this experiment, ergothioneine was administered to stallions in the experimental group (Ex + ERG) before exercise to evaluate its ameliorative effect on haematological profile and erythrocytes osmotic fragility against the stress of exercise. The leucocyte count post-exercise in Ex + ERG (5.33 ± 0.24 × 109/L) was lower (P < 0.05) than the count recorded in Ex − ERG which was the untreated group (8.73 ± 0.94 × 109/L). After the exercise, erythrocyte count (15.22 ± 3.74 × 1012/L) recorded in Ex + ERG group was higher (P < 0.05) than counts (12.03 ± 0.68 × 1012/L) obtained in the Ex − ERG group after exercise. Neutrophil/lymphocyte ratio recorded in Ex + ERG group (2.02 ± 0.03) was lower (P < 0.05) than the ratio obtained in Ex − ERG (3.63 ± 0.73). It was concluded that ergothioneine modulated some haematological profiles and decreased leucocyte count and neutrophil/lymphocyte count but increased erythrocyte count and stabilised the membrane of erythrocytes in Arabian stallions subjected to a 2000 m. [ABSTRACT FROM AUTHOR]

Experiments were performed to determine the effects of melatonin on erythrocytes indices in Arabian stallions following a sub-maximal exercise of 30 km. Twelve, apparently, healthy stallions of average age 6.3 ± 4.4 years and mean weight 403.44 ± 12.46 kg were used. They were divided into two groups of six stallions each. The stallions in MT which was the experimental group were administered with melatonin before exercise while stallions in the second group (NT) which served as the control were not administered with melatonin. Erythrocyte count in the MT group was higher (p = 0.023) than the count obtained in the NT group. Packed cell volume of NT group was lower (p = 0.038) than the value obtained in the MT group post-exercise. Haemoglobin concentration of the MT group was higher (p = 0.041) than the value obtained in the NT group after exercise. The values of mean corpuscular volume, mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration of the MT group were higher than the corresponding values recorded in the NT group (p = 0.033, 0.029 and 0.025 respectively). It was concluded that melatonin enhanced erythrocytes indices in the stallions studied. [ABSTRACT FROM AUTHOR]

In animal groups, individual interactions achieve coordinated movements to maintain cohesion. In horse-harem groups, herding is a behaviour in which stallions chase mares from behind; it is considered to assist with group cohesiveness. The mechanisms of the group cohesion were studied using the methods of drone filming and video tracking during herding and two phases of interactions were found based on the mares' timing of movement initiation. The study shows that mares that move first are those nearest to the stallion; while the movement initiation of the later mares is determined by the distance from the nearest moving mare. Thus, as a second step to the full understanding of group cohesion, we propose a mathematical model of mares herded by a harem stallion, which is a modification of a sheep model during shepherding. Our model is a linear combination of the five components: inertia, repulsion from the stallion, short-range repulsion, synchronisation attraction, and attraction to the centre of the group. We tune the parameters of our proposed models based on the data and successfully reproduce the movements and directional trends of the mares. [ABSTRACT FROM AUTHOR]

Different forms of direct paternal investment have been described in mammals. One such species where paternal care was noticed, but remains poorly understood, is the horse (Equus caballus), where the male keeps a long-term relationship with several females and offspring. Therefore, the aim of this study was to analyse the interactions between the harem stallion and his foals. Two herds of Exmoor ponies living under semi-feral conditions in two separate reserves within Czech Republic were studied, each during one of the two consecutive breeding seasons (in 2016 and 2017). Both herds consisted of a stallion, 14 mares and their offspring (12 and 10 foals). The behaviour of all group members was recorded focusing on the stallion–foal interactions. The results show that the stallion receives more friendly interactions, snapping and playful behaviour from foals compared with adult mares. Furthermore, the stallion is more tolerant than mares, and actively plays with his offspring. There is no statistical difference in the sex of the foals in the stallion–foal interactions; however, male foals are more active than female foals in interacting with their father. The probability of a certain behaviour occurring between adult and foals changed over time. The stallion's presence might, therefore, be crucial for the physical and psychological development of the foals, especially the colts. These results may bring new insight into the common management of domestic horses, where stallions are usually kept separately and are not allowed to form natural groups. [ABSTRACT FROM AUTHOR]

