![[Feedback]](/icons/banner/feedbackACT.gif){kind=icon}
![[For Subscribers]](/icons/banner/subscriberACT.gif){kind=icon}
![[Archive]](/icons/banner/archiveACT.gif){kind=icon}
![[Search]](/icons/banner/searchACT.gif){kind=icon}
![[Contents]](/icons/banner/tocACT.gif){kind=icon}
|
|
|
|
|
||
* Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Ås, Norway and Department of Zoology, University of Aberdeen, Aberdeen, Scotland
4 To whom correspondence should be addressed. E-mail: oystein.ahlstrom{at}umb.no.
KEY WORDS: • hunting dog • energy expenditure • water turnover • doubly labeled water • exercise
Hunting dogs display an extraordinary working capacity. They can work for several hours a day for a week or more and cover considerable running distances. The great physical effort displayed by hunting dogs has led to an increased desire among dog breeders for greater knowledge of their specific nutrient requirements, especially for energy and drinking water, which are crucial for endurance. Most experiments regarding sporting dogs have been conducted with Greyhounds and sled dogs, representing the extremes in dog racing, as Greyhounds are sprinters relying on both anaerobic and aerobic fuel, whereas sled dogs are long-distance runners using aerobic energy. Hunting dogs (gun dogs) are likely intermediate in their energy usage, primarily exhibiting endurance activity for several hours interrupted with bouts of sprinting (1). There is also considerable interest among dog owners regarding distance covered and actual speed of their working dogs. The distance covered is likely a major factor influencing the energy spent by the hunting dog. In addition, environmental factors such as air temperature, ground conditions, terrain, and vegetation must have significant influence, although this has to our knowledge never been studied in hunting dogs.
The present pilot study aimed at measuring energy expenditure (EE)5 and body water turnover (BWT) in hunting dogs. Three different running conditions were studied: hunting, road running in harness, which is a common used training activity for hunting dogs, and running on a treadmill, focusing on indications of differences in EE as a result of different ground conditions. The doubly labeled water technique was used to determine EE, and the repeatability of this method was examined by letting the same dogs undertake similar exercise 3 times.
 |
MATERIAL AND METHODS |
|---|
 TOP MATERIAL AND METHODS RESULTS AND DISCUSSIONLITERATURE CITED |
|---|
The experiments were carried out at Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Norway. The three 14-d sessions began 14 January. 2004 (hunting), 19 April 2004 (road running), and 24 May 2005 (treadmill). The first 7 d of the sessions consisted of the high-activity period followed by a 7-d low-activity period in which the dogs were exercised 3 km/d. The experimental dogs were 2 privately owned female Brittany spaniels, 2–3 and 5–6 y old during the experimental period, and with a body weight (BW) of 
15 kg. The general health status of the dogs was high, and the body score indexes, scale 1 (cachectic) to 5 (obese), were 2 in the younger and 3 in the older. The older (Dog 1) showed less running willingness than the younger (Dog 2). The dogs were generally exercised 1–2 h/d. Their exercise terrain was flat with rounded hills (maximum altitude difference 50 m), consisting of partly cultivated land and partly woods. In the three 14-d experimental periods, the dogs were allowed 3 periods of 6–8 min of outdoor exercise on a leash daily. When not exercising, the dogs were kept together inside, confined to 2 adjacent rooms (total 18 m2, 20°C). The owner was present in the house 18 h/d, and resting was the primary observed activity of the dogs during this period. Use of live animals in experiments at the Department of Animal and Aquacultural Sciences is supervised by the Norwegian National Animal Research Authority.
Hunting session
During the hunting session the dogs ran for 3 h/d in the high-activity period. The mean temperature in the 7-d period was –9.1°C (range 0°C to –19°C). The terrain was mainly flat with partly cultivated land and partly wooded areas with frozen lakes. Maximum altitude difference was 50 m, and hill climbing was moderate. The snow depth was 0.15–0.3 m, depending on vegetation and snowdrift. The snow was crusted in most places. The geographic start and endpoint of the session was identical to balance up- and downhill running.
Road-running session
Procedures for the road running in a harness alongside a bicycle were adapted to the running motivation of the dogs, 1.2 h/d for Dog 1 and 1.6 h/d for Dog 2. The exercise was divided into 2 or 3 periods a day. The ambient mean temperature was 8°C (range 5°C to 10°C) during the experiment. The running was carried out on gravel roads in the same area as the hunting sessions; thus, the topography was similar.
