Practical considerations regarding the implementation of a temperament test into horse performance tests: Results of a large-scale test run

Considering the ever-growing demand of various breeding organizations for an objective, inexpensive, reliable, and easily conducted assessment of the behavior of horses, the aim of our study was to implement a novel-object test and a startling test into any kind of breeding performance testing to assess horses' temperament. Additionally, the influence of testing areas (familiar or unfamiliar), riders, and horse factors such as levels of training, breed, and age were of interest. Furthermore, recommendations for the practical implementation concerning the parameters should be given. Therefore, 1,028 horses over a period of 3 years participated in a temperament test consisting of 5 different stimuli. The horses were either ridden (61.8 %) or led by hand (38.2 %) by an unfamiliar professional rider (N = 43) or a familiar rider (N = 20). Live behavioral observations were taken by a trained observer. Overall, horses' scores for reactivity in the present temperament test were distributed over the whole scale, with lower means and higher standard deviations (6.7 ± 2.2-7.6 ± 2.1) than corresponding scores from the conventional personality evaluation in performance tests (7.7 ± 0.8-8.2 ± 0.5; P < 0.01). High correlations (r = 0.3-0.9; P < 0.001) between the scores for reactivity and the other behavioral parameters (emotional expression, activity, time to calm down, rider's aids) show a large influence of these parameters in assessing the horses' temperament. Factors like breed type, sex, and age had significant influences (P < 0.001) on different scores of the temperament test. In most cases, the rider or handler had no influence on the different scores assessed during the temperament test. The training level and the testing modus never had a significant influence on different scores. Only the testing station or location had a small influence on the scores for the stimulus “bridge” in some horses. Based on the results, it could be concluded that an implementation of a temperament tests into performance testing is possible during various types of testing procedure. Especially the assessment of reactivity, emotional expression, interest in the stimulus and rider's aids during and after passing the stimulus, as well as the time to calm down are important parameters for analyzing the horses' personality.     

Cortisol release and heart rate variability in sport horses participating in equestrian competitions

Equestrian competitions require both physical activity and mental adaptation in horses. Cortisol, heart rate, and heart rate variability (HRV) are accepted stress parameters and, in this study, have been determined in horses (n = 13) participating in equestrian competitions for up to 3 consecutive days. Participation in competitions caused an increase in salivary cortisol concentrations (e.g., on day 1 from 1.0 ± 0.2 before to 2.2 ± 0.4 ng/mL after the competition, days 1 and 2: P < 0.001, day 3: P < 0.05) and an increase in heart rate (days 1 and 2: P < 0.001, day 3: P = 0.01). A consistent decrease in HRV occurred only in response to the final competition on day 3 (P < 0.01). When horses competing in dressage and show jumping were compared, cortisol release and HRV did not differ between groups, but after the competition, heart rate was lower in dressage than in show jumping horses (P < 0.05). Heart rate increased not only during the actual competition but already when horses were prepared in their stables (e.g., day 1: ?60 minutes, 38.6 ± 2; ?5 minutes, 77 ± 7; competition, 81 ± 10 beats per minute; P < 0.01). In conclusion, participation in equestrian competitions caused an increase in cortisol release and heart rate and a decrease in HRV variables. However, competitions were not a major stressor compared with other anthropogenic challenges such as transport, to which horses are exposed regularly.     

Effects of Intravenous Detomidine on Schirmer Tear Test Results in Clinically Normal Horses

