Chickens have been bred in the US to maximize yield to feed ratios and breast size. This news article has a figure from a paper from the University of Alberta s

Chickens have been bred in the US to maximize yield to feed ratios and breast size. This news article has a figure from a paper from the University of Alberta showing chickens breeds from different decades as well as their size given the same amount of feed: https://www.cbc.ca/news/canada/calgary/chickens-are-4-times-bigger-today-than-in-1950s-1.2792628 https://www.cbc.ca/news/canada/calgary/chickens-are-4-times-...