788 



REPRODUCTION AND MIGRATION IN BIRDS 



80 



Fig. 1. Egg production of hen in tests 1 and 2 during five weeks of 



darkness. Test 2 was terminated at the end of the dark period, 

 that continued to lay was 60.2 and 77.1 % for the first and second 

 tests, respectively. 



The loss in body weight was associated with pausing. The hens that 

 paused lost approximately 20% of their initial weight, whereas those 

 that laid throughout the test lost only 2.8 and 10.7% of their initial 

 weight in tests 1 and 2, respectively. 



One might assume that a hen that does not stop laying immediately 

 because of darkness would continue to mature and lay only those ova 

 that were in the process of maturation before the bird was deprived of 

 light. If so, most hens would stop laying after about 10 to 14 days. We 

 observed that 43 and 5% of the hens stopped laying in the second 

 week in the first and second test, respectively. 



It is apparent from these tests that some hens in our strain of White 

 Leghorns did not require light for either ovulation or oviposition, and 

 that factors other than Ught had a regulatory influence on these func- 

 tions. 



REFERENCE 



Wilson, W. O., and H. Abplanalp. 1956. Intermittent light stimuli in egg pro- 

 duction of chickens. Poultry ScL, 35, 532-38. 



