316 MASS. EXPERIMENT STATION BULLETIN 259 



late March hatching is superior to later hatching from the standpoint of 

 chick weight at four weeks of age. 



Weight at Sixteen Weeks of Age 



Records of 16-week weights of chicks are available only for 1918 and 

 1921. The total number of chicks weighed was 2642. Although this number 

 is rather small, it nevertheless furnishes some criterion of the relation of 

 hatching date to chick weight at this age. The summary at the end of Table 

 4 discloses a fairly consistent decline in 16-week mean weights with weekly 

 advances of the hatching date. The first hatch chicks averaged 21.70 per 

 cent heavier than the last hatch chicks at the same age. This difference is 

 somewhat less pronounced than was observed at four weeks when the first 

 hatch chicks weighed 28.79 per cent more than the last hatch chicks. 



Weight at Twenty-one Weeks of Age 



Data on weight at 21 weeks cover the six-year period from 1923 to 1928. 

 The total number of birds included is 6941. The summary indicates some- 

 thing of a downward trend in mean weight as the hatching date advances. 

 The 1002 birds in the first hatch averaged 17.13 per cent heavier than the 668 

 birds in the last hatch. A more rapid growth rate enables the early hatched 

 pullets to attain more weight when sexually mature because hatching date 

 within these limits does not affect age at sexual maturity (Hays, Sanborn and 

 James 1924, loc. cit.). On the whole, for Rhode Island Reds under Massa- 

 chusetts conditions, late March hatching is superior to later hatching from 

 the standpoint of body weight to at least 21 weeks of age. 



4. Relation of Age of Mothers to Weight of Chicks 



The writer (Hays, 1929) has shown that in the Massachusetts Agricul- 

 tural Experiment Station flock of Rhode Island Reds the mean weight of eggs 

 during the hatching season from 84 birds was as follows: pullets, 55.90 grams; 

 yearlings, 60.12 grams, with no further increase in egg weight after the year- 

 ling season. Since there is an intimate correlation between egg weight and 

 chick weight at hatching, it seems logical to anticipate that chicks from hen 

 mothers would be superior in weight at hatching and might retain this greater 

 weight for a period after hatching. Table 6 gives the record of chick weights 

 at hatching, at 4 weeks, at 16 weeks and at 21 weeks of age from hen mothers 

 and from pullet mothers. 



Weight of Eggs 



The mean egg weight during the hatching season for all of the females 

 whose oft'spring was weighed is recorded in Table 5. The mean weight of 

 eggs for the pullet mothers was 56.19 grams and for the hens was 59.56 

 grams. These data agree well with previous data already referred to 

 from this Station on the mean weight of pullet eggs and yearling eggs dur- 

 ing the hatching season (Hays, 1929, loc. cit.). Egg weights recorded in Table 

 6 are also in complete agreement with those reported by Jull and Quinn {loc. 

 cit.). 



