WINTER PAUSE IN RHODE ISLAND REDS 9 



12. Laying-House Mortality in Pause and Nonpause Birds 



Any relation between the presence or absence of winter pause and mortality 

 in the laying houses is very important to the breeders. In table 2 the mortality 

 rates for the pullet laying year are recorded in the two flocks. These data 

 suggest a somewhat higher mortality rate in the birds with winter pause. 

 There is certainly no evidence from these limited data to indicate that a pause 

 period during the winter will reduce laying-house mortality. 



Table 2. — Mortality in Relation to Winter Pause 

 Nonpause Birds Pause Birds 



Total 



97 



216 



30.99 



259 



434 



37.37 



13. Hatchability from Pause and Nonpause Birds 



Poultrymen generally believe that pullets which exhibit a winter pause and 

 partial molt are more likely to give superior hatches than those laying con- 

 tinuously, particularly when the pullets were hatched early. Bronkhorst 

 and Hall (1935) classified Leghorns as low in hatchability if less than 50 per- 

 cent of their eggs hatched, and as high if 75 percent or more hatched. They 

 reported that their high-hatching birds averaged to pause 79.3 days and their 

 low-hatching birds 72.8 days, but considered this difference in length of rest 

 period to be of questionable significance. Warren (1934) obtained similar 

 results with Leghorns and Rhode Island Reds. He reported for Leghorns a 

 mean hatchability of 66.37 percent for nonpause birds and 72.48 percent for 

 pause birds; for Rhode Island Reds, 54.34 percent for nonpause birds com- 

 pared with 66.15 percent for those with winter pause. He did not believe that 

 the higher hatchability in the pause birds was due to the rest from production. 



In Table 3 data are presented on pause and nonpause pullets used for breeding 

 for two hatching years. The nonpause birds showed a slightly higher hatch- 

 ability in both years, which is not in agreement with Warren's observations. 

 In the station flock of Rhode Island Reds, pullets hatched at weekly intervals 

 from March 4 to April 23 and exhibiting no winter pause were at least equal 

 in hatchability to those with pause. There was no evidence to indicate that 

 a period of nonproduction in winter will raise the hatching percentage. 