This study was conducted to determine the effects of intravenous detomidine on Schirmer tear test (STT) results in clinically normal horses. Eighteen adult horses were randomly divided into two groups of nine horses each. The treatment group was sedated with intravenous detomidine alone (20 μg/kg), and the control group received only intravenous saline (0.2 mL/100 kg). Schirmer tear test was performed just before intravenous administration of detomidine or saline in treatment and control groups, respectively. Schirmer tear tests were repeated 5, 20, 60, and 120 minutes later. Horses enrolled in this study consisted of nine males and nine females. Breeds were Arabian and Hanoverian, ranging from 3 to 6 years in age. In the treatment group, the pretreatment and subsequent posttreatment mean ± standard deviation values were 17.0 ± 6.9 (0 minutes), 11.8 ± 2.9 (5 minutes), 12.1 ± 2.0 (20 minutes), 12.1 ± 3.1 (60 minutes), and 15.0 ± 2.8 (120 minutes) mm wetting/min. In this group of horses, a significant reduction was observed in STT values at 5, 20, and 60 minutes after treatment with detomidine hydrochloride in comparison to the pretreatment values (analysis of variance with post hoc testing; P₅ = 0.004, P₂₀ = 0.007, P₆₀ = 0.006). There was no significant difference between baseline values and posttreatment values in the control saline group (P ≥ .08). We conclude that intravenous detomidine causes a significant reduction in STT values in clinically normal horses. In horses, practitioners should measure STT values before intravenous administration of detomidine to accurately assess the results.     

Distances Walked by Long Established and Newcomer Horses in an Open Stable System in Northern Germany

Group housing is claimed to possibly provide horses with a species-appropriate movement possibility, and hence, better welfare. Thus, this study analyzed the daily walked distances of 51 horses held in one group in a “HIT Active Stable” (Hinrichs Innovation + Technik) in Northern Germany by using global positioning system (GPS) technology during a 7 ½-month time span. The daily walking distances of the whole group, as well as newcomers, were investigated. The horses traveled an average of 8.43 km/day. Linear mixed models were applied. The observation day had a significant effect on the daily walking distances (P < .01) due to season and the available area per horse. The age as covariate also had a significant effect (P < .01). The breed had no significant effect (P = .96). No significant differences were found in sex (P = .69), which can be explained by the fact that only mares and geldings were investigated, which do not show increasing locomotion caused by sexual behavior as stallions do. On six of the first nine days, new horses moved significantly more compared to the remaining 24 of the 30 observation days directly after individuals’ inclusion. This is probably due to more exploration and rank-fighting behavior. Similar walking distances were seen among the horses on the single observation days because all horses had to travel the same distance to reach resources. Further, it is suspected that not all horses can sufficiently live out their urges to move, especially in winter, when pasture is inaccessible.     

Relationships Among Plasma Proteins,Hematological Values,and Gender in Thoroughbred and Miniature Horses

Our objective was to investigate the relationships among plasma proteins, hematological values, and gender in Thoroughbred (nine females and 16 males) and miniature (30 females and four males) horses. Twenty-two protein bands, ranging from 8 to 264 kDa, were detected in horse plasma. Red blood cells, hemoglobin, and hematocrit were negatively correlated (r ≤ −0.29; P < .05) with bands 13 and 17 but positively correlated (r ≥ 0.40; P < .01) with band 3. A negative correlation (r ≤ −0.27; P < .05) was detected between bands 1, 8, and lymphocytes. Neutrophils were positively correlated with bands 1 and 8. Basophils had a positive correlation (r = 0.36) with band 12 and negative correlation with bands 11 (r = −0.30) and 13 (r = −0.48). Platelets had positive correlations (r ≥ 0.24; P < .10) with bands 3, 4, 5, 10, 14, 19, and 22. The relative intensities of protein bands 4, 16, and 22 were affected (P < .05) by an interaction of breed and gender. Gender effects (P < .05) were detected for plasma protein bands 1 (1.6 vs. 2.4 ± 0.23), 5 (2.6 vs. 3.6 ± 0.25), and 11 (8.7 vs. 13.2 ± 1.1), respectively, for females and males. Breed effects (P < .05) were detected for plasma protein bands 5 (2.5 vs. 3.8 ± 0.25) and 11 (9.0 vs. 12.9 ± 1.1), respectively, for Thoroughbreds and miniatures. When developing new pathophysiological tools for equine disease diagnosis and therapy, breed and gender effects should be considered.     

