. Bulletin - Massachusetts Agricultural Experiment Station. Agriculture -- Massachusetts. BODY WEIGHT AND EGG PRODUCTION 5 that in the various studies body weights were taken at various ages by different investigators. In most cases there was no uniform measure of body weight such as maximum weight in the first laying year or weight at the end of the first laying year. On the other hand, a summary of Canadian National Egg Laying Contests from 1924 to 1928, reported in their Blue Book for 1931, showed a decided correlation between weight of birds and egg production in Leghorns, Barred Plymouth
. Bulletin - Massachusetts Agricultural Experiment Station. Agriculture -- Massachusetts. BODY WEIGHT AND EGG PRODUCTION 5 that in the various studies body weights were taken at various ages by different investigators. In most cases there was no uniform measure of body weight such as maximum weight in the first laying year or weight at the end of the first laying year. On the other hand, a summary of Canadian National Egg Laying Contests from 1924 to 1928, reported in their Blue Book for 1931, showed a decided correlation between weight of birds and egg production in Leghorns, Barred Plymouth Rocks, White Wyandottes, and Rhode Island Reds. Birds Used for Study The birds used were hatched in 1934, 1935, and 1936. They were all Rhode Island Reds that were used in various breeding experiments. The methods of feeding and management were kept constant. All birds were placed in the laying houses when about 170 days of age. Individual weights were taken on each pullet when housed, and subsequent weighings were made on the same calendar date each month for a full year. Body Weight During the First Laying Year 1. Monthly Body Weight The frequency distribution in body weight for all birds weighed at monthly intervals throughout three years and the weight at first egg are recorded graph- ically in Chart 1. All individual weighings were included to round out the fre- quency graphs, because the monthly means were not significantly changed when only birds surviving the whole period were included. A study of the frequency distributions in body weight from September to January indicates skewness in the direction of lighter weight. The graphs further reveal rather compact distributions for body weight during the first half of the laying year. There was some evidence of a bimodal distribution at this time around one mode of about 6 pounds and another mode of about pounds. The exact meaning of this apparent bimodal distribution has not been determined. Beginning with the February
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