Atypical for northern ungulates, energy metabolism is lowest during summer in female wild boars (Sus scrofa)

Multi-omics analysis of gut microbiota and metabolites reveals contrasting profiles in domestic pigs and wild boars across urban environments

The gut microbiota plays a crucial role in host health and metabolism. This study explores the differences in gut microbiota and metabolites between domestic pigs (DP) and wild boars (WB) in urban environments. We analyzed gut microbial composition, metabolic profiles, virome composition, antibiotic resistance genes (ARGs), and human pathogenic bacteria (HPB) in both DP and WB. Our results revealed that DP exhibited a higher Firmicutes/Bacteroidetes ratio and were enriched in bacterial genera associated with domestication and modern feeding practices. Metabolomic analysis showed distinct profiles, with WB significantly enriched in the Pantothenate and CoA biosynthesis pathway, highlighting dietary and environmental influences on host metabolism. Additionally, DP had a distinct gut virome composition, particularly enriched in lytic phages of the Chaseviridae family. ARG analysis indicated a higher abundance of tetracycline resistance genes in DP, likely due to antibiotic use in pig farms. Furthermore, variations in HPB composition underscored potential health risks associated with contact with pig feces. These findings provide valuable insights into the microbial ecology of domestic pigs and wild boars, emphasizing the importance of these comparisons in identifying zoonotic pathogen transmission pathways and managing antibiotic resistance. Continued research in this area is essential for developing effective strategies to mitigate public health risks and promote sustainable livestock management practices.

Fecal thyroid hormone metabolites in wild ungulates: a mini-review

This review aims to analyse the fluctuations of fecal thyroid hormone metabolites (FTMs) related to environmental and individual variables in different species of wild ungulates and provide a collection of assay methods. The great advantage of fecal sampling is being completely non-invasive. A systemic search was conducted from 2019 to 2024, using data sources PubMed, Scopus, Web of Science, and the World Wide Web, and ten studies were found on this topic. Three studies used the radioimmunoassay method for FTMs analysis, while the others used a less expensive enzyme-linked immunosorbent assay. Most of these papers validated the method for the species-specific matrix. Related to the studied variables, some authors analysed FTM fluctuations only concerning individual variables, and others in response to both. Temperature and fecal cortisol metabolites (FCMs) were the most studied environmental and individual variables, respectively. Since FTMs are an integrative measure of plasma thyroid hormones, the information obtained from a non-invasive-assay method regarding wild ungulate physiology is becoming of great interest to the scientific community.

Thermoregulation in the wild boar (Sus scrofa)

The wild boar (Sus scrofa) originates from warm islands but now inhabits large areas of the world, with Antarctica as the only continent not inhabited by this species. One might be tempted to think that its wide distribution results from increasing environmental temperatures. However, any effect of temperature is only indirect: Abundant availability of critical food resources can fully compensate the negative effects of cold winters on population growth. Here, we asked if temperature as a habitat factor is unimportant compared with other habitat indices, simply because wild boars are excellent thermoregulators. We found that the thermoneutral zone in summer was approximately 6-24 °C. In winter, the thermoneutral zone was lowered to 0-7 °C. The estimated increase in the heart rate and energy expenditure in the cold was less than 30% per 10 °C temperature decline. This relatively small increase of energy expenditure during cold exposure places the wild boar in the realm of arctic animals, such as the polar bear, whereas tropical mammals raise their energy expenditure several fold. The response of wild boars to high Ta was weak across all seasons. In the heat, wild boars avoid close contact to conspecifics and particularly use wallowing in mud or other wet substrates to cool and prevent hyperthermia. Wild boars also rely on daily cycles, especially of rhythms in subcutaneous temperature that enables them to cheaply build large core-shell gradients, which serve to lower heat loss. We argue it is predominantly this ability which allowed wild boars to inhabit most climatically diverse areas in the world.