Trimming and Re-shoeing Results in More Steps per Day and More Time Spent Lying per Day

To examine the impact of trimming and re-shoeing on behavior, light horse geldings (3–21 year-old Quarter Horse, Dutch Warmblood, or Thoroughbred) were fitted with three-axis accelerometers (IceTag, Ice Robotics, Edinburgh, Scotland) on the left rear limb. Boots were placed under the accelerometer, and both were removed daily for approximately 1 hour while horses were stalled for morning feeding to examine the horses’ limb. After a two-day adaptation period and five days of activity tracking, horses were treated by having shoes removed, feet trimmed, and new shoes fitted (re-shod; n = 3) or being handled but not trimmed or fitted with new shoes (sham; n = 4). Horse activity was monitored for five days after treatment. Steps per day, time spent lying per day, and the number of lying bouts were tested for effects of treatment, time (before or after treatment), and interaction of treatment by time using procedures for repeated measures with JMP Software (version 7, SAS Inst. Inc, Cary, NC). Means separation was performed using the Student’s t-test. There was a treatment by time interaction on time spent lying per day (P = .0447) and steps per day (P = .0501). Re-shod spent more time lying after treatment than before (121.4 ± 22.8 vs 66.8 ± 22.8 minutes per day, respectively). After treatment, re-shod also took more steps than sham (3499 ± 527 vs 3056 ± 456 steps per day, respectively). These results may indicate increased mental and physical comfort following trimming and re-shoeing in horses.     

A note on the effect of number (single or twin) and sex of contemporary siblings on male-like play behavior of lambs (Ovis aries)

This study evaluates the effect of the number and sex of contemporary siblings on male-like play behavior of Suffolk lambs (Ovis aries). Fourteen males and 14 females, all single born, plus 26 ram lambs born co-twin to another male (n = 14) or female (n = 12) as well as 26 ewe lambs born co-twin to another male (n = 12) or female (n = 14) were observed daily for 7 weeks from 1 week of age. Two observers sitting outside a sand-bedded pen (10 × 5 m) recorded received and performed behavior (butts, nudging, attempts to mount, and mounts) by the lambs in the pen from 08:00 to 09:00 and 16:00 to 17:00 hours. Animals were in the pen only during the observation periods; the rest of the day they remained with their mothers in individual pens. Male-like play behavior patterns were displayed by both male and female lambs. Males were more active (P < 0.05) than females. Butting was the most frequent activity and performed mostly by ram lambs, recipients were generally males, and most resulted in reciprocal simultaneous encounters (sparring). Single males performed most of the nudging activity, which was the least frequent of the observed behaviors. Males with twin brothers mounted significantly (P < 0.05) more than males with twin sisters, and females with twin sisters performed the lowest amount of gutting and nudging. Lower (P < 0.05) levels of activity were found during the first 2 weeks. Overall, it was concluded that male lambs performed and received more male-like play behaviors than female lambs and the influence of sex of contemporary sibling was restricted to some behaviors: butting and nudging in females and mounting in males.     

Validation and Implementation of an Automated Chew Sensor–Based Remote Monitoring Device as Tool for Equine Grazing Research

Field studies characterizing equine grazing activity primarily rely on observational protocols, limiting the quantity and accuracy of collected data. The objectives of this study were to validate an automated chew sensor technology, the EquiWatch System (EWS), for detecting grazing behaviors and to demonstrate potential applications of the EWS in equine grazing research. Eight mature standardbred mares were used in this study. EquiWatch System validation was completed in two phases: grazing time was evaluated in experiment 1 and chew counts in experiment 2. The correlation between visual observations and system-recorded grazing time was high (concordance correlation coefficient [CCC] = 0.997). There was also a high agreement between the sum of manually counted bites and chews and total chew counts reported by the EWS (CCC = 0.979). Following validation, a pilot study was conducted using the EWS to assess feeding behaviors of horses with unrestricted pasture access (PAS) versus horses offered ad libitum hay (HAY). Horses spent more time engaged in feeding behavior on PAS (14.79 ± 0.48 hr/d) than HAY (11.98 ± 0.48 hr/d; P < .0001). Chewing rate also differed by forage (PAS 83.92 ± 1.61; HAY 68.50 ± 1.61 chews/min; P < .0001). However, although the magnitude of these behavioral parameters was influenced by treatment, the underlying 24-hour patterns were largely preserved regardless of forage type. These results demonstrate that the EWS can generate data necessary for characterizing feeding behavior in horses. Future studies implementing this tool could provide a greater understanding of biological, environmental, and nutritive factors driving grazing behavior in horses.     

