Search Results (206)

This study investigated the interactive pathogenic characteristics of co-infection with Streptococcus equi (S. equi) and Streptococcus dysgalactiae (S. dysgalactiae) isolated from diseased foals. Integrating genomic analysis, in vitro phenotypic assays, and a murine intranasal infection model, we comparatively analyzed the biological traits and pathogenic differences between single and dual infections. Comparative genomic analysis revealed divergent virulence profiles between the two isolates, and both species harbored open pan-genomes. In vitro, the biofilm biomass of strain F1 was higher than that of all other groups. No synergistic hemolytic activity was observed in co-cultures of the two isolates. In vivo infection results indicated that streptococcal infection significantly altered the structure and abundance of pulmonary microbiota in mice. Furthermore, single and dual infections displayed strain-specific and time-dependent microbial disparities at early and late infection stages, which were associated with differential enrichment of multiple immune- and metabolism-related Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, including the Tumor Necrosis Factor (TNF) and Mitogen-Activated Protein Kinase (MAPK) signaling pathways. Notably, co-infection triggered the most severe pulmonary microbiota dysbiosis and aberrant functional pathway regulation. This study preliminarily characterized the distinct phenotypic and pathological alterations induced by dual streptococcal infection, providing experimental evidence and novel insights for further exploring the interactive features of equine streptococcal mixed infections. Full article

Lactation imposes substantial metabolic demands on mares, and milk composition is a major determinant of neonatal development. Although β-hydroxy-β-methylbutyrate (HMB) can regulate protein turnover and energy metabolism in several livestock species, its role in the lactation-growth axis of equids remains insufficiently defined. This study evaluated maternal HMB-Ca supplementation in lactating Yili mares, focusing on milk yield measured during a standardized five-session daytime collection schedule, calculated milk-component output during that schedule, foal growth, and day-30 serum and milk metabolomic profiles. Maternal HMB-Ca supplementation was associated with greater milk yield at day 30 and with greater foal average daily gain during early lactation. To reduce over-interpretation of pathway enrichment alone, we performed a structured phenotype-metabolite correlation analysis. First, the day-30 milk-yield endpoint was correlated with serum differential metabolites; second, the serum features showing strong correlations with this endpoint were compared with milk differential metabolites; third, these serum features were related exploratorily to foal body weight and ADG. This analysis identified 26 serum features with |rho| ≥ 0.60 and nominal p < 0.05 for milk yield, 15 of which met FDR q < 0.10. Several of these features showed annotation-level overlap with the milk differential metabolome and exploratory associations with early foal growth traits. These findings support candidate serum-milk-growth metabolic links accompanying improved lactation performance, but they do not establish a causal pathway. Full article

The Mugalzhar horse is an important native breed of Kazakhstan, valued for its adaptability, milk production, and meat productivity under extensive pasture-based management. This study evaluated the relationships among first-lactation milk yield, productive longevity, lifetime milk production, growth, morphometric traits, and milk composition in the Mugalzhar horse breed using data from 100 mares with complete lifetime production records, 108 adult mares and 12 stallions for morphometric evaluation, and 68 foals (35 colts and 33 fillies) for growth analysis. The study was conducted on Mugalzhar horses maintained at the “Senim” farm in the Turkestan region of Kazakhstan. Morphometric measurements of adult horses, growth dynamics of foals from birth to 18 months of age, milk productivity records, productive longevity indicators, and milk composition data were analyzed. PCA, Pearson correlation analysis, and HCA were applied to assess relationships among productive and compositional traits. Adult stallions and mares closely conformed to breed standards, with stallions exceeding mares by approximately 7.8% in live weight. Foals exhibited intensive postnatal growth, with live weight increasing 6.8–6.9-fold between birth and 18 months of age. Milk yield increased from 722.3 kg during the first lactation to 986.9 kg during the fifth lactation before declining in later lactations, whereas milk composition remained relatively stable. Moderate-to-high first-lactation milk yield groups (G3–G4) achieved the greatest lifetime milk production (24,961–25,997 kg), longest productive life (7.9–8.5 years), and highest number of completed lactations (6.6–6.9). PCA revealed two major biological gradients representing productivity and longevity, while HCA identified G3–G4 as the most favorable production cluster. Milk fat and protein concentrations were negatively associated with milk yield traits. Moderate first-lactation milk yield was associated with the greatest lifetime productivity and longest productive herd life, whereas extremely high first-lactation milk yield was not associated with superior lifetime performance. These findings suggest that first-lactation milk yield may be considered together with longevity and other functional traits in future breeding programs for Mugalzhar horses; however, the results should be interpreted in light of the observational design of the present study. Full article

