Experimental work in breeding for egg production was started with this flock of Single Comb White Leghorns in 1907. The flock of 1907 was hatched from eggs from a small flock that had been introduced into the plant two or three years before.
After two years' records of these flocks had been completed and studied it was found that nearly three-fourths of the first flock had made better records the second year than they did the first and that there was a great variation in the two years' records of individual hens. This raised the question of whether the first year's record was a proper basis of selection--and it was decided to keep a number of hens long enough to test this point.
Ball, E. D.; Turpin, Geo.; and Alder, Byron, "Bulletin No. 135 - A Study in Annual Egg Production: Based on the Records of a Flock of Seven-Year-Old Hens and Their Progeny" (1914). UAES Bulletins. Paper 86.