Treadmill session
The dogs were adapted to the treadmill running the week before the session started. The treadmill was a high-speed treadmill for horses with running surface 0.9 m x 4.1 m (Haico 4000). The dogs ran simultaneously 7.5 km at 10 km/h in 4 periods, covering a total distance of 30 km/d. In between the 7.5-km periods, they were allowed to rest for 30 min with free access to drinking water. The indoor temperature was stable at 16°C.
Measurement of running distance
Running distance during the high-activity periods of the hunting and road-running sessions was recorded by global positioning system (GPS), type GEKO 201 (Garmin Int. Inc.), weighing 85 g with a highest accuracy of 2 m. The GPS receivers were placed in a pocket on top of the dog's marker cloth. The repeatability of the 2 GPS receivers was tested for 2 distances 4 times, measuring 90.40 km (n = 8, SEM ± 0.02) and 2.96 km (n = 8, SEM ± 0.01). The same distances were measured to 94.0 km and 3.1 km by a car speedometer. In the tests, the two GPS receivers measured close to identical distances. The shorter distance measured by the GPS than by the car speedometer was most likely a result of the GPS determining horizontal movements, whereas the car speedometer measures rotations of the car wheel. Thus, the actual distance covered by the dogs was 3–4% longer than that given by GPS recordings. During the experiments the GPS functions were checked every 30 min, and new batteries were provided every 2 h.
Measurement of energy expenditure
The general practical procedures used in measuring EE by the doubly labeled water technique are described in Speakman (2). On the day 1 of each of the 3 sessions, the dogs were subcutaneously injected with 6 mL (accuracy 0.0001 g) of doubly labeled water (2H18O) concentrated to 33% of 2H and 68% of 18O in the 2 first sessions and 39% and 60%, respectively, in the final session. The ready mix of water isotopes was supplied by Department of Zoology, University of Aberdeen, Scotland. Before injections, a plasma sample was collected from the cephalic vein to determine the background isotope enrichment. The injectate was allowed to equilibrate for 5–6 h before the initial sample was collected. The next samplings were carried out after 3 d and 7 d in the high-activity period and in the following low-activity period, 10 and 14 d after the initial sampling. To determine EE in the high-activity period, the initial sample and the 7-d sample were used, and for the low-activity period, the initial sample and the 14-d sample were applied. To determine the EE in the low-activity periods, the EE in high activity periods was subtracted from the EE for the entire period (initial sample to the 14-d sample). Blood was sampled in 3-mL vacutainers and centrifuged immediately. Three 100-µL capillaries were filled with plasma and heat sealed pending analysis. The isotope analyses (3–4 repetitions) were conducted at the University of Aberdeen following the procedure described by Speakman et al. (3). Dilution spaces for 18O (No) and 2H (Nd) and respective elimination curves for the isotopes, ko and kd, were used to estimate CO2 production. The "plateau" approach was applied in estimation of dilution spaces (2). Calculations to determine EE were based on Schoeller et al. (4) using a respiration quotient of 0.85. BWT was calculated by the elimination curve for 2H using the formula: k = (lnC1 – lnC2) /
t, where k is the elimination rate for 2H, C1 and C2 are initial and final values of the 2H enrichment in body water, respectively, and t is the time between samplings. BW (accuracy 0.01 kg) was recorded at every blood sampling.
Statistics
The number of observations did not allow statistical analysis. Variation is given as SEM.
|
RESULTS AND DISCUSSION |
|---|
|
TOPMATERIAL AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
|---|
50% longer than Dog 1 (Table 1). The difference in willingness to run was also reflected by a difference in maximum speed, which was higher for Dog 2.
|
The EE measurements for both dogs reflected the running distance within each of the 3 sessions. However, the EE/km traveled was higher for Dog 2 than for Dog 1. This may result from a higher energy maintenance requirement for Dog 2 (Table 2), and the generally higher activity level and willingness to run of this dog. The higher activity of Dog 2 was particularly apparent during the hunting session when she often ran into deep snow areas, whereas Dog 1 often avoided these areas. Furthermore, Dog 1 refused to pull during the road running, whereas Dog 2 constantly exhibited willingness to urge forward in the harness. These activities were obviously energy consuming but could not be measured. In the treadmill session there was a minor difference in EE between the dogs because both exhibited the same or very similar activity.
|
Differences in the EE among the 3 running sessions must be interpreted with caution because the study comprised only 2 animals, and conditions influencing EE besides running activity were somewhat different among sessions. However, the EE measured in kJ/(BWkg0.75 · km) were lowest in the treadmill session, indicating that both hunting and road running required more energy. The differences may result from the fact that performance during hunting or road running includes additional activity compared with running at a uniform speed and direction on a treadmill. During hunting, and to a lesser extent during road running, additional EE may be required for muscle activity for such things as changing running direction, running in snow and over rough ground, and stopping and accelerating. For road running, pulling in the harness may be an extra energy-consuming activity. In addition, when comparing EE at different running conditions in the present study, one must remember that the distance covered during hunting and road running may have been 3–4% longer than that measured by the GPS.
