RATE OF GROWTH OF CHICKS 305 



The 21-week weight records were started in 1923 and extend through 

 1928. All Rhode Island Reds in the flock were weighed. 



All weight records were taken individually on all living chicks. 



Weights are reported in grams and also in pounds or fractions thereof. 

 This is in agreement with the practice followed by all experiment stations in 

 the Northeastern States. 



Scope of This Report 



This report furnishes a considerable body of records of weight of chicks 

 at hatching, at 2 weeks, at 4 weeks, at 16 weeks and at 21 weeks of age. 



Information is also given on the relation of egg weight to weight of 

 chicks at hatching, at 4 weeks and at 21 weeks, to indicate possible advantages 

 in large egg size from the standpoint of chick growth. 



Extensive data on the relation of hatching date to weight of chicks at 

 diflferent ages are also presented. 



A study is made on the relation of age of mothers to weight of chicks 

 at 4 weeks, 16 weeks and 21 weeks of age. 



The importance of early growth as a criterion of vigor and of later egg 

 production is fully considered. Pullets that weighed under .5 pound at four 

 weeks of age are compared for mortality rate in the laying houses and for 

 annual egg production with those that weighed .5 pound or more. Pullets 

 that weighed under 4.5 pounds at 21 weeks of age are compared for mortal- 

 ity rate in the laying houses and for annual egg production with those that 

 weighed 4.5 pounds or over. 



1. Weight of Chicks at Different Ages 



WeUjht at Hatching' 



Hatching weight of these Rhode Island Red chicks varied somewhat from 

 year to year. These variations in the six-year period covered are probably not 

 significant. In general, the males were slightly heavier than the females. The 

 mean hatching weight of the 640 males was 36.8 grams; of the 689 female 

 chicks, 36.6 grams. Males were but .55 per cent heavier than females, and 

 such a difference can not be considered significant. 



Card and Kirkpatrick (1918) record the average weight of 865 Rhode 

 Island Red chicks when hatched as 37.20 grams. Their weight records agree 

 rather closely with those given in Table 1. 



JuU and Quinn (1925) report the mean hatching weight of male Rhode 

 Island Red chicks as 38.76 grams, and of female chicks as 37.93 grams. Their 

 records include 228 chicks and show heavier chicks and a significantly greater 

 difference in the weight of the sexes than do the data in Table 1. 



JuU and Titus (1928) report the mean hatching weight of 83 Rhode Is- 

 land Red males as 34.9 grams and of 74 females as 34.3 grams. The mean 

 weight of their 157 chicks at hatching was 34.6 grams. 



The data presented in Table 1 on the mean M'eight of chicks at hatching 

 agree with those of Halbersleben and Mussehl (1922), their figure being 36.2 

 grams. Unfortunately their report fails to state what breed or variety of 

 poultry was studied. 



