>Owners can also feed their pets lower-quality proteins, as dogs and cats can happily chow on meat byproducts, such as marrow, kidneys and spleen, left from processing meat for humans.

Us humans don't choose what parts of animals we eat based on any kind of health-centric metric. It just based on what parts we deem distasteful to eat. So the bits that are deemed undesirable/low quality are not necessarily any worse for the consumer. Some amount of organ meat may even be beneficial to health. Arguably meat eating humans would do well to include some amount of kidney, liver, marrow etc in place of some of the muscle tissue that we tend to eat a lot of.

There are many problems with modern industrial agriculture and mass produced food, but efficiency is not one of them. There is very little waste in these operations and those kidneys, livers, and marrow bones are already being put to good use, whether its for human consumption or animal.

I won’t pretend to know what proportion of pets are fed standard, ‘low quality’ food (ie. food made from corn, grain, and what most would consider as low quality meats and byproducts) but if I had to guess I would wager its >90%.

Maybe modern industrial agriculture is efficient, but modern food consumption isn't. Over a third of all available food is wasted in the USA. How much of that food waste would be OK to be re-processed as pet food?

I don’t mean to sound like an apologist (or even a fan) of industrial agriculture, but I think its important to acknowledge the reality that while its an imperfect system, it is also a modern marvel that enables us as a society to feed an enormous amount of people at extraordinarily low costs to the consumer.

I don't see why not, with a correct definition of "quality". See below.

> Arguably meat eating humans would do well to include some amount of kidney, liver, marrow etc in place of some of the muscle tissue that we tend to eat a lot of.

Sure, if those items are all processed with the same level of care and attention to detail, cleanliness, etc. But because they are treated as "by products", they're not.

For the record, I don't think that everyone is feeding steaks to their pets. This was just an example. But the article does point out the worrying trend of pet owners giving them high-end foods.

As far as I can tell, what the article means by "lower quality" is "processed as by-products instead of as primary food". Which means they're going to be less healthy because they're not processed with the same level of care and attention to cleanliness and other important factors. That's the issue I have. (Well, that and the issue of what the animals that will supply the products are fed on--see below.)

> A ribeye-steak is very high-grade protein, but it doesn't mean it's healthy

I don't think a ribeye steak from a grass fed, free range, antibiotic-free animal is particularly unhealthy. But it's probably not easy to find such in many grocery stores, at least in the US.

It's unhealthy as in "not bringing enough diversity in nutrients". Kidney, liver meat are much richer sources of nutrients. Nothing wrong with indulging with a nice steak once a week, as long as you're having lots of plants/seeds/fruits-based meals as well.

Same goes for pets, but since you can't feed almonds to your cat, it's better off eating a mix of muscle, liver, bone marrow, etc.

I wouldn't worry too much about the cleanliness of pet food - it's been thoroughly cooked and processed to guarantee a long shelf life.