The Effect of a Seaweed-Derived Calcium Supplement on Gastric Juice pH in the Horse

Low gastric pH for extended periods of time can increase the risk of gastric ulceration in horses. Therefore, nutritional interventions that buffer stomach acid may be helpful to decrease ulcer risk. The objective of this trial was to evaluate whether the incorporation of calcified Lithothamnion corallioides and Phymatolithon calcareum (Calmin; Celtic Sea Minerals, Cork, Ireland) into an equine ration would buffer equine gastric juice. Nine mature, Thoroughbred-cross horses, including 6 geldings and 3 mares (524 ± 49 kg) were housed in stalls and fed 2 kg/day of a texturized concentrate (Purina Omolene 100) and 1.5% BW grass hay/day. On testing days 0, 7, and 14, the horses received one of three pelleted dietary treatments (CON, MIN1 ×, MIN2 ×) in a randomized, crossover design. CON contained no added Calmin, MIN1 × provided Calmin at a 1 × concentration, and MIN2 × provided a 2 × dose. All horses underwent gastroscopy (Karl Storz, El Segundo, CA) prior to feeding the treatments, and at 2 and 4 hours postfeeding. Gastric juice was aspirated and pH measured using a benchtop pH meter (ThermoOrion pH Meter Model 410A). Overall, there was a significant time effect (P < .0001) with an increase in gastric juice pH from time 0 (2.31 ± 0.58) to 2 hours (5.52 ± 0.48) and 4 hours (3.59 ± 0.48). Gastric juice pH at 2 hours was higher (P = .0122) in MIN1 × (5.92 ± 0.58) and MIN2 × (5.92 ± 0.57) than CON (5.08 ± 0.58). These results demonstrate that adding Calmin to a meal increases buffering capacity at 2 hours postfeeding.     

Prolonged latency of pupillary light reflex in confined sows: Possible stress-related symptom?

This study aimed to compare pupillary light reflex (PLR) of stall-housed sows with group-housed sows because PLR is a sensitive indicator reflecting psychological state in humans and animals. Six hundred thirty-seven pregnant sows confined in gestation stalls were examined and PLR times (PLRTs) were measured. The results of the chi-square test showed that no significant difference was found in the pupils with PLRT ≥10 seconds between the left and the right pupils (χ2 = 0.03, P > 0.05), and the right-sided pupils with PLRT ≥10 seconds was significantly correlated to left-sided ones (χ2 = 181.85, P < 0.01). Among the 637 individuals, only 38 individuals were found whose PLRT showed >10 seconds on both pupils, accounting for 5.5% of the total. With the treatment of 0.125% of pilocarpine, neither 64 pupils with PLRT ≥10 seconds on the left nor 66 pupils with PRT ≥10 seconds on the right showed sensitivity to pilocarpine. The results also showed that the confined sows had longer PLRT than that of the grouped sows on both the left (13.97 ± 2.96 vs. 8.15 ± 0.97, P < 0.001) and the right (14.01 ± 2.87 vs. 8.19 ± 0.82, P < 0.001) pupils. However, the difference in ratio of the initial pupil size to maximally constricted size was not significant between the 2 groups (P > 0.05). In conclusion, the prolonged latency of PLR or increased PLRT found in the confined sows appeared to be a stressful response to chronic stress. PLRT has the potential to be an indicator used to measure stressed animals.     

