scholarly journals Supplemental Fiber Affects Body Temperature and Fecal Metabolites but Not Respiratory Rate or Body Composition in Mid-Distance Training Sled Dogs

2021 ◽  
Vol 8 ◽  
Author(s):  
Emma Thornton ◽  
Eve Robinson ◽  
James R. Templeman ◽  
Lindy Bruggink ◽  
Michael Bower ◽  
...  
Keyword(s):  
Body Composition ◽  
Body Temperature ◽  
Respiratory Rate ◽  
Dry Matter ◽  
Gut Health ◽  
Soluble Fiber ◽  
Post Exercise ◽  
Distance Training ◽  
Sled Dogs ◽  
Matter Basis

Dietary fiber affects canine physiology in many ways, such as increasing colonic absorption of water and improving gut health, both of which may positively impact exercise performance. The objectives of this study were to investigate the effects of increased dietary soluble fiber and incremental training on respiratory rate (RR), internal body temperature (BT), body composition, and fecal metabolites in mid-distance training sled dogs. Fourteen dogs (12 Siberian and 2 Alaskan Huskies) were blocked by age, sex, and body weight (BW) and then randomly allocated into one of two diet groups. Seven dogs were fed a dry extruded control diet (Ctl) with an insoluble:soluble fiber ratio of 4:1 (0.74% soluble fiber on a dry-matter basis), and seven dogs were fed a dry extruded treatment diet (Trt) with an insoluble:soluble fiber ratio of 3:1 (2.12% soluble fiber on a dry-matter basis). Fecal samples were taken once a week. All dogs underwent 9 weeks of incremental exercise conditioning where the running distance was designed to increase each week. Every 3 weeks, external telemetry equipment was used to non-invasively measure and record RR and internal BT at resting, working, and post-exercise recovery states. Body composition was measured on weeks −1 and 9 using quantitative magnetic resonance. Body composition, RR, BT, and fecal metabolites were analyzed using a mixed model with dog as a random effect and week and diet group as fixed effects. Dogs on Trt had lower working and post-exercise BT than Ctl (P < 0.05). In addition, Trt dogs had lower recovery BT at weeks 2 and 5 than Ctl dogs (P < 0.05). Treatment dogs had greater fecal short-chain fatty acid concentrations than Ctl (P < 0.05). Diet had no effect on RR or body composition (P > 0.10), but exercise resulted in an overall 7% increase in lean and 3.5% decrease in fat mass (P < 0.05). These data suggest that increasing dietary soluble fiber may positively influence BT and gut health; however, it has no effect on RR or body composition. Soluble fiber did not negatively impact any measures of overall health and performance and should be considered for use in performance dogs.

scholarly journals Exercise but Not Supplemental Dietary Tryptophan Influences Heart Rate and Respiratory Rate in Sled Dogs

2020 ◽  
Vol 7 (3) ◽  
pp. 97 ◽  
Author(s):  
Emma Thornton ◽  
James R. Templeman ◽  
Michael Bower ◽  
John P. Cant ◽  
Graham P. Holloway ◽  
...  
Keyword(s):  
Heart Rate ◽  
Amino Acid ◽  
Respiratory Rate ◽  
Control Diet ◽  
Neutral Amino Acid ◽  
Large Neutral Amino Acid ◽  
Post Exercise ◽  
Sled Dogs ◽  
Exercise Regimen ◽  
Acid Ratio

Tryptophan (Trp), an indispensable amino acid for dogs, is the precursor of serotonin, a neurotransmitter with a variety of effects throughout the body, including the ability to modulate cardiac and pulmonary activity. This study aimed to investigate the effects of a 12-week incremental exercise regimen and supplemental dietary Trp on heart rate (HR) and respiratory rate (RR) in client-owned sled dogs. Sixteen Siberian huskies were randomly allocated to either treatment or control diet groups. Both groups were fed a control diet (Trp to large neutral amino acid ratio of 0.047:1); however, treatment dogs received a Trp supplement to achieve a Trp to large neutral amino acid ratio of 0.075:1. Every three weeks, external telemetry equipment was used to non-invasively measure and record HR and RR at a resting, working, and post-exercise state in a controlled exercise challenge. A mixed model was used to test differences between diet, activity parameter, and week. Dietary Trp supplementation had no effect on HR or RR. Independent of diet, resting, working, post-exercise HR, and time to recover post-exercise HR decreased from week −1 to week 11 (p < 0.05). Resting HR had the greatest reduction from week −1 to week 11 (21%, p < 0.05). Working RR did not change with exercise (p > 0.10), but rRR and postRR decreased from week −1 to week 11 (p < 0.05). These data suggest that the exercise regimen the dogs were subjected to may have positively impacted the dogs’ capacity to sustain aerobic exercise, whereas Trp supplementation had no effect on HR or RR.

