and it stuns me people tell me I ought to serve them a non-meat diet. I've read more than I care to admit on the topic and the estimates I see is doing this can cut 2-3 years off of their lives.

Now Hell's Kitchen is a terrible show, but Gordon Ramsay's BBC show is amazing. In one show he buys a number of pigs. Has his children raise them. Then allows them to witness how they get to our table.

I am sure some would scream "child abuse" but I think it is a pretty insightful concept.

First off, the modern American diet contains way more meat than humans have historically eaten, outside of the arctic.  The book, "The Third Chimpanzee", referenced an average of about 80-20 in terms of calories from plants versus meat.  So, what we're doing is just as "unnatural".  Many cultures throughout history -- including almost a billion people in India today -- are vegetarian.  Humans are perfectly capable of living on a vegetarian diet, just like they're capable of living on the American "way too much meat" diet.

It's not just about animal rights.  The environmental and energy impact from growing meat is really mind boggling.  If you take anything from this, at least read the first page of that NYT article for the comparisons of how much energy goes into a pound of meat.  Example:

To put the energy-using demand of meat production into easy-to-understand terms, Gidon Eshel, a geophysicist at the Bard Center, and Pamela A. Martin, an assistant professor of geophysics at the University of Chicago, calculated that if Americans were to reduce meat consumption by just 20 percent it would be as if we all switched from a standard sedan - a Camry, say - to the ultra-efficient Prius. Similarly, a study last year by the National Institute of Livestock and Grassland Science in Japan estimated that 2.2 pounds of beef is responsible for the equivalent amount of carbon dioxide emitted by the average European car every 155 miles, and burns enough energy to light a 100-watt bulb for nearly 20 days.

Lastly:

The best ones are those who carry on about putting their cats on vegetarian diets - talk about cruelty to animals!

Want to talk about cruelty to animals?  Vegetarian diets for cats include supplements to make up for the nutrients that the cats can't get naturally (if they don't have those nutrients, then yes, it is cruelty).  Well, guess what?  Cats will suffer in the exact same way on a diet of cooked meat, which is also not part of their natural diet.  Cooking meat denatures some of the nutrients that cats need to survive.  Cat food companies take meat scraps, cook them (this losing the nutrients), then add them back in, in the same way that vegetarian cat foods do.  All that changes is the base -- whether the protein comes from things like yeast or whether it comes from things like cow innards (again, not part of a cat's natural diet, which is mostly the whole bodies of rodents and birds).  Yes, I'd call commercial cat food closer to their natural diet, but it is anything but natural.