RATE OF GROWTH OF CHICKS 317 



Table 5.— Relation of Age of Mothers to Egg Weight. 



MEAX WEIGHT OF HATCHING EGGS GRAM8 



Year I'ullet mothers Hen mothers 



1925 56.39 60.97 



1926 53. 92 60.67 



1927 55.42 58.91 



1928 56.86 58.48 

 Average 56.19 59.56 



Weight of Chicks at Hatching 



The 743 chicks from pullet mothers had a mean weight of 35.9 grams, and 

 the 586 from hen mothers averaged 37.7 grams. The chicks from hen mothers 

 were 5.01 per cent heavier than those from pullet mothers. Jull and Quinn 

 (loc. cit.) report about the same relative difference in hatching weight of 

 both male and female chicks from pullet mothers versus hen mothers but 

 their chicks were slightly heavier than those reported in Table 6. 



Weight of Chicks at Four Weeks of Age 



At the age of four weeks both male and female chicks from hen mothers 

 were heavier than those from pullet mothers. The 8759 chicks from hen 

 mothers averaged 17.7 grams or 8.62 per cent heavier than the 9109 chicks 

 from pullet mothers. The fact should be noted in this connection that the 

 hen eggs incubated averaged 6.00 per cent heavier than the pullet eggs, and 

 the chicks from hen mothers were 5.01 per cent heavier at hatching than those 

 from pullet mothers. These data therefore indicate that the relative weight 

 difference in chicks from pullet mothers and hen mothers persisted at four 

 weeks of age. 



Weight of Chicks at Sixteen Weeks of Age 



At the age of 16 weeks there was still a significant weight difference in 

 both male and female chicks from pullet mothers and from hen mothers. The 

 mean 16-week weight for 2003 chicks from pullet mothers was 1366.9 grams, 

 and for 639 chicks from hen mothers the weight was 1462.2 grams. The chicks 

 from hen mothers were 6.97 per cent heavier, indicating a significant differ- 

 ence in weight at 16 weeks between chicks from pullets and from hens. 



Weight of Chicks at Ticenty-one Weeks of Age 



Table 6 presents data to indicate that when chicks froim pullet mothers 

 were compared with those from hen mothers at 21 weeks of age, weight dif- 

 ferences observed earlier had practically disappeared. The 1259 males from 

 pullet dams averaged 2366.9 grams compared with 1846 males from hen moth- 

 ers with an average weight of 2422.8 grams. Since the actual difference was 

 small, and because there was lack of consistency from year to year as shown 

 in the table, it is very probable that the difference is not significant. For the 

 female chicks, the mean weights from the two classes of mothers were almost 

 identical at 21 weeks. When the sexes were taken together, pullet offspring 

 had practically the same mean weight as hen offspring. 



In general, the data in Table 5 and 6 show that hen mothers laid larger 



