Oct. 7>i9i8 Crosses between Dairy and Beef Breeds of Cattle 45 



SEGREGATION OF THE POLEED CHARACTER 



In his interesting review of the Hterature on domestic cattle and their 

 origin Morse (25) and others (5) give briefly the theories as to hornless 

 cattle (47). The different views held all go back to the conception of use 

 in selection to account for the loss of horns. Durst {14) and Ewart (75) 

 take the ground that domestication has brought about the loss of horns. 



Auld (4) considers that a reduction in the horns took place in between 

 the upper Eocene and lower Miocene period. Contradictory to this, 

 Arenander (2) says the first cattle were hornless. Major (25) found 

 skulls in the tertiary deposits in Italy the males of which were horned 

 and the females hornless. Thus he considers a progressive extension of 

 this would bring about the hornless race. This is something of the idea 

 of Keller (16), when he cites the African cattle with movable horns to 

 be ancestors of the hornless animals. 



Based on rough notes collected at the Smithfield Club, Bateson and 

 Saunders (7, 8) treated these data on the homed character in cattle as 

 if it were a single Mendelian factor and conclude that the presence and 

 absence of horns are almost certainly allelomorphic characters. Further 

 data collected by Spillman (41) on 165 cases led him to conclude that 

 polledness is a simple Mendelian dominant. Boyd (lo) has given later 

 data on polledness in his cross of mutant polled Herefords onto pure 

 horned Herefords and in his crosses of polled cows to the American 

 bison. In both of these the polled character is dominant. In one of 

 his bulls. Variation, he thinks he gets a significant difference from the 

 expected ratio of i to 1 . Thus, in crosses of Variation with pure horned 

 cows he obtains 22 polled to 6 horned, or a difference from the expected 

 14 to 14 of 3.1 times the probable error of the theoretical half, or what 

 might seem a significant difference. Lloyd-Jones and Eward (20) 

 have added materially to the data already presented. In 71 matinga 

 of Shorthorn bulls to Galloway cows 70 were clear-polled, 6 scurred, 

 and 2 horned. This would seem to indicate that the polled factor is 

 dominant. By this view the tw^o horned heifers are exceptions to this 

 conclusion. On this point, however, it seems well to quote them, as it 

 appears to the author that the explanation they offer is correct. In 

 reference to the dams of these horned heifers, they say {20, p. looa) : 



The cows 154 and 49 are referred to as "pure-bred Galloway," but their behavior 

 in respect to the transmission of horns is not in harmony with what we should be 

 justified in expecting if this were the case. Of all the pwlled breeds of cattle the 

 Galloways have been longest established and, in the matter of horns perhaps the most 

 rigidly selected , and they are recognized as practically never producing homedoffspring. 

 On the other hand, it must be pointed out that there does not exist an inevitable 

 incompatibility between the heterozygous condition for polled, on the one hand, 

 and the "pure-bred" condition, on the other. To be pure bred, from the breeders' 

 standpoint, an animal must be recorded in the record books of the breed associations, 

 or eligible for such record, or it must be from parents whose recent ancestors were 

 thus recorded or eligible to record. To be sure, homed Galloways are not eligible 

 to record, but the herd-book associations make no biological restrictions as to the 