Postprandial Blood Glucose and Insulin Responses of Horses to Feeds Differing in Soluble Fiber Concentration

In humans, the consumption of soluble fibers reduces glycemic response after a meal. We hypothesized high soluble fiber diets would reduce and delay postprandial glucose and insulin responses in horses. In a 4 × 4 Latin square design experiment, four Quarter Horse geldings were adapted to diets containing orchardgrass hay (ORCH) or ORCH with 1 of 3 treatment ingredients: molassed sugar beet pulp (BEET), almond hulls (HULL), or steam-crimped oats (OATS). Blood was serially sampled for 6 hours after feeding 0.15% body weight (BW) of the treatment ingredient (meal test) or 1.1 g starch/kg BW from oats plus the treatment ingredient (starch test) to evaluate glycemic and insulinemic responses. Glycemic response during the meal test peaked between 60 and 90 min after feeding (P < .05) and tended to be altered by diet (P = .071) and diet × time (P = .076). Serum insulin was affected by diet (P = .008), time (P < .001), and diet × time (P < .001) during the meal test, with concentrations lower in ORCH compared with BEET and OATS (P < .05). In the starch test, glucose was lower (P < .05) in ORCH and HULL compared with BEET and insulin was lower (P = .046) in ORCH compared with BEET. In both tests, horses took longer (P < .05) to consume HULL, likely influencing postprandial responses. Future research integrating the functional properties of feeds with physiological responses will be necessary to elucidate how soluble fiber affects postprandial glucose metabolism in horses.     

Preemptive Analgesia,Including Morphine,Does Not Affect Recovery Quality and Times in Either Pain-Free Horses or Horses Undergoing Orchiectomy

Recovery quality and times from general anesthesia in horses may be influenced by surgery, analgesia with morphine or combinations of both. Twenty-three adult healthy horses were enrolled in this prospective experimental trial in a clinical setting and were randomly allocated to one of the following groups: anesthesia only (GA; n = 6), preemptive analgesia and anesthesia (GAA; n = 5), anesthesia and castration (GC; n = 6), or preemptive analgesia, anesthesia, castration, and intraoperative local analgesia (GCA; n = 6). All horses were sedated with intramuscular (IM) xylazine (0.5 mg/kg). Anesthesia was induced with intravenous (IV) guaifenesin (100 mg/kg) and thiopental (5 mg/kg) and maintained with isoflurane in oxygen. Animals in groups with preemptive analgesia received IM morphine (0.2 mg/kg) and dipyrone (10 mg/kg) and IV flunixin meglumine (1.0 mg/kg) immediately before sedation. Recoveries from general anesthesia were rope-assisted. Recovery scores (from 8 [excellent recovery] to 70 [worst recovery]) and times were compared between groups, using a one-way analysis of variance followed by a Tukey's test (P < .05). Mean ± standard deviation (SD) and range recovery scores were 22 ± 14 (8–45), 9 ± 2 (8–12), 14 ± 5 (8–22), and 12 ± 1 (10–13) in groups GA, GAA, GC, and GCA, respectively. Mean ± SD times to stand in minutes were 21 ± 10, 18 ± 7, 33 ± 12, and 35 ± 21 in groups GA, GAA, GC and GCA, respectively. No statistically significant differences were found for any of the variables. Neither preoperative administration of analgesics, including morphine, nor castration interfered with the recovery qualities and times in horses undergoing general anesthesia. Preemptive morphine did not worsen anesthetic recovery quality in horses.     