Body water spaces were similar in the 3 sessions, except for Dog 2, which for unknown reasons had a higher value (78.6%) in the hunting session than in the 2 other sessions (61.6 and 59.9%). In lean adult dogs, body water should be 56–66% (2). Possible reasons for the high value for Dog 2 in the hunting session include an injection leakage, or possibly leakage in the capillaries or too short an equilibration time. By assuming body water content of 61.6% for Dog 2 in the hunting period, the EE could be recalculated to 7777 kJ/d in the high-activity period and 2833 kJ/d in the low-activity period. However, there are no data in support of this recalculation, and the finding remains to be elucidated in further studies.
Water requirements can be met by drinking water, water in food, or water produced through metabolism of protein, fat, or carbohydrates. The voluntary water intake in dogs is influenced by factors such as the amount of food consumed, dietary salt, ambient temperature, and severity of exercise. BWT in the dogs varied from 11.8 to 16.2%, 1030–1630 mL/d or 129–197 mL/(BWkg0.75 · d) (Table 1). These values are not particularly high and concur with results that the ratio of water requirement (mL) to ME intake (kJ) should be 1:4.2 (5). Water supply is vital for exercising dogs to avoid hyperthermia and reduced endurance. Dogs have very limited possibilities to expel surplus body heat during exercise except in cold conditions. The BWT values revealed in the present study indicate the necessity for hunting dogs to have access to water at all times, particularly during performance. Hinchcliff et al. (6) reported BWT rates of 430 mL/(kgBW0.75·d) in sled dogs during very heavy exercise in cold conditions. The EE was much lower in our study than in the latter; thus, the BWT rates were also lower (Table 1).
In the low-activity periods, the average daily EE was determined to be 3023 kJ and 3391 kJ, for Dogs 1 and 2, respectively (Table 2). These values are similar to the maintenance energy requirement reported in other studies (7), but the variation in EE between sessions was high, possibly because of differences in physical activity when the dogs were kept indoors. BWT was as in accordance with EE in the low-activity periods.
Conclusions
The present pilot study with hunting dogs reveals that GPS can measure running distance. The results obtained on effects of different activity on EE and BWT remains to be verified in large-scale experiments.
|
FOOTNOTES |
|---|
2 Author disclosure: no relationships to disclose.
3 This study was financed by the Norwegian Research Council project 145607.
5 Abbreviations used: BW, body weight; BWT, body water turnover; EE, energy expenditure; kd, turnover rate for 2H; ko, turnover rate for 18O; ME, metabolizable energy; Nd, dilution space for 2H; No, dilution space for 18O.
|
LITERATURE CITED |
|---|
|
TOPMATERIAL AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
|---|
1. Davenport GM, Kelley RL, Altom EK, Lepine AJ. Effect of diet on hunting performance of English Pointers. Vet Ther. 2001;2:10–23.[Medline]
2. Speakman J. Doubly labelled water. Theory and practice. London: Chapman & Hall; 1997.
3. Speakman J, Perez-Camargo G, McCappin T, Frankel T, Thomson P, Legarnd-Defrein V. Validation of the doubly labelled water technique in the domestic dog (Canis familiaris). Br J Nutr. 2001;85:75–87.[Medline]
4. Schoeller DA, Ravussin E, Schutz Y. Energy expenditure by doubly-labelled water validation in humans and proposed calculations. Am J Physiol. 1986;250:R823–30.
5. Lewis LD, Morris ML, Hand MS. Small animal nutrition III. Topeka, KS: Mark Morrison Associates; 1986.
6. Hinchcliff KW, Reinhart GA, Burr JR, Schreiner CJ, Swenson RA. Metabolizable energy intake and sustained energy expenditure of Alaskan sled dogs during heavy exertion in the cold. Am J Vet Res. 1997;58:1457–62.[Medline]
7. Burger IH. Energy needs of companion animals: matching the food intake intakes to requirements throughout the life cycle. J Nutr. 1994;124:2584S–93S.
This article has been cited by other articles:
|
|
 |
|
  O. Ahlstrom, A. Skrede, S. G. Vhile, and K. Hove Effect of Exercise on Nutrient Digestibility in Trained Hunting Dogs Fed a Fixed Amount of Food J. Nutr., July 1, 2006; 136(7): 2066S - 2068S. [Full Text] [PDF]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
