Abstracts / Journal of Equine Veterinary Science 31 (2011) 230-356 253

glycemic response, insulin sensitivity and glucose-insulindynamics in horses.Materials and Methods: Horses and Diets. Ten light horse typemares aged 4 to 17 with body condition scores ranging from 6 to 8were paired according to age and body condition and randomlyassigned to two groups. The control group (CON) receiveda commercial pelleted feed having DE of 3.30 Mcal/kg, and thetreatment group (FISH) received the same pelleted feed plus fishoil having 14% EPA and 10% DHA (OmegaEquis, Omega Protein,Houston, TX), fed at 324mg oil/kg BW,[2] mixed into the feed. Theconcentrate portions of the CON and FISH groups were fed ata rate to supply 40% of the DE requirement of each horse, withhay supplying the remainder. Since the mares were used in theuniversity riding program, DE requirements were determinedbased on body weight and a designation of light workthroughout the study. Mares fed fish oil were fed slightly lesspelleted feed so that DE intake/kg BW of the FISH group wasisocaloric to the CON group. The menhaden oil was wellaccepted with no adverse effects. Supplementation continuedfor 60 days.Sample collection and analysis. Blood samples were collected every6 days for plasma fatty acid analysis. Ameal-related challengewasconducted on day 59 to determine the influence of diet on gly-cemic response. For the meal challenge, horses were fastedovernight with access to water. Jugular catheters were placedusing aseptic technique and local anesthetic. Baseline sampleswere collected, and then the regular diets were fed to each horse,followed by sample collection every 15min through 360min afterthe meal. Frequently sampled intravenous glucose tolerance tests(FSIGT) were conducted on days 0 and 60 to assess effect of dieton insulin sensitivity [3].Plasma fatty acids were analyzed using gas chromatography.Blood glucose was analyzed using a glucometer previously vali-dated for horses. Plasma insulin was analyzed using an Enyme-Linked Immunosorbent Assay (Mercodia, Inc., Uppsala, Sweden),validated for equine insulin [4]. Area under the curve (AUC) formeal-related glycemic response was calculated by graphicalapproximation. For estimation of insulin sensitivity in unitscommonly used for the minimal model of glucose dynamics, theinsulin ELISA data (ug/L) were transformed to mU/L using thevalidation equation (r ¼ .97) in the companion paper [4]. Insulinsensitivity (Si), glucose effectiveness (Sg), acute insulin responseto glucose (AIRg) and the disposition index (DI) were calculatedusing MinMod Millennium and WinSAAM software.Statistical analysis. Data were tested for normality using theShapiro-Wilk statistic. All data were normally distributed exceptfor insulin sensitivity, which was transformed to its reciprocal inorder to fit a normal distribution for parametric analysis. Plasmafatty acids, meal-related glucose response, glucose AUC, baselineglucose and insulin, 1/Si, Sg, AIRg and DI were analyzed usinga mixed model with repeated measures, with main effects of diet,horse and time. Diet and time were considered fixed effects, andhorse was considered a random effect.Results and Discussion: Over the 60 d period, FISH horsesexhibited an increase (P < .01) in plasma EPA and DHA. Meal-relatedglucoseAUCwere lower (P¼ .032) inhorses fedFISH(45.7�7.84 g*min*L�1) compared to the CONdiet (77.4� 9.03 g*min*L�1).Basal glucose and insulin concentrations of FISH and CON horseswere not different (P > .10). Insulin sensitivity, Sg, AIRg and DI ofFISH and CON horses were not different (P > .10). Overall glucoseclearance during the FSIGTwasmore rapid on day 60 than day 0 inboth groups (P < .019).The increase in EPA and DHA concentrations over the 60 d periodis consistent with previous reports [2]. The lower glucose AUC inhorses fed FISH compared to CON could be an effect of less feed,thus less starch, fed to the FISH group. Starch intakes were 0.88and 1.13 g/kg BW and NSC intakes were 1.12 and 1.45 g/kg BW in

the FISH and CON meals, respectively. This difference alone wasnot enough to contribute to the significant suppression in meal-related glucose AUC [5], so the fish oil was likely a factor. Althoughworkload did not increase, the more rapid glucose clearance onday 60 compared to day 0 in both groups may have beena training effect, as the horses were used in the university ridingprogram.Conclusion: Supplementation of dietary fish oil increasedplasma EPA and DHAwhile moderating blood glucose response toa concentrate meal, but it did not affect insulin sensitivity innormal horses.Acknowledgments: This project was supported in part by theSTEP-MT undergraduate research program and the Mary E. MillerChair of Excellence in Equine Health at MTSU. Menhaden oil wasdonated by OmegaEquis, Omega Protein, Houston, TX.