Higher feeding diets effects on age and liveweight gain at puberty in crossbred Nelore × Hereford heifers

This study was conducted to determine the age and liveweight at puberty of 120 crossbred beef heifers submitted to four diets to achieve predetermined weight gains (kg/day): 0.5 (G500; n?=?32), 0.75 (G750; n?=?32), 1.0 (G1000; n?=?29), and 1.25 (G1250; n?=?27). Animals were classified depending on their level of crossing between Nelore (N) and Hereford (H): 25%N-75%H, 37.5%N-63.5%H, 43.7%N-56.7%H, 50%N-50%H, and 75%N-25%H. Reproductive evaluation was performed at the beginning and at the end of the experimental period by ultrasonography and hormone analysis. The average age and liveweight at puberty were 388.0?±?1.9 days and 331.4?±?1.3 kg, respectively. Animals from the 25%N-75%H group reached puberty earlier than heifers from other genetic groups supplemented with G1250 diet (P?<?0.05). Heifers with higher degree of Nelore (75%N-25%H) fed with G1000 diet showed estrus 42 days prior to mating, but only 57 % reached puberty at mating (P?<?0.05). Heifers with follicles of higher diameter reached puberty (P?<?0.05) earlier. Higher average daily weight gain showed a positive effect on follicular diameter and IGF-I level at puberty (P?<?0.01). Concentrations of GH were lower in heifers fed G1250 compared to G1000 diet (P?<?0.05). There was a significant interaction between nutritional level and insulin levels at puberty (P?<?0.01). We demonstrated the relationship between IGF-I and average daily gain on the onset of puberty in heifers. In conclusion, heifers submitted to the higher feeding level showed a higher follicular diameter and were younger at puberty.     

The Effect of Feeding Two or Three Meals Per Day of Either Low or High Nonstructural Carbohydrate Concentrates on Postprandial Glucose and Insulin Concentrations in Horses

Eight mature idle gelding horses (mean body weight [BW], 558 ± 45 kg) were used in a replicated 2 × 2 Latin square design study. Horses received either two or three meals per day (MPD) for 7 days, of either a high (H; 43%; 215 g/100 kg BW) or low (L; 18%; 90 g/100 kg BW) nonstructural carbohydrate (NSC) concentrate feed to achieve four treatment groups: low NSC in two MPD (L2), low NSC in three MPD (L3), high NSC in two MPD (H2), and high NSC in three MPD (H3). On day 7 of the treatments, blood was collected before (baseline) and for 5 hours after feeding the morning meal (10, 20, 30, 40, 50, 60, 90, 120, 150, 180, 210, 240, 270, and 300 minutes after feeding). Baseline insulin concentrations tended (P = .093) to be higher for horses fed high NSC than low NSC, and horses fed two MPD tended (P = .092) to have higher baseline insulin concentrations than horses fed three MPD. In addition, baseline glucose-to-insulin ratio (GIR) was higher in horses fed high NSC compared with low NSC (P < .001). Horses fed high NSC had higher area under the curve of insulin and higher peak insulin after feeding than those fed low NSC. These findings suggest that NSC content of a concentrate feed has an impact on baseline insulin and GIRs and on postprandial insulin concentrations. Meanwhile, the number (and therefore size) of MPD had fewer impacts on glucose metabolism.     

Training Program Intensity Induces an Acute Phase Response in Clinically Healthy Horses

Physiological and hematochemical changes associated with exercise have been extensively investigated in equine species. It is known that stress elevates circulating levels of acute phase proteins (APPs). This survey evaluated whether horses trained with different training programs exhibit changes in APP levels after exercise event. Twenty Saddle Italian horses (11 geldings and 9 females, 9 ± 1 years old, body weight of 425 ± 35 kg) were divided into two equal groups according to the intensity of training programs they were subjected: group A was subjected to an intense training program, group B was subjected to a moderate training program. At the end of the training period, horses were subjected to a simulated exercise event (show jumping course of 400 m length with 12 obstacles). From horses, blood samples were collected at rest conditions (T_REST) and after 12 and 24 hour from the end of exercise (T_{12 h} and T_{24 h}); the concentration of serum amyloid A (SAA), haptoglobin, albumin, total proteins, iron, and fibrinogen was assessed. The circulating levels of SAA, fibrinogen, and iron were influenced by simulated exercise event (P < .01), starting from 12 hour after the end of exercise, suggesting the onset of an acute phase–like response, and it would seem that training program intensity the horses underwent also affected the degree of response, although only SAA values were significantly different between groups (P < .001). The findings obtained suggest that jumping exercise induces an acute phase response; however, further studies are advocated to better evaluate mechanisms by which exercise activates this response in the athletic horse.     