Effect of conditioning on exercise-induced hyperthermia and post-exercise cooling in dogs

2018 ◽  
Vol 14 (2) ◽  
pp. 91-97 ◽  
Author(s):  
J.A. Baker ◽  
M.S. Davis
Keyword(s):  
Thermal Stress ◽  
Body Temperature ◽  
Prospective Study ◽  
Oxygen Concentration ◽  
Rectal Temperature ◽  
Post Exercise ◽  
Temperature Changes ◽  
Hypoxic Conditions ◽  
Sled Dogs ◽  
Exercise Induced

Our objective was to evaluate the effect of conditioning and hypoxia on rectal and gastrointestinal temperature changes in dogs exercising at cold ambient temperature. Six Alaskan Husky sled dogs, each in a physically conditioned and unconditioned state, were used in the prospective study. Dogs in peak physical condition were run untethered on a treadmill under normoxic and hypoxic conditions of 20 and 12.5% environmental oxygen concentration, respectively, on separate days. After undergoing a deconditioning period of four months, the same dogs were run again under the same environmental conditions of 20 and 12.5% O2. Body temperature measurements were obtained via digital rectal thermometer and ingestible gastrointestinal thermistor at baseline, every 5 min for 30 min of exercise, and for 15 min following cessation of exercise. Under hypoxic conditions, peak gastrointestinal temperature was lower in conditioned vs unconditioned dogs. Gastrointestinal cooling was faster in conditioned dogs under normoxic conditions only. There was no difference in the peak rectal temperature, or rate of rectal temperature cooling in either normoxic or hypoxic conditions. 3 of 6 (50%) of the conditioned dogs reached a plateau temperature after approximately 20 to 25 min. This was observed less frequently when the dogs were unconditioned. Gastrointestinal and rectal temperatures reacted differently to exercise depending on conditioning or environmental oxygen concentration and this suggests that they cannot be used interchangeably to assess body temperature. Under these conditions, conditioning had no effect on rectal temperature. Presence of a plateau effect of rectal or gastrointestinal temperature may demonstrate a thermoregulatory balance of heat production and heat loss and may be a helpful measure in assessing individual dogs’ level of conditioning with regard to resistance to thermal stress.

scholarly journals 84 Effects of incremental conditioning and supplemental dietary tryptophan on pre, mid, and post-exercise heart rate and respiratory rate in sled dogs

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 58-59
Author(s):  
Emma Thornton ◽  
James Templeman ◽  
Michael Bower ◽  
John Cant ◽  
Graham Holloway ◽  
...  
Keyword(s):  
Heart Rate ◽  
Body Weight ◽  
Respiratory Rate ◽  
Conditioning Regimen ◽  
Whole Body ◽  
Exercise Heart Rate ◽  
Large Neutral Amino Acid ◽  
Post Exercise ◽  
Sled Dogs ◽  
Time Required

Abstract Repetitive bouts of resistance and aerobic exercise can have dramatic effects on whole body physiology. Dietary tryptophan supplementation supports protein turnover and serotonin production, which assist in responses to exercise. The objective of this study was to investigate the effects of a 12-week incremental exercise regimen and supplemental dietary tryptophan on pre-, mid-, and post-exercise heart rate and respiratory rate in sled dogs. Sixteen dogs (mean age of 4.8 ± 2.5 years, body weight 24.3 ± 4.3 kg) were blocked for sex, age, and body weight, and randomly allocated to a control diet or the control plus tryptophan diet (tryptophan to large-neutral-amino-acid ratio of 0.075:1). All dogs participated in a 12-week conditioning regimen with controlled exercise challenges at week -1 and subsequently every 3 weeks. Electrocardiogram electrodes and thoracic rib bands were worn to record heart rate and respiratory rate (EMKA Tech., Falls Church, VA, USA) prior to, during, and following each exercise challenge. A trans regression, mixed, and correlation model were used where appropriate to assess the fixed effects of treatment and week, and explore linear relationships between recovery time and week in SAS (v 9.4). No differences were found in heart rate between treatment groups for any training level (P &gt; 0.10). Working, recovery, and time required for heart rate to recover post-exercise decreased from week -1 to week 11 (P &lt; 0.05). Correlation analysis indicated that treatment dogs recovered respiratory rate faster post-exercise compared to control (r = -0.421, P &lt; 0.05). Resting, recovery and time required for respiratory rate to recover post-exercise decreased from baseline to week 11 (P &lt; 0.05). This data suggests improvement in cardiorespiratory fitness was observed over 12 weeks of training and that tryptophan may support respiratory function during exercise recovery.