The aim of this work was to estimate the effect of vaccinating stallions against anthrax on the sperm quality and its criostability. Vaccination of stallions against anthrax led to a decrease in the sperm quality. During the first week after vaccination, the sperm productivity decreased by 10%. In freshly diluted sperm, the sperm motility decreased by 12%, survival by 38% (Р > 0.99), and membrane integrity by 20% (Р > 0.95) on average. Their recovery was observed not earlier than 28 days after vaccination. Vaccination had an especially strong effect on sperm quality after cryopreservation: sperm motility decreased by 35% (P > 0.99), survival by 45% (P > 0.99), and membrane integrity by 46% (P > 0.99) on average, and these parameters remained low for 1 month. Rejection of sperm doses in the postvaccination period was 50% because of the decrease in quality below the standard level. The amount of pathological types of sperm increased 45 days after vaccination: by 27% (Р > 0.95) in fresh sperm and 34% (Р > 0.99) in deconserved sperm. In the case of cryoconservation of stallions' sperm, it is necessary to take into account the recovery period after antiepizootic measures. [ABSTRACT FROM AUTHOR]

The objective of the present study was assessment of gender differences in hair trace element content in English Thoroughbred horses (North Caucasus, Russia) using ICP-DRC-MS and calculation of the reference values. Trace element content in mane hair of 190 stallions and 94 mares (3–7 years old) bred in North Caucasus (Russia) was assessed using inductively coupled plasma mass spectrometry. Mane hair Co, Cr, Mn, Li, Si, and Sr levels in mares exceeded those in stallions by 77%, 63%, 64%, 42%, 39%, and 64%, respectively. Hair Fe and Si content was nearly twofold higher in female horses as compared to the males. Only hair Zn content was 5% higher in stallions as compared to mares. In addition, mares were characterized by 63%, 65%, 29%, and 40% higher levels of As, Pb, Sn, and Ni levels in hair as compared to the respective values in stallions. In turn, hair Al and Hg were more than twofold higher in mares than in stallions. The reference intervals of mane hair content (μg/g) for Co (0.006–0.143), Cr (0.028–0.551), Cu (4.17–6.84), Fe (10.11–442.2), I (0.026–3.69), Mn (0.551–12.55), Se (0.108–0.714), Zn (97.43–167), Li (0.011–0.709), Ni (0.060–0.589), Si (0.665–29.12), V (0.006–0.584), Al (1.98–168.5), As (0.006–0.127), Cd (0.002–0.033), B (0.494–16.13), Pb (0.018–0.436), Sn (0.002–0.144), Sr (1.0–9.46), and Hg (0.0018–0.017) in the total cohort of horses were estimated using the American Society for Veterinary Clinical Pathology Quality Assurance and Laboratory Standard Guidelines. The reference intervals were also estimated for stallions and mares bred in North Caucasus (Russia) and may be used for interpretation of the results of hair trace element analysis in horses. [ABSTRACT FROM AUTHOR]

Established breed-specific reference intervals are important for monitoring the health status of horses. Serum biochemical breed-specific reference intervals have been evaluated in horses and other animal breeds, but there are no studies for the Italian Heavy Draft horse. The aim of this study was to determine biochemical reference intervals for the Italian Heavy Draft horse living in central Italy. Moreover, the comparison between different physiological status (pregnancy and no pregnancy) and age (foals and adults) has been executed. Inclusion criteria were established before blood collection. Blood samples were collected from 309 apparently healthy horses (mares, stallions and foals). Serum parameters were evaluated in the Clinical Pathology Laboratory at the Teaching Veterinary Hospital of the University of Perugia. Reference intervals were determined by using well-described, modern analytical and statistical methods (Anderson-Darling test, Mann-Withney U test). Serum biochemical RIs for the IHDH are reported. Differences between the IHDH and both sport and other working horses are evident. Significant differences are indicated between pregnant and non-pregnant mares and between foals and adults. This is the first study reporting the serum biochemical RIs in the IHDH. The results suggest that breed-specific RIs should be used for the IHDH. Moreover, significant variations of biochemical analytes have been found between subjects with different physiological status and age. [ABSTRACT FROM AUTHOR]

