effect of age, sex, reproductive status, body composition ... · the objective of this study was to...

Effect of age, sex, reproductive status, body composition, and environmental temperature on the basal metabolic rate of working Labrador Retrievers

Abstract

Introduction

Methods

Results 1

Results 2

As the pet industry continues to grow, understanding the needs of different demographics of canines is becoming increasingly important to ensure optimal nutrition. Energy requirements have been shown to vary based on individual factors in many species, but few trials using many dogs under the same controls

exist. The objective of this study was to investigate the effect of age, sex, reproductive status, body composition, and environmental temperature on the BMR of working Labrador Retrievers (Labs).

An open-circuit indirect calorimetry machine attached to a chamber (Oxymax; Columbus Inst) was used to determine resting BMR in 96 Labs. Body composition in 33 Labs of varying age was determined using DXA scans to determine effect of lean/fat mass on BMR. Cooling and heating implements were applied to the

chamber to determine temperature effect on BMR.

Each of the following demographics were compared using a mixed model: male, female, intact, altered, young (6mo-2yo), adult (3-6yo), and senior (7yo+). Mean BMR for all dogs was 130 (27) kcal/kg0.75. Males were significantly higher at 136 (28) kcal/kg0.75 than females at 125 (25) kcal/kg0.75 (p=0.045). Intact Labs were significantly higher at 121 (3) kcal/kg0.75 compared to altered Labs at 109 (25) kcal/kg0.75 (P<0.001). Young and adult Labs had BMRs of 136 (19) kcal/kg0.75

and 135 (29) kcal/kg0.75, respectively, which was significantly higher than seniors at 120 (26) kcal/kg0.75. Body composition comparisons showed significant negative linear relationships between BMR and fat mass (p<0.001) and positive linear relationships between BMR and lean mass (p<0.001).

BMR was found to have a negative linear relationship (R2=0.51) from cool to warm temperatures but was elevated at both cold (<5°C) and hot (>35°C) temperatures (p<0.001).

The determination of energy requirements found in this study prove useful as the pet industry develops diets specific to the needs of different demographics of canines.

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Jessica L. Varney, Jason W. Fowler, Jordan T. Weil, Charlene F. Watson, Mary Ann Boggess, & Craig N. Coon

Four Rivers Kennel, LLC

Dr. Craig N. Coon

CANINE SENIOR NUTRITION

RESEARCH CENTER

In order to understand energy requirements in canines, indirect calorimetry can be used to determine basal metabolic rate (BMR). As the pet food industry continues to grow, understanding the needs of different demographics of canines is becoming more important to ensure optimal nutrition.

Metabolic rate and energy requirements have been shown to vary significantly based on individual factors in many species, with meta-analysis of smaller trials being a popular way to evaluate larger populations of dogs1. Few trials using a large number of dogs under the same controls exist.

Energy requirements are also largely determined based on feeding trials via calculation of actual calorie consumption and maintenance of weight. Variables such as environmental temperature and husbandry can impact these results, making it difficult to determine the root cause of discrepancies between reported energy requirements. Current studies often focus on one variable of the energy requirement equation, such as age2, reproductive

status3, breed2, body size4, etc.

Labrador Retrievers serve well as a representative of a typical large breed dog in North America. Labrador Retrievers are consistently one of the most popular dog breeds with the highest registration numbers around the world6 and are well represented in various roles from pets to service and

working dogs. The objective of this study was to determine the effect of age, sex, reproductive status, body composition, and environmental temperature on the basal metabolic rate of working Labrador Retrievers. The determination of basal metabolic rate in this study may prove useful as

the pet industry develops diets specific to the needs of different demographics of canines.

Abstract

Introduction

Methods

Results 1

Results 2

Conclusion



Jessica L. Varney, Jason W. Fowler, Jordan T. Weil, Charlene F. Watson, Mary Ann Boggess, & Dr. Craig N. Coon


Basal Metabolic RateEnergy required to maintain homeostasis in an animal in a post-absorptive state that is laying down but

awake in a thermoneutral environment to which it has been acclimatized. Typically measured via calorimetry.

Age

Young

6m-2y

Adult

3-6y

Senior

7y +

Sex

Male Female

Reproductive Status

Intact Altered

Body Composition

Lean Mass

Fat Mass

Environmental Temperature

Cold Cool Neutral Warm Hot

Exploring the relationship of the following factors on the basal metabolic rate of working Labrador Retrievers:

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Dr. Craig N. Coon


RESEARCH CENTER

Abstract

Introduction

Methods

Results 1

Results 2

Conclusion





• All dogs tested at the same time of day- in the morning, prior to feeding, 24h fasted• All testing performed in a thermoneutral environment (except for temperature specific readings)• Measurements taken via an Oxymax open-circuit indirect calorimetry machine attached to a chamber• Data collected from dogs that were acclimated to the chamber and were in a calm, resting state• Each dog in chamber long enough to achieve 15-30min of steady flow and heat production• Respiratory data collected from each dog and calculated for BMR