Early and accurate detection of foaling is important for reducing perinatal mortality and labor demands in commercial breeding farms. This study evaluated a fully noninvasive foaling prediction system integrating thermal imaging with artificial intelligence-based behavioral analysis in Thoroughbred mares. A total of 115 pregnant mares across 13 farms were monitored during the 2024 foaling season. Locomotor activity and body surface temperature relative to ambient temperature were extracted from thermal images, while posture changes and tail-raising behavior were identified from visible-light images using a trained prediction model. Prediction was performed at 5 min intervals using a pretrained neural network model implemented in Python, which generated logistic probabilities based on locomotor activity, body surface temperature, posture change frequency, and tail-raising behavior. Data obtained during the 5 h preceding foaling were analyzed. Locomotor activity and surface temperature significantly increased 70–90 min before foaling (p < 0.05), whereas posture changes and tail-raising behavior markedly increased 25–45 min before foaling. These temporal patterns suggest a biologically interpretable two-phase pre-foaling process derived from sequential changes in behavioral and thermal indicators. The model based on locomotor activity and surface temperature achieved an 80.0% detection rate with a mean lead time of 186 ± 20 min. Incorporating posture changes and tail-raising parameters improved detection to 94.8% and reduced the detection-to-foaling interval to 89 ± 14 min. The system achieved high predictive performance under commercial conditions without requiring invasive or wearable devices. Full article

Neonatal assessment in donkey foals is essential for reducing perinatal mortality and improving early management, yet breed-specific data remain scarce, particularly for indigenous Chinese breeds such as the Luxi Black donkey—an economically and genetically valuable breed of Shandong Province for which neonatal vitality has not been previously characterized. This prospective observational study aimed to describe the distribution of a modified four-parameter Apgar score and to summarize early physiological and morphometric parameters in Luxi Black donkey foals at birth. The study further explored whether these early parameters differed across Apgar score categories, with the aim of providing preliminary breed-specific reference data for neonatal assessment in this indigenous donkey breed. Fifty Jennies and the resulting 51 foals were enrolled at the National Black Donkey Breeding Center in Dong’e County, Shandong, China. Within 5 min of delivery, each foal was scored using a modified Apgar system (heart rate, respiratory rate, muscle tone, reflex response; maximum 8), and heart rate, respiratory rate, time to first suckling, rectal temperature, birth weight, body height, body length, chest girth, and abdomen girth were recorded. Foals were grouped according to their observed modified Apgar score categories (8/8, 7/8, 6/8, and 0/8). All 51 foals were included in the descriptive analysis of Apgar score distribution, while the three stillborn foals with an Apgar score of 0/8 were described separately and excluded from statistical comparisons. Physiological and morphometric parameters were compared only among live-born foals with Apgar scores of 8/8, 7/8, and 6/8. Of the 51 foals, 35 (68.63%) scored 8/8, 7 (13.73%) scored 7/8, 6 (11.76%) scored 6/8, and 3 (5.88%) were stillborn. Among live-born foals, respiratory rate (p = 0.008), time to first suckling (p < 0.001), and rectal temperature (p = 0.001) differed significantly among Apgar score categories, whereas heart rate showed no significant difference (p = 0.052). Birth weight and morphometric measurements did not differ significantly among live Apgar score categories. These preliminary findings suggest that the modified Apgar score may support early descriptive observation of neonatal status in Luxi Black donkey foals, although further studies with larger cohorts and objective outcome-based measures are needed. Full article

