We don't really eat "working/valuable" animals either: the goat that delivers milk and cheese won't be slaughtered, neither will be the bull ...well at least not until his castration. A milk farmer won't slaughter his cows either, nor are egg producing chickens. The animals that do get slaughtered are specifically bred for human consumption.
This is not true.
While on our epic SD trip, Wally and I were talking. I said "I wonder what they do with all the excess bulls that are born to milk cows?" Being a man, of course he said "They use them for stud"
I said "You only need a few bulls. If 50% of births are males, that's a lot of excess bulls"
It just so happened that the lifeguard at the pool of our first hotel only did this part time, and the rest of her time was out on her husbands ranch. I asked her that question and she smiled. It just so happens that was her own little sideline. She took all the males born and hand fed them. When they got to a certain size, she sold them in lots to whatever slaughter house wanted them. She told me that, let's say a beef cattle earns you a dollar a pound on the hoof. A milking breed male will get you something like 75-80 cents a pound.
I asked her if the males she sold were used for pet food or similar uses, and she said she had no idea what they were used for, as long as she got her price. Then she told me they ate young bull meat all the time, no difference whatsoever in the quality as compared to beef cattle.
So, I'm sure a lot of the beef we buy are from cattle that were not being bred for their beef.
Hamburger is differentiated by its fat content, but by the breed it came from.
I lived in the middle of a dairy area for a while, and those cows have a sad life. I can't drink cow milk, and even if I could all of a sudden, I wouldn't start now.
I can have small to moderate amounts of goat yogurt and goat milk, and the goats actually have a very nice life. The goats that produce the brand of yogurt I buy are out in the fields all day, come in happily for milking, and when they are no longer producers, are allowed to live out their natural life hanging out.
I don't however, feel optimistic about the fate of all the little billy goats.
ditto chickens. I buy a brand of eggs that comes from a chicken farm about 60 miles from here. I know people who live in that down, and they verify that the chickens have a lot of space to run around in.
The eggs aren't fertilized so I'm not eating a future hen or rooster, they aren't being mistreated, so I'm fine with that.