Plasma relaxin, estrogens and progestogens concentration in coldblooded and hot-blood mares in the second half of gestation

Monitoring estrogens, progestogens, and relaxin plasma concentration can be important for determining pregnancies at risk of failure in mares. However, significant breed-related differences in values of reproductive hormones are known, and data concerning coldblooded (CB) mares are missing. The aim of the study was to determine and compare serum relaxin, estrone sulphate (E1S), estradiol-17β (E2), and progestogens concentration in pregnant CB and hot-blood (HB) mares during the second half of gestation. Blood samples obtained from 94 healthy mares in the second half of gestation with known mating dates were analyzed. Samples were collected from 36 CB mares aged from 3 to 16 years and 58 HB mares aged from 4 to 17 years. The hormone concentrations were measured using immunoenzymatic equine species-specific commercial kits. The serum relaxin concentration was almost three times lower in CB, whereas E1S and E2 almost twice as low, as compared to HB mares (P < 0.05). In conclusion, the extremely low concentration of relaxin in CB mares could be one reason for the increased amounts of difficult parturition requiring veterinary intervention noted in these breeds.

The Influence of Selected Factors on the Nutritional Value of the Milk of Cold-Blooded Mares: The Example of the Sokólski Breed

This study assessed the effect of access to pasture, lactation number, and foals’ sex on the nutritional value of milk (79 samples) from nine mares. The following were analysed: content of dry matter, protein, fat, lactose, and ash; percentages of α-lactalbumin (α-La), β-lactoglobulin (β-Lg), serum albumin (SA), immunoglobulins (Ig), lactoferrin (Lf), and lysozyme (Lz) in the total protein; and the fatty acid profile. Mares without access to pastures were shown to produce milk with a higher dry matter content, including fat, lactose, and ash; higher percentages of β-Lg, α-La, Ig, and Lf; and a better fatty acid profile. The milk from mares with access to pasture contained more protein, including higher percentages of SA and Lz. Milk from mares in lactations 4–6 had the highest fat and protein concentrations and the lowest lactose concentration. The α-La level was highest in lactation 1, Lf in lactations 2–3, and Lz in lactations 4–6. Milk from mares in lactations 4–6 had the best fatty acid profile (the lowest concentration of saturated fatty acids (SFAs) and the highest concentration of monounsaturated fatty acids(MUFA) and polyunsaturated fatty acids (PUFA)). Milk from mothers of female offspring had higher dry matter, fat, and protein concentrations, a higher share of lysozyme, and a better fatty acid profile.

Variation of Physiological and Behavioural Parameters during the Oestrous Cycle in Mares

The behaviour of oestrous mares is well-known in horse breeding. However, alterations in their physiological and behavioural indices during the whole oestrous cycle are scarcely known. The objective of the study was to analyse changes in cardiac activity variables, rectal and superficial temperatures, behaviour towards humans and conspecifics, and the time of standing and locomotor activity in mares during their oestrous cycle. Fifteen adult mares in oestrus were examined in the morning and evening (six successive days) and in dioestrus (five days-once every third day). The oscillation of physiological and behavioural variables accompanies changes in mares' sexual behaviour. Most physiological variables studied in oestrus indicate the elevated activity of the adrenergic nervous system and, opposite to that, both behaviour towards humans and conspecifics and the time of standing relate to a relaxed state. The end of oestrus, manifested by a rapid decrease in most of the physiological variables studied, is followed by changes of behavioural variables at the beginning of dioestrus. The time of locomotor activity arises at the end of oestrus. The outcomes may contribute to the knowledge of, among others, mare owners who evaluate the oestrus by mares' sexual behaviours without regarding other rhythmically changing variables.

Can Sound Alone Act as a Virtual Barrier for Horses? A Preliminary Study

Virtual fencing is an innovative alternative to conventional fences. Different systems have been studied, including electric-impulse-free systems. We tested the potential of self-applied acoustic stimulus in deterring the horses from further movement. Thirty warmblood horses were individually introduced to a designated corridor leading toward a food reward (variant F) or a familiar horse (variant S). As the subject reached a distance of 30, 15 or 5 m from a finish line, an acute alarming sound was played. Generally, a sudden and unknown sound was perceived by horses as a threat causing an increase in vigilance and sympathetic activation. Horses' behaviour and barrier effectiveness (80% for F vs. 20% for S) depended on motivator (F/S), while the cardiac response indicating some level of stress was similar. The motivation for social interactions was too strong to stop the horses from crossing a designated boundary. Conversely, the sound exposure distance did not vary the barrier effectiveness, but it differentiated HRV responses, with the strongest sympathetic activation noted at a distance of 5 m. Thus, the moment of a sound playback has important welfare implications. Due to the limited potential of sound as a virtual barrier, auditory cues cannot be used as an alternative for conventional fencing.

