Georgios Ioannis Papakonstantinou

B-mode ultrasonography is widely used for pregnancy monitoring in small ruminants, yet direct longitudinal comparisons of ovine and caprine foetal biometry under a common protocol remain scarce. This study characterised foetal development and derived biometric predictors of gestational age in 27 primiparous Lacaune ewes (42 foetuses) and 14 primiparous native Greek does (24 foetuses). Fifteen biometric parameters were measured weekly by transabdominal ultrasonography from gestational week 3 until parturition, and population-specific linear equations were derived for each parameter. Thoracic diameter, biparietal diameter and thoracic diameter at the sixth rib gave the most accurate within-sample gestational-age estimates in both populations (R² = 0.97–0.99; RMSE ≤ 0.9 weeks), with femur length and abdominal diameter also performing well. Foetal size and growth differed between the two populations for most parameters, and the number of offspring per dam and foetal sex were further associated with biometric variation, particularly in does. Late-gestation measurements correlated with birth weight (r ≤ 0.76 in does), and exploratory models explained up to 57% of its variance. These findings provide detailed longitudinal reference data and practical, population-specific equations for estimating gestational age, useful for flock and herd management, although independent validation is required before extrapolating them to other breeds or flocks.

Background/Objectives: Heat stress is one of the most economically and physiologically important constraints on pig (Sus scrofa domesticus) production, affecting welfare, reducing feed intake, growth, and reproductive efficiency, while increasing morbidity and mortality; because pigs lack functional eccrine sweat glands and have a limited capacity for evaporative heat dissipation, their ability to cope with high ambient temperature depends heavily on behavioral, physiological, and cellular stress-response mechanisms, which vary among individuals and genetic backgrounds. This review synthesizes current knowledge of the genetic and molecular pathways underlying the pig heat-stress response, spanning the HSF1–heat shock protein axis and epigenetic regulation, as well as genomic regions, candidate genes, nutrigenomic modulation, and reproductive consequences in boars and sows. Methods: A narrative literature review, informed by key principles of the PRISMA 2020 statement, synthesized 58 peer-reviewed transcriptomic, genomic, epigenomic, proteomic, and physiological studies published mainly between 1998 and 2026. Results: Heat exposure activates HSF1-driven heat shock protein transcription, oxidative stress, gut tight-junction disruption, hypothalamic–pituitary proteomic remodeling, and sex-dimorphic apoptotic/inflammatory transcriptional programs that also compromise boar semen quality. GWAS and QTL studies have mapped genomic regions and candidate genes for thermoregulatory, reproductive, and growth traits. At the same time, breed comparisons suggest, but do not prove on their own, a genetic contribution to the smaller physiological responses observed in some tropical and Mediterranean-adapted breeds. Heritability estimates for individual heat-stress-related traits, rather than for heat tolerance as a composite phenotype, range from low (0.02–0.20) for reproductive traits, to moderate (0.35–0.39) for thermoregulatory traits in lactating sows, to moderate-to-high (0.49–0.83) for physiological responses to acute heat challenge in gilts; circulating cortisol (h² ≈ 0.68) is a heritable biomarker of the stress response rather than a measure of heat tolerance itself. Conclusions: Several traits associated with the response to heat stress in pigs are heritable and polygenic, supporting the potential of genomic selection, reaction-norm modeling, and marker-assisted introgression, although functional validation of candidate genes and larger multi-population studies, together with an explicit definition of heat tolerance as a composite selection objective, remain priorities.

Livestock systems are expected to convert human-inedible biomass into animal-source food while reducing their environmental footprint, and the circular economy (CE) provides a framework for this transition. This review argues that the circular value of a feed resource depends less on its availability than on three conditions: the processing required before it can be fed safely, the controllability of its variability and hazards, and the comparability of the life cycle assessment (LCA) evidence for its environmental benefit. Accordingly, resources are classified as suitable for direct feed use (e.g., oilseed meals, distillery co-products, former foodstuffs), requiring biological or technological upgrading (e.g., solid-state fermented residues, insect meal, single-cell protein), or better suited to non-feed valorisation. Nutritional evidence, LCA findings, One Health hazards and regulatory constraints are compared across these classes, distinguishing LCA values reported by original studies from qualitative estimates. A Mediterranean case study on olive mill by-products and phytogenic additives in swine, largely conducted by the authors, is presented separately, with its limits of generalisation. Linkages and trade-offs with the Sustainable Development Goals are examined, and precision livestock farming is evaluated as a conditional enabler rather than a prerequisite. Research priorities are proposed.