Established breed-specific reference intervals (RIs) are important for monitoring the health status of horses. Breed-specific RIs have been evaluated in horses and other animal breeds, but there are no studies on breed-specific RIs for Italian Heavy Draft horse (IHDH). The aim of this study was to determine hematologic RIs for the IHDH living in central Italy. The comparison between different physiological status (pregnancy) and age (foals and adults) have been executed. Inclusion criteria were established for selection of subjects and for blood collection and handling. Blood samples were collected from 309 apparently healthy horses (mares, stallions and foals). Complete blood count (CBC) was performed on Sysmex-XT1800iV hematology at the Teaching Veterinary Hospital of the University of Perugia. RIs for IHDH were determined by using well-described, modern analytical and statistical methods as recommended by the CLSI and QALS guidelines. Hematologic RIs for the IHDH are reported. Differences between hot-blooded, cold-blooded, and warm-blooded horses are evident. Significant differences have been found for five analytes (WBC, MCHC, PLT, monocytes, basophils) between pregnant and non-pregnant mares and 12 analytes (RBC, Hgb, MCV, MCH, MCHC, RDW, PLT, WBC, lymphocytes, monocytes, eosinophils, basophils) between foals and adults. This is the first study reporting the hematologic RIs in the IHDH. The results suggest that breed-specific RIs should be used for IHDH due to the difference with published data regarding cold-blooded, hot-blooded, and warm-blooded breeds. Moreover, significant variations of hematological analytes have been found between subjects with different physiological status and age. [ABSTRACT FROM AUTHOR]

Apocrine sweat gland carcinomas are very rare skin tumors in horses. A 5-year-old Arabian stallion was presented with a mass in the pastern region of the left forelimb. Grossly, a hairless and ulcerative mass measuring approximately 1 × 1 cm was noted. Complete surgical excision with wide, clean margins was selected as a method of treatment. Histopathological examination of the excised mass identified the apocrine sweat gland ductal carcinoma. There was no evidence of local tumor recurrence during the subsequent follow-up evaluations. [ABSTRACT FROM AUTHOR]

A 7-year-old stallion with progressive left testicular enlargement was presented. Grossly, the excised testicle measured 25 × 15 × 12 cm and weighed 3.7 kg. It was multinodular with a gray-white surface; however, the right testis was normal. Histologically, the neoplastic cells were disseminated diffusely in the tumoral stroma with a minimal fibrovascular stroma. Neoplastic cells were round to polygonal with abundant eosinophilic cytoplasm and large round to oval vesicular or hyperchromatic nucleous with a single prominent nucleolus. Immunohistochemically, the neoplastic cells were positive nuclear immunostaining for C-KIT and negative for OCT3/4. According to gross, histopathological, and immunohistochemical characteristics, the diffuse type of seminoma was diagnosed. Nine months later, the follow-up observation of the case showed that the tumor had no recurrence and metastasis. [ABSTRACT FROM AUTHOR]

The results of an electron microscopy study of the ultrastructural characteristics of stallion spermatozoa in native sperm and after freezing-thawing are given. Changes occurring in spermatozoa under the effect of cryopreservation are shown. Maximum damages are found in acrosomes. [ABSTRACT FROM AUTHOR]

The influence of individual factors on dominance rank and the relationship between rank distance and patterns of aggression predicted by models of evolutionarily stable strategies (ESS) of animal conflict were investigated in a managed bachelor group of Sorraia horses, Equus caballus. The group was composed of four to six stallions 3- to 12-years-old during the study period. The dominance hierarchy was significantly linear and rank was not related to age, weight, height or aggressiveness. Frequency and intensity of agonistic interactions were low, but higher-ranking stallions did not receive lower aggressiveness than lower-ranking stallions. There was some evidence that dominance relationships were more contested among close-ranking stallions, as predicted. Agonistic-related interactions among close-ranking stallions served similar functions to those among distant-ranking stallions, but the latter interacted more frequently than expected for access to resting sites and/or resting partners. Therefore, we found some evidence that agonistic-related interactions among distant-ranking stallions play a larger role in providing access to valuable and defendable resources than those among close-ranking stallions. Nevertheless, the fact that space to escape from aggression was limited and breeding access was independent from dominance rank may have reduced the benefits relative to costs of aggression and therefore limited the occurrence of contests over dominance and resources. [ABSTRACT FROM AUTHOR]