References

[1] Huang T, Wahlqvist ML, Xu T, et al. Increased plasma n-3 unsaturatedfatty acid is associated with improved insulin sensitivity in type 2diabetes in China. Mol. Nutr. Food Res 2010;54(Suppl 1):S112-9.

[2] O0Connor CL, Lawrence LM, Hayes SH. Dietary fish oil supplementa-tion affects serum fatty acid concentrations in horses. J. Anim. Sci2007;85:2183-9.

[3] Hoffman RM, Boston RC, Stefanovski D, et al. Obesity and diet affectglucose dynamics and insulin sensitivity in Thoroughbred geldings. J.Anim. Sci 2003;81:2333-42.

[4] Kayser JP, Hoffman RM, Haffner JC, et al. Standardization of EquineSpecific Enzyme-Linked Immunosorbent Assay for measuring seruminsulin. J. Equine Vet. Sci; 2011. In press.

[5] Hoffman RM, Haffner JC, Crawford CA, et al. Nonstructural carbohy-drate and glycemic response of feeds: how low is 0low0 starch? J.Equine Vet. Sci 2009;29:379-80.

The body condition score of leisure horses competingat an unaffiliated championship in the UK

I.J. Harker 1, P.A. Harris 2, and C.F. Barfoot 11Mars HorseCare UK Ltd, Milton Keynes, Bucks, UK, 2 EquineStudies Group, Waltham Centre for Pet Nutrition, MeltonMowbary, Leics, UK

Introduction: Obesity is increasingly recognised as an equinewelfare issue, and excessive weight may compromise both healthand performance. In most instances horses become overweightbecause they are given the opportunity to consume calories inexcess of their energy requirements. Certain breeds/types (e.g.cobs and native ponies) appear to be more prone to weight gainand therefore require even more careful management to try toprevent this energy imbalance from occurring. Evaluating bodycondition (BC), together with bodyweight, helps to assess andmonitor the calorie intake of an individual horse relative to itsown energy needs.A recent survey carried out in Scotland on pleasure ridinghorses reported that 45% were obese (i.e. 5 or 6 on authors'own 6 point scale) [1]. It is therefore likely that owners arebecoming increasingly accustomed to seeing overweight horsesand may consider this to be the acceptable norm. This may beespecially true with respect to animals within the pleasuresection of the equine industry where many horses are notregularly exercised or competed. The objectives of this surveywere to assess whether overweight animals also comprisea high proportion of the UK pleasure horses which are beingregularly competed, and whether there is any influence of thecompetitive discipline.Materials and Methods: Horses and ponies were evaluatedwhich had qualified via regional events to compete at the national

Abstracts / Journal of Equine Veterinary Science 31 (2011) 230-356254

unaffiliated championship show in a variety of equestrian disci-plines (show jumping by senior riders [over 16 years of age], showjumping by junior riders [less than 17 years of age], dressage andshowing (where judged when ridden and/or in hand halter forconformation, movement and condition etc.). A total of 331horses and ponies ranging in size from 8-18hhwith amean heightof 15.2hh and a mean age of 11 (ranging from 2-26 yrs) werecondition scored over 10 days in July 2010. Horses were randomlyassigned to one of a team of 6 trained assessors to be bodycondition scored (BCS) using a 1-9 system adapted from Hennekeet al 1983 [2]. Overall whole number scores were allocated to eachhorse based on descriptions and pictures. Horses were thencategorised into binary variables based on BCS such that horsesclassified as having a BCS of �6 were considered to beoverweight, a BCS of �7 as fat and a BCS of �8 as obese. Cross-tabulations and chi-squared or Fishers exact tests were used tocompare the proportions of horses overall and for the threebinary categorisations (<8 vs �8, <7 vs �7 and <6 vs �6)among disciplines. Results are presented with P-values with thelevel of significance set at P < .05 for all tests.Results and Discussion: Overall 62 percent of animals were cat-egorised as being overweight, fat or obese, with a BCS >5, despitebeing in regularwork and competing in this national championship.The distribution of BCS by discipline shows that there is a significantdifference among the different disciplines (overall chi-square testP¼ .0002, Table 1). Using the cut-off for fat and obese horses (<7 vs�7), then dressage horses were fatter than senior show jumpers(P ¼ .03), show horses were fatter than senior show jumpers(P < .0001) and junior show jumpers were fatter than seniors (P ¼.002). Finally, using the cut-off for overweight, fat and obesehorses together (<6 vs �6), then show horses were fatter thandressage horses (P ¼ .045) which were fatter than senior showjumping horses (P ¼ .006) and junior show jumpers were fatterthan seniors (P ¼ .002). Show horses were also fatter than seniorshow jumping horses (P < .0001).Conclusion: The fact that more show jumping horses beingridden by juniors had higher BCS than those ridden by seniorscould reflect that a greater number of the animals ridden byjuniors were of pony type (70% described as natives or nativecross breeds vs. only 26% of senior show jumping horses beingnatives or native cross breeds). Perhaps not surprisingly thehorses being shown were the most likely to be classified asoverweight. This may reflect what is considered an 'ideal' BCS forthis discipline. In addition, a proportion of classes in this disci-pline are not ridden which may make it difficult for owners toachieve a fit well muscled, conditioned horse without fat.Despite the increased focus on the dangers of obesity and thewelfare implications, these survey results suggest that even inregularly exercised pleasure horses over half could be categorisedas being overweight or fat. Therefore, further education isnecessary to ensure horse owners are able to identify animals thatare overweight and that they have the knowledge to adjust their