Consolidated, multi-pathogen, multi-year surveillance data are scarce for the Greek swine industry. We compiled a retrospective dataset from 55 diagnostic laboratory reports (2024–2026) covering 38 commercial farrow-to-finish pig farms across mainland Greece. Individual sera (n = 8272 valid ELISA results) were tested for antibodies against Aujeszky’s disease virus (gE), Mycoplasma hyopneumoniae, porcine reproductive and respiratory syndrome virus (PRRSV), porcine parvovirus, porcine circovirus type 2 (PCV2), Erysipelothrix rhusiopathiae, Actinobacillus pleuropneumoniae, and swine influenza A virus (swIAV), and 663 pooled blood samples were tested using real-time RT-PCR (PRRSV) or droplet digital PCR (PCV2). Associations with sampling year, age/production stage, and region were assessed using farm-clustered models. Seroprevalence was high for PCV2 (87.2%), PRRSV (80.4%), and porcine parvovirus (80.4%), moderate for A. pleuropneumoniae (56.0%), M. hyopneumoniae (50.9%), and swIAV (48.2%), lower for E. rhusiopathiae (34.3%), and very low for the Aujeszky’s disease gE marker (3.3%). Sows were routinely vaccinated against PRRSV, porcine parvovirus, E. rhusiopathiae, swIAV, and Aujeszky’s disease, and piglets against PCV2 and M. hyopneumoniae; for these agents, seroprevalence therefore largely reflects vaccination rather than natural exposure alone. Because the gE-deleted marker vaccine used in sows does not induce anti-gE antibodies, the low gE seroprevalence indicates limited field virus exposure. Seroprevalence differed significantly between age/production stages for every pathogen, whereas year and regional effects were not confirmed after small-sample-corrected adjustment for farm clustering. PRRSV RNA and PCV2 DNA were detected in 34.6% and 19.5% of pools, respectively; these results confirm the presence of viral nucleic acid in the tested pools but do not indicate the number of infected animals or, for PRRSV, distinguish field from vaccine virus. The dataset provides a quantitative baseline for comparable commercial farms rather than a nationally representative estimate.

Heat stress (HS) constrains livestock production under climate change, impairing health, welfare, productivity and survival. Because fixed resource use is then spread over less output, HS is also a systems-level sustainability problem. This narrative review, based on a targeted search of PubMed, Web of Science and Scopus (2013–2026), proposes a framework linking climate exposure, animal responses, resource flows, circular interventions and Life Cycle Assessment (LCA) across dairy cattle, pigs, poultry and small ruminants, and grades the evidence behind each link. A decomposition of meta-analytic data indicates that HS raises the impact per kg of milk by approximately 3–12% during heat-stress periods, mainly through non-feed burdens. Monte Carlo analysis shows that the direction of this effect is robust, whereas its magnitude depends mainly on the feed share of the total burden. A Heat-Stress Circularity Index (HSCI) is operationalized with explicit metrics, normalization bounds, a geometric aggregation rule and a minimum-welfare gate. A worked example shows that system rankings depend on the aggregation rule, and a pilot application to a commercial Mediterranean pig farm shows that heat-season piglet and weaner mortality triggers the welfare gate despite moderate productivity retention. Evidence is strong for physiological responses but absent for LCA under measured heat stress; five falsifiable hypotheses, with the corresponding validation designs and sample sizes, are therefore proposed.

Swine influenza A virus (swIAV) is an endemic respiratory pathogen of pigs with zoonotic relevance. We analysed retrospective serological data from routine diagnostic submissions (January 2023–May 2026) to a single laboratory, comprising 2003 sera from 66 reports on 44 commercial farrow-to-finish farms in seven regions of mainland Greece, tested with a nucleoprotein ELISA that cannot distinguish vaccine-, maternally, or infection-derived antibodies. Overall seroprevalence was 46.4% (929/2003; farm-clustered 95% CI 39.1–53.8%); at least one seropositive animal was found in 51 of 61 farm-years and in 36 of 44 farms. Seroprevalence differed by production stage (p < 0.001): it was highest in multiparous sows (75.9%) and suckling piglets (70.7%), both likely influenced by sow vaccination and maternally derived antibodies, intermediate in gilts (46.0%) and nursery pigs (38.6%), and lowest in growers (24.8%) and finishers (24.0%), in which antibodies indicate prior exposure rather than current circulation. No consistent temporal trend was detected, although some adjusted models suggested higher seroprevalence in 2025–2026. Regional seroprevalence ranged from 10.1% (Thessaly) to 61.0% (West Greece); the association was significant with the standard but not the bias-reduced cluster-robust estimator (p = 0.014 and p = 0.39) and persisted after adjustment for year and stage, but it rests on few farms per region and is considered exploratory. As a convenience sample of diagnostic submissions, these data provide descriptive rather than nationally representative estimates and support the addition of molecular, subtype-level surveillance.

Livestock production occupies a paradoxical position with respect to climate change: farm animals are highly vulnerable to heat stress, feed and water scarcity, and climate-sensitive disease, while the sector contributes an estimated 14.5% of anthropogenic greenhouse gas emissions, most of which is biogenic methane from enteric fermentation. This review evaluates the evidence for precision livestock farming (PLF)—continuous, automated, real-time monitoring of individual animals’ health, welfare, production and environmental impact—across dairy and beef cattle, small ruminants, pigs, and poultry. For mitigation, precision feeding and additive-dosing strategies have been associated with enteric methane reductions of approximately 10–25%; for adaptation, wearable and non-invasive sensors have been reported to detect heat-stress-related behavioural changes before productivity losses become apparent, and smart climate-control systems have been associated with housing energy-use reductions of roughly 5–10%. Much of this evidence derives from single-farm, small-sample or short-duration studies and should be read as indicative rather than generalisable. Adoption remains constrained by high investment costs, limited interoperability, insufficient technical support, and uneven applicability to extensive and smallholder systems. We conclude that PLF is a valuable enabling technology that, combined with genetic, nutritional, and management strategies, can strengthen the resilience and environmental sustainability of livestock systems under a changing climate.