scholarly journals Effects of incremental exercise and dietary tryptophan supplementation on the amino acid metabolism, serotonin status, stool quality, fecal metabolites, and body composition of mid-distance training sled dogs

2020 ◽  
Vol 98 (5) ◽  
Author(s):  
James R Templeman ◽  
Emma Thornton ◽  
Cara Cargo-Froom ◽  
Eli J Squires ◽  
Kelly S Swanson ◽  
...  
Keyword(s):  
Body Composition ◽  
Fixed Effects ◽  
Control Diet ◽  
Random Effect ◽  
Post Exercise ◽  
Nutritional Interventions ◽  
Sled Dogs ◽  
Exercise Regimen ◽  
Composition Optimization ◽  
Exercise Induced

Abstract Exercise improves the health of dogs; however, the extreme exertion experienced by sled dogs may lead to variable metabolic and fecal characteristics. Nutritional interventions, such as dietary tryptophan (Trp), may reduce the prevalence of these exercise-induced disturbances. Sporting diets tend to have high crude protein concentrations in contrast to adult maintenance diets and this results in less Trp relative to other amino acids (AA). Therefore, sporting dogs represent an ideal cohort to assess the effects of supplemental Trp. The objective was to evaluate the effects of supplemental dietary Trp and an incremental training regimen on AA and serotonin status, fecal scores and metabolites, and body composition in client-owned Siberian huskies. Sixteen dogs (nine females and seven males) were used, with a mean age of 4.8 ± 2.5 yr and body weight (BW) of 24.3 ± 4.3 kg. Dogs were blocked for sex, age, and BW and randomly allocated into two groups with eight fed a dry extruded control diet (Ctl) and eight fed Ctl supplemented with Trp to reach a Trp:large-neutral AA (LNAA) ratio of 0.075:1 (treatment, Trt). The exercise regimen was designed to increase in distance each week, but weather played a role in setting the daily distance. Each week BW was recorded and food allotments were adjusted to maintain initial BW. Pre and post-exercise blood samples were taken every 3 wk, dogs then received a meal followed by 1, 2, and 4 h post meal blood collections (serum AA, serotonin). Stool collection and scoring occurred each week and body composition was measured on weeks −1 and 11. Serotonin, AA, fecal metabolite, and body composition data were analyzed using PROC MIXED of SAS with dog as a random effect and week and Trt as fixed effects. Stool score data were analyzed using PROC FREQ to compare stool score and Trt, and PROC CORR was used to analyze associations between fecal score, temperature, humidity, and run distance. Dogs on Trt had greater fasted Trp compared with baseline, greater post-meal Trp and serotonin compared with baseline, greater post-meal Trp compared with fasted, and greater post-meal Trp and serotonin compared with Ctl (P &lt; 0.05). Fecal data indicated that Trp improved stool scores (P &lt; 0.05) yet had no effect on fecal metabolites. An overall increase in lean and decrease in fat mass was found (P &lt; 0.05), but Trt had no effect on body composition. Optimization of the dietary Trp:LNAA ratio may help to improve GI health without compromising performance in actively training sled dogs.

scholarly journals 76 Investigating the effects of increased soluble fiber and incremental exercise on the voluntary physical activity and behaviour of sled dogs

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 56-57
Author(s):  
Eve Robinson ◽  
James Templeman ◽  
Emma Thornton ◽  
Candace Croney ◽  
Lee Niel ◽  
...  
Keyword(s):  
Physical Activity ◽  
Repeated Measures ◽  
Mixed Model ◽  
Video Recording ◽  
Control Group ◽  
Gut Health ◽  
Soluble Fiber ◽  
Voluntary Activity ◽  
Sled Dogs ◽  
Voluntary Physical Activity