Minimizing the Effects of Social Isolation of Horses by Contact with Animals of a Different Species: The Domestic Goat as an Example

This study aimed to perform a comparative analysis of the horses’ heart rate parameters and locomotor activity in a herd or isolation, with or without the company of goats. Twenty horses were tested in a paddock, accompanied (or not) by three goats. The experiment comprised four tests (a control test of a herd of horses without goats, a horse isolation test without goats, a test of a herd of horses with goats and a test of an isolated horse with goats). The horse’s locomotor behavior, and the HR, RR, rMSSD, LF, HF, and LF/HF were recorded. The data analysis included a 15-min rest, procedural and recovery HR/HRV periods, and a 5-min period at the beginning of the test. The duration of the horses standing in the company of goats increased significantly. The rMSSD parameter was the significantly lowest in the test of a herd of horses with goats. The company of goats in a paddock does not eliminate the emotional effects of the phenomenon. However, the locomotor behavior decreases. Goats in a paddock can provide a positive distraction for horses in a herd as a decrease in emotional excitability can be regarded as having a relaxing impact on a different animal species.

Correction: Wiśniewska et al. Heterospecific Fear and Avoidance Behaviour in Domestic Horses (Equus caballus). Animals 2021, 11, 3081

The authors wish to make the following correction to this paper [...]

Behavioural responses of Konik Polski horses to natural, familiar sound of thunderstorm, and unfamiliar similar-sounding sounds of volcanic eruption and sea storms

Background

It is not clear, if modern Konik Polski horses have retained the ability to identify sounds in terms of danger. The aim of the study was to identify differences in their behaviour in response to the reproduction of volcanic eruption and sea storm sounds, assumed to be unfamiliar to these horses, as compared to their response to a thunderclap sound, considered by the horses as potentially dangerous. The study included 13 adult mares of the Konik Polski breed, kept under a free-range system. Their behavioural responses to the reproduction of the three natural sounds with an intensity of over 50 dB, were registered. They were analysed distance of each horse to the central point of the pasture and to the exit from the enclosure, and time and/or frequencies of elements of behaviour categorised as: increased anxiety (walking, trotting and cantering), vigilance (snoring, vocalisation, high head position, high tail position, sticking together), foraging (time of grazing), comfort (playing, examining the surroundings, sniffing), maintenance of hygiene (rubbing against objects, auto- or allogrooming, rolling) and resting. The obtained data were analysed by the Dwass, Steel and Critchlow-Fligner method using the SAS program.

Results

Most of analysed elements increased in response to reproduced sounds and decreased after sounds were stop playing (p < 0.05), however, they were no significant differences in general response to each studied sound.

Conclusions

The responses of horses to similar sounds of both known and unknown origins, i.e. the sound of a thunderstorm, sea storm and volcanic eruption, are similar. The sound stimuli applied were not too stressful for the horses.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03314-4.

Horses’ Response to a Novel Diet: Different Herbs Added to Dry, Wet or Wet-Sweetened Oats

Simple Summary

The commercial horse feed industry uses palatants to mask undesirable tastes of feed and enhance consumption. However, an unknown smell or taste may also hinder feed intake, due to, among other aspects, novelty. The acceptability of herbs by horses has not been studied. We analysed whether five herbs (field mint, common yarrow, common chamomile, common sage and common nettle) added alternately to oats and presented within a dry, wet or wet-sweetened diet influence horses’ willingness to consume. Twenty horses were given different diet combinations of a feed presentation and a herb consecutively, once daily. Seven parameters showing the willingness to consume were measured: times of olfaction and consumption, times and numbers of intervals in consumption and drinking water, and mass of leftovers. The results show that the herbs in the amount offered did not influence the time of intake and only the dry oats with common sage added were smelled longer before consuming. However, wetting or wetting and sweetening the feed increased the willingness to eat. In conclusion, herbs in small amounts do not affect the feed intake, whereas wetting and sweetening the diet is of great importance and should be regarded when preparing horse diets.

Abstract

The commercial horse feed industry uses palatants to mask undesirable tastes of feeds and enhance product acceptance. However, an unknown odour or taste may also hinder feed intake, due to, inter alia, novelty. The objective of the study was to assess the horses’ response to novel diet: five different herbs added alternately to dry, wet or wet-sweetened oats. Twenty adult horses were given different diet combinations of a feed presentation and a herb: field mint, common yarrow, common chamomile, common sage and common nettle, consecutively, once daily. The response to novelty was assessed regarding traits showing the willingness to consume: times of olfaction and consumption, times and numbers of intervals in consumption and drinking water, and the mass of leftovers. The results show that properties of the herbs studied did not hinder the consumption and only the odour of the dry common sage delayed the intake. Wetting or wetting and sweetening the diet accelerated the intake. In conclusion, herbs in small amounts do not significantly affect the willingness to consume feed. Although wet and wet-sweetened diet presentations may be novel to horses, they increase the feed palatability and can be suggested for use when preparing horse diets.

Heterospecific Fear and Avoidance Behaviour in Domestic Horses (Equus caballus)

Simple Summary

Horses lacking exposure to cattle often show a fearful response when confronted with cows. In controlled conditions, we tested the responses towards two cows and a novel moving object in twenty horses in arena and hand-leading tests. The horses avoided the proximity of all stimuli, but of one of the cows the most. However, both cows provoked a stronger cardiac response than an inanimate object. We hypothesise that this response may be due to both neophobia and heterospecific interactions.

