BREEDING EARLESS SHEEP 
E. G. RItzMAn 
N. H. Agricultural Experiment Station, Durham 
\OUR years ago the writer re- 
ported! a rather clear cut case of 
asimple Mendelian unit character 
governing the transmission of ear 
lergth ia sheep. 
The following extract from that 
article will explain the traits differ- 
entiating the unlike parental ear types. 
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. (234 inches). Since no inter- 
mediate types either as to length, shape, or 
thickness have so far appeared, length as 
a character forms quite a distinctive con- 
trast between this type and that of Ram- 
bouillet ears, which measure about 11.5 cm. 
(4144 inches); Southdowns, which measure 
about 9.5 cm. (334 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). 
The results of the matings as shown 
by diagram were such that the short 
ear trait was accepted as a gametically 
pure parental unit character. S indi- 
cates short ear; L, long ear; offspring 
grouped one above the other indicate 
twins: 
First Cross 
Recessive X Dominant or Simplex 6 3LX 9 69S Matings 3 
F, Offspring 9 127S+ 9 222S+ 9 2548S ~ Offspring 38 
Back Cross 
Recessive X Simplex 63LX 9127S 6 361LX% 9127S Matings 3 
Offspring 6 255L+ 9° 3138S 9 459L Offspring 3S-3L 
9 25659 3148 9 460L 
Back Cross 
Extracted Recessive X Simplex 6255LX 9127S Matings 1 
Offspring 6 422S Offspring 1S-1L 
6 423L 
; Fi X Fi 
Simplex Simplex 6 422S XK 9 256S 6422SX 9127S Matings 3 
Offspring 9 573S+ 9 461S 9572S Offspring 3S-1L 
9 462L 
Although but a few individuals a long-eared ewe.2 This ram was 
possessing the short ear trait had been 
bred, the result of the matings was so 
clear cut that further breeding was 
discontinued. 
Incidentally, however, the short ear 
trait was reintroduced through a ram, 
No. 632, who was a son of No. 422 by 
secured for the purpose of introducing 
a high twin potency into a flock of 
seven long-eared ewes kept for a 
study of this problem. 
These matings and offspring are 
shown in the following diagram (S 
indicating short ear, L, long ear): 
! Ritzman, E.G. Mendelism of Short Ears in Sheep; Journ, Agrl. Research, Vol. VI, No. 20, 
August 14, 1916. 
2 No. 632 was bred by Dr. C. B. Davenport of the Station for Experimental Evolution. 
