Abstract Iron is an essential micromineral involved in various physiological functions such as oxygen transport. The National Research Council’s Nutrient Requirements of Horses has iron requirements set at 400 mg iron daily for a 500 kg horse at maintenance; however, a survey found that Thoroughbreds consumed well over the daily requirement at 3,900 mg of iron from hay and grain alone. Additionally, a previous study has found a correlation between hyperinsulinemia and increased ferritin, an indicator of iron body stores. Therefore, the objective of the present study was to determine the effects of iron supplementation on body iron stores as well as insulin and glucose dynamics. It was hypothesized that iron supplementation would influence body iron stores and insulin and glucose responses. Mixed-breed geldings [n = 12; 558.9 ± 74.4 kg body weight (BW)] were housed individually for the study. Horses were fed 2% of their BW in grass hay and an iron-free vitamin mineral supplement, consuming an average of 600 mg of iron daily for the first 28 d (Hay Phase). Horses were then assigned to continue on the hay diet (CTRL; n = 4) or an iron-supplemented diet (IRON; n = 8), in which an oral iron supplement was given daily in the form of ferrous sulfate, with IRON horses consuming an average of 4,000 mg of iron daily for 28 d (Supplement Phase). Oral sugar tests (OSTs) were performed at the beginning of the study as well as the end of each phase, using a 0.45 mL/kg of BW Karo Light Syrup dose to determine insulin response, with jugular venous samples taken prior to the dose and 60 min after. All statistical analysis was performed in GraphPadPrism Version 10.2.0 (GraphPad Software, Boston, MA), using analysis of variance for repeated measures and correlation analysis. All OSTs throughout the study had a significant time effect (P < 0.05) for both insulin and glucose. There was a time X treatment trend (P = 0.1) for insulin during the Supplement Phase and when using multiple comparisons, insulin response was significantly greater (P < 0.0007) at 0 versus 60 min in IRON horses. Although there was no correlation found between 60-min insulin and ferritin concentrations in both IRON and CTRL horses, mean ± SD insulin and ferritin in the IRON group were 23.6 ± 10 uU/mL and 570 ± 195.8 ng/mL, respectively, while in the CTRL group these were 12.7 ± 2.9 uU/mL and 453 ± 31.1 ng/mL, respectively. In conclusion, iron supplementation with an inorganic form at 10 times the daily requirement appears to result in increased insulin responses as well as body iron stores. Further research needs to determine if feeds naturally enriched in iron impact glucose metabolism.

Obesity is an important health concern in horses, along with humans and companion animals. Adipose tissue is an inflammatory organ that alters the insulin-signaling cascade, ultimately causing insulin dysregulation and impaired glucose metabolism. These disruptions can increase the risk of metabolic disease and laminitis in horses and may also impact energy metabolism during exercise. A single bout of exercise, along with chronic exercise conditioning, increases insulin sensitivity and glucose disposal via both contraction- and insulin-mediated glucose uptake pathways. Regular exercise also increases calorie expenditure, which can facilitate weight (as body fat) loss. This paper explores the metabolic pathways affected by adiposity, as well as discusses the impact of exercise on insulin metabolism in horses.

Excessive adiposity in horses is associated with equine metabolic syndrome and laminitis, and additional weight due to fat accumulation may cause further stress on the horse. This study aimed to determine the effect of additional weight carriage on work effort in horses, as estimated by changes in heart rate (HR) and body temperature (Temp). Eight mature mixed-breed horses were paired based on body size in a randomised crossover study. Each day tested a pair of horses with one horse carrying additional weight (15% of body weight; to represent approximately 3 body condition scores) and the other horse serving as a control, with treatments reversed the following week. Heart rate was determined before adding the weight, after a 2 h period of stall rest (prior to the exercise bout), and at the end of a 34 min exercise challenge of walking and trotting on an automated exerciser. Temp was recorded prior to exercise and after the horses were removed from the exerciser. Two-way ANOVA was conducted to determine the effect of exercise and weight carriage on HR and Temp, and paired t-tests were used to compare differences in HR and Temp pre- and post-exercise. HR increased with exercise (P < 0.001) and was higher following exercise in horses carrying additional weight (P < 0.0001). Exercise increased Temp (P < 0.001) and the difference in Temp was greater in the weight-carrying group (P = 0.0023). This study documents the effect of weight carriage that could be imposed with body fat, in addition to the known health detriments of adiposity.