Abstract

Ridden horses have been reported to be fearful of cows. We tested whether cows could provoke behavioural and cardiac fear responses in horses, and whether these responses differ in magnitude to those shown to other potential dangers. Twenty horses were exposed to cow, a mobile object or no object. The time spent at different distances from the stimulus was measured. In a separate test, heart rate (HR), root mean square of successive differences between heartbeats (RMSSD) and the horses’ perceived fear were assessed at various distances from the stimuli. The horses avoided the area nearest to all stimuli. During hand-leading, the cow elicited the highest HR and lowest RMSSD. Led horses’ responses to the cow and box were rated as more fearful as the distance to the stimulus decreased. Mares had a higher HR than geldings across all tests. HR positively correlated with the fearfulness rating at the furthest distance from the cow and box, and RMSSD negatively correlated with this rating in cow and control conditions. Our results show that these horses’ avoidance response to cows was similar or higher to that shown towards a novel moving object, demonstrating that potentially, both neophobia and heterospecific communication play a role in this reaction.

Does the type of exercise affect tryptophan catabolism in horses?

Tryptophan (Trp) is an essential amino acid which metabolises via the kynurenine pathway to generate a number of bioactive substances referred to as kynurenines. Among those are 3-hydroxykynurenine (3-HKyn) and quinolinic acid, which are neurotoxic, as well as kynurenic acid (Kyna) and xanthurenic acid (XA), which, similarly to nicotinamide (NAm), show neuroprotective and anti-depressive effects. Routine exercise is known to modulate Trp metabolism in skeletal muscle and is thus believed to reduce the risk of depressive states in humans and laboratory animals. Analogously, it was hypothesised that exercise can influence Trp metabolism in horses as well. The aim of this study was to evaluate the influence of two different types of exercise on Trp metabolism in horses of the same breed. A total of 32 purebred Arabian horses were involved in the study. The 22 three-year-old racehorses were subjected to short-time intense exercise. Ten other horses were made to perform endurance competitions at a distance of 80 km. Blood samples were collected at rest and following the end of the exercise period. Plasma concentrations of Trp, kynurenine (Kyn), Kyna, 3-HKyn, XA and NAm were determined using Ultra-High Performance Liquid Chromatography-Electrospray Ionisation-Tandem Mass Spectrometry. Short-time intense exercise led to an increase in plasma concentrations of Kyn, Kyna and XA. The endurance effort induced an increase in Kyna and a decrease in Trp and NAm levels. Both types of exercise, short-time intensive exercise and endurance exercise induced an increase in Trp metabolites, especially Kyna, and did not induce an increase in Trp level. Thus, from a pathophysiological perspective of the kynurenine pathway's influence on mental state, both types of exercise induced beneficial effects in horses.

Plasma Activin A and Decorin in Exercised Purebred Arabian Horses - Preliminary Study

Development of the musculoskeletal system occurs, in part, through an impact on regulatory proteins, such as activin A and decorin. Activin A induces atrophic effects on skeletal muscle, and decorin regulates the formation of connective tissue proteins like collagen and elastin in tendons and ligaments. The aim of this study was to evaluate the influence of different intensities of exercise on blood plasma activin A and decorin concentrations in horses. Ten young purebred Arabian horses were subjected to routine training sessions on a racetrack, and another 11 adult horses of the same breed participated in endurance rides. Race horses were examined during gallop tests over a distance of 1200 m and endurance horses at distances from 20 to 80 km. Blood samples were collected at rest and after exercise to determine plasma concentrations of activin A, decorin and cortisol. Despite differences in the intensity of exercise, the plasma decorin concentration remained unchanged, and activin A tended to decrease in endurance horses only. The exercise-induced changes in plasma activin A concentrations correlated with the covered distance (r = -0.43; P < .05), but not with the changes in cortisol values. Further studies are needed to confirm the usefulness of plasma activin A as a potential indicator of a horse's endurance performance.

Exploratory Behaviours of Primitive Horses Based on Konik: A Preliminary Study

This study aimed at assessing the behaviour of Konik geldings and mares, kept in a stable and in a free-range system, during behavioural tests regarded as a determinant of the exploration urge. A total of 19 Konik horses kept in individual stables and in a free-range system were included in the study. The experiment was conducted in five phases separated by five-day breaks. A one-stage passive human test was performed during the first phase, a three-stage active human test-2nd phase, a three-stage unknown object test-3rd phase, a two-stage unknown surface test-4th phase, and a one-stage test of social isolation-5th phase. Ten attributes were analysed, including the horse sex and the keeping system. The results were also correlated with one another. Konik horses were found to show the urge to explore, although their behavioural responses are individual and stimulus dependent. In many cases, the horse sex and the keeping system influence the exploratory behaviour, although it is manifested by a greater intensity in geldings than in mares, and in free-range horses than in those kept in a stable. The study is regarded as preliminary due to the small number of horses in the study groups.