Molecular microbiology has revolutionized our understanding of the complex host-associated microbiomes required for normative development and physiology. Horses and other members of the family Equidae are particularly reliant on the early maturation and lifelong maintenance of an unusually rich hindgut microbiome for optimal digestion and overall health and performance. Research on the equine gut microbiome has accelerated in the past several years, necessitating a renewed appraisal of the field. The present work is a comprehensive and critical review of the literature regarding the bacterial gastrointestinal microbiome of horses. First, the developmental trajectory of the foal gut microbiome is discussed, followed by descriptions of the taxonomic membership of the core equine gut microbiome, its primary functions and effects on host physiology, and intrinsic and extrinsic factors that shape the equine microbiome during health, with a focus on diet and supplements. Next, evidence supporting adverse effects on the equine gut microbiome of gastrointestinal conditions including colic and colitis, extraintestinal conditions including obesity and laminitis, and pharmacological interventions including antibiotics and non-steroidal anti-inflammatory drugs is summarized. Lastly, clinical and experimental research investigating the effects of treatments targeting the gut microbiome of horses, including probiotics, prebiotics, and fecal microbiome transfer, is critically examined. Conclusions summarize the connection between natural (i.e., wild) equine behavior and the health of the equine gut microbiome and the impacts of human management. Full article

Rhodococcus equi (R. equi) primarily induces fatal pulmonary and extrapulmonary pyogenic granulomatous infections in foals, imposing substantial economic burdens on the equine industry. The emergence and spread of multidrug-resistant (MDR) R. equi have led to a therapeutic impasse in clinical settings. Although vaccination is a proven strategy against MDR pathogens, no commercial vaccine is currently available for R. equi. In this study, we employed a bioinformatics approach to systematically identify and prioritize antigenic epitopes derived from R. equi for multi-epitope vaccine design. Using ABCPred, NetMHCpan EL, and IEDB servers, 27 MHC-I and 9 MHC-II epitopes were selected from five previously validated R. equi vaccine candidates: ABC transporter, PBD2, NlpC/P60, Esterase, and M23. These epitopes were coupled with distinct peptide linkers to construct six multi-epitope vaccine constructs, designated V1–V6. The physicochemical properties, antigenicity, immunogenicity, and toxicity of the six vaccine constructs were analyzed, and the V3 and V4 constructs were ultimately selected. Using the HDOCK and Gromacs tools, the intermolecular interactions, binding affinity, and thermal stability of the V3 and V4 constructs with the equine MHC molecules EQCA-I and EQCA-II were evaluated. The results confirm that V3 and V4 exhibit strong binding affinity to EQCA-I and EQCA-II, with stable conformations following binding, indicating theoretical potential to induce humoral and cellular immunity in foals. Recombinant plasmids for V3 and V4 were constructed, and the V3 and V4 proteins were successfully prepared, confirming the feasibility of prokaryotic expression for these vaccine constructs. Immunization assays in SPF BALB/c mice showed that the multi-epitope vaccines elicited robust antigen-specific IgG antibody responses, reflecting preliminary humoral immunogenicity. However, these murine data have translational limitations, as they cannot fully represent equine immune responses. The findings establish a crucial theoretical foundation for the advancement of vaccines targeting R. equi while offering a reference for the design of vaccines against other drug-resistant microbial pathogens. Full article

Apart from vigilance and flight, anti-predator defense behavior in horses has not been well documented despite its importance during natural selection. In this study, observations of a feral herd (around 140) of Venezuelan horses sympatric with puma and jaguar divided such defense into precaution and reaction. Group living and the avoidance of danger areas are precautionary measures enhanced by the stallion’s vigilance and his actions to keep small foals with the band. Reactions to perceived threats comprise communication of alarm; bunching, or cohesion, as a primary response; massed flight following self-organizing principles; and reassembly of bands. Stallions usually initiated this behavioral process. Stallions’ initial reactions to perceived threats were “investigation”, “move away”, “run away”, and “stampede”, and resulting herd behavior was categorized into 27 responses. Data analysis through Observation Oriented Modeling indicated that each category of initial stallion response to perceived threats was associated with a recurring pattern of subsequent herd behavior. Prominent behaviors enhanced cohesion and synchrony, as well as velocity and direction matching. A fourth observed category was the cohesive “run to band” of a startled outlying member, in which the individual’s alarm might transmit to the band or the band’s calm transmit to the individual. The results emphasize the importance of communication, social cohesion, and synchronous action in times of perceived threats, their continuous practice during maintenance activities, and the social needs and understanding management of domestic horses. Full article

