The relevance of the second part of the statement.
I agree that it is quite possible the sows are artificially inseminated on a 2 weekly cycle, and think it is unlikely that the sows are relocated every 2 weeks. On the Pig-Vision
(www.pig-vision.com) project at least, they were never relocated.
However, it seems a bit of a leap to say the sows are inseminated every 2 weeks and then the piglets are removed after 21 days. Where did the pregnancy go?
Is it perhaps that the pregnancy stage was mentioned in the previous paragraph, and this sentence is more like an adjunct to explain the time aspects?