Genetic and Environmental Factors Influencing Gestation Length in Lusitano Horses

Breeding and parturition records collected over a period of 35 years in the Alter Real stud of Lusitano horses were used to calculate gestation length (GL). The 1027 gestations by 209 mares mated to 60 stallions had a mean GL of 338.1 ± 9.26 days. The mixed model analysis of variance indicated that the sex of the foal and inbreeding of the dam and foal had no significant effect on GL (P > .05). On the other hand, GL increased linearly with mare age, with an estimated regression coefficient of 0.155 ± 0.069 days/year (P < .05). Year and conception month affected GL (P < .05), with longer gestations observed when breeding occurred between January and April, followed by a decline of about 5 and 10 days in GL of mares bred in May and in June–July, respectively. Important differences were observed between stallions (P < .05), with most stallions resulting in a distribution of GL in an interval of ±5 days. The inclusion of the mare as a random effect in the mixed model resulted in an estimated repeatability of GL of 0.427, indicating that mares tend to be regular in having long or short gestations across their lifetime. Variance components estimated in an Animal Model resulted in heritability estimates of 0.39 for maternal genetic effects and 0.19 for direct genetic effects, with no association between the two components. Overall, the mare seems to have the major genetic influence on GL in Lusitano horses, but environmental factors, such as month of conception and also the age of the mare, have a noticeable effect.     

Does heterosexual experience matter for bucks' homosexual mating behavior?

Our aim was to compare bucks' homosexual mating behavior after mixing 2 groups of bucks, one that was reared in permanent contact and another in complete isolation from female goats, and determine if this behavior was related with testosterone concentration. Two groups of 1-year-old Saanen bucks were reared in permanent contact with 4 adult females until 1 week before the experiment (n = 8; group RF) or isolated from females (n = 9; group RI). When bucks were 1 year old, both groups were mixed (day 0), and mount attempts and matings were recorded on days 1, 3, 6, and 9. Testosterone concentrations were determined by radioimmnoassay from blood samples collected twice daily on days ?7, 0, 1, 3, 6, and 9. Each RI male attempted to mate more RF than RI males (31.9 ± 5.1% vs. 16.7 ± 3.6%, respectively; P = 0.01), but there was no difference on the frequency in which RF males attempted to mate RI (19.4 ± 0.1%) or RF (11.1 ± 0.1%) males (P = 0.24). Similarly, RI males mated more RF than RI males (12.5 ± 2.9% vs. 5.6 ± 0.02%, respectively; P = 0.04). Furthermore, there was no difference on the frequency in which RF males mated RI (10.7 ± 8.9%) or RF (3.6 ± 0.02%) males (P = 0.23). Testosterone concentrations tended to be greater in RF than RI (P = 0.054), but no interaction between time and group was observed (P = 0.13). We propose that as RI bucks never had contact with females, they directed their sexual behavior toward other males that had the stimulating effect of the novelty. On the other hand, for RF bucks, although the novelty effect of the new bucks existed, the previous knowledge of females determined that other bucks were not considered as highly sexual attractive. This difference was not related to the differences in testosterone concentration.     