Heart rate variability in Konik and purebred Arabian horses in response to different predator vocalisations

The current predation threat of domestic horses is generally low, and horses do not know predators' frightening cues. We studied whether horses still recognise predation threats. The aim of the study was to analyse the emotional response of purebred Arabian horses (Arabian) and Polish Konik horses (Konik) to an Arabian panther (Panthera pardus nimr) (panther) growl and a grey wolf (Canis lupus) (wolf) howl. Panther vocalisation was known to Arabian ancestors, whereas ancestors of Konik knew wolf vocalisation. The response to the howls of golden jackals (Canis aureus) (jackal), which did not prey on equids, was also studied comparatively. Two groups of 10 adult horses of each breed were subject to predator sounds of one predator daily for 5 min during a turn out on pasture. The test was performed for 18 days in total. The sound of each predator was interchangeably featured from one loudspeaker for 3 days followed by four loudspeakers simultaneously to imitate a group of predators for 3 days. The horses' emotional agitation in response to the sounds was measured based on the parameters of heart rate variability (HRV) using telemetric devices. The results showed that the predators' sounds were identified by horses as stressful or neutral. Horses generally retained their anti-predator responses even in the current habitat, which typically lacks predation cues. The results are not always coherent and may demonstrate that the response is somewhat attenuated. The wolf howl elicited a stronger response in Koniks. The panther growl more strongly influenced Arabians, whereas the jackal howl minimally elicited an agitation in the horses. The differentiated response of the two horse breeds to the three predator species suggests that the response is an innate adaptation to the predation risk in the habitat of the breed ancestors. This response occurs regardless of the emotional arousal specific to a breed, and the frightening cue is not the sound per se but the possible attack of predators. Horses display a type of understanding of the sound meaning. Their HRV response seems to be adequate for the threat signalised by the sound.

Social Behaviour of Horses in Response to Vocalisations of Predators

We tested the hypothesis that social defensive responses to the vocalisation of a predator still exist in horses. The recordings of a grey wolf, an Arabian leopard and a golden jackal were played to 20 Konik polski and Arabian mares. Durations of grazing, standing still, standing alert and the number of steps in walk and trot/canter were measured. In one-minute scans, the distances of the focal horse from the reference horse (DIST-RH) and from the nearest loudspeaker (DIST-LS) were approximated. The vocalisation of a leopard aroused the Arabians more than the Koniks (less grazing, stand-still and walk, more stand-alert and trotting/cantering). Koniks showed more relaxed behaviours to the leopard vocalisation (more grazing, stand-still and walk), but high alertness to the wolf playback (stand-alert, trotting/cantering). Spatial formation of the herd of Koniks showed tight grouping (lower DIST-RH) and maintaining distance from the potential threat (DIST-LS) in response to the wolf howling, while the Arabians approached the loudspeakers in linear herd formation when the leopard growls were played. Adult horses responded to potential predation by changing spatial group formations. This ability to apply a social strategy may be one of the explanations for the least number of horses among all hunted farm animal species.

Concentrations of Circulating Irisin and Myostatin in Race and Endurace Purebred Arabian Horses-Preliminary Study

Simple Summary

Irisin and myostatin are regulatory proteins produced by muscle cells. The aim of the study was to evaluate the effect of exercise on plasma irisin and myostatin concentrations in horses in different types of training (speed versus endurance). To find out, we tested 20 Arabian horses, submitted to the two different equestrian disciplines, and consequently different training regimes. The first group of horses realized a short-term, high-speed bout of exercise whereas the second group of horses were submitted to long-lasting, endurance effort. The obtained results showed that the single bout of exercise induced an increase in plasma myostatin concentration. Plasma irisin level decreased during the race season in racehorses. This means that irisin and myostatin may play a regulatory role in the maintenance of the energy balance processes.

Abstract

Skeletal muscle is considered to be the largest endocrine organ determining the maintenance of energy homeostasis. Adaptive changes in skeletal muscles in response to physical exercise influence the production as well as secretion of myokines, which are bioactive factors that play a crucial role in energy expenditure processes. The aim of the study was to investigate the impact of two different types of exercise on the circulating level of two of these, myostatin and irisin, in trained horses. Twenty purebred Arabian horses were involved in the study: 10 three-year-old horses trained on the racetrack and 10 endurance horses aged 7.4 ± 1.9 years. The horses from both groups were regularly trained throughout the entire season, during which they also participated in Polish National competitions. To assess the influence of the training sessions on plasma myostatin and irisin concentrations, blood samples taken at rest and 30 min after the end of exercise were analyzed. In the studied horses, the single bout of exercise did not influence plasma irisin but induced an increase in plasma myostatin concentration. In racehorses, plasma irisin concentration decreased with the length of the training season. Plasma myostatin was higher in endurance horses than in three-year-old racehorses. Lack of exercise-induced fluctuation in circulating irisin in studied horses suggests that myostatin released in response to exercise provides a negative feedback signal to irisin release.