This narrative review presents examples of omega-3 fatty acids supplementation in horse nutrition. Fats are essential in equine nutrition, serving not only as an energy source but also as functional components influencing health. Among them, omega-3 polyunsaturated fatty acids (PUFAs), particularly EPA and DHA, play a key role in modulating inflammatory and metabolic processes. This review summarizes their effects on respiratory health, equine metabolic syndrome (EMS), musculoskeletal function, reproduction, and early development. Omega-3 supplementation has been shown to support airway inflammation in horses, especially when combined with low-dust management practices. In EMS, these fatty acids support insulin regulation and reduce systemic inflammation, although they are not curative. In the musculoskeletal system, omega-3s help limit inflammation and cartilage degradation. Their reproductive benefits include improved semen quality in stallions and enhanced fatty acid profiles in mare’s milk, supporting foal development. The proposed mechanisms of omega-3 fatty acids’ effect are also provided. Overall, omega-3 fatty acids are a valuable supplement in equine functional nutrition and disease management. Full article

Zn-CS chelate has shown beneficial effects on gut health and growth in piglets, but its impact on weaned foals remains largely unknown. This study evaluated the effects of dietary Zn-CS supplementation on growth performance, nutrient digestibility, physiological status, and fecal microbiota in weaned Ili foals. Thirty-two six-month-old foals were randomly assigned to four treatment groups receiving 0, 2, 4, or 6 mg Zn-CS/kg body weight per day for 90 days. Growth performance, nutrient digestibility, plasma biochemical parameters, liver function enzymes, serum hormones, antioxidant indices, fecal pH, volatile fatty acids, and fecal microbial composition were measured. Dietary Zn-CS supplementation significantly increased final body weight, total weight gain, and average daily gain (p < 0.05), while linearly improving body size indicators. Apparent digestibility of dry matter, digestible energy, metabolizable energy, and acid detergent fiber was markedly enhanced (p < 0.05). Zn-CS supplementation also effectively regulated plasma albumin and total cholesterol levels and hepatic enzyme activities, and strongly enhanced antioxidant function by increasing superoxide dismutase, glutathione peroxidase, catalase activities, and total antioxidant capacity, while reducing malondialdehyde content (p < 0.01). Additionally, Zn-CS upregulated plasma growth hormone, insulin, and triiodothyronine concentrations, decreased somatostatin secretion (p < 0.05), reduced fecal pH, and increased VFA contents. Notably, Zn-CS reshaped the fecal microbial structure by increasing beneficial bacteria and inhibiting potential pathogens. In conclusion, dietary Zn-CS supplementation effectively promotes growth and health in weaned Ili foals, with 6 mg/kg BW/day being the optimal supplemental dose under experimental conditions. Full article