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There is ample research describing the increased risk of health concerns associated with equine obesity, including insulin dysregulation and laminitis. For athletes, the negative effect of weight carriage is well documented in racing thoroughbreds (i.e., handicapping with weight) and rider weight has been shown to impact the workload of ridden horses and to some degree their gait and movement. In many groups of competitive and athletic horses and ponies, obesity is still relatively common. Therefore, these animals not only are at risk of metabolic disease, but also must perform at a higher workload due to the weight of their adipose tissue. Excess body weight has been documented to affect gait quality, cause heat stress and is expected to hasten the incidence of arthritis development. Meanwhile, many equine event judges appear to favor the look of adiposity in competitive animals. This potentially rewards horses and ponies that are at higher risk of disease and reinforces the owner’s decisions to keep their animals fat. This is a welfare concern for these animals and is of grave concern for the equine industry.

Obesity is a critical problem in the equine industry, with ponies being at particularly high risk of de-veloping obesity-related conditions such as metabolic syndrome and laminitis. The purpose of this study was to estimate the level of adiposity in an elite level of competitive show ponies, and to determine if adiposity was related to performance based on their model score (judged on conformation and appear-ance). Two researchers visually evaluated the body condition score (BCS) and cresty neck score (CNS) of 377 ponies at a national hunter competition. Thirty five percent of the ponies in the competition were considered obese, with BCS scores of 7 or higher. Mean BCS of the ponies was 6.7 +/- 0.6 with a range of 5.25 - 8.25 and mean CNS was 2.8 +/- 0.6, with a range of 1.75 - 4.5. Medium ponies had higher BCS (P < 0.0 0 01) and higher CNS (P = 0.015) than the large ponies. There was a tendency for a relationship between body condition score and the model score in all ponies (r = 0.08; P = 0.059), and this was stronger within the large ponies (r = 0.20; P < 0.01). These findings show that elite competition ponies are dangerously overweight and that adiposity may influence performance in a judged event. This is of grave concern to the horse industry and needs to be addressed. Published by Elsevier Inc.

The equine fecal microbiome may vary across horse populations due to the diversity of the habitual diet. The purpose of this study was to assess and compare the microbial population of different horse populations, specifically the differences between feral versus domesticated populations. Samples were collected from 3 different populations of horses: horses from the Shackleford Banks (n = 24), a feral horse population living on the Outer Banks of North Carolina who eat native grasses such as Spartina marsh and island grasses; horses from the NCSU Equine Educational Unit (n = 18) that are predominantly kept on cool season mixed pastures and may be supplemented with hay and concentrates from time to time; and finally, privately owned horses (n = 36) that are fed mixed diets consisting of pasture, hay and concentrates. Horses were monitored and samples were collected immediately following a void by swabbing the middle of the void. Swabs were placed in a tube containing 500 uL DNA/RNA shield (Zymo Research, Irvine, CA) and were sent to the Emerging Technology Center (Purina Animal Nutrition, Gray Summit, MO) where they were stored at −80°C and then the V3 and V4 regions of the 16S rRNA gene were sequenced following the Illumina 16S Protocol (San Diego, CA). Samples were processed, filtered and trimmed through DADA2 using the QIIME2 pipeline. Statistical analysis was performed in R(Version 4.1.1) and a P-value of ≤0.05 was considered significant. After processing to eliminate samples with low sampling depth (<20,085), 78 total samples across the 3 populations were analyzed. For the results, when testing α diversity with Shannon's Index, a Kruskal-Wallis rank sum test revealed a significant difference between all populations (P = 0.01). There was a visual distinction between the Shackleford Banks population compared with the others when utilizing Bray-Curtis to assess β diversity. Additionally, an apparent significant difference between all populations using the PERMANOVA UniFrac test (P < 0.001) was observed. The 3 most predominant bacterial phylum seen across all populations were Firmicutes, Bacteroidetes and Spirochaetes. The top 5 phyla observed in the Shackleford Banks population were Firmicutes, Bacteroidetes, Spirochaetes, Kiritimatiellaeota and Fibrobacteres. Based on the results, there is a distinctive separation in microbial diversity between these horse populations, specifically between the Shackleford Banks horses versus the NCSU and privately owned horses. This separation is likely due to the habitual diet of these specific horse populations influencing the composition of their microbiome within the hindgut.