One Health challenges for pig reproduction

The current state of the world challenges pig reproduction as an important part of One Health, which involves interrelationships between animal, human and environmental health. The One Health concept underlines a comparative aspect in reproductive physiology and disease occurrence, bridging knowledge from one species to another. Seasonal changes in the environment affect pig reproduction and climate change may further strengthen those effects. Endocrine-disrupting chemicals (EDCs), and specifically phthalates and heavy metals, interfere with endocrine function, and thereby sexual behavior, fertilization capacity and steroidogenesis. Reproductive infections and extended semen storage are important indications for antimicrobial use. Innovative solutions are needed to explore alternatives to antimicrobials. Efforts to ensure reproductive efficiency have prolonged farrowing as litter size has doubled over the past three decades, compromising immune transfer and welfare. Physiological, metabolic and programming related events around parturition are key areas for future One Health research in pig reproduction. In conclusion, climate change challenges reproductive management and breeding. More resilient pigs that can tolerate harsh environment but maintain high reproductive performance are needed. EDCs continue to grow as an environmental challenge for reproductive management and alternatives to antibiotics will be required.

The Influence of Photoperiod, Intake of Polyunsaturated Fatty Acids, and Food Availability on Seasonal Acclimatization in Red Deer (Cervus elaphus)

Hypometabolism and hypothermia are common reactions of birds and mammals to cope with harsh winter conditions. In small mammals, the occurrence of hibernation and daily torpor is entrained by photoperiod, and the magnitude of hypometabolism and decrease of body temperature (T_b) is influenced by the dietary supply of essential polyunsaturated fatty acids. We investigated whether similar effects exist in a non-hibernating large mammal, the red deer (Cervus elaphus). We fed adult females with pellets enriched with either linoleic acid (LA) or α-linolenic acid (ALA) during alternating periods of ad libitum and restricted feeding in a cross-over experimental design. Further, we scrutinized the role of photoperiod for physiological and behavioral seasonal changes by manipulating the amount of circulating melatonin. The deer were equipped with data loggers recording heart rate, core and peripheral T_b, and locomotor activity. Further, we regularly weighed the animals and measured their daily intake of food pellets. All physiological and behavioral parameters measured varied seasonally, with amplitudes exacerbated by restricted feeding, but with only few and inconsistent effects of supplementation with LA or ALA. Administering melatonin around the summer solstice caused a change into the winter phenotype weeks ahead of time in all traits measured. We conclude that red deer reduce energy expenditure for thermoregulation upon short daylength, a reaction amplified by food restriction.

Providing baseline data for conservation-Heart rate monitoring in captive scimitar-horned oryx

Heart rate biologging has been successfully used to study wildlife responses to natural and human-caused stressors (e.g., hunting, landscape of fear). Although rarely deployed to inform conservation, heart rate biologging may be particularly valuable for assessing success in wildlife reintroductions. We conducted a case study for testing and validating the use of subcutaneous heart rate monitors in eight captive scimitar-horned oryx (Oryx dammah), a once-extinct species that is currently being restored to the wild. We evaluated biologger safety and accuracy while collecting long-term baseline data and assessing factors explaining variation in heart rate. None of the biologgers were rejected after implantation, with successful data capture for 16-21 months. Heart rate detection accuracy was high (83%-99%) for six of the individuals with left lateral placement of the biologgers. We excluded data from two individuals with a right lateral placement because accuracies were below 60%. Average heart rate for the six scimitar-horned oryx was 60.3 ± 12.7 bpm, and varied by about 12 bpm between individuals, with a minimum of 31 bpm and a maximum of 188 bpm across individuals. Scimitar-horned oryx displayed distinct circadian rhythms in heart rate and activity. Heart rate and activity were low early in the morning and peaked near dusk. Circadian rhythm in heart rate and activity were relatively unchanged across season, but hourly averages for heart rate and activity were higher in spring and summer, respectively. Variation in hourly heart rate averages was best explained by a combination of activity, hour, astronomical season, ambient temperature, and an interaction term for hour and season. Increases in activity appeared to result in the largest changes in heart rate. We concluded that biologgers are safe and accurate and can be deployed in free-ranging and reintroduced scimitar-horned oryx. In addition to current monitoring practices of reintroduced scimitar-horned oryx, the resulting biologging data could significantly aid in 1) evaluating care and management action prior to release, 2) characterizing different animal personalities and how these might affect reintroduction outcomes for individual animals, and 3) identifying stressors after release to determine their timing, duration, and impact on released animals. Heart rate monitoring in released scimitar-horned oryx may also aid in advancing our knowledge about how desert ungulates adapt to extreme environmental variation in their habitats (e.g., heat, drought).