The intensity of physiological and behavioral responses of horses to predator vocalizations

Background

Predatory attacks on horses can become a problem in some parts of the world, particularly when considering the recovering gray wolf populations. The issue studied was whether horses transformed by humans and placed in stable-pasture environments had retained their natural abilities to respond to predation risk. The objective of the study was to determine the changes in cardiac activity, cortisol concentrations, and behavior of horses in response to the vocalizations of two predators: the gray wolf (Canis lupus), which the horses of the breed studied had coevolved with but not been exposed to recently, and Arabian leopard (Panthera pardus nimr), from which the horses had been mostly isolated. In addition, we hypothesized that a higher proportion of Thoroughbred (TB) horse ancestry in the pedigree would result in higher emotional excitability in response to predator vocalizations. Nineteen horses were divided into groups of 75%, 50% and 25% TB ancestry. The auditory test conducted in a paddock comprised a 10-min prestimulus period, a 5-min stimulus period when one of the predators was heard, and a 10-min poststimulus period without any experimental stimuli.

Results

The increase in heart rate and saliva cortisol concentration in response to predator vocalizations indicated some level of stress in the horses. The lowered beat-to-beat intervals revealed a decrease in parasympathetic nervous system activity. The behavioral responses were less distinct than the physiological changes. The responses were more pronounced with leopard vocalizations than wolf vocalizations.

Conclusions

The horses responded with weak signs of anxiety when exposed to predator vocalizations. A tendency towards a stronger internal reaction to predators in horses with a higher proportion of TB genes suggested that the response intensity was partly innate. The more pronounced response to leopard than wolf may indicate that horses are more frightened of a threatening sound from an unknown predator than one known by their ancestors. The differing response can be also due to differences in the characteristic of the predators’ vocalizations. Our findings suggested that the present-day horses’ abilities to coexist with predators are weak. Hence, humans should protect horses against predation, especially when introducing them into seminatural locations.

Effect of air temperature and humidity in a stable on basic physiological parameters in horses

The aim of the study was to analyse selected air parameters in a stable (microclimate) and the basic physiological parameters of horses housed in the stable in different seasons of the year. The research material was 12 adult hot-blooded horses kept in a brick stable with stalls. Air parameters in the stable (temperature in the passageway, temperature in the stall at two points, relative humidity in the passageway, and relative humidity in the stall at two points) were determined four times in one year, in summer, autumn, winter and spring. Measurements were made with a Bluetooth BLE-LOGGER LB-518 battery-operated cordless thermo-hygrometer at 12 noon at five points in the stable located 300 cm apart. Physiological parameters of the horses, i.e. internal body temperature (Veterinär SC 12 veterinary thermometer), heart rate (Polar ELECTRO OY RS800CX with PolarProTrainer 5.0. software), and respiratory rate (with a manual stopwatch) were measured at 6 a.m. and 6 p.m. on each day of the study. The season of the year was found to have a significant influence on the microclimate of the stable. To ensure optimal air humidity, airing of the stable should be limited only in winter and periodically in autumn. It is also worth emphasizing that the stable microclimate has a marked effect on the basic physiological parameters of horses. High temperature and relative humidity in the stable can cause unfavourable changes in the form of an increase in evening body temperature in the summer and a decrease in the winter. The remaining parameters, i.e. heart rate and respiratory rate, can also unfavourably increase, mainly in the summer. Horses should have fewer problems maintaining normal physiological parameters in winter, even fewer in autumn, and the fewest in spring.

Bee Pollen Supplementation to Aged Horses Influences Several Blood Parameters

In humans and animals, aging leads to a decrease in immune function and an increased susceptibility to infection. Decreased immunity and an increase in the incidence of infectious diseases are particularly notable during the autumn. Bee pollen supplementation improves immunity and antioxidant enzyme activity, as well as general performance. The aim of this study was to evaluate the effects of bee pollen supplementation during the autumn on blood parameters in aged horses. The study was performed on 16 warmblood horses aged 15-26 years. Half of this group received 60 g of bee pollen (soaked in water) daily for 30 days during the autumn season. Blood samples were taken from all horses before and after the supplementation period. Numerous hematological and plasma biochemical parameters including indicators of oxidative stress were determined. The data collected after the supplementation were compared with data collected before the experiment using one-way analysis of variance and paired Student's t-test. In the control group, there was a decline in the total number of red blood cells, hemoglobin, and hematocrit and an increase in some lipid parameters, urea, total plasma proteins, and sulfhydryl groups. Supplementation with bee pollen prevented the variation of these parameters, except for low-density lipoprotein cholesterol. We believe that bee pollen supplementation for aged horses during autumn has beneficial effects because it inhibited some of the adverse changes observed in the control horses during this season.

Body temperature of horses spending time in paddocks in various weather conditions during the summer

The aim of the study was to determine the internal and surface temperature of selected body parts of horses during their stay in paddocks in various weather conditions in the summer. The study was conducted on 10 adult thoroughbred mares. The experiment was carried out on horses spending time in the paddock in four eight-hour stages with differing weather conditions in summer (sunny, cloudy, rainy and windy). Measurements of internal temperature (Veterinär SC 12 veterinary thermometer) and surface temperature of the head, rib area and croup (Thermal Imagers Ti9 FLUKE infrared camera and SmartView 4.1 software) were carried out at rest and again after four and eight hours in the paddock. It was concluded that the time horses spend in the paddock in summer should depend on weather conditions. Many hours spent outside the stable during sunny weather accompanied by high air temperature can contribute to overheating. On the other hand, rain and wind can cause hypothermia. Therefore, it is worth considering leaving horses in the stable or limiting their stay in the paddock to no more than four hours.

