July 9, 191 7 Family Performance a Basis for Selection in Shifep 97 



experiments, Southdown and Rambouillet.^ These were size and con- 

 formation of the former and wool characters of the latter, but inter- 

 mediateness in thickness of fiber and length of not less than 3 inches. 

 As the Southdown ram 28169 represents an exceptionally desirable type, 

 combined with unusual size for the breed, his measurements were 

 adopted to represent the "ideal" as regards conformation and size. 

 The ideal score, then, is shown in Table III. 



Table III. — The ideal score for size and conformation of rams 



Measiires.i 



Weight pounds. . 200 



Height, shoulder mm . . 635 



Head length mm . . 200 



Head width mm. . 135 



Neck length mm . . 285 



Neck circumference mm. . 475 



Trunk length mm . . 645 



Chest circumference mm . . i, 100 



Chest depth mm . . 350 



Chest width mm . . 300 



Loin width mm . . 200 



Croup length mm . . 180 



Foreleg length mm . . 380 



Hindleg length mm . . 455 



Hindleg circumference mm. . 485 



Ratiop. 



Head width 1 



— — . > o. 



Head length! 



Nec k l ength 1 

 Neck circumference / 

 Foreleg length"! 



Trunk length J 



Chest width \ 



Chest depth] 



Chest width \ 

 Trunk length J 



Loin width \ 



Trunk length/ 



Croup length \ 



Trunk length/ 



o These measurements can all be taken with a simple and inexpensive caliper or with a string. 



The results of this method of selection can not yet be given in detail, 

 as the experiment is still in progress. The uniformity of the progeny 

 and the high quality already shown by the earlier generations give us 

 every reason for confidence that this method of selecting by family per- 

 formance in place of individual traits is well worth the extra trouble 

 it entails, if, indeed, it is not indispensable. 



* An "ideal" score may, of course, be subject to change. It must be progressive, as animal breeding is 

 progressive. 



