I got an email back from Arden Grange tonight explaining the slight difference in amount of food suugested for daily feeding.
"I have been asked to contact you by my colleague Vanessa, who has explained that you are querying the differing feed guidelines for the Adult Chicken & Rice and Mini Lamb products.
The reason for this is that although the energy density of the food is almost identical; the chicken based feeds have lower volumes because chicken has a higher biological value than lamb. This basically means that it's a protein source for dogs which is one of the most easily metabolised into its constituent amino acids for use in the body so less energy is expended by the dog's digestion in processing it. Chicken is also a little more digestible - although both lamb and chicken are great ingredients for dogs and a lot easier on the digestion than meats such as beef and pork.
The feed guides really are just intended as a broad guideline, and sometimes you can find your dog may need more or less than suggested because there are many other factors apart from weight that influence the calories needed. These include temperament (stressed or busy dogs have higher energy requirements than very relaxed dogs), activity level and of course the individual's own unique digestion and rate of metabolism. These means metabolic energy requirements can be very variable. A 10kg dog could need as few as 500 calories per day if he was very inactive or overweight, and as many as 900+ if he was was very highly active/undertaking strenuous endurance work."