Performance analysis is utilised by coaches and athletes to identify areas to work on in training and to identify strengths in athlete performance in various sports. However, performance analysis is not commonly used within equestrian sports. The purpose of this study was to evaluate minors and their ponies competing in show jumping at a national pony competition to see if course variables affected performance. All jumping rounds were watched online. Type of faults (e.g. rails, refusals, time faults, fall of horse and or rider), type of fence (e.g. vertical, oxer), approach angle, section of the course where fault(s) occurred and round time were recorded. Spearman's Correlation assessed if round time was correlated to total faults and a series of Kruskal-Wallis analyses determined if significant differences in faults occurred between sections of the course, where these existed, post hoc tests established where differences occurred between rounds. There was no significant difference in total faults across the 4 rounds of competition and no meaningful correlation between round time and total faults (r = 0.34; P = 0.008). There were no differences between fence type and faults although more faults occurred at verticals (51.7%, n = 46 faults at verticals versus 48.3%, n = 43 at oxers; P = 0.610). Faults were more likely to occur during the final quarter of the course (32.6%, n = 29) when compared to the first quarter (23.6%, n = 21; P = 0.028). These results showed that faults were more likely to occur in the final quarter of a round. The information gained from this performance analysis could be beneficial to inform training or riding strategies, especially when preparing for a competition.

The use of an in-vitro model of the equine microbiome is beneficial to assess how fermentation patterns differ based on a horse populations’ habitual diet. The purpose of this study was to determine the in-vitro fermentation patterns of the microbial community within different horse populations before and following a starch challenge. Fecal samples were taken from three different populations of horses: horses from the Shackleford Banks, a North Carolina feral horse population living on native grasses; horses from the NCSU Equine Educational Unit that are predominantly kept on cool season mixed pastures, though may be supplemented with hay and concentrates when warranted; and privately owned horses that were fed mixed diets consisting of grass hay, concentrates and some pasture. Horses were monitored and fecal samples were collected immediately following a void and were stored on dry ice and frozen until analysis. Fecal samples from individual horses were pooled to form a representative sample for each population and mixed with an anaerobic medium to prepare an inoculum. The inoculum was placed into bottles containing either a treatment substrate of alfalfa (A) or of alfalfa and starch (AS). Bottles were capped, purged with CO2 and placed in a water bath at 39°C to incubate for 0, 2, 4 or 24 hours. Culture samples were processed to measure methane and short chain fatty acids (SCFAs; acetate, propionate, butyrate and other isoacids) using gas chromatography. Results were analyzed using the Proc Mixed procedure in SAS to compare the effects of horse population, time and treatment. Methane was significantly greater after 24 hours within all populations with AS, as the inoculum compared with A alone (P = 0.03). Propionate was greater for AS (molar percentage, mean ± standard deviation; 2.21 ± 4.97%) versus the A treatment (11.95 ± 4.97%, P = 0.02). Acetate concentrations were significantly (P < 0.001) greater within the A treatment in the Shackleford and NCSU horses (60.31 ± 10.3% and 62.18 ± 11.47%, respectively) compared with the AS treatment (59.09 ± 11.21% and 59.77 ± 8.85%, respectively). Privately owned horses showed similar values of acetate concentration when comparing the treatment of A (63.42 ± 10.13%) versus AS (63.55 ± 10.77%). Butyrate concentrations were greater in the Shackleford Banks and NCSU horses (13.16 ± 1.92% and 2.64 ± 4.22%, respectively) compared with the privately owned horses (10.96 ± 2%). Isoacids were greater in the Shackleford Banks horses (10.19 ± 4.15%) than the NCSU horses (9.87 ± 3.98%) and the privately owned horses (9.52 ± 3.53%; P< 0.0001). It appears that fermentation of starch differs between these horse populations, likely due to their habitual diet.