Plasma Apelin Concentration in Exercised Horses: Preliminary Study

Physical effort is one of the key aspects of keeping horses in good condition. The condition of the animal is reflected by multiple blood parameters. The newly discovered cytokine-apelin can pose one of them, however, so far, has not been studied in the horse population. Apelin is produced by adipocytes and myocytes and plays an important role in the energy metabolism of the body through the influence, for example, on the process of adipogenesis and lipolysis. The aim of this study was to investigate if physical effort of various intensity affects the plasma concentration of apelin in horses. The study involved 20 purebred Arabian horses divided into two groups. The first group included 10 race horses, aged 3 years, and second group included 10 horses aged from 6 to 12 years, used in endurance rides. Blood samples were collected from each horse at rest and after exercise. The concentrations of apelin, lactic acid, cortisol, uric acid (UA), triacylglycerols, total plasma protein, and glucose were determined in plasma samples. Race training sessions induced significant decreases in plasma apelin concentrations (P < .05). In endurance horses, significant correlations were found only between exercise-induced changes of apelin and cortisol (r = 0.55) and apelin and UA (r = 0.67) concentrations. In conclusion, the concentration of apelin in equine plasma decreases in response to short-time exercise unlike endurance exercise. Blood plasma apelin concentration determined at rest is lower in long-time regularly trained horses than in the ones at the beginning of their training process.

Assessment of affiliative behaviour in mares

The first aim of study was to assess the feelings of friendship and companionship among mares released into a paddock in different combinations by analysing the duration of behaviours occurring there as well as changes in heart rhythm. The second aim of the study was to develop a procedure for creating different herd configurations based on the individual affiliative needs of horses, expressed as a score. The study was conducted on 12 one-year-old Thoroughbred mares. It was carried out on three consecutive days during the horses’ 30-minute stay in the paddock. On the first day, all mares were in the paddock together. On the second day, they were released in pairs, and on the third day, they were released individually. Expressions of affiliative behaviours (feelings of friendship and companionship) towards another horse were timed. The activity of the parasympathetic system was measured as well. The results were used to score the mares’ affiliative behaviour using a procedure of our own design. Feelings of friendship and companionship were found to be most strongly expressed when a herd of horses with an established hierarchy including each individual was present on the paddock. Releasing horses in pairs is a good substitute for releasing the entire herd, but cannot replace true herd relations, due to decreased expression of feelings of closeness and companionship, such as play or grooming. Releasing horses into the paddock individually is not recommended because it disturbs social behaviour, thus increasing emotional excitability. Emotional excitability is calmed when horses are released in pairs, so this configuration can be used for excitable horses. The best solution, however, seems to be the use of the affiliative behaviour score proposed in the study, as an indicator of the individual needs of mares when creating various herd configurations.

Use of Music Therapy in Aiding the Relaxation of Geriatric Horses

The aim of the study was to evaluate the effect of music therapy on changes in the level of parameters describing heart rate (HR) and heart rate variability (HRV) as excitability indicators in geriatric horses. The study involved 20 warmblood geriatric horses, aged 20 years or more. Animals were kept in two identical stables in one facility. Horses from stable No. 1 were considered the experimental group, whereas horses from stable No. 2 constituted a control group. The experiment consisted in playing relaxation new age music to the horses in the experimental group for 28 days use special sound system (MyPetSpeaker). To examine the emotional excitability of horses from both groups, HR and HRV parameters were used. The subsequent measurements were performed morning at rest at 7-day intervals, counting from the first day of the experiment, and four measurements were recorded. HR and HRV measures indicated that daily exposure for several hours to new age music had a positive effect on relaxation of geriatric horses. A short-term effect of 1-2 weeks duration was observed beginning 1 week after onset. Unfortunately, the effect disappears after subsequent 2-3 weeks of therapy application, without leaving spectacular results.

