What does this mean?

Hi, I m learning English by myself, and there was a sentence I couldn t understand from this documentary I watched today. It s about a chicken farm. The farmers said they tend to eat the chickens when they get new batches of them. What does it mean? New batches? Does it mean they eat the chickens when they have too many chickens as to new born chicks? Or what does it supposed to mean? Thank you in advance.
Answers

oikoσ

Chickens have a limited time to "earn" their way by laying eggs. When they reach two or three years, they cost more in food than they produce in eggs. You have to replace them with younger chickens (bought or raised). The older, non-productive ones become soup or stew.

busterwasmycat

It means that when new chickens are brought in, the old chickens get eaten. The idea of batch just means that a lot of new chickens are obtained at basically the same time, as a group, rather than in small numbers every day or few, forever. Batch (group) rather than continuous (frequent individual) replacement.