• All dogs selected from colony of Labrador Retrievers at Four Rivers Kennel (Table 1)• All dogs housed in controlled kennel environment• All dogs aired outside in social groups for approximately six hours daily and kenneled

individually overnight• Free access to automatic waterers, fed once daily in the morning after testing

• 33 dogs scanned for body composition using a dual energy x-ray absorptiometry machine (GE Lunar) to determine body fat percentage, lean mass, and fat mass

• All dogs acclimated to temperature in chamber prior to collecting BMR readings• Heating elements applied to chamber to achieve desired temperature range for warm and hot

readings• Ice, cool packs, and ambient outside temperature applied to chamber to achieve desired

temperature range for cool and cold readings

Kennel Facility

Oxymax and Metabolic Chamber

Number of Labs Used

Total Male Female Intact Altered Young Adult Senior

100 53 47 79 21 21 45 34

DXA Scanner

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Dr. Craig N. Coon


RESEARCH CENTER

Abstract

Introduction

Methods

Results 1

Results 2

Conclusion





Average BMR for all Labrador Retrievers: 130 ± 27 kcal/kg0.75/day

Young (6m-2y) 136 ± 19a

Adult (3-6y) 135 ± 29a

Senior (7y+) 120 ± 26b

P-value 0.03

Young Male 134 ± 22

Adult Male 140 ± 32

Senior Male 127 ± 22

P-value 0.364

Young Female 138 ± 12a

Adult Female 128 ± 24ab

Senior Female 117 ± 27b

P-value 0.03

Intact 136 ± 24

Altered 109 ± 25

P-value <0.001

Intact Male 143 ± 25

Altered Male 112 ± 23

P-value <0.001

Intact Female 129 ± 22

Altered Female 103 ± 28

P-value 0.006

Male 135 ± 28

Female 125 ± 25

P-value 0.045

Intact Adult Male 153 ± 26

Altered Adult Male 115 ± 27

P-value 0.002

Intact Senior Male 135 ± 21

Altered Senior Male 107 ± 10

P-value 0.028

Intact Adult Female 132 ± 24

Altered Adult Female 109 ± 12

P-value 0.135

Intact Senior Female 122 ± 23

Altered Senior Female 100 ± 35

P-value 0.118

• Young and adult Labs had significantly higher BMR compared to senior Labs (P=0.03)• Males had significantly higher BMR compared to females (P=0.045)• Intact labs had significantly higher BMR compared to altered Labs (P<0.001)

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Dr. Craig N. Coon


RESEARCH CENTER

Abstract

Introduction

Methods

Results 1

Results 2

Conclusion





Labs have significantly elevated BMR during very cold and very hot temperatures (p<0.001)

Lowest BMR during warm temperatures, 25°C - 34°C During cold temperatures, BMR of Labs increases to regulate body temperature As temperature increases, BMR decreases up to 34°C Formula: BMR= -1.6477(ºC)+155.47

R2=0.32

R2=0.39

R2=0.43

R2=0.29

Senior dogs have a significantly lower lean:fat ratio than young Labs and adult Labs (P=0.05) Lower lean mass/higher fat mass = contributes to lower BMR!

Positive linear relationship between BMR and lean mass (P<0.001)

Positive linear relationship between BMR and lean:fat mass ratio (P<0.001)

Negative linear relationship between BMR and fat mass (P<0.001)

Negative linear relationship between BMR and percent body fat (P<0.001)

BMR increases as lean mass increases and decreases as fat mass increases.

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Dr. Craig N. Coon


RESEARCH CENTER

Abstract

Introduction

Methods

Results 1

Results 2

Conclusion

1. Bermingham, E.N., Thomas, D.G., Cave, N.J., Morris, P.J., Butterwick, R.F., & German, A.J. (2014). Energy requirements of adult dogs: a meta-analysis. PLoS One. 9(10), e109681

2. Speakman, J.R., van Acker, A., & Harper, E.J. (2003). Age-related changes in the metabolism and body composition of three dog breeds andtheir relationship to life expectancy. Aging Cell, 2, 265-275.

3. Jeusette, I., Detilleux, J., Cuvelier, C., Itasse, L., & Diez, M. (2004). Ad libitum feeding following ovariectomy in female Beagle dogs: effect onmaintenance energy requirements and on blood metabolites. J Anim Physiol a Anim Nutr, 88, 117-121.

4. Hill, R.C., & Scott, K.C. (2004). Energy requirements and body surface area of cats and dogs. J Am Vet Med Assoc, 225(5), 689-694.5. AKC Staff (2018, March 28).Most Popular Dog Breeds – Full Ranking List. Retrieved from: https://www.akc.org





Basal metabolic rate in Labrador Retrievers is significantly impacted by sex, age, reproductive status, body composition, and environmental temperature

Young and adult Labs had significantly higher BMR than senior Labs, male Labs had higher BMR than female Labs, and intact Labs had higher BMR than altered Labs

Basal metabolic rate increases in Labrador Retrievers as lean mass increases and decreases as fat mass increases

Basal metabolic rate in Labs decreases as temperature increases, but becomes significantly elevated during very cold and very hot temperatures

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Dr. Craig N. Coon


RESEARCH CENTER

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