Changes

'''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''')<ref>Klieber M. The fire of life. 1961 New York: John Wiley & sons.</ref>. '''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.  

'''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''')<ref>Klieber M. The fire of life. 1961 New York: John Wiley & sons.</ref>. '''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 cats<ref name ="Berm">Bermingham EN, et al. Energy Requirement of adult cats. Br J Nutr 2010;103:1083-1093.</ref> can range from 29-85.5 kcal/BWkg0.75''' and in '''dogs<ref>Bermingham EN, et al. Energy Requirement of adult dogs: A meta-analysis. PLOSone 2014;9:e109681.</ref> 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<ref name="Berm"/>. In a meta-analysis study on energy requirements of adult cats, the MER was best represented by the equation 77.7 * BWkg 0.711.  

'''Normal MER variation in cats<ref name ="Berm">Bermingham EN, et al. Energy Requirement of adult cats. Br J Nutr 2010;103:1083-1093.</ref> can range from 29-85.5 kcal/BWkg0.75''' and in '''dogs<ref name="Bermingham">Bermingham EN, et al. Energy Requirement of adult dogs: A meta-analysis. PLOSone 2014;9:e109681.</ref> 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<ref name="Berm"/>. 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.  

'''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<ref name="Bermingham"/>. 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<ref>Christian NE, et al. Dog ownership and physical activity: A review of the evidence. J Phys Act Health 2013; 10:750-759.</ref>. The average activity level for those receiving regular walks was four 40 minute walks per week. In a recent meta-analysis<ref name="Bermingham"/> study pet dogs with the lowest activity (resting) level had an energy requirement of 95*BWkg0.75.  

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

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

*'''Growth''':  

*'''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.

:*Energy requirements for newborn puppies and kittens are estimated at 25 kcal/100g BW and 20-25 kcal/100g BW, respectively, until weaning<ref name="NRC">National Research Council (NRC). Energy. In Nutrient Requirements for Dogs and Cats. 2006 Washington, DC: National Academies Press p.28-48.</ref>. 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<ref>Loveridge GG. Body weight changes and energy intake of cats during gestation and lactation. Anim Technol 1986;38:7-15.</ref>.

*'''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<ref name="NRC"/>.  

:*'''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<ref name="Berm"/><ref name="NRC"/>. 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<ref>Kienzle E and Rainbird A. The maintenance energy requirement of dogs-What is the correct figure for the calculation of the metabolic body weight in dogs?  J Nutr 1991;121:39-40.</ref><ref>Backus RC, et al. Gonadectomy and high dietary fat and not high dietary carbohydrate induced gains in body weight and fat of domestic cats. Br J Nutr 2007;98(3):641-650.</ref><ref>Root MV. Early spay-neuter in the cat: effect on development of obesity and metabolic rate. Vet Clin Nutr 1995;2:132-134.</ref>.

*'''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<ref name="Berm"/><ref>Donoghue S, et al. Body composition and diet of relatively healthy older dogs. J Nutr 1991;121:S58-S59.</ref>.

==Consequences of Energy Deficiency==

==Consequences of Energy Deficiency==

==Toxicity==

==Toxicity==

Excess energy intake is not toxic, though long-term excess intake can result in obesity and its associated health risks. Obesity is associated with an increased risk of Diabetes Mellitus in cats,13 in growing puppies can result in development skeletal abnormalities,14,15 and can worsen clinical sign of orthopaedic disease and decrease longevity in adult dogs.16

Excess energy intake is not toxic, though long-term excess intake can result in obesity and its associated health risks. Obesity is associated with an increased risk of [[Diabetes Mellitus|diabetes mellitus]] in cats<ref>Lutz TA and Rand JS. A review of the new developments in type 2 diabetes mellitus in human beings and cats. Brit Vet J 1993;149:527-536.</ref>, in growing puppies can result in development skeletal abnormalities<ref>Hedhammer A, et al. Overnutrition and skeletal disease. Cornell Vet 1974;64(suppl 5):9-150.</ref><ref>Kealy RD, et al. Effects of limited food consumption on the incidence of hip dysplasia in growing dogs.  JAVMA 1992;201:857-863.</ref>, and can worsen clinical sign of orthopaedic disease and decrease longevity in adult dogs<ref>Kealy RD, et al. Effects of diet restriction on life span and age-related changes in dogs.  JAVMA 2002;220:1315-1320.</ref>.

==Dietary Sources==

==Dietary Sources==

'''Foods differ in the amount of energy, and this is a primarily a function of the amount of moisture, digestibility, and the amount and proportions of macronutrients'''. Digestibility (i.e., feeding) studies are the most accurate way of determining the ‘available’ energy content of a food, but these studies are expensive and require the use of laboratory animals. Many pet food companies do not have the resources to conduct digestibility studies and use predictive equations instead. There are different predictive equations for pet foods and human foods, which in part reflects differences in the digestibility of these foods. Typically for highly digestible human foods such as chicken breast, egg, rice or oils, the [[Nutrition Glossary#Atwater Factors|‘Atwater’ factors]] [protein (4 kcal per gram), fat (9 kcal per gram), and carbohydrate (4 kcal per gram)] can be used to calculate energy content.  