Abstract Optimization of the insoluble:soluble fibers in the diets of dogs can improve gastrointestinal health by increasing commensal bacterial growth. A growing body of research suggests that improved gut health can influence behavior via the gut-brain axis. Therefore, the objectives of this study were to investigate the effects of an increased soluble fiber diet on the behavior and voluntary activity of actively training, client-owned Siberian huskies. Fourteen dogs were blocked for age, BW and sex and randomly allocated to either the control or treatment groups. The control group was fed a dry extruded diet that contained an insoluble:soluble fiber ratio of 4:1, and the treatment group was fed a dry extruded diet that contained an insoluble:soluble fiber ratio of 3:1. All dogs underwent eight weeks of incremental conditioning where they trained four days a week. Once a week, a 5-minute video recording was taken immediately pre- and post-exercise to evaluate behaviors. Activity monitors were used to record voluntary activity on two rest days and one active day during weeks -1, 1, 4, 5, and 7. All behavioral and physical activity count data were analyzed using a repeated measures mixed model to test for differences between dietary treatments and week. No differences were observed between treatment or control dogs for any behavior or voluntary physical activity levels (P &gt; 0.05); however, all dogs experienced an exercise-induced reduction in locomotive behaviors prior to exercise throughout the 8-week conditioning period (P &lt; 0.05). Additionally, all dogs were more active during the second consecutive day of rest relative to the first (P &lt; 0.05). These data suggest that while increased soluble fiber in the diets of sled dogs may not affect their behavior, the exercise-related reduction in activity observed begins to recover within one rest day.

scholarly journals 267 Supplementing Ca salts of soybean oil to late-gestating beef cows: Impacts on performance and physiological responses of the offspring

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 192-192
Author(s):  
Alice Brandão ◽  
Reinaldo F Cooke ◽  
Kelsey Schubach ◽  
Bruna Rett ◽  
Osvaldo Souza ◽  
...  
Keyword(s):  
Soybean Oil ◽  
Dry Matter ◽  
Body Condition Score ◽  
Physiological Responses ◽  
Average Daily Gain ◽  
Plasma Concentrations ◽  
Beef Cows ◽  
Late Gestation ◽  
Muscle Area ◽  
Matter Basis

Abstract This experiment compared performance and physiological responses of the offspring from cows supplemented with Ca salts of soybean oil (CSSO) or prilled saturated fat (CON) during late gestation. Non-lactating, pregnant Angus × Hereford cows (n = 104) that conceived during the same fixed-time artificial insemination protocol, using semen from 2 sires, were used in this experiment. Cows were ranked by pregnancy sire, body weight (BW), and body condition score (BCS). On d 180 of gestation (d -15), cows were randomly assigned to receive (dry matter basis) 415 g of soybean meal per cow daily in addition to 1) 195 g/cow daily of CSSO (n = 52) or 2) 170 g/cow daily of CON (n = 52). Cows were maintained in 2 pastures (26 cows/treatment per pasture), and received daily 12.7 kg/cow (dry matter basis) of grass-alfalfa hay. From d 0 until calving, cows were segregated into 1 of 24 feeding pens thrice weekly and received treatments individually. Cow BW and BCS were recorded, and blood samples were collected on d -15 of the experiment and within 12 h after calving. Calf BW was also recorded and blood sample collected within 12 h of calving. Calves were weaned on d 290 of the experiment, preconditioned for 35 d (d 291 to 325), and transferred to a feedyard where they remained until slaughter. Upon calving, CSSO cows and calves had greater (P &lt; 0.01) plasma concentrations of linoleic acid and total ω - 6 FA compared with CON cohorts. No differences in calf birth BW, weaning BW, and final preconditioning BW were noted (P ≥ 0.36) between treatments. Average daily gain and final BW in the feedlot were greater (P ≤ 0.05) in steers from CSSO cows compared with CON. The incidence of calves diagnosed with BRD that required a second antimicrobial treatment was less (P = 0.03) in calves from CSSO cows, resulting in reduced (P = 0.05) need of treatments to regain health compared with CON (Table 5). Upon slaughter, longissimus muscle area was greater (P = 0.03) in calves from CSSO cows compared with CON. Collectively, these results suggest that supplementing CSSO to late-gestating beef cows stimulated programming effects on postnatal offspring growth and Page 2 of 15 For Peer Review health. Therefore, supplementing late-gestating beef cows with CSSO appears to optimize offspring welfare and productivity in beef production systems.

