Hi M & C,
Last year?? I called Hill’s Pet Nutrition, Royal Canin and Purina and asked for copper levels in multiple diets. Interesting to me, was that the levels from all three companies fell within a narrow range of as I recall ~3-4 mg/1000 kcals with exception of the therapeutic diets, which were much lower, and breed specific formula by RC was right at AAFCO min ~1.8. The situation I found with small companies’ raw/freeze dried raw offerings was vastly different. Like you I found wild fluctuations among the products they made with some near 100 mg/kg DM Wow just Wow
I first started looking because of a comment I read by Dr Sharon Center who said, as I recall, in her opinion, one factor in the rising cases of copper storage disease ( CSD) was the trend towards “natural” diets, resulting in liver/organ meat being used to meet certain nutrient needs and the side effect feeding high organ content was the high copper levels that came with their use. In contrast, I’ve found posts from random people giving advice on CSD to avoid commercial diets that have copper supplements and instead feed “natural” diets. Considering that I found that even though the commercial kibble made by the large companies listed a supplement, the diets had lower levels in general than the “natural diets,” that advice seems very reckless.
That advice reminded me of something I learned long ago. From a biological standpoint the natural diet is meant to sustain an animal through reproduction. After successful reproduction, it is in the interest of the species for the parental generation to die off so that they do not compete with the new generation. In other words, the natural diet may not be the optimum diet to sustain an animal long term.
I suspect copper levels may be lower in poultry based foods because chickens are slaughtered at such a young age so little time for copper to accumulate in their livers as opposed to cattle.