Table 1Distribution of BCS for horses within each equestrian discipline andoverall

BCS Dressage(n ¼ 68)

Showing(n ¼ 80)

ShowJumpingJuniors(n ¼ 97)

ShowJumpingSeniors(n ¼ 86)

Overall(n ¼ 331)

<5 4% 0% 1% 8% 3%Ideal ¼ 5 32% 21% 35% 51% 35%Overweight

¼ 644% 46% 40% 34% 41%

Fat ¼ 7 15% 25% 19% 7% 16%Obese �8 5% 8% 5% 0% 5%Total 100% 100% 100% 100% 100%

feeding regimens in order to reach an ideal body condition scorebefore clinical disease is seen.It may be valuable to undertake further research to identify whatBCS owners of these competitive pleasure horses consider is thenorm and acceptable.

References

[1] Wyse CA, McNie KA, Tannahil VJ, et al. Prevalence of obesity in ridinghorses in Scotland. Vet Rec 2008;162:590-1.

[2] Henneke DR, Potter GD, Krieder JL, Yeates. Relationship betweencondition score, physical measurements and body fat percentage inmares. Equine Vet J 1983;15:371-2.

Evaluation of the safety and performance of an enteral dietformulated specifically for horses

K.R. Vineyard, M.E. Gordon, K.K. Williamson, and M.L. JerinaLand O'Lakes Purina Feed, Gray Summit, Missouri, USA

Introduction: Information and studies that address the enteraldelivery of nutrients for the sick and/or inappetent horse islimited1,2,3. A series of experiments were conducted to assess therelative safety and performance of a low soluble carbohydrate,fiber-rich enteral formulation (Wellsolve Well-Gel�) intended toprovide nutritional support for hypophagic horses.Materials and Methods: A series of three experiments and onefield trial were conducted during the development of this equine-specific enteral formula (EF) (36% CP, 6% fat, 14% max fiber, 4%starch, 7% sugar), formulated to meet 100% of NRC requirementsfor protein, vitamins, and minerals when supplied at a rate of 0.3%BW/d. In Experiment 1, 4 mature horses received either 0.45 kg ofa ration balancer (Enrich 32�) or an isoenergetic amount ofhydrated EF (2:1 water:EF) offered for voluntary consumptiononce daily. Horses also received approximately 1.5% BW in grasshay/d. After a 6 d acclimation period, horses were catheterized ond 7 and blood was collected prior to the meal and at 15-minintervals for 120 min and analyzed for total serum and plasmaprotein and hematocrit. Differences between treatments wereanalyzed using the Student's t-test and considered significant atP < .05. In experiment 2, 8 mature horses received 1.8-2.3 kg ofhydrated EF (1:1 water:EF) divided into 2 daily feedings forvoluntary consumption for 30 d. An additional 4 horses wereenterally administered 0.45 kg of hydrated EF (3:1water:EF) twicedaily for 5 d. Horses also received approximately 1.5% BW in grasshay/d. General horse health (manure consistency, signs of colic,gastric disturbance) was recorded daily throughout the experi-ment. In experiment3, eightmaturehorseswereassigned tooneoftwo dietary treatments in a replicated 4x4 Latin Square design:0.45 kg of hydrated EF (1:1 water:EF) offered for voluntaryconsumption (treatment A) or .45 kg of hydrated EF (3:1 water:EF)administered enterally (treatment B). Horses were fed a basalconcentrate ration (Strategy�) along with approximately 1.5% BWin grass hay/d for 6 d. On d 7 horses were catheterized and bloodwas collected prior to treatment administration and at 30-minintervals for 360 min. Blood was analyzed for glucose, insulin,triglycerides and non-esterified fatty acids (NEFA). Differencesbetween treatments were analyzed using PROC MIXED withrepeated measures in SAS (SAS Inst. Inc., Cary, NC) and consideredsignificant at P < .05. In the field trial, over 500 kg of the EF wasshipped to selected veterinary hospitals across the United States(n¼11) tobe utilized over a 9-monthperiod. Clinicianswere askedto complete a detailed survey for each patient that was adminis-tered the EF and to evaluate the product's overall performance.Results andDiscussion: Although specific information regardingnutritional requirements of the critically ill horse is limited,