Effects of genotype and dietary forage to concentrate ratio during the finishing period on carcass characteristics and meat quality of lambs from hill sheep systems

2001 ◽  
Vol 137 (2) ◽  
pp. 205-220 ◽  
Author(s):  
A. F. CARSON ◽  
B. W. MOSS ◽  
L. E. R. DAWSON ◽  
D. J. KILPATRICK
Keyword(s):  
Meat Quality ◽  
Dry Matter ◽  
Carcass Characteristics ◽  
Live Weight ◽  
The Other ◽  
Grass Silage ◽  
Classification Score ◽  
Forage:Concentrate Ratio ◽  
Matter Basis

The study investigated the effects of lamb genotype produced from hill flocks on feed efficiency, carcass characteristics and meat quality in animals finished on either a high forage:concentrate ratio diet (HFC) or a low forage:concentrate ratio diet (LFC). Purebred Scottish Blackface (BXB) lambs were compared with Blue-Faced Leicester×Scottish Blackface (BLXB) and Texel×Scottish Blackface (TXB) lambs. Purebred Cheviot (CXC), Suffolk×Cheviot (SXC) and Texel×Cheviot (TXC) lambs were also investigated. Lambs on the LFC diet were offered grass silage and concentrates mixed in the proportion of 0·80 silage and 0·20 concentrates on a dry matter basis. The LFC diet consisted of 0·20 grass silage and 0·80 concentrates on a dry matter basis. Representative lambs were slaughtered at the start of the experiment and on reaching 38 and 46 kg live weight. Averaged over the two slaughter weights, within the Blackface cross lambs, BXB had a lower liveweight gain (P < 0·01) than either BLXB or TXB (138, 207 and 203 (S.E. 11·1) g/day, respectively). Within the Cheviot cross lambs, CXC had a lower liveweight gain (P < 0·05) than SXC (188 v. 220 (S.E. 11·1) g/day), while SXC and TXC (204 g/day) had similar liveweight gains. Lambs on the LFC diet had a higher dressing proportion (P < 0·001) compared with lambs finished on the HFC diet (0·466 v. 0·434 (S.E. 0·0018) kg carcass per kg live weight). Averaged over the two slaughter weights BXB lambs had a lower (P < 0·05) dressing proportion than the other genotypes. Carcass conformation classification (assessed on a five-point scale) was higher (P < 0·001) in lambs finished on the LFC diet (3·0 v. 2·4 (S.E. 0·04)). Conformation classification was higher in lambs produced from Cheviot compared with Blackface ewes (P < 0·05). Within the Blackface cross lambs, BXB and BLXB lambs had a lower conformation classification (P < 0·001) than TXB lambs (2·4, 2·4 and 2·9 (S.E. 0·08) respectively). Within the Cheviot ewes, TXC lambs had a higher (P < 0·001) classification than either CXC or SXC (3·1, 2·7 and 2·7 (S.E. 0·08) respectively). Lambs finished on the LFC diet had a higher fat classification score compared with lambs on the HFC diet (P < 0·001) (3·4 v. 2·8 (S.E. 0·04)). Fat classification was similar across all genotypes. Lambs finished on the LFC diet had a lower ash content in the carcass than lambs finished on a HFC diet (P < 0·01) (44 v. 47 (S.E. 0·8) g/kg). Lamb genotype and dietary forage:concentrate ratio had no significant effect on cooking loss, sarcomere length, Warner–Bratzler shear force and L* values. Ultimate pH (pHU) was not influenced by dietary forage:concentrate ratio, but was significantly (P < 0·01) higher in BXB lambs compared with BLXB, TXB, CXC and TXC lambs. Lambs offered the LFC diet during the finishing period had significantly higher values for a* (P < 0·05), b* (P < 0·001), C* (P < 0·001) and H0 (P < 0·05) than lambs offered a HFC diet. Of these parameters only b* was significantly affected by lamb genotype, with BXB lambs having a lower value (P < 0·05) than the other genotypes.

The effects of different amounts of liquid skim-milk on pork pigs with particular reference to carcass quality

1965 ◽  
Vol 7 (2) ◽  
pp. 153-164 ◽  
Author(s):  
R. S. Barber ◽  
R. Braude ◽  
Zena D. Hosking ◽  
K. G. Mitchell
Keyword(s):  
Dry Matter ◽  
Skim Milk ◽  
Live Weight ◽  
Experimental Period ◽  
Carcass Quality ◽  
Eye Muscle ◽  
Caloric Value ◽  
Calculated Energy ◽  
Matter Basis