Under grazing conditions, it is difficult for lactating Yili mares to meet their nutritional requirements and those of their suckling foals solely through the consumption of natural pasture. Furthermore, seasonal variations and rainfall significantly influence the quality and nutrient content of forage, which severely constrains the healthy breeding of Yili horses and the industrial development of mare milk resources. Therefore, this study aimed to investigate the effects of concentrate supplementation on lactation performance and milk concentrations of amino acids, fatty acids, and mineral elements in Yili horses under grazing conditions. Twenty-two healthy Yili mares in early lactation, with similar ages (3–4 years), foaling dates, and body weights (391.5 ± 13.74 kg), were randomly assigned to either a grazing group (G, n = 11) or a grazing + supplementation group (GS, n = 11). Mares in group G grazed naturally on pasture, while those in group GS received 1 kg of concentrate supplement twice daily (totaling 2 kg/day) in addition to grazing. The experimental period lasted for 100 days, including a 10-day adaptation period and a 90-day formal experimental period. The results showed that: (1) In terms of lactation performance, the GS group exhibited highly significant increases in milk yield and lactose yield (p < 0.01), as well as significant increases in milk protein and milk fat yields (p < 0.05), with an extended duration of the peak lactation period. (2) Regarding the amino acid profile, the concentrations of threonine (Thr), serine (Ser), glycine (Gly), and alanine (Ala) in the milk of the GS group were significantly higher than those in the G group (p < 0.05), whereas the proline (Pro) content was significantly lower (p < 0.01); supplementation improved the uptake of certain functional amino acids by the mammary gland. (3) Concerning the fatty acid profile, the concentrations of polyunsaturated fatty acids (PUFA) and alpha-linolenic acid in the milk of the G group were significantly or highly significantly higher than those in the GS group (p < 0.05 or p < 0.01). (4) For mineral elements, concentrate supplementation highly significantly decreased the potassium (K) content and the K/Na ratio in horse milk (p < 0.01), highly significantly increased the levels of iron (Fe) and cobalt (Co) (p < 0.01), and significantly enhanced the chromium (Cr) content (p < 0.05). In conclusion, concentrate supplementation during grazing improved lactation performance in Yili mares, primarily by increasing milk yield and extending the peak lactation period. However, grazing alone was more favorable for maintaining higher PUFA and α-linolenic acid proportions in milk. Therefore, concentrate supplementation should be regarded as a nutritional strategy that increases milk output and modifies amino acid and mineral element composition, but may involve a trade-off with some beneficial fatty acids. Full article

Despite a monovalent G3P[12] (‘G3’) vaccine being available for horses, equine rotavirus A (ERVA) is still the predominant infectious pathogen causing diarrhea in foals in the United States of America (U.S.). Previous research has shown that maternal neutralizing antibody (NAb) titers are too high and will interfere with the vaccination of foals at 30 and 45 days of age. We aimed to determine if it is possible to increase NAb titers in foals through vaccination before they are vulnerable to ERVA infection. We immunized two foals with the commercially available vaccine (G3) at solely three months of age and seven foals at both two and three months of age, respectively. Two mock foals were vaccinated with saline buffer in this study. The dams of these foals were not vaccinated during their gestation period. All pre-vaccination G3 and G14P[12] (‘G14’) NAb titers in this foal cohort were 256 or lower. Following vaccination, NAb titers in foals were increased up to 1024 against G3 and up to 512 against G14 viruses, respectively. Interestingly, ERVA NAb titers either increased or stabilized in immunized foals depending on the pre-vaccination NAb titer, which contrasts with unvaccinated foals showing a rapid decline in NAb titers over time. Full article

Klebsiella pneumoniae has been associated with reproductive infections in equines. The detection of β-lactam resistance determinants, especially extended-spectrum β-lactamase (ESBL) genes, within genomic regions linked to horizontal gene transfer (HGT), is of a particular concern. In this study, we characterize the whole-genome sequences (WGS) of three K. pneumoniae equine isolates harboring multiple antimicrobial resistance genes. Two isolates were recovered from uterine washes of mares: one with endometritis (YAH-KPEM1) and one clinically normal (YAH-KPSE1), and a third from the feces of a diarrheic foal (YAH-KPF132). WGS was performed using the Illumina MiSeq platform, and the reads were subsequently processed through hybrid assembly in Unicycler v0.5.1. Genome annotation was completed using PROKKA v1.14.5. Strain YAH-KPEM1 was classified as ST127, whereas YAH-KPSE1 and YAH-KPF132 belonged to ST1630 and ST224, respectively. Notably, K. pneumoniae ST1630 and ST224 have not been reported before in equines. All three genomes encoded multiple antimicrobial resistance (AMR) determinants, including two encoding ESBL genes (CTX-M-15), as well as virulence factors and regions associated with HGT. Additionally, two (YAH-KPEM1 and YAH-KPSE1) isolates were found to be multidrug resistant (MDR), harboring an IncFIB(K) plasmid replicon, and another isolate, YAH-KPF132, carried an IncFII replicon. The detection of AMR and virulence genes in equine Klebsiella isolates has important clinical implications for guiding antimicrobial selection and improving treatment success. Full article