Exercise-induced changes in skin temperature and blood parameters in horses

The aim of the study was to assess the effects of training on haematological and biochemical blood parameters as well as on the changes in body surface temperature in horses. In order to identify the predictive value of surface temperature measurements as a marker of animal's performance, their correlations with blood parameters were investigated. The study was carried out on nine horses divided into two groups: routinely ridden and never ridden. Infrared thermography was used to assess surface temperature changes before (BT) and just after training (JAT) on a treadmill. Seven regions of interest (ROIs) located on the neck, shoulder, elbow, back, chest, gluteus and quarter were analysed. The blood samples were taken BT, JAT and 30 min after training (30AT). Haematological parameters including white blood cells, lymphocytes (LYMs), monocytes (MONOs), granulocytes (GRAs), eosinophils (EOSs), haematocrit (HCT) and platelets (PLTs) as well as biochemical parameters such as glucose (GLUC), urea, Na+, K+ and Ca2+, and creatine phosphokinase (CPK) were analysed. Our results indicated a significant increase in surface temperature JAT (p=0.043) in the neck, shoulder, elbow, gluteus and quarter in routinely ridden horses. Significant changes in EOS (p=0.046) and HCT (p=0.043) in the case of the never-ridden and routinely ridden group, respectively, were found between the times of blood collection. In addition, there was a significant effect of the horse group and the time of blood collection on the CPK activity (p=0.025 to p=0.045) and urea concentrations (p=0.027 to p=0.045). In the routinely ridden horses, there were significant correlations between the changes in MONO (ρ=0.40), GRA (ρ=-0.40), PLT (ρ=-0.77), HCT (ρ=-0.36), GLUC (ρ=0.56) and urea (ρ=0.56) and the total ROI temperature changes. Moreover, significant correlations between the changes in MONO (ρ=-0.86), EOS (ρ=-0.65), GLUC (ρ=0.85), urea (ρ=0.85), Na+ (ρ=0.59) and K+ (ρ=-0.85) and the total ROI temperature changes were found in never-ridden horses. Different changes in body surface temperature and blood parameters in routinely ridden and never-ridden horses could be associated with different conditioning and performance. A significantly higher surface temperature in routinely ridden horses, as well as the dynamics of changes in HCT, CPK and urea after training indicate better performance of these horses. Significant correlations between MONO, GLUC, and urea and a total ROI surface temperature as well as a negative correlation between MONO and the total ROI temperature in never-ridden horses indicated poor performance.

Emotional excitability and behaviour of horses in response to stroking various regions of the body

Touching the skin by gentle stroking is frequently used to reward horses. The objective of the study was to examine emotional excitability and behaviour of horses in response to stroking different regions of their bodies. The study included 15 adult warmbloods and 15 adult ponies, nine geldings and six mares within each type of horse. First, a novel-object test was conducted. For five successive days, one of five regions of the horse's body was stroked on each side for 5 min. Heart rate and heart rate variability were monitored at rest, during the test and stroking. Simultaneously, horse behaviour was assessed on a 1-5 scale. The data were analysed using analysis of variance GLM, Tukey's Honestly Significant Difference test and Spearman's correlation coefficient. When stroked, horses were more excited than when at rest. Differences in emotional excitability and behaviour while stroking various body regions depended on the type and sex of horses. Parameters studied indicated that both in warmbloods and ponies, stroking the head may be beneficial, whereas the trunk should be treated with caution. Stroking may have a more positive influence in horses of lower emotionality and highly estimated behaviour at rest and during the novel-object test.

Taste Preferences of Horses in Relation to Their Breed and Sex

The aim of this study was to determine the taste preferences of horses in relation to their breed and sex. Forty-eight adult purebred Arabian, Anglo-Arabian, Polish Konik, and Polish cold-blooded horses-stallions and mares in equal numbers-were examined in the study. During the experiment, five types of industrially processed feeds based on oats and natural dried products commonly regarded as horse treats (i.e., sour and sweet apples, carrots, sugar beet molasses, and barley with salt) were given to horses in buckets on three consecutive days. The behavior of the horses during the experiment was evaluated, as was the way in which they expressed their taste preferences, the sequence in which they consumed the pellets, the time they took to become interested in the pellets, and the time they took to consume each kind of pellet. The taste preferences of the horses were found to depend on their breed and sex. Pellets containing molasses were consumed more willingly by mares than stallions. Feeds with the addition of apples or carrots were the favorite treats of all tested breeds. The greatest variety in pellet taste preferences was found in purebred Arabian horses. Pellets with a distinct sweet taste or slightly salty cereals should be given to horses if other options are not available. In most cases, these two additions were chosen last by the horses in the experiment. Primitive horses had a distinct manner of expressing taste sensations. Horse behavior indicating an interest in a feed should not be taken as a proof of its tastiness. The first food chosen is not necessarily the one consumed most quickly.

Leisure riding horses: research topics versus the needs of stakeholders

Horses intended for leisure riding do not undergo any selection and most often retired sports horses or defective horses are chosen, as a low selling price determines their purchase by a leisure riding center. Unfortunately, horses bought at low prices usually have low utility value, are difficult to handle, require a special or individual approach and do not provide satisfaction in riding. However, neither modern horse breeding nor scientific research address the need to breed horses for leisure activities. There is no clear definition of a model leisure horse and criteria or information for its selection are not readily available in scientific publications. A wide spectrum of research methods may be used to evaluate various performance traits in horses intended for leisure activities. The fact that the population of recreational horses and their riders outnumber sporting horses should attract the special attention of scientific research. Their utility traits need to be determined with modern technology and methods in the same way they are for sporting horses. Such a system of evaluation would be very helpful for riders.

The effect of relaxing massage on heart rate and heart rate variability in purebred Arabian racehorses

The objective of this study was to assess the effect of relaxing massage on the heart rate (HR) and heart rate variability (HRV) in young racehorses during their first racing season. In the study, 72 Purebred Arabian racehorses were included. The study was implemented during the full race season. The horses from control and experimental groups were included in regular race training 6 days a week. The horses from the experimental group were additionally subject to the relaxing massage 3 days a week during the whole study. HR and HRV were assumed as indicators of the emotional state of the horses. The measurements were taken six times, every 4-5 weeks. The HRV parameters were measured at rest, during grooming and saddling the horse and during warm-up walking under a rider. The changes of the parameters throughout the season suggest that the relaxing massage may be effectively used to make the racehorses more relaxed and calm. Moreover, the horses from the experimental group had better race performance records.

