brookcove
Posted : 7/2/2008 10:34:58 AM
Okay, first, wolves don't eat cattle, they eat game meats like elk and rabbit. Lamb is far closer to elk in nutritional makeup than beef, and in fact some wolves would have access to actual wild sheep and goats. So let's use lamb. Really this is all justification for the fact that I don't have information on bone-in beef, and I do for lamb.
if I'm doing my math right, 100 grams of lamb rib has 12.87 mg of iron and provides 340 kcal. Shank provides 51.70 but only 190 calories. Let's go with the worst case scenario and pretend that our wolf only ever eats lamb shanks for some strange reason.
My very hard working 150 pound intact male Maremma sheepdog requires about 2000 kcals per day to stay in shape. That is probably the top energy requirement for a canid that size - anything less efficient would die of starvation before it could hunt enough food for itself. For simplicity's sake, we can multiply 51.70 by ten and come up with the amount of iron that would be in an all-lamb-shank diet for our wolf. We have 517. This is only about half the level that would be considered deleterious for any mammal that size.
I've been all over my raw food spreadsheets and it seems like anything that is more concentrated in energy, provides less mineral content. Possibly this is related to the fact that bones provide more minerals but fewer calories. And obviously a wild animal would eat differnt parts of the prey animal, not just the parts where iron is most concentrated. Remember that kibble manufacturers must provide their mineral content in consistent, concentrated forms.
With regard to what the NRC numbers represent: here is the pre-publication press release explaining the 2006 publication: http://www8.nationalacademies.org/onpinews/newsitem.aspx?RecordID=10668 and a summary of their goals in presenting information on nutrients:
For example, the report establishes not only minimum daily nutrient requirements, but also recommended allowances that
take into account the ability of dogs and cats to absorb nutrients
found in typical pet foods. When there is not enough evidence to set a
minimum requirement, an "adequate intake" has been established. And a
safe upper limit is set when there is sufficient evidence to
demonstrate that adverse health effects may occur if that limit is
exceeded. The report provides nutrient recommendations based on an
animal's physical activity level and stage in life, the two most
important factors influencing nutrient needs. It also looks at how
nutrients are metabolized in the bodies of dogs and cats, indications
of nutrient deficiency, and diseases related to poor nutrition.
Hope this helps.