Rhodococcus equi is an opportunistic intracellular pathogen responsible for severe pneumonia in foals and has emerged as an important cause of infection in immunocompromised humans. The treatment of R. equi infections in foals relies mainly on the combination of macrolides and rifampin. However, the increasing incidence of multidrug-resistant (MDR) isolates has raised significant therapeutic challenges. The mechanisms underlying this resistance include mutations in target genes, activation of efflux pumps, and biofilm formation, which collectively compromise the efficacy of conventional antibiotics. Recently, growing concern over antibiotic failure has accelerated research into alternative and synergistic strategies to enhance antibacterial efficacy and reduce the development of resistance. Natural and synthetic compounds, as well as optimized antibiotic combinations, have shown promising synergistic effects by enhancing intracellular accumulation, disrupting redox homeostasis, or inhibiting efflux systems. Experimental models employing checkerboard and time-kill assays, as well as redox-sensitive biosensors, have demonstrated that certain antibiotic combinations can influence bacterial susceptibility to antibiotic exposure. Furthermore, integrating molecular tools provides valuable insight into bacterial responses to oxidative and antibiotic stress, paving the way for novel therapeutic designs. This review summarizes the current understanding of the molecular factors contributing to antimicrobial resistance in R. equi and assesses new therapeutic approaches aimed at overcoming these challenges. It highlights recent findings on strategies to improve treatment outcomes and manage antimicrobial resistance. Full article

This study evaluated the effects of dietary protein levels during late gestation on nutrient digestibility, plasma amino acid profiles in jennies, and donkey foal growth performance. Twenty-four pregnant jennies were randomly assigned to one of three diets with different crude protein (CP) contents during late gestation: 12.48% (HP), 11.52% (MP), and 10.54% (LP) on a dry matter basis. All animals received the same diet immediately after parturition for a duration of 30 days. During the trial, two digestion experiments were conducted, blood samples were collected at 28 and 7 days prepartum, and weekly weight measurements of jennies and foals were recorded. The results indicated that the dietary protein level did not significantly affect feed intake in late gestation. However, apparent nutrient digestibility of dry matter (DM), neutral detergent fiber (NDF), acid detergent fiber (ADF), crude protein (CP), and ether extract (EE), and calcium (Ca) and phosphorus (P) was generally higher in the MP and LP groups than in the HP group, with MP showing the most consistent improvements across nutrients and timepoints (p < 0.05). Although the HP diet increased plasma concentrations of certain amino acids, including glutamic acid (Glu), valine (Val), methionine (Met), leucine (Leu), essential amino acids (EAAs), functional amino acids (FAAs), and branched chain amino acids (BCAAs), and elevated serum levels of glucose (GLU), blood urea nitrogen (BUN), and creatinine (CRE), it failed to improve postpartum weight recovery in jennies, highlighting that weight dynamics during this period are governed by factors beyond dietary protein content alone. Specifically, the LP group exhibited significantly higher cumulative postpartum weight loss over weeks 1–4 than the HP group (p = 0.004). Regarding offspring performance, both HP and MP diets improved foal birth weight, weekly body weight up to 4 weeks, average daily gain, and body height compared to the LP group (p < 0.05), with no significant differences observed between the HP and MP groups. In conclusion, for jennies under the current confined feeding system, a late-gestation diet containing 11.52% CP was adequate to support higher nutrient digestibility in the jennies and better growth performance in their foals, compared to a lower protein level (10.54% CP). However, increasing the dietary CP to 12.48% provided no additional benefits in nutrient utilization or overall productivity. Full article