Length of winter coat in horses depending on husbandry conditions

This paper analyzes changes in the length of coat on selected body areas in horses and ponies kept under different husbandry (stable) conditions during the winter-spring period. The study included 12 Małpolski geldings and 12 geldings of Felin ponies aged 10-15 years. Horses were kept in two stables (six horses and six ponies in each stable). The type of performance, husbandry conditions and feeding of the studied animals were comparable. As of December 1, samples of hair coat from the scapula, sternum, back and abdomen areas of both body sides were collected seven times. The lengths of 20 randomly selected hair fibers were measured. Daily measurements of air temperature in the stables were also taken. An analysis of variance (ANOVA) was performed using the following factors: the body part from where the coat was sampled, the subsequent examination and the stable as well as the interaction between these factors. The significance of differences between means was determined with a t-Tukey test. The relations between air temperature in the stable and hair length were calculated using Pearson's correlation. It was found that air temperature in the stable impacts the length of winter coat in horses and ponies. The effect of this factor is more pronounced in ponies; as in the stables with lower temperatures it produces a longer hair coat which is more evenly distributed over the body in comparison with horses. Keeping horses and ponies in stables with a low air temperature accelerates coat shedding by approximately 25 days. Coat shedding begins from the scapula area.

Changes of coat cover in primitive horses living on a reserve

Changes in the coat cover are important for mammalian thermoregulation. This is especially true where variable environmental conditions exist throughout the seasons. Coat cover shedding is the replacement of old coat hair with new hair. The process differs in various equids. The aim of the study was to examine the changes in the coat of primitive Polish Konik horses living on a reserve in southeast Poland (50.6319° N). The reserve is located in a temperate climate. The mean temperature is below 0°C in winter (December 8 to March 9) and over 15°C in summer (June 8 to September 8). Five adult mares were included in the study. The study used a specific methodical approach to quantitatively assess coat cover changes. Photos were taken once every 2 wk throughout the whole year to document the state of the mares' coat. MultiScanBase software was used to analyze 260 photos. The percentage of the skin surface covered with short hair in relation to the surface of the body (without the head, neck, and limbs; short hair body [SHB]) was determined. To assess the topography of coat changes, surface parts covered with short hair within 6 regions of the body (shoulder, back, chest, loins, belly, and hindquarters; short hair part [SHP]) were considered separately. The regression coefficient was calculated for the SHB and the air temperature. Correlations in SHP and SHB between the left and right sides of the body were determined. The correlations within the right side of the body concerned particular SHP. As the results show, the coat changes take place at the same time on both sides of the horse's body. In spring, the winter hair is shed, and in the fall, the winter hair grows in longer. High regression (0.901; < 0.0001) proved that air temperature strongly affected the coat changes. The most important increase of SHB occurs in April and the first half of May, whereas the main decrease of SHB takes place in September. Changes between SHP are highly correlated (0.967-0.994; < 0.05). Spring and fall coat changes demonstrate that the shoulders, back, and loins require the winter cover for a longer time than the chest and belly, whereas the hindquarters are the least demanding in this respect. The phenomenon may be associated with, among others, the stronger effect of rain and snow on the upper parts of the body.

Can Releasing Racehorses to Paddocks be Beneficial? Heart Rate Analysis – Preliminary Study

The aim of the study was to assess the effect of allowing racehorses to use paddocks, on the heart rate (HR). HR was used as a measure of horses’ psychosomatic response to environment effect. The study involved 90 Purebred Arabian horses divided into three groups of equal numbers of stallions and mares. The control group (C) was trained at the racetrack. The other two groups were trained in an off-the-racetrack centre and therefore, they were regularly transported to the races. One of those groups (T) was maintained in the same manner as horses at the racetrack, without access to paddocks. Horses from the other group (TP) were additionally released into a paddock every day. Each horse was examined within five three-week measuring periods, during one training season. HR was registered at rest, during saddling, and while walking with a rider. A multivariate analysis of variance (ANOVA, GLM) was used to compare HR. The significance of differences between means was determined using Tukey’s test. HR registered from 2nd to 5th measuring periods during saddling and walking was generally lower in TP than in C. For example, in stallions during saddling, HR amounted to: 54.4±14.7 vs 65.3±12.1, 53.2±13.5 vs 64.4±13.1, 55.4±12.2 vs 65.0±11.0 and 53.4±14.0 vs 66.5±13.8 beats/min, respectively. In T stallions and mares, HR tended to increase when the transportation began which was particularly pronounced at rest. The study revealed that the possibility of turnout into paddocks reduced HR in racehorses, in comparison to horses trained at racetrack. Training for horse racing in an off-the-racetrack centre with the use of paddocks was assessed as beneficial, provided the horses were used to being transported.