Where the Numbers Came From

Here is a list, by animal, of where I got my assumptions for the values in columns 2 and 3 of the table in the piece, How Much Direct Suffering Is Caused by Various Animal Foods? In general, a good resource for this type of information is the National Agricultural Statistics Service of the US Department of Agriculture.

Farmed Catfish

Catfish take 18 to 36 months to grow. I assume the average is 2 years.

The average live weight of catfish is 1.5 pounds (source, p. 3). I assume that 70% of this weight ends up as edible meat.

Farmed Salmon

Salmon take 18 and 24 months to grow. I assume 2 years, as for catfish.

The average live weight of food salmon is 8.6 pounds (source, p. 6). I assume that 70% of this weight ends up as edible meat.

Eggs

I assume a laying hen survives for a year on average. (Note that the exact figure is relatively unimportant, because there are more precise data on the average numbers of eggs laid per year. The lifespan of a hen is only relevant to factoring in the painfulness of death.)

In 2006, hens layed an average of 263 eggs. I assume an egg weighs 0.05 kg without a shell.

Chicken

A typical lifespan for a broiler chicken is 42 days.

In May 2007 in the US, 795,639,000 chickens were slaughtered, yielding a final edible weight of 3,213,272,000 pounds (source).

Turkey

"Turkeys are slaughtered at between 12 and 26 weeks, depending on the size of bird being produced" (source). I assume 18 weeks.

In 2007 in the US, 22,536,000 turkeys were slaughtered, yielding a final edible weight of 509,529,000 pounds (source).

Pork

I assume the lifespan of a typical pig is half a year.

In May 2007 in the US, 8.76 million pigs were slaughtered to produce 1.76 billion pounds of edible meat (source).

Beef

I take a cow's lifespan to be 1.1 years, or 402 days. I count here both the six months that cattle spend in feedlots and the seven months they spend grazing (see this page and references therein). The period of grazing contributes to my relatively low estimate for suffering per day of life.

In May 2007 in the US, 2.28 billion pounds of edible beef were produced from 3.05 million head (source).

Milk

Factory-farmed dairy cows typically live 5-6 years (I assumed 5.5).

In 2006 in the US, the average milk cow produced 20,210 pounds = 9,167 kg of milk. Multiplied by 5.5 years, this amounts to 50,420 kg per cow.