1921.] 



Recent Research in Ecu; Production. 



1031 



matter of plants, much in the same way that the colour of butter 

 fat is produced. 



Fertility of Eggs. — It has been found in pigeons that the 

 presence of the male stimulates egg production in the female, 

 but experiments on a small scale with fowls have showm very 

 little effect. Nelson^) kept two pens of 10 hens each for a 

 year, one pen with a cock and the other without; the yearly 

 average egg yield per hen in the former was 126, and in the 

 latter 118. There were no differences in the keeping qualities 

 of the eggs from each pen. 



Numerous investigators have observed the time that elapses, 

 after the cock has been put with the hens, before the first 

 fertile egg is laid. In the trials at Copenhagen^ 4 ) it was 

 found that the first fertile eggs were produced three or four 

 days after mating. 



Observations have also been made as to the time a 

 hen remains fertile after the cock is removed from the pen. 

 Chappellier(42) found it to be 10 to 18 days. Elford^3) 

 states that a drop in fertility of the eggs occurs on the 

 sixth day after removal of the cock, while at the tenth day 

 only 50 per cent, of the eggs are fertile, by the nineteenth day 

 only 16 per cent, are fertile, and thereafter all are infertile. 

 Philips^ 44 ) observed that no fertile eggs were laid after the 

 fifteenth day from the last mating. Kaupp( 45 ) concluded from 

 his experiments that it is not advisable to save for hatching 

 eggs laid five days after the cock has been removed. He also 

 states that if hens have been running with a mongrel cock 

 and are required for pure breeding it would be safe to mate 

 them eighteen days after the mongrel cock has been removed. 

 i.e., fertility is considerably reduced after five days, but a 

 number of eggs remain fertile up to the eighteenth day. 



In-breeding. — No extensive investigations on the effect of 

 in-breeding on the fertility of the eggs have been made. 

 Gray and Kaupp( 46 ) found that when daughters were bred to 

 their sires the fertility of the eggs was only slightly reduced, 

 but the hatchability of the eggs was affected to the extent of 

 10 to 30 per cent. Indeed, as in-breeding is so often used by 

 poultry keepers to fix characters, and as cross-breeding is so 



(41) New Jersey Sta. Repf., 1906. 



(42) Compt. Rend., Ass. Franc. Adv. Sei., 1914. 



(43) Canada E^. Farms Report, 1916. 



(44) Jour. Arner. Ass. Instr. avid Invest. Poultry Husbandry, Xo. 4 1918 



(45) North Carolina Exp. Sta. Bui, 1915. 



(46) Xorth Carolina Station Report. 1917. 