Animal groups arise from individuals’ choices about the number, characteristics, and identity of associates. Individuals make these choices to gain benefits from their associations. As the needs of an individual change with its phenotype, so too we expect the nature of its associations to vary. In this paper, we investigate how the social priorities of male plains zebra ( Equus burchelli) depend on reproductive state. An adult male is either a bachelor, and lacking mating access, or a stallion defending a harem. Multiple harems and bachelor males aggregate in larger herds. Herds frequently split and merge, affording males opportunities to change associates. Over a 4-year period, we sampled the herd associations in a population of 500–700 zebras. To isolate the effects of reproductive state on male social behavior, we account for potential confounding factors: changes in population size, grouping tendencies, and sampling intensity. We develop a generally applicable permutation procedure, which allows us to test the null hypothesis that social behavior is independent of male status. Averaging over all individuals in the population, we find that a typical bachelor is found in herds containing significantly more adults, bachelors, and stallions than the herds of a typical stallion. Further, bachelors’ bonds with each other are more persistent over time than those among stallions. These results suggest that bachelors form cohesive cliques, in which we may expect cooperative behaviors to develop. Stallion–stallion associations are more diffuse, and less conducive to long-term cooperation. [ABSTRACT FROM AUTHOR]

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Twenty-four 4-year-old Andalusian (Spanish breed) stallions were used to examine the plasticity of myosin heavy chain (MHC) phenotype and the metabolic profile in horse skeletal muscle with long-term endurance-exercise training and detraining. Sixteen horses underwent a training programme based on aerobic exercises for 8 months. Afterwards, they were kept in paddocks for 3 months. The remaining eight horses were used as controls. Three gluteus medius muscle biopsy samples were removed at depths of 20, 40 and 60 mm from each horse before (month 0), during (month 3) and after (month 8) training, and again after 3 months of detraining (month 11). MHC composition was analysed by electrophoresis and immunohistochemistry with anti-MHC monoclonal antibodies. Fibre areas, oxidative capacity and capillaries were studied histochemically. The activities of key muscle enzymes of aerobic (citrate synthase and 3-hydroxy-acyl-CoA-dehydrogenase) and anaerobic (phosphofructokinase and lactic dehydrogenase) metabolism and the intramuscular glycogen and triglyceride contents were also biochemically analysed. Early changes with training (3 months) included hypertrophy of type IIA fibres, a reduction of MHC-IIX with a concomitant increase of MHC-IIA, a rise in the number of high-oxidative fibres and in the activities of aerobic muscle enzymes and glycogen content. Long-term changes with training (8 months) were a further decline in the expression of MHC-IIX, an increase of slow MHC-I, additional increases of high-oxidative fibres, capillary density, activities of aerobic enzymes and endogenous glycogen; intramuscular lipid deposits also increased after 8 months of training whereas the activities of anaerobic enzymes declined. Most of exercise-induced alterations reverted after 3 months of detraining. These results indicate that endurance-exercise training induces a reversible transition of MHC composition in equine muscle in the order IIX→IIA→I, which is co-ordinated with changes in the metabolic properties of the muscle. Furthermore, a dose–response relationship was evident between the duration (in total) of training and the magnitude of muscle adaptations. [ABSTRACT FROM AUTHOR]

In the social organization of feral horses, adult males compete to monopolize groups or bands of females, sometimes called harems. Alternative male strategies are to remain alone or with other bachelors or, less commonly, to accept subordinate status within a harem. The hypothesis that dominant harem stallion status confers a reproductive advantage was tested in free-ranging feral horses. The presence of foals in harems headed by vasectomized (VSX) versus intact stallions was used to assess the ability of these stallions to control reproduction in their harems. Of harems headed by VSX stallions, 17 and 33% contained foals during years 2 and 3 post-treatment, respectively. In contrast, 86 and 80% of harems headed by non-VSX stallions contained foals in those years. Acquisition of pregnant mares appeared more likely than sneak copulations by bachelor stallions to account for foals in harems with a single stallion. However, most foals were born into harems that included a subordinate stallion, an occurrence that was undoubtedly exacerbated by the extended breeding season resulting from the sterility of the harem stallion. Thus, in comparing alternative reproductive tactics, bachelors appeared less successful than subordinate stallions within a harem. However, the highest reproductive success was achieved by the harem stallion, further demonstrating that alternative tactics are not equally profitable. [ABSTRACT FROM AUTHOR]

