RATE OF GROWTH OF CHICKS 307 



Card and Kirkpatrick (loc. cit.) found the average weight of Rhode 

 Island Red chicks at two weeks of age to be 73.48 grams. Their records in- 

 cluded 798 individuals. 



Kaupp {loc. cit.) after weighing several hundred chickens gives the mean 

 weight at two weeks for Rhode Island Reds as 72.58 grams. 



Upp {loc. cit.) reports the mean weight of his 1858 chicks when two 

 weeks of age as 60.69 grams. 



Kaupp {loc. cit.) in his records found the cockerels when two weeks of 

 age to be 5.88 per cent heavier than the pullets. 



Jull and Titus (1928, loc. cit.) report the two-week mean weight of 83 

 male Rhode Island Red chicks as 79.6 grams and of 73 female chicks as 84.6 

 grams. The mean weight of the 156 chicks was 82.0 grams. 



Available data indicate that the birds used in the studies at the Mass- 

 achusetts Station were significantly heavier at two weeks than were birds 

 studied at other stations. The normal weight of Rhode Island Red Chicks at 

 two weeks probably ranges from 60 to 88 grams, and males run from 3 to 6 

 per cent heavier than females. 



Weight at Four Weeks of Age 



Mean weight of chicks at four weeks shows rather wide yearly fluctuations 

 in Table 1. In the eleven-year period covered by the data there is a range 

 from 183.0 grams in 1920 to a maxuiium of 255.2 grams in 1922. The very 

 heavy weights recorded from 1922 to 1926 are probably due in part to liberal 

 feeding of semi-solid buttermilk. During 1927 and 1928 milk was fed only in 

 powdered form mixed in the mash. 



Weight differences in the sexes appear a little more pronounced at four 

 weeks of age. The 8654 males averaged 222.4 grams, and the 9214 females 

 averaged 206.3 grams. Males weighed 7.80 per cent more than females at this 

 age. Mean four-week weight of both sexes consisting of 17,868 individuals 

 was 214.1 grams. 



Card and Kirkpatrick {loc. cU.) give the mean four-week weight of 714 

 chicks as 165.11 grams. 



Kaupp {loc. cit.) found 185.98 grams to be the average weight of a large 

 number of Rhode Island Red chicks. 



Upp {loc. cii.) presents records on 1581 chicks with an average four- 

 week weight of 115.63 grams. 



Jull and Titus (1928 loc. cit) report the mean four- week weight of 82 

 males as 204.5 grams. On 73 females they report a mean weight of 205.6 

 grams. Their 155 chicks averaged 205.0 grams. 



Kaupp {loc. cit.) also records the males as being 12.5 per cent heavier 

 than the females at four weeks. 



These data suggest that there exists a wide variability in weight of chicks 

 of the same strain from year to year, and also that there is a very great dif- 

 ference in weights obtained at four weeks by different investigators. Prob- 

 ably an average weight of 200 grams at four weeks would be about normal 

 under present methods of feeding and management. Males average to weigh 

 somewhere between 8 and 12 per cent more than females at this age. 



