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=== Introduction ===

=== Introduction ===

Most pet foods provide owners with guidance on how much, and sometimes how often they should feed their dog or cat. The amount of food a pet needs is a function of the energy content of the food and the [[Energy - Nutrition|energy requirement]] of the pet. Feeding guides should be used as '''starting point''' to '''estimate''' how much food to offer. Because energy requirements differ among animals, and can also vary for a cat or dog over time, the exact amount to feed must be tailored according to the needs of the individual.

Most pet foods provide owners with guidance on how much, and sometimes how often they should feed their dog or cat. The amount of food a pet needs is a function of the energy content of the food and the [[Energy - Nutrition|energy requirement]] of the pet. Feeding guides should be used as a '''starting point''' to '''estimate''' how much food to offer. Because energy requirements differ among animals, and can also vary for a cat or dog over time, the exact amount to be fed must be tailored according to the needs of the individual.

There is also no standard way in which feeding guidelines are presented on the packaging. For example, dry foods may describe serving amounts by weight (grams per serving), or volume (cup), or both. Wet foods generally describe serving amounts by volume i.e. as fraction and/or multiple of a can, pouch or tray.

There is also no standard way in which feeding guidelines are presented on the packaging. For example, dry foods may describe serving amounts by weight (grams per serving), or volume (cup), or both. Wet foods generally describe serving amounts by volume i.e. as fraction and/or multiple of a can, pouch or tray.

The limited physical space available on package labels constrains how much information can be included, and this is a particular challenge for dog products because of the wide size range that needs to be covered. For example, some products provide guidance for discreet weight ranges (table 1), whereas others to do this for specific weights (table 2). In both circumstances, owners may need to extrapolate to estimate a food allowance if the weight of their pet falls between these ranges.

The limited physical space available on package labels constrains how much information can be included, and this is a particular challenge for dog products because of the wide size range that needs to be covered. For example, some products provide guidance for discreet weight ranges (table 1), whereas others do this for specific weights (table 2). In both circumstances, owners may need to extrapolate to estimate a food allowance if the weight of their pet falls between these ranges.

[[File:Table 1 Feeding Guides - Nutrition Page.png|thumb|left|300px|Table 1 – example feeding guide designed for weight ranges]]

[[File:Table 1 Feeding Guides - Nutrition Page.png|thumb|left|300px|Table 1 – example feeding guide designed for weight ranges]]

=== Estimating Energy Density of the Food===

=== Estimating Energy Density of the Food===

Manufactured pet foods may provide this information on package labels, or it may be available through ‘off pack’ materials such as web sites, or on request from customer care services. In the U.S.A., calorie content statements are now required on all pet food labels, including those for treats and supplements. Information on the label must be provided in terms of kcal/kg and kcal per common unit (e.g., cups, cans, pieces). To use the formula above, the value in kcal/kg must be divided by 10 to provide the energy density in terms of kcal/100 g. If this information is not available it can be calculated indirectly from the amounts of macronutrients ([[Protein - Nutrition|protein]], [[Fats - Nutrition|fat]] and [[Carbohydrates - Nutrition|carbohydrate]]), and [[Fibre - Nutrition|fibre]] in the food. The equation to calculate energy content is quite complex and there are [http://energycalculator.info/en tools available] that help avoid the need to manually calculate.

Manufactured pet foods may provide this information on package labels, or it may be available through ‘off pack’ materials such as web sites, or on request from customer care services. In the U.S.A., calorie content statements are now required on all pet food labels, including those for treats and supplements. Information on the label must be provided in terms of kcal/kg and kcal per common unit (e.g., cups, cans, pieces). To use the formula above, the value in kcal/kg must be divided by 10 to provide the energy density in terms of kcal/100 g. If this information is not available it can be calculated indirectly from the amounts of macronutrients ([[Protein - Nutrition|protein]], [[Fats - Nutrition|fat]] and [[Carbohydrates - Nutrition|carbohydrate]]), and [[Fibre - Nutrition|fibre]] in the food. The equation to calculate energy content is quite complex and there are [http://energycalculator.info/en tools available] that help avoid the need to manually calculate it.