SUMMARY1. Seventy-two individually fed pigs on six treatments were used to determine the effects on performance and in particular on carcass quality of (a) giving quantities of liquid skim-milk (preserved with formalin) in excess of those normally recommended; (b) replacing meal by skim-milk in the ration on a calculated dry-matter basis (1 gal. skim-milk equivalent to 1 · 1 lb. meal) as compared with a calculated energy basis (1 gal. skim-milk equivalent to 1 · 3 lb. meal) and (c) giving skim-milk for only a part of the growing period instead of throughout. The experimental period continued from 9–10 weeks of age until slaughter at an average live-weight of 135 lb.2. Extensive carcass measurements were taken and in addition assessment of the carcasses was made by a representative of the County Quality Pork Association and by an expert pork butcher.3. Carcasses from pigs given an all-meal diet were comparable in all respects with those from pigs given skim-milk throughout up to a maximum of either 5¼ or 10½ pints per pig per day.4. Carcasses from pigs given the highest level of skim-milk (maximum of 15¾ pints per pig per day) were superior in many respects to those on any of the other treatments, but the possibility that this was due to their slower rate of growth rather than to the high level of milk per se, is discussed.5. Pigs given skim-milk as replacement of part of their meal allowance on a calculated dry matter basis grew significantly faster than those in which the replacement was made on a calculated energy basis or than those given an all-meal diet. The importance is stressed of ensuring that in assessing the value of skim-milk for pigs the caloric value of the rations being compared is similar. The need for experiments based on actual determinations of the caloric value of the rations used is also emphasised.6. While the performance of pigs given skim-milk up to 75 lb. live-weight only was similar to that of pigs given skim-milk throughout, evidence was obtained that the quality of their carcasses was slightly inferior.7. There was some suggestion that as the level of skim-milk in the diet increased an eye muscle of a rather paler colour was produced.

A note on effect of starvation on the bovine alimentary tract and its contents

1980 ◽  
Vol 31 (1) ◽  
pp. 111-113 ◽  
Author(s):  
J. J. Bass ◽  
D. M. Duganzich
Keyword(s):  
Body Composition ◽  
Dry Matter ◽  
Alimentary Tract ◽  
Composition Studies ◽  
Stomach Contents ◽  
Live Weight ◽  
Intestinal Contents ◽  
Gut Fill

ABSTRACTFifty-one cattle were allocated into five groups varying in time of starvation (0, 17, 24, 41 and 48 h). Most of the loss in fasted live weight, stomach and intestinal contents occurred within 24 h. Weights of water, dry matter and potassium present in the stomach showed a significant decrease in the first 24 h, although the percentage of water in the stomach contents rose slowly over a 48-h period. It is suggested that cattle from pasture need be starved for no more than 24 h to minimize the effect of gut fill for body composition studies.

Effect of a single bout of exercise and chronic exercise training on insulin sensitivity in racing sled dogs

2014 ◽  
Vol 10 (3) ◽  
pp. 167-172 ◽  
Author(s):  
S.E. Pratt-Phillips ◽  
R.J. Geor ◽  
M. Buser ◽  
A. Zirkle ◽  
A. Moore ◽  
...  
Keyword(s):  
Insulin Sensitivity ◽  
Exercise Training ◽  
Exercise Bout ◽  
Post Exercise ◽  
Exercise Challenge ◽  
Sled Dogs ◽  
Significant Difference ◽  
Single Bout ◽  
Three Stages

Two experiments were designed to investigate the role of exercise on insulin sensitivity (IS) in Alaskan racing sled dogs. In both experiments, IS was quantified with an isoglycemic-hyperinsulinemic clamp (IHC), whereby IS was defined as the glucose infusion rate (GIR) divided by the mean insulin concentration during the clamp. In Experiment 1, IS was quantified in 12 racing sled dogs during three stages of exercise training: unexercised for 4 months over the summer (deconditioned), and after two and four months of exercise conditioning. At each stage IS was assessed in unexercised dogs (n=6) and 60 h following a standard exercise challenge (n=6) consisting of a 35.4 km run completed in 2.5 h. In Experiment 2, IS was assessed in deconditioned dogs (n=6) and in well-conditioned dogs that had either completed a 708 km race 5-days prior (n=3) or were unraced for the previous month (n=3). In Experiment 1, there were no significant differences (Pã0.05) in GIR or IS between the three levels of conditioning, nor were there any effects of the exercise bout 60 h prior to the IHC. In Experiment 2 there was no significant difference in IS between well-conditioned dogs and untrained dogs (Pã0.05). However, dogs that completed a 708 km race 5-days prior to the IHC had a significantly higher IS than dogs that were deconditioned and those that were conditioned but unraced. These results suggest that the workload of an exercise challenge is a factor in post-exercise changes in IS but that exercise conditioning has little impact on IS in Alaskan sled dogs.

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