A healthy body condition is essential for equine health and performance. Therefore, recognizing equine body condition and adjusting nutritional management are required for the best output. This study aimed to determine: 1) general feeding practice and desired body condition scores (BCS) by the owners, 3) body condition scores and morphometric measurements, and 2) feedstuffs used and estimated nutritional intake, of racing ponies in West Nusa Tenggara, Indonesia. An online initial survey form was sent to the farmers via Whatsapp and Facebook groups. The form also included a list of pictures of ponies with different BCS. Owners were asked if the ponies in the pictures were ideal for racing purposes. Fifty-two pony owners filled in the survey and 21 owners of 54 ponies that actively raced signed up for the next part of the study. The ponies’ age was 3.6 ± 3.6 years. Meanwhile, the breeds consisted of 37% (20/54) Sumbawa ponies, 25.9% (14/54) Sandalwood-cross ponies, 20.4% (11/54) Sandalwood ponies, 11.1% (6/54) Flores ponies, and 3.7% (2/54) Lombok ponies. Ponies were accessed, BCS and cresty neck scores (CNS) were assessed, and morphometric parameters were measured. These were also used to estimatebodyweight. Feeds were weighed, identified and sent for nutritional analysis. Owners’ answers indicated that they were aware of the importance of nutrition and proper body conditions for their ponies. Moreover, the highest agreement on how ideal a pony for racing was on a pony with BCS 5.5. Furthermore, mean BCS of ponies signed up for this study was 5.16 ± 0.5 (out of 9). The most commonly fed forage species were Cynodon dactylon, Leersia hexandra, and Eulalia aurera, with rice bran as the main concentrate. Mean DE intake was ∼1 Mcal above NRC recommendation. Mean protein intake was 19% higher than NRC recommendation. Calcium intake was below NRC recommendation with phosphorus intake above NRC recommendation. The calcium: phosphorus ratio was concerning as phosphorus intake was 5 times calcium intake. Finally, owners’ answers (21/21) indicated that they would need educational materials about equine nutrition, particularly on feeding balanced diets for the animals.

Calming supplements are common in the equine industry. This study tested the hypothesis that Phytozen EQ, a blend of citrus botanical oils, magnesium, and yeast would reduce startle response as well as reduce behavioral and physiological signs of stress in young (1.5–6 years of age) horses (n = 14) when tied in isolation and when trailered in isolation. During the 59-day trial, horses were assigned to either the control (CON; n = 7) or treatment (PZEN; n = 7) group that received 56 g of Phytozen EQ daily. Horses underwent a 10-minute isolation test on d 30 and a 15 minute individual trailering test on day 52 or 55. For both tests, blood samples were obtained pre, immediately after, and 1-hour post for analysis of plasma cortisol concentrations, which were analyzed by repeated measures ANOVA. On day 59, horses underwent a startle test, for which time to travel 3 m and total distance traveled were recorded. These data were analyzed using a T-test. During trailering, PZEN horses tended to have lower overall geometric mean (lower, upper 95% confidence interval) cortisol concentrations than CON (81 [67, 98] vs. 61 [48, 78] ng/mL; P = .071). For the startle test, PZEN horses tended to have longer geometric mean times to travel 3 m than CON horses (1.35 [0.39, 4.70] vs. 0.26 [0.07, 0.91 seconds, P = 0.064). Other data points were not different between treatments (P > .1). It is possible that this dietary supplement could have beneficial calming effects on horses undergoing trailering or in novel situations.

