Changes

==Roles in the Body==

==Roles in the Body==

Energy expenditure and requirement for intake is dependent on the Basal Metabolic Rate (BMR, the energy required for normal physiologic functions in a fasted, thermoneutral environment); activity level (normal physical activity and exercise); dietary thermogenesis (energy used during digestion and assimilation of food); and adaptive thermogenesis (energy needed to maintain body temperature in cold environments). In a thermoneutral environment BMR accounts for approximately 60% of the animal’s total daily energy expenditure, while normal activity is 30%, and dietary thermogenesis accounts for 10% energy utilization.1 Energy expenditure for adaptive thermogenesis will vary with temperature, humidity and coat thickness.2

'''Energy expenditure and requirement for intake is dependent on the '''Basal Metabolic Rate''' ('''BMR''', the energy required for normal physiologic functions in a fasted, thermoneutral environment); activity level (normal physical activity and exercise); dietary thermogenesis (energy used during digestion and assimilation of food); and adaptive thermogenesis (energy needed to maintain body temperature in cold environments)'''. In a thermoneutral environment BMR accounts for approximately 60% of the animal’s total daily energy expenditure, while normal activity is 30%, and dietary thermogenesis accounts for 10% energy utilization.1 Energy expenditure for adaptive thermogenesis varies with temperature, humidity and coat thickness.2

Resting energy requirement (RER) accounts for both BMR and dietary thermogenegisis. RER is determined by lean body mass, but may vary with age, breed, gender, neuter status, and the presence of disease.  

 

For both dogs and cats, RER can be calculated using exponential equations based on body weight using (70*BWkg0.75).3 A number of factors can influence daily energy requirements, such as breed, reproductive or neuter status, activity level (e.g., sedentary vs. working dog), and environment (e.g., indoor vs. outdoor, kennel/cattery vs. a home) and relying on published maintenance energy requirement (MER) equations can be problematic if these variants are not account for. Normal MER variation in cats4 can range from 29-85.5 kcal/BWkg0.75 and in dogs5 can range from 54.5-441.1 kcal/BWkg0.75. It is important to note that in both dogs and cats daily MER values can actually fall below calculated RER based solely on body weight. Adipose tissue is less metabolically active than muscle and obese dogs and cats will have lower than expected RER based on body weight measurements alone. Larger cats (>5.5 kg) have lower metabolic energy requirements on a per kg basis than lean or “normal” weight cats.4 In a meta-analysis study on energy requirements of adult cats, the MER was best represented by the equation 77.7 * BWkg 0.711. Activity level has the most significant impact on canine energy requirements with inactive dogs having lower metabolic energy requirements on a per kg basis than sporting or working dogs.5 In one cross-sectional survey of pet owners in Australia and the US, only 60% of dog owners reported walking their dogs on a regular basis, with 40% receiving no walks at all.6 The average activity level for those receiving regular walks was four 40 minute walks per week. In a recent meta-analysis5 study pet dogs with the lowest activity (resting) level had an energy requirement of 95*BWkg0.75.  

'''Resting energy requirement (RER)''' accounts for both BMR and dietary thermogenegisis. RER is determined by lean body mass, but may vary with age, breed, gender, neuter status, and the presence of disease. For both dogs and cats, RER can be calculated using exponential equations based on body weight using ('''70*BWkg0.75''').3 '''A number of factors can influence daily energy requirements, such as breed, reproductive or neuter status, activity level (e.g., sedentary vs. working dog), and environment (e.g., indoor vs. outdoor, kennel/cattery vs. a home)''' and relying on published maintenance energy requirement (MER) equations can be problematic if these variants are not account for.  

Energy requirements for different life-stages:

 

*'''Growth''': Energy requirements for newborn puppies and kittens are estimated at 25 kcal/100g BW and 20-25 kcal/100g BW, respectively, until weaning.7 After weaning puppies and kittens should be fed approximately 2*MER until they reach 40-50% of expected adult weight, this should be decreased to 1.6*MER until 80% of their expected adult weight is reached, and then further decreased to 1.2*MER until they are fully grown. At maturity food intake should be adjusted to maintain an optimal body condition. Rate of growth and time to reach each change will vary with breed and individual requirements.

'''Normal MER variation in cats4 can range from 29-85.5 kcal/BWkg0.75''' and in '''dogs5 can range from 54.5-441.1 kcal/BWkg0.75'''. It is important to note that in both dogs and cats daily MER values can actually fall below calculated RER based solely on body weight. Adipose tissue is less metabolically active than muscle and obese dogs and cats will have lower than expected RER based on body weight measurements alone. Larger cats (>5.5 kg) have lower metabolic energy requirements on a per kg basis than lean or “normal” weight cats.4 In a meta-analysis study on energy requirements of adult cats, the MER was best represented by the equation 77.7 * BWkg 0.711.  

