MASS. EXPERIMENT STATION BULLETIN 359 

 Table L — Outside Temperature and Fertility* 



Late Group. Hatched March 25 to May 15 Early Group. Hatched March 4 to April 27 



1922-1932 1933-1936 



Hatch Number Number Mean Mean Hatch Number Number Mean Mean 



No. of of Tempera- Fertility No. of of Tempera- Fertility 



Birds Eggs ture °F. Percent Birds Eggs ture °F. Percent 



1 492 2759 15.86 54.47 



2 511 2094 20.75 61 02 



3 552 2339 27.34 64.58 



4 609 2665 23.39 66.70 



5 656 2883 33.09 70.24 



6 670 3096 34.00 74.93 



7 643 3086 37.41 78 52 



8 616 3006 38 95 76 96 



*Includes all experiments. 



A study of mean fertility for successive hatches in a different group of females 

 in successive years showed considerable parallelism between outside temperature 

 and fertility. When the mean outside temperature averaged below 36°, fertility 

 was significantly lower, as shown by the first three hatches. When the outside 

 temperature rose to 40° or 45°, the maximum fertility was attained. Within 

 the temperature ranges studied, there appears to be a relation between outside 

 temperature and fertility. 



Considering the group where hatching took place three weeks earlier, it will 

 be noted that the mean outside temperature was well below freezing at the time 

 eggs were laid for the first four hatches. As the temperature rose during the 

 collection of eggs for the first four hatches, there was a consistent increase in mean 

 fertility. As the temperature increased during the collection of eggs for the last 

 four hatches, fertility still increased, attaining a maximum at 37°. 



Hatch 1 of the late group was made from eggs collected on the same dates as 

 hatch 4 in the early group. The mean temperature was higher during the ten 

 years that data were collected for the late group than during the four years that 

 data were collected for the early group, but in both cases the temperature averaged 

 below freezing. Mean fertility was also significantly higher for the late group. 

 Late hatch 2 and early hatch 5 are not consistent in that the former showed a 

 significantly greater fertility than the latter, when the mean temperatures were 

 about the same. There was a slight superiority in late hatch 3 over early hatch 6, 

 and the temperature was also slightly higher when the eggs for hatch 3 were laid. 

 There was slightly higher fertility in late hatch 4 than in early hatch 7, although 

 the temperature differences were negligible. In late hatch 5 and early hatch 8, 

 from eggs produced under the same temperature conditions, hatch 5 had superior 

 fertility. 



The data in Table 1 furnish further information on the relation between out- 

 side temperature and fertility. The mean fertility for the eight hatches was 

 81.11 percent in the late group, while in the early group it was 68.43 percent. The 

 mean temperature was 38.10° during the time the eggs were laid for the late 

 group and 28.85° during the time the eggs were laid for the early group. Since 

 the character of the stock was not changed and the methods of feeding and manage- 

 ment were kept constant, it is very probable that lower temperatures were in 

 large measure responsible for the lower fertility of the early group. 