A survey was conducted to evaluate how prebiotics and probiotics are used and perceived among horse owners or leasers in North Carolina. This survey was deemed exempt from full review by the NCSU Institutional Review Board. Qualtrics was used to develop the survey and it allowed for multiple horses to be represented by one owner. There were 14 questions in the survey and these included information about if the respondent resided in North Carolina and their county, number of horses owned, information about the feed offered to their horses and the owner's use and perception of supplemental prebiotics and probiotics. The survey was shared to 7 different Facebook groups representing horse owners and equestrians of North Carolina, potentially reaching up to 63,300 members, though it is likely that many horse owners were members of multiple groups or were inactive. Therefore, neither true reach nor the response rate could be accurately determined, though a total of 501 surveys were completed. Of these, 52.9% reported offering feeds containing prebiotics or probiotics while 22.0% were unsure if their feed contains them. In addition, 32.7% of respondents offered a supplemental prebiotic or probiotic. Gastric/hindgut ulcers (39.8%) and colic (28.1%) were the most common health concerns reported by the owners. The majority of responders (82.7%) believe prebiotics and/or probiotics benefit their horse's gut health. When respondents were asked to comment on their experience regarding the use of prebiotics and probiotics, common words used included “health,” “beneficial,” “difference,” “happy,” “ulcer” and “diarrhea,” implying that prebiotics and probiotics are perceived to be beneficial by these horse owners and may be helping manage some of their equine's conditions. Further, 68.2% of the respondents believe that horse owners should consider implementing prebiotics and/or probiotics into a horse's daily feeding program. In conclusion, the results of this survey indicate that these horse owners are frequently using prebiotics and/or probiotics and are seeing beneficial changes to their horse's gut health. Since most prebiotic/probiotic efficacy studies are conducted on research animals, more work is required to establish the use and effectiveness of prebiotics and probiotics in privately owned horses.

Chromium propionate (Cr Prop) was recently approved by the US FDA for supplementation to horse feed at a level not to exceed 4 mg Cr/horse/day. This approval was based on the ability of Cr Prop to improve insulin sensitivity in adult horses following oral consumption of grain or intravenous administration of glucose, and also on the safety of Cr Prop when supplemented to horse diets at up to 2 times the FDA approved level. The objective of the current study was used to determine the safety of Cr Prop based on health, body weight (BW) gain, body condition score, and blood chemistry and hematological parameters when supplemented at levels of 0, 2, 4, or 8 mg Cr/day. Forty-eight registered Quarter horses were used in this study. The study was conducted as 4 trials, due to a limitation of individual stalls at the testing facility. Horses were housed individually and fed twice daily an oat-based concentrate mix at a rate of 0.2 kg/100 kg BW, and grass hay (2 kg/100 kg BW). Supplemental Cr was provided in 50 g of ground corn/day that was top dressed on the morning feeding of concentrate. In the fourth trial, 12 horses (n = 3/treatment) were bled before feeding on d 0 and 28 of the trial for blood chemistry and hematological measurements. Serum was analyzed for an Equine Chemistry panel, that consisted of calcium, phosphorus, magnesium, sodium, potassium, chloride, bicarbonate, osmolality, anion gap, glucose, urea, total protein, albumin, bilirubin, alkaline phosphatase, aspartate aminotransferase, and creatine kinase. A sample of whole blood also was obtained for a variety of hematological measurements. Each horse served as its own control, because d 28 blood data were statistically analyzed using d 0 blood values as a covariate. Feeding Cr Prop for 42 d did not affect health, body weight gain, or body condition score. Control horses had lower (P ≤ 0.05) RBC counts than those fed 8 mg Cr/day, and tended to have lower RBC counts than those receiving 2 (P = 0.07) or 4 (P = 0.06) mg Cr/day. Other hematological measurements were not affected by dietary Cr. Serum clinical chemistry parameters measured were not affected by treatment. The present study indicates that Cr Prop is safe when supplemented to horses at up to 2 times the FDA approved feeding level.