'''Foods differ in the amount of energy, and this is a primarily a function of the amount of moisture, digestibility, and the amount and proportions of macronutrients'''. Digestibility (i.e., feeding) studies are the most accurate way of determining the ‘available’ energy content of a food, but these studies are expensive and require the use of laboratory animals. Many pet food companies do not have the resources to conduct digestibility studies and use predictive equations instead. There are different predictive equations for pet foods and human foods, which in part reflects differences in the digestibility of these foods. Typically for highly digestible human foods such as chicken breast, egg, rice or oils, the [[Nutrition Glossary#Atwater Factors|‘Atwater’ factors]] [protein (4 kcal per gram), fat (9 kcal per gram), and carbohydrate (4 kcal per gram)] can be used to calculate energy content.  

Two different approaches are commonly used for estimating the energy content of manufactured pet foods. One uses pet foods the [[Nutrition Glossary#Modified Atwater Factors|modified Atwater factors]] of 3.5 kcal per gram of protein, 8.5 kcal per gram of fat, and 3.5 kcal per gram of carbohydrates. Whilst this equation is mathematically simple it has limitations, because it can over and underestimate foods with a digestibility that is lower or higher than ‘average’. An alternative but more complex equation which does account for differences in digestibility has been developed and this does appear to provide a better estimate of the ‘available’ energy content of the food.17

Two different approaches are commonly used for estimating the energy content of manufactured pet foods. One uses pet foods the [[Nutrition Glossary#Modified Atwater Factors|modified Atwater factors]] of 3.5 kcal per gram of protein, 8.5 kcal per gram of fat, and 3.5 kcal per gram of carbohydrates. Whilst this equation is mathematically simple it has limitations, because it can over and underestimate foods with a digestibility that is lower or higher than ‘average’. An alternative but more complex equation which does account for differences in digestibility has been developed and this does appear to provide a better estimate of the ‘available’ energy content of the food<ref>Kienzle E, et al. The development of an improved method of predicting the energy content in prepared dog and cat food. J Anim Physiol Anim Nutr 1998; 79:69-79.</ref>.  

*'''Step 1:''' calculate carbohydrate (NFE) content:  Carbohydrate (NFE; g/100g)) = 100 - (Moisture + Protein + Fat + Ash + Crude Fibre)

*'''Step 1:''' calculate carbohydrate (NFE) content:  Carbohydrate (NFE; g/100g)) = 100 - (Moisture + Protein + Fat + Ash + Crude Fibre)

*'''Step 2:''' calculate the Gross Energy (GE) content of the food:  GE (kcal/100g) = (5.7 x protein) + (9.4 x fat) + (4.1 x [NFE + Crude Fibre])

*'''Step 2:''' calculate the Gross Energy (GE) content of the food:  GE (kcal/100g) = (5.7 x protein) + (9.4 x fat) + (4.1 x [NFE + Crude Fibre])

*Semi-moist (>14% and <60% moisture) provides between 250-350+ kcal per 100g;  

*Semi-moist (>14% and <60% moisture) provides between 250-350+ kcal per 100g;  

*Wet food (>60% moisture) typically provides 80-100+ kcal per 100 g.  

*Wet food (>60% moisture) typically provides 80-100+ kcal per 100 g.  

'''Since fat provides a larger proportion of energy relative to protein and carbohydrates, diets with higher fat levels will provide more energy per 100g as-fed'''. The energy contribution of total dietary fibre is negligible for dogs and cats, yet inclusion of high levels of dietary fibre, especially insoluble, non-fermentable fibre will increase volume of food while decreasing energy content.18,19

'''Since fat provides a larger proportion of energy relative to protein and carbohydrates, diets with higher fat levels will provide more energy per 100g as-fed'''. The energy contribution of total dietary fibre is negligible for dogs and cats, yet inclusion of high levels of dietary fibre, especially insoluble, non-fermentable fibre will increase volume of food while decreasing energy content<ref>Fahey GC Jr, et al. Dietary fiber for dogs. II. Isolated total dietary fiber (TDF_ additions of divergent fiber sources to dog diets and their effects on nutrient intake, digestibility, metabolic energy and digesta mean retention time. J Anim Sci 1990;68:4229-4235.</ref><ref>Kienzle, E, et al. Prediction of Energy Digestibility in Complete Dry Foods for Dogs and Cats by Total Dietary Fiber. J Nutr 2006;136:2041S-2044S.</ref>.

==Diagnosing Energy Deficiency==

==Diagnosing Energy Deficiency==