BREEDING FOR EGG PRODUCTION 23 



The Breeding Procedure Recommended for Increasing Egg Production 



Egg production of each succeeding generation in the flock can be increased 

 only by using a superior class of breeding stock to produce each generation. 

 The outstanding experiment to support this view was carried on by Gowell at 

 the Maine Agricultural Experiment Station with Barred Plymouth Rocks. 

 The detailed results in relation to egg production are reported by Pearl and Surface 

 (1909a and b) and by Pearl (1911). Each year Gowell selected for breeding year- 

 ling hens with records of 150 or more eggs in the pullet year. Each year these 

 hens were mated to cockerels from mothers laying 200 eggs or more. All daughters 

 were trapnested from November 1 to October 30 each year. The standard for 

 breeders was not raised as the experiment progressed. The mean annual egg 

 records of the daughters hatched from 1899 to 1906 were 136, 143, 156, 135, 118, 

 134, 140, and 113 in the respective years. The variation in annual production 

 did not decline and there was actually a significant decline in egg production of 

 daughters in the eight-\ear period. A very great decrease was observed in 

 winter egg production during this period, the means ranging from 41 eggs in 1899 

 to 16 eggs in 1907. 



Pearl and Surface (1909a) hatched 250 pullets from hens that had laid 200 

 eggs during their pullet year. These pullets were sired by cockerels whose 

 female ancestors had laid not less than 200 eggs for seven generations. These 

 pullets were trapnested from November 1 to July 1 and compared with 600 

 pullets from the line previously developed by Gowell. The mean winter pro- 

 duction of the first group of pullets was about 16 eggs compared with about 19 

 eggs for the second group. The notation is made by the authors that the pullets 

 from 200-egg dams were inferior to those of the other group. It is very evident, 

 in view of modern information, that neither method of selection of breeders was 

 rigid enough to increase the production of the daughters. 



Marble and Hall (1931) report results in breeding high- and low-producing 

 lines of White Leghorns. The mean annual egg production of the high line 

 was raised by careful breeding from 127 eggs in 1908 to 196 eggs in 1927. Egg 

 weight and bod\" weight did not decrease, and length of cycle increased as egg 

 production increased. Mean age at first egg did not change significantly after 

 ten or eleven >ears of breeding. 



Lippincott (1920) mated three lines of mongrel pullets and their daughters to 

 purebred cockerels and one line to mongrel cockerels for three generations, with 

 the following results: 



A\erage Percentage of Increase or Decrease in First- Year Egg 



Production of Each Generation of Offspring Compared with the 



Original Mongrel Pen 



Single Comb White Leghorn Grades. 



Barred Pl\ mouth Rock Grades 



White Orpington Grades 



Mongrels 