Forty-eight Quarter Horse geldings (3–8 yr of age) were used to determine the effects of dietary chromium (Cr), in the form of Cr propionate (Cr Prop), on insulin sensitivity. Horses were blocked by age, body condition score, and glucose response to concentrate feeding on d 0, and randomly assigned to treatments. Treatments consisted of 0, 2, 4, or 8 mg Cr/d from Cr Prop. Horses were fed daily a concentrate mix at a rate of 0.2 kg/100 kg BW and grass hay at 1.75 to 2.0 kg/100 kg BW. After an overnight fast, jugular blood samples were obtained at 0, 2, and 4 h after concentrate feeding on d 0 and 28 for determination of glucose and insulin. Plasma glucose on d 28 was affected (P < 0.05) by treatment, time, and treatment x time. Horses fed 4 mg Cr/d had lesser (P < 0.05) plasma glucose concentrations than those in the other treatments at 0 h. At 2 h post feeding glucose concentrations were greater (P < 0.05) in control horses than in those given 4 mg Cr. Horses fed 2 mg Cr/d had lesser (P < 0.05) plasma glucose at 4 h post feeding compared to controls. Plasma glucose did not differ among horses receiving 2 or 4 mg Cr/d at 2 or 4 h. Insulin concentrations were greater (P < 0.05) in horses fed 0 or 2 mg Cr/d than in those given 4 or 8 mg Cr at 0 h. At 4 h post feeding insulin concentrations were greater (P < 0.05) in control horses than in those fed 2 or 4 mg Cr/d. Results of this study indicate that 2 or 4 mg Cr/d from Cr Prop increased insulin sensitivity in adult horses following oral carbohydrate consumption.

Forty-eight Quarter Horse geldings (3 to 8 yr of age) were used to determine the effects of dietary chromium (Cr), in the form of Cr propionate (Cr Prop) on insulin sensitivity. Horses were blocked by age, body condition score, and glucose response to concentrate feeding on day 0 and randomly assigned to treatments. Treatments consisted of 0, 2, 4, or 8 mg Cr/d from Cr Prop. Horses were fed daily a concentrate mix at a rate of 0.2 kg/100 kg body weight (BW) and grass hay at 1.75 to 2.0 kg/100 kg BW. All horses were fed the control diet for 7 d prior to the initiation of the study. After an overnight fast, blood samples from the jugular vein were obtained at 0, 2, and 4 h after concentrate feeding on days 0 and 28 for the determination of glucose, nonesterified fatty acids, and insulin. A glucose tolerance test (GTT) was conducted on day 42. Glucose was infused via jugular vein catheters, and blood samples were collected at various times relative to dosing for glucose and insulin determination. Plasma glucose on day 28 was affected (P < 0.05) by treatment, time, and treatment × time. Horses fed 4 mg Cr/d had lesser (P < 0.05) plasma glucose concentrations than those in the other treatments at 0 h. At 2 h post-feeding glucose concentrations were greater (P < 0.05) in horses fed 0 or 8 mg Cr/d than in those given 4 mg Cr. Horses fed 2 mg Cr/d had lesser (P < 0.05) plasma glucose at 4 h post feeding compared with those fed 0 or 8 mg Cr. Plasma glucose did not differ among horses receiving 2 or 4 mg Cr/d at 2 or 4 h. Serum insulin was affected (P < 0.05) by treatment, time, and treatment × time. Insulin concentrations were greater (P < 0.05) in horses fed 0 or 2 mg Cr/d than in those given 4 or 8 mg Cr at 0 h. At 4 h post-feeding insulin concentrations were greater (P < 0.05) in horses given 0 or 8 mg Cr than in those fed 2 or 4 mg Cr/d. Plasma glucose was affected (P < 0.05) by treatment and time, but not by treatment × time following the GTT. Mean plasma glucose (across sampling times) concentrations were greater (P < 0.05) in controls than in horses fed 2 or 4 mg Cr/d. Glucose concentrations following the GTT did not differ among controls and horses given 8 mg Cr/d. Following glucose infusion, serum insulin concentrations were greater (P < 0.05) in horses fed 2 or 4 mg Cr and tended to be greater in those fed 8 mg Cr/d compared with controls. The results of this study indicate that 2 or 4 mg Cr/d from Cr Prop increased insulin sensitivity in adult horses following oral carbohydrate consumption.

