MENDELISM OF SHORT EARS IN SHEEP 



By E. G. Ritzman, 

 Animal Husbandman, New Hampshire Agricultural Experiment Station 



Among the various features under observation in the experimental 

 breeding carried on at this Station with sheep the "short" ear trait is a 

 very clear example of a simple Mendelian unit factor. 



Short ears as referred to here are of a distinctive type with nearly 

 straight lines running from the base and forming an abrupt, sharp point. 

 They are also somewhat thicker than the ordinary type of ear. The 

 longest of these ears so far observed in a mature animal measure 7 cm. 

 (2%* inches). Length as a character therefore forms quite a distinctive 

 contrast * between this type and that of Rambouillet ears, which measure 

 about 1 1.5 cm. (finches); Southdowns, which measure about 9.5 cm. 

 (2,H inches) ; and Shropshires and native, which measure about 10 cm. 

 (4 inches). In fact, all ordinary ear lengths observed among various 

 breeds and types seem to run close around 10 cm. (4 inches) or over. 



The experimental data given here are derived from one native ewe 

 and her progeny, which number 15 head. This ewe was purchased from 

 a neighboring farm with 19 other native ewes, none of which had short 

 ears or short-ear offspring. The character of her dam is unknown, but 

 her sire is known to have possessed long ears. She was therefore in all 

 probability simplex as to the character of ear length. This short-ear 

 ewe (No. 69) was bred to a Hampshire ram (No. 3) for three successive 

 years, producing three female offspring, all short-eared. Two of these 

 died, leaving only one (No. 127). As no F t males of this type were avail- 

 able, she was used twice on a back cross with her sire (who was a pure 

 long ear) and once on a similar back cross with No. 361 (also a pure long 

 ear). From this cross three sets of twins were obtained with an equal 

 number of short and long ears, which corresponds to the results expected 

 from a back cross of a simplex to the recessive parent in a simple Men- 

 delian unit character. She was later bred to her own son (No. 255), 

 an offspring of this back cross, who showed the recessive trait. Being 

 recessive, he should have been pure to long ears, and the cross on his 

 dam should give similar results as the former matings of 127 with pure 

 long-eared sires (No. 3 and 361). The actual result was one pair of twins, 

 including one short-eared and one long-eared individual. This gave a 

 total of four short-eared and four long-eared offspring from simplex X 

 recessive parents. 2 



1 No intermediate types either as to length, shape, or thickness have so far appeared. 



2 One mating was simplex X extracted recessive. 



Journal of Agricultural Research, Vol. VI, No. 20 



Dept. of Agriculture, Washington, D. C Aug. 14, 1916 



eu N. H— 1 



(797) 