'''Estimating the energy content of home-made foods can be a challenge.''' It requires access to reliable published information on the nutritional content of food ingredients commonly used in pet foods <ref name="NRC">National Research Council (NRC). (2006) '''In Nutrient Requirements for Dogs and Cats and CTS.''' 2006 ''Washington, DC: National Academies Press '' p.28-48</ref>, or human foods <ref name="Food Standard 2004">Food Standards Agency (2002). '''McCance and Widdowson’s The Composition of Foods.''' ''Sixth Summary Edition. Cambridge: Royal Society of Chemistry'' - [https://www.gov.uk/government/publications/composition-of-foods-integrated-dataset-cofid Online Resource]''</ref> and the ability to quantify the relative contribution of each ingredient to total daily intake of each nutrient. This may require access to complex databases and software, or seek advice from an independent expert that can assess the nutritional value of home-made diets link <ref name="WSAVA">WSAVA Global Nutrition Guidelines. ''[http://www.wsava.org/sites/default/files/JSAP%20WSAVA%20Global%20Nutritional%20Assessment%20Guidelines%202011_0.pdf Online Resource]''.</ref>. This is a significant disadvantage in feeding foods prepared at home (link to section on home prepared foods)

'''Estimating the energy content of home-made foods can be a challenge.''' It requires access to reliable published information on the nutritional content of food ingredients commonly used in pet foods <ref name="NRC">National Research Council (NRC). (2006) '''In Nutrient Requirements for Dogs and Cats and CTS.''' 2006 ''Washington, DC: National Academies Press '' p.28-48</ref>, or human foods <ref name="Food Standard 2004">Food Standards Agency (2002). '''McCance and Widdowson’s The Composition of Foods.''' ''Sixth Summary Edition. Cambridge: Royal Society of Chemistry'' - [https://www.gov.uk/government/publications/composition-of-foods-integrated-dataset-cofid Online Resource]''</ref> and the ability to quantify the relative contribution of each ingredient to the total daily intake of each nutrient. This may require access to complex databases and software, or seek advice from an independent expert that can assess the nutritional value of [[Feeding Types of Pet Food#Home-Made Diets|home-made diets]]<ref name="WSAVA">WSAVA Global Nutrition Guidelines. ''[http://www.wsava.org/sites/default/files/JSAP%20WSAVA%20Global%20Nutritional%20Assessment%20Guidelines%202011_0.pdf Online Resource]''.</ref>. This is a significant disadvantage in feeding foods [[Feeding Types of Pet Food#Home-Made Diets|prepared at home]].

=== Estimating Energy Needs ===

=== Estimating Energy Needs ===

The specific [[Energy - Nutrition|energy]] need of an individual pet can be estimated using a mathematical equation that relates energy requirements to bodyweight <ref name="NRC"/>, and in most species (including dogs and cats) this is best estimated from an exponential equation based on bodyweight <ref name=''Kleiber''> Kleiber, M. '''The Fire of Life.''' 1961. ''New York: John Wiley and Sons''.</ref>. It is important to note that different equations exist for healthy adult dogs and cats, puppies, kittens, gestating or lactating mothers, and overweight pets <ref name="NRC" />, and link to energy section).

The specific [[Energy - Nutrition|energy]] need of an individual pet can be estimated using a mathematical equation that relates energy requirements to bodyweight <ref name="NRC"/>, and in most species (including dogs and cats) this is best estimated from an exponential equation based on bodyweight <ref name=''Kleiber''> Kleiber, M. '''The Fire of Life.''' 1961. ''New York: John Wiley and Sons''.</ref>. It is important to note that [[Energy - Nutrition|different equations]] exist for healthy adult dogs and cats, puppies, kittens, gestating or lactating mothers, and overweight pets <ref name="NRC" />.