Among many hypotheses in the literature that explain overmarking in mammals, most studies favour a sexual selection hypothesis. However, results in the literature are conflicting. In this study, we tested two hypotheses that could explain overmarking by males: (i) as a part of sexual selection, more specifically to mask scent of receptive females and (ii) as a form of communication serving to aid group cohesion. We observed each of the three zebra species in eight different herds at four zoos. In total, we recorded 1395 eliminations (760 defecations, 635 urinations) performed by 78 individuals including 8 stallions. Stallions investigated 248 eliminations and overmarked 124. The rate of overmarking by stallions was higher than those of all other sex and age categories. Stallions of all species overmarked all age and sex categories, except Grévy's zebra stallions did not overmark foal eliminations. In contrast to our first hypothesis, when attracted to the elimination, stallions overmarked non-oestrus females more often than oestrus ones. Thus, our results did not support the hypothesis that overmarking by males has a sexual selection function, but it could be explained by the group cohesion hypothesis. Based on our results, it seems that overmarking by equid males plays a greater role in intra-specific communication than in intra-sexual competition. In addition, this behaviour might play different roles in different species based on their social organisation. Significance statement: Overmarking is ubiquitous among terrestrial mammals; however, the function of this behaviour has not been fully explained. In addition, previous studies came to differing conclusions. In this study, we tested two hypotheses possibly explaining overmarking by adult males in three equid species. We found that adult males overmarked at a much higher rate than individuals of all other sex and age categories. In contrast to many other studies, our results did not support the hypothesis that overmarking by males has a sexual selection function, but it could be explained by a group cohesion hypothesis. [ABSTRACT FROM AUTHOR]

Time is a limited resource and how well it is allocated to competing behaviours can profoundly affect Darwinian fitness. Life history theory predicts that the amount of time allocated to vital behaviours will change with life history stage, resulting in trade-offs between competing behaviours. Moreover, a range of environmental factors can also affect activity budgets. We studied diurnal time allocation by migratory plains zebras (Equus quagga) in the Serengeti ecosystem, Tanzania, and investigated the effect of life history stage, social environment, habitat structure, and day time on time allocation to five behavioural categories (grazing, resting, vigilance, movement, other). We expected (1) increased vulnerability to predation and impeded predator detection to increase vigilance and decrease resting and grazing; (2) energetically costly life stages to increase grazing and decrease resting; and (3) increasing age in young to result in increased vigilance and grazing and decreased resting. Our findings revealed that in young zebras, resting decreased and grazing increased from the youngest to the oldest age class. Band stallions spent more time grazing and less time resting and moving than bachelors. Lactating mares devoted more time to grazing but less to resting and vigilance than other mares. Mares spent most time vigilant in the last third and stallions in the first third of the day. Adult zebras moved more, and mares were more vigilant in the woodland boundary than on short grass plains. Taken together, our study identifies intrinsic and extrinsic factors shaping time allocation decisions and trade-offs between competing behaviours in plains zebra. Significance statement: How well animals allocate their limited time to competing behaviours will affect their survival and reproduction. For example, energetically costly life history stages often require an increase in foraging whereas when predators threaten survival, more time should be allocated to vigilance. Increased investment of time in one behaviour requires decreased investment in another or other behaviours; thus, trade-offs in time are expected. Life history theory predicts substantial changes in the time allocated to vital behaviours between life stages. We investigated the effect of life history stage and environmental factors on the behavioural time budgets of migratory plains zebras in the Serengeti ecosystem. Our results showed that life history stage, juvenile age and environmental factors determine how time is invested in vital behaviours, and the behavioural trade-offs this entails. [ABSTRACT FROM AUTHOR]

Antivenoms are fundamental in the therapy for snakebites. In elapid venoms, there are toxins, e.g. short-chain α-neurotoxins, which are quite abundant, highly toxic, and consequently play a major role in envenomation processes. The core problem is that such α-neurotoxins are weakly immunogenic, and many current elapid antivenoms show low reactivity towards them. We have previously developed a recombinant consensus short-chain α-neurotoxin (ScNtx) based on sequences from the most lethal elapid venoms from America, Africa, Asia, and Oceania. Here we report that an antivenom generated by immunizing horses with ScNtx can successfully neutralize the lethality of pure recombinant and native short-chain α-neurotoxins, as well as whole neurotoxic elapid venoms from diverse genera such as Micrurus, Dendroaspis, Naja, Walterinnesia, Ophiophagus and Hydrophis. These results provide a proof-of-principle for using recombinant proteins with rationally designed consensus sequences as universal immunogens for developing next-generation antivenoms with higher effectiveness and broader neutralizing capacity. Antivenoms, obtained by venom immunization, have narrow species coverage due to low immunogenicity of venom neurotoxins. Here the authors immunize horses with a designed recombinant consensus neurotoxin, and the resulting antisera protect mice from envenomation by a broad spectrum of elapid snakes. [ABSTRACT FROM AUTHOR]