Horse owners and carers are responsible for judging the health and welfare status of animals in their care, deciding if and when professional advice should be sought and following any recommendations for treatment. However, little is known about how horse owners perceive and determine the well-being of horses in their care, or the themes that inform their beliefs about the social and behavioural requirements of horses. In this article, we present findings of an online survey of horse owners in Australia to consider if horse owners and carers believe the horses in their care have their social and behavioural needs met, how they know, and what improvements they would like to see. Most participants believed that their horses had their social and behavioural needs met, mostly because they had company from another horse, lived in a paddock situation, and/or had contact with another horse. When discussing the improvements they would like to make, participants noted more company, increased paddock time and size, and more/improved training. The extended free-text responses suggest that four themes impact the beliefs and decision-making of horse owners/carers: work, outings, interaction, and nature. We discuss these in relation to the potential for anthropomorphism to have a positive impact on horses’ well-being, when integrated into a sophisticated behaviour change and social marketing strategy that communicates the ways in which horses and humans are different and the ways in which they are alike.

Some horses are more prone to obesity than others. This study aimed to compare energy intake and expenditure between obese and lean horses. Ten mature, stock-type geldings (aged 11.8 +/- 4.0 years; 577 +/- 52 kg) maintained on the same pasture were classified as obese (n = 6, body condition score [BCS] >= 7) or lean (n = 4, BCS = 4-5) and adapted to free-choice grass hay over 25 days. Dry matter intake (DMI) was measured for 11 days, with body weight (BW) and blood samples (analyzed for serum leptin) collected on Days 0, 2, 4, 7, 9, and 11. Behavior was observed for 24 hours. Apparent dry matter digestibility and gross energy digestibility were measured using 48-hour total fecal collection. Digestible energy intake was calculated. Activity (distance traveled, average heart rate [HR], and maximum HR) was quantified using HR monitors with GPS tracking. Average HR was used to estimate energy expenditure. Serum leptin, DMI, and BW were analyzed as repeated measures. Other variables were analyzed using unpaired t-tests. P < .05 was considered significant. Serum leptin, intake, digestibility, and activity were not affected by group. Dry matter intake was correlated with average HR (r = 0.70; P = .03). Obese horses spent more time active (interacting with other horses, moving around; P = .003) and less time eating (P= .03). Overall, the results of this study identified some differences in behavior but did not identify any differences in energy intake or expenditure between obese and lean horses. (C) 2018 Elsevier Inc. All rights reserved.