No-Contact Microchip Monitoring of Body Temperature in Yearling Horses

In clinics, temperature is used as an indicator of health. Mostly rectal temperature is recorded, requiring handling and time. Temperature-sensitive identification microchips could be an alternative. Foals (26 males and 17 females), 4–12 months old, were housed in stalls over two winters (December–February). They were equipped with an identification and temperature sensor microchip implanted in the neckline. Temperature was recorded using an antenna located near the drinking trough. Animals were fed concentrated feed and forage twice daily, with free access to water. Rectal temperatures (79 measurements) were recorded simultaneously in 26 animals. Data were analyzed with a linear mixed model, using natural cubic splines for the mean curve and a random horse effect. All animals remained healthy throughout the study. More than 100,000 recordings were obtained. Mean temperature for all individuals at all times was 37.5 ± 0.1°C. Time of the day affected temperature with a daily amplitude of 0.96°C (P < .001). Lowest temperatures were observed before dawn, the acrophase occurring around 18:00, with a smaller increase around midday. Mean temperature was 0.26°C higher in males (P < .05). It was also 0.1°C higher in light (<200 kg) compared with heavier foals (P < .001). Temperature decreased with increasing daylight (−0.35°C over the study period, P < .001). Microchip and rectal temperatures remained within normal limits and were significantly correlated (R² = 0.16, P < .001). This noninvasive tool does not require extra-handling and will allow a better monitoring of normal body temperature values taking into consideration time of the day, meal time, and sex.     

Serum Amyloid A (SAA) Concentration after Vaccination in Horses and Mules

Serum amyloid A (SAA) is a sensitive acute-phase response (APR) marker in equids. Prominent APRs with elevations of SAA concentrations ([SAA]) have been reported after vaccination. The authors hypothesized that vaccination with an inactivated EHV-1/-4 vaccine would cause increase in [SAA] and antibody responses and that higher [SAA] would be positively correlated with the antibody titer in both equids. Twelve Haflinger horses and 12 mules were included in this longitudinal prospective study. All horses and mules were vaccinated with a commercially available EHV-1/-4 vaccine. Blood was sampled before and after vaccination to measure [SAA] and virus-neutralizing response (VN-T). In horses and mules, significantly higher [SAA] were measured on days 1, 3, and 5 after EHV-1/-4 vaccination; [SAA] on day 1 after vaccination were only measured in animals that developed fever, where mean [SAA] were significantly higher in horses than in mules (horses: 1,365.75 ± 87.64 mg/L, mules: 615.5 ± 153.444 mg/L) (P > .05). Four horses and 2 mules developed fever after vaccination, lasting for ≤24 hours. Increased antibody responses (VN-T) on days 7 and 14 after vaccination were observed in all animals, whereas mules showed higher overall antibody responses. Nevertheless, [SAA] did not correlate with the intensity of the antibody responses (VN-T) stimulated by the vaccine (P < .05). EHV-1/-4 vaccination caused a prominent APR, higher in horses than in mules, but [SAA] did not correlate with antibody responses. Measuring [SAA] after vaccination could help identify severe APRs that may require longer resting intervals before training or competition.     

Comparison of Nutrient Digestibility Between Adult and Aged Horses

There is little published work comparing digestibility in healthy adult versus healthy aged horses. Researchers hypothesized that there would be no differences in macronutrient digestibility between eight adult (5–12 years) and nine aged (19–28 years) horses fed three diets in a Latin square design. Seventeen stock-type mares were randomly assigned for a 5-week period to one of three diets: hay only (HAY), hay plus a starch- and sugar-rich concentrate (CHO), or hay plus a fat- (oil) and fiber-rich concentrate (FF). Each diet period comprised 3 weeks of outdoor group drylot feeding, 2 weeks of indoor stalled individual feeding, followed by a 72-hour digestibility trial including total urine and fecal collection. Feed, fecal, and/or urine samples were analyzed to determine dry matter, crude protein, fat, energy, calcium, and phosphorus apparent retention as well as apparent digestibility. Neutral detergent fiber digestibility was also determined. Mean body weight was lower in aged than in adult horses (455 ± 12 kg vs. 500 ± 13 kg; P = .02), but body condition score (BCS) did not differ between groups (aged horses, 4.8 ± 0.2 BCS and adult horses, 5.1 ± 0.2 BCS; P = .20). No age differences in digestibility, apparent digestibility, or apparent retention were seen for any of the variables measured. Based on the results of this study, total tract macronutrient digestibility appears to be similar between healthy adult and aged horses.