64 Size of Egg in Eelation to Aveeage Production. [Apr.^ 



The influences which tend to the production of a greater 

 namber of small eggs may be briefly summarised: — 



(1) When eggs are laid by pullets at a much earlier period 



than the normal, and before the body has attained 

 maturity; such early laying checks the growth of the 

 body, so that in process of time, in the absence of 

 selective breeding, the size of the egg is reduced. 



(2) When an increased number of eggs is laid within a 



given period there is a tendency towards reduction 

 in weight; investigations and observations both in 

 this country and America have shown that in a cycle 

 of continuous laying each egg is slightly lighter than 

 its predecessor, and that the maximum is not regained 

 until a break in laying has taken place. 



(3) There are periods w^hen, in certain breeds, over entire 



flocks, a marked reduction in the size of egg takes 

 place. The accompamang graphs illustrate this in 

 the case of Wliite Wyandottes, Leghorns, Ehode 

 Island Reds and Plymouth Eocks. Periodical 

 variations occur which differ according to breeds, but 

 which, nevertheless, seem to follow a definite rule 

 of variation within a breed. 



(4) The use of breeding stock before maturit}^ has been 



reached; birds hatched from eggs smaller than the 

 full size tend to smaller eggs. 



At the Harper Adams Poultry Conference, held in August, 

 1920, it was advocated by some breeders that market standards 

 for eggs should be reduced. There seems no reason, however, 

 for any change from the present 2 oz. to 2.] oz. standard. 



A study has been made of records presented in the Eeport 

 of the 1918-19 Small Flocks Laying Trials at the Harper 

 Adams Agricultural College, with a view to obtaining data as 

 to (1) the relative proportion of undersized eggs to the total 

 production; (2) the extent to which there was an increase in 

 size during the whole year; (3) whether heavy winter laying 

 has an appreciable influence upon the size of egg during the 

 remaining periods of the year; and (4) the relation between 

 total annual production and the size of the eggs laid. The 

 breeds selected for observation were White Wyandottes 

 (33 pens) ; White Leghorns (32 pens) ; Ehode Island Eeds 

 (8 pens) ; and Plvmouth Eocks (8 pens) . Each pen contained 

 six pullets. These birds were carefully selected from much 

 larger flocks, which had been bred with a view to early laying. 