 

Activity level has the most significant impact on canine energy requirements with inactive dogs having lower metabolic energy requirements on a per kg basis than sporting or working dogs.5 In one cross-sectional survey of pet owners in Australia and the US, only 60% of dog owners reported walking their dogs on a regular basis, with 40% receiving no walks at all.6 The average activity level for those receiving regular walks was four 40 minute walks per week. In a recent meta-analysis5 study pet dogs with the lowest activity (resting) level had an energy requirement of 95*BWkg0.75.  

 

====Energy requirements for different life-stages:====

*'''Growth''':  

:*Energy requirements for newborn puppies and kittens are estimated at 25 kcal/100g BW and 20-25 kcal/100g BW, respectively, until weaning.7 After weaning puppies and kittens should be fed approximately 2*MER until they reach 40-50% of expected adult weight, this should be decreased to 1.6*MER until 80% of their expected adult weight is reached, and then further decreased to 1.2*MER until they are fully grown. At maturity food intake should be adjusted to maintain an optimal body condition. Rate of growth and time to reach each change will vary with breed and individual requirements.

*'''Gestation''':  

*'''Gestation''':  

:*'''Dogs''': Most foetal weight gain occurs after day 40 of gestation. Until that time, maternal energy requirements do not change significantly. After day 40, energy demand increases and bitches should be allowed free access to food.

:*'''Dogs''': Most foetal weight gain occurs after day 40 of gestation. Until that time, maternal energy requirements do not change significantly. After day 40, energy demand increases and bitches should be allowed free access to food.

:*'''Cats''': Energy requirements for queens do not change significantly during gestation, but they will lose 40-50% of their body weight during lactation. During the last half of gestation queens should be fed 140*BWkg0.67 in anticipation of this extreme weight loss.8

:*'''Cats''': Energy requirements for queens do not change significantly during gestation, but they will lose 40-50% of their body weight during lactation. During the last half of gestation queens should be fed 140*BWkg0.67 in anticipation of this extreme weight loss.8

*'''Lactation''':

*'''Lactation''':

:*'''Dogs''': Typically lasts 6 - 8 weeks, and energy demand will vary depending on litter size and breed. Peak lactation occurs around week 4 post-partum, when weaning typically starts. The energy requirement for milk production is estimated to be 24 kcal/BWkg of bitch per puppy for litters of for 1-4 puppies; and   12 kcal/BWkg of bitch per puppy for additional puppies i.e 5 or more. The energy requirements to support lactation are added to maternal MER.7  

:*'''Dogs''': Typically lasts 6 - 8 weeks, and energy demand will vary depending on litter size and breed. Peak lactation occurs around week 4 post-partum, when weaning typically starts. The energy requirement for milk production is estimated to be 24 kcal/BWkg of bitch per puppy for litters of for 1-4 puppies; and 12 kcal/BWkg of bitch per puppy for additional puppies i.e 5 or more. The energy requirements to support lactation are added to maternal MER.7  

:*'''Cats''': Typically lasts 7-9 weeks. Queens experience a net loss of body mass during lactation and should be fed at 2*MER.  

:*'''Cats''': Typically lasts 7-9 weeks. Queens experience a net loss of body mass during lactation and should be fed at 2*MER.  

*'''Athletes''':

*'''Athletes''':

:*'''Dogs''': Energy intake should be adjusted to environment and condition and will vary with the activity.4,7 Racing sled dogs may have a daily energy requirement of 6-10*MER depending on temperature, pack weight, and distance covered; whereas a  racing greyhound (sprint races) may have a daily requirement of 2*MER during training and racing.

:*'''Dogs''': Energy intake should be adjusted to environment and condition and will vary with the activity.4,7 Racing sled dogs may have a daily energy requirement of 6-10*MER depending on temperature, pack weight, and distance covered; whereas a  racing greyhound (sprint races) may have a daily requirement of 2*MER during training and racing.

*'''Neutering''':

*'''Neutering''':

:*Neutering can influence energy requirements due to changes in activity, and/or in ghrelin levels in response to changes in sex hormone concentrations.9-11.  

:*Neutering can influence energy requirements due to changes in activity, and/or in ghrelin levels in response to changes in sex hormone concentrations.9-11.  

*'''Age''':

*'''Age''':

:*Digestive efficiency decreases with age, and older dogs and cats may need to increase energy intake to offset changes in digestive efficiency and maintain optimal body weight.4,12

:*Digestive efficiency decreases with age, and older dogs and cats may need to increase energy intake to offset changes in digestive efficiency and maintain optimal body weight.4,12

==Consequences of Energy Deficiency==

==Consequences of Energy Deficiency==