Worrying about my food

I noticed this tweet via Andrew Revkin over the holidays:

I'm starting to get worried that I'm starting to develop a guilty conscience over meat eating.

I'm not entirely sure of the metrics I use to avoid worrying about animal life and suffering.   Can 7 weeks as a broiler hen in a shed ever be called a happy life?   Should I worry too much about what a hen would like to be doing, given that left alone, they'll spend a lot of time fighting other hens anyway (depending on living conditions, though, I guess.)   But what about the rooster chicks in the egg industry who get conveyor-belted into a grinder while they are still cheeping because they were born with the wrong genitals?  Is that more or less "tragic" than  being fed in a shed for 6 weeks purely to put on weight and having bodies that couldn't cope in the wild anyway?   

And 65 billion chickens a year killed to satisfy our fried chicken lust?  Seems a bit, well, excessive.  I mean, we do factor in numbers in assessing degree of tragedy involving death - should that also apply in some complicated fashion to working out if the egg industry or the broiler meat industry is the "worst" in terms of least justified termination of animal lives?

Look, I don't think I am ever in any danger of worrying about interfering with the life (or life enjoyment) of a prawn, or fish.   But when it comes to mammals and chickens, it's starting to feel complicated. 

Perhaps I should feel more sympathy for relatively smart creatures like cattle fearing what's coming at the abattoir, but at least they have gotten "more out of life" by having lived in the sunshine for a number of years before meeting their fate.   (At least in this country.) 

But back to the other hand - in terms of environmental impact, I think it's pretty well acknowledged that chicken does way less harm than big mammal farming.

And if I concede on chicken, there is a danger I'll start to fret about certain things further down the evolutionary scale - I recently saw this at the back of food market in Chinatown, Singapore:

Now look, I don't even like frogs, but looking at a bunch piled up, some peering out of the cage; one with its little, um, hand on the wire:

...and I felt sorry for them.   Of course, they are probably big enough that they would eat a small mouse given half a chance, and I like mice a lot more than I like frogs, so that would change my feelings again. 

Anyway.

I remember reading an essay by Paul Johnson in a collection he put out a decade or so ago, written probably in his 70's, in which he said ageing had made him feel more sympathetic to all life, and that he found himself even giving flies a chance to escape out of the window before reaching for the spray. 

I'm getting a bit worried I am heading the same way...