Weight loss plans in horses typically use dietary restriction, but exercise may have additional benefits. This study aimed to compare the effects of a diet or exercise protocol resulting in comparable caloric restriction in obese horses. Ten obese horses were paired according to sex, age, and breed or breed type. One horse from each pair was randomly assigned to either diet (DIET)-intake restricted to approximately 85% of digestible energy requirements or exercise (EX)-exercised to expend approximately 15% of digestible energy requirements, resulting in 85% of requirements available, for 4 weeks. Body weight (BW), heart girth (HG), girth-to-height ratio (G:H), neck circumference (NC), neck circumference-to-height ratio (NC:H), belly girth (BG), body condition score (BCS), cresty neck score (CNS), serum insulin, plasma leptin, and plasma ghrelin concentrations were measured weekly. An oral sugar test was conducted on days 0 and 28 to measure insulin to glucose ratio (Ins:glc) and 60-minute insulin sensitivity index (ISI60). Results were analyzed using repeated measures. A P ≤ .05 was considered significant, and .05 <P ≤ .10 was considered a tendency. Both groups showed similar decreases over time in BW, HG, G:H, BG, BCS, and CNS, but the EX group showed significantly greater losses in NC (and NC:H). The EX group showed significant improvements in (log) Ins:glc, as well as a tendency for improvements in (log) ISI60 and plasma leptin concentrations, while the DIET group showed no change. Horses showed no changes in (log) plasma ghrelin with weight loss.

In a previous study, exercise resulted in weight loss and improvements in insulin and glucose metabolism, but horses on free-choice forage may increase feed intake in response to exercise, potentially negating the benefits. This study aimed to determine if light exercise increases intake in mature horses, and if horses on ad libitum forage achieve the benefits previously observed. Eight mature, stock-type geldings (594.3±50.5 kg; 12.0±1.7 yr) were adapted to a diet of ad libitum grass hay. Baseline dry matter intake (DMI) was measured for 7 d. Horses then remained idle (CON, n=4) or entered an exercise program (EX, n=4) for 3 weeks. Voluntary DMI was quantified daily. Body weight (BW), heart girth (HG), girth to height ratio (G:H), neck circumference (NC), neck circumference to height ratio (NC:H), rump fat thickness (RF), percent body fat (BF), serum insulin, plasma ghrelin, and plasma leptin were quantified weekly. An oral sugar test was conducted on day 0 and 21, and insulin to glucose ratio (Ins:glc) and 60-min insulin sensitivity index (ISI60) were calculated. Statistical analysis was performed using repeated measures. Insulin, ghrelin, Ins:glc, and ISI60 were not normally distributed, so they were log-transformed for analysis. P≤0.05 was considered significant. The EX group showed no difference in DMI or (log) ghrelin compared to the CON group. The CON group showed increases in BW, RF, and BF, while the EX group showed decreases in HG, G:H, NC, NC:H, (log) insulin, and leptin. EX showed lower (log) Ins:glc than CON after treatment. Overall, light exercise did not alter DMI in mature horses on ad libitum forage, but resulted in improvements in morphometric measurements, (log) Ins:glc, and plasma leptin concentrations, and avoided gains in BW and rump fat.

Due to the high prevalence of obesity in some horses and ponies (especially in the leisure horse sector), effective and safe weight loss strategies are required. The present study evaluated the effect of two different energy restriction rates on physical, morphometric and welfare parameters in 18 obese (body condition score [BCS] 7-9/9) Shetland geldings. The trial was divided into three periods: (1) a 4 week adaptation period, during which the maintenance energy intakes to maintain a stable obese bodyweight were determined (100% MERob); (2) a 16.5-week weight loss period during which the ponies were randomly divided into three groups (n = 6/group) comprising a control group (CONTROL), moderate energy restricted (MOD), and severe energy restricted (SEV) groups that were respectively fed at 100%, 80% and 60% of their individual MERob; and (3) a 3 week follow up period in which the ponies were again fed at their outset individual 100% MERob.Between the start and end of the weight loss period, significant pairwise differences between the three treatment groups were seen for bodyweight, BCS, heart girth, belly girth, and relative ultrasound fat depth at the level of loin and ribs at several time points (P < 0.05). The higher energy restriction was associated with a faster decrease in BCS, tail head, and heart plus belly girth, but no gastric ulcers or stereotypic behaviours were seen.