An article in the Star and Tribune on March 24th stated that chicken breeding has resulted in great changes in the rate at which chickens grow and the size to which they grow – it now takes ~ 42 days to raise a 5 pound chicken, compared to ~ 60 days 30 years ago. Let’s say you think this is great, and also think it would be a good idea to breed chickens that grow bigger even faster. You consider two strategies. One strategy is to impose selection for faster growth on chickens living in a facility where each chicken is given the same amount of food, the same amount of space, and lives in a controlled environment in which temperature and day length are regulated. The second strategy is to select for faster growth on chickens living in a pasture where they spend their days pecking around for food and have a hen house from which they are free to come and go.
Explain which strategy you think would lead to more rapid genetically-based gains in the rate at which chickens grow? (assume the starting populations for both strategies have the same genetic composition).