In addition to bodyweight, there are a number of other factors that influence the energy requirement of the pet. These include activity, life-stage, reproductive status, and environmental conditions. Activity level can contribute to more than 30% of the daily energy requirement in highly active working dogs, such as Border Collies <ref name="NRC" />. However, recent studies have shown that adult pet dogs are relatively ‘inactive’ receiving on average only 4 walks of 40 minutes duration per week <ref name=''Christian''>Christian, NE, et al. '''Dog ownership and physical activity: A review of the evidence.''' ''J. Phys Act Health 2013''; 10:750-759</ref>. The energy requirement of inactive dogs is lower than their active counterparts <ref name=Bermingham>Bermingham EN et al. '''Energy requirement of adult dogs.''' ''[http://www.ncbi.nlm.nih.gov/pubmed/27417154 PLOSone 2014; 9:e109681.]'' </ref> <ref name=Thes>Thes, M, et al. '''Metabolizable energy intake of client-owned adult dogs.''' ''[http://www.ncbi.nlm.nih.gov/pubmed/274171548 J. Anim. Phys. Anim. Nutr.]'' </ref> and this represents a more realistic starting point for most adult pet dogs and cats.

In addition to bodyweight, there are a number of other factors that influence the energy requirement of the pet. These include activity, life-stage, reproductive status, and environmental conditions. Activity level can contribute to more than 30% of the daily energy requirement in highly active working dogs, such as Border Collies <ref name="NRC" />. However, recent studies have shown that adult pet dogs are relatively ‘inactive’ receiving on average only 4 walks of 40 minutes duration per week <ref name=''Christian''>Christian, NE, et al. '''Dog ownership and physical activity: A review of the evidence.''' ''J. Phys Act Health 2013''; 10:750-759</ref>. The energy requirement of inactive dogs is lower than their active counterparts <ref name=Bermingham>Bermingham EN et al. '''Energy requirement of adult dogs.''' ''[http://www.ncbi.nlm.nih.gov/pubmed/27417154 PLOSone 2014; 9:e109681.]'' </ref> <ref name=Thes>Thes, M, et al. '''Metabolizable energy intake of client-owned adult dogs.''' ''[http://www.ncbi.nlm.nih.gov/pubmed/274171548 J. Anim. Phys. Anim. Nutr.]'' </ref> and this represents a more realistic starting point for most adult pet dogs and cats.

=== Calculating Food Allowances ===

=== Calculating Food Allowances ===

Food allowances can be calculated, based on these energy requirements by entering the energy density of the food in this tool (link to excel food allowances). To convert the amount in grams per day from the tool to cans or trays per day, divide the g/d as calculated for that animal by the net

Food allowances can be calculated, based on these energy requirements by entering the energy density of the food in this tool (link to excel food allowances). To convert the amount in grams per day from the tool to cans or trays per day, divide the g/d as calculated for that animal by the net weight of the can or tray in grams. To determine cups per day of a dry food, the density of the food in terms of grams per cup must be known. If that information is not provided as part of the calorie content statement as required under AAFCO model regulations, it can be calculated by dividing the kcal/cup value by the kcal/kg value, then multiplying the result by 1000 to give you g/cup. The pet's food allowance in g/d is then divided by g/cup to give you cups/d. There is no standard international cup size, in the United States of America, a standard measuring cup is 8 fluid ounces (approximately 237 mL) by volume, however in other countries, different volumes or weights of typical dry ingredients are used to determine a cup unit.

weight of the can or tray in grams. To determine cups per day of a dry food, the density of the food in terms of grams per cup must be known. If that information is not provided as part of the calorie content statement as required under AAFCO model regulations, it can be calculated by dividing the kcal/cup value by the kcal/kg value, then multiplying the result by 1000 to give you g/cup. The pet's food allowance in g/d is then divided by g/cup to give you cups/d. There is no standard international cup size, in the United States of America, a standard measuring cup is 8 fluid ounces (approximately 237 mL) by volume, however in other countries, different volumes or weights of typical dry ingredients are used to determine a cup unit.