Over the past two decades, genetic selection has increased average total litter size in commercial sow herds from approximately 9–10 piglets to more than 14 piglets per farrowing, an achievement that has delivered clear economic benefit but has been accompanied by a parallel rise in pre-weaning mortality (PWM), which is now commonly reported in the range of 12–20% and, by some indicative estimates, is trending upward even in well-managed herds. This review synthesizes the veterinary and reproductive-physiology literature on hyperprolificacy in sows, examining its downstream consequences for individual piglet birth weight, farrowing duration, colostrum access, and passive immunoglobulin G (IgG) transfer. Attention is given to the biological mechanism by which litter size dilutes colostral IgG, including vaccine-induced maternally derived antibody (MDA) against porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2), and to the strength of the supporting evidence with regard to each pathogen, which differs considerably. This evidence is considerably stronger for PCV2, where maternal vaccination has a directly demonstrated effect on offspring antibody titres, than for PRRSV, where litter-size-specific dilution of maternally derived antibody has not yet been directly measured and remains an inferred, biologically plausible mechanism rather than a demonstrated one. The review further appraises management interventions including cross-fostering, split suckling, nurse sows, immunoglobulin supplementation, and structured neonatal triage, together with their documented trade-offs and considers the animal-welfare dimension of continued genetic selection for litter size. A dedicated section evaluates the current state of precision livestock farming (automated farrowing and crushing surveillance, computer-vision piglet weighing, and genomic selection for litter uniformity and robustness), concluding that these tools are promising but largely still at the research or early-adoption stage. We conclude that inadequate transfer of passive immunity behaves as an independent risk factor for mortality, separate from birth weight, and that management responses should be viewed as necessary complements to, rather than substitutes for, a re-balancing of genetic selection indices toward piglet survivability.

The intensification of global pig production has increased the pressure to reconcile productivity with animal health, food safety, and environmental sustainability. Phytogenic feed additives (PFAs)—plant-derived compounds including essential oils, oleoresins, phenolics, and polyphenol-rich extracts—have emerged as candidate alternatives to antibiotic growth promoters, with reported benefits of variable consistency for gut health, oxidative status, reproductive performance, and mycotoxin mitigation across the pig production cycle. In parallel, the pig sector is under increasing scrutiny for its environmental footprint, driving the adoption of circular economy (CE) principles and life cycle assessment (LCA) methodologies to quantify and reduce resource use and emissions. This narrative review synthesizes published evidence on the zootechnical, physiological, and health-related effects of phytogenics in swine, identified through literature searches of PubMed, Scopus, and Web of Science). It examines how their production, sourcing, and use intersect with circular economy strategies—particularly the valorization of agro-industrial by-products as phytogenic sources—and with the LCA-based evaluation of pig production systems. No specific study was identified through the search described that directly measured the environmental footprint of phytogenic feed additive use; the health/performance benefits of phytogenics and the environmental benefits of by-product substitution in pig diets are each independently well supported, but their combined net environmental effect remains unknown, and not all phytogenics originate from by-products; this review integrates the two bodies of evidence into a testable hypothesis—that phytogenics, via reduced morbidity/mortality and, where by-product-derived, circular sourcing, may contribute to a lower environmental footprint, rather than a demonstrated outcome. We regard phytogenics as a promising, mechanistically grounded candidate—rather than a confirmed lever—for reducing the environmental footprint of pig production and propose a concrete LCA methodology to test this hypothesis directly.

Heat stress (HS) suppresses voluntary feed intake in lactating sows, yet individual-level characterization of indoor and outdoor Temperature–Humidity Index (THI) linked to feed intake is rare in Mediterranean commercial settings. This prospective observational study enrolled 272 F1-crossbred sows (parities 1–7) farrowing from May–October 2025 at a commercial Greek farm. Outdoor THI was computed from 8760 hourly records and indoor THI from calibrated dataloggers; individual daily lactation feed intake (days 1–30) was recorded via RFID transponder-feeders. Building cooling (ΔTHI = 3.7–14.3) attenuated but did not eliminate mild-to-moderate indoor stress from June–September. Only parity and stillbirth count were Bonferroni-significant correlates of feed intake (parity: β = +0.142, p = 0.002). A sow-day Gradient Boosting model, evaluated by grouped cross-validation to prevent within-sow leakage, achieved CV-R² = 0.406 ± 0.045, providing a validated, herd-tested framework for parity-stratified feeding management, pending external validation across farms, genetics, and climates.