THE RELATION BETWEEN POLLED AND HERMAPHRODITIC CHARACTERS IN DAIRY GOATS

Abstract

H E problem of the occurrence of hermaphrodites in dairy goats, especially T in purebred herds where attention is given to the breeding of polled animals , has led to inquiries regarding the relation between the polled condition and the birth of hermaphrodites. Several observers have noted the fact that horned hermaphrodites are very rare or perhaps do not occur a t all. ADDING-TON and CUNNINGHAM (1935), of the New Mexico Station, in a study of the heredity of horns in goats noted that four hermaphrodites, all polled, appeared in matings between animals heterozygous for the polled condition. PAGET (1943) reported that horned hermaphrodites are a very great rarity, known only in occasional instances among British goats. ASDELL (1944) has observed about 2 0 0 intersexual goats both in England and in America and found all to be hornless. These observations and direct inquiries have led to a study of the polled or horned condition of hermaphrodites and normal animals in the UNITED STATES DEPARTMENT OF AGRICULTURE'S herd of Saanen and Toggenburg goats a t Beltsville, Md. EXPERIMENTAL DATA The period included in this study covers 2 0 years from 1925-1944, inclusive. The data recorded include number of polled and horned animals, number of normal males, females, and hermaphrodites, and the various types of matings. These data are shown separately for Saanens and Toggenburgs in table I. The horned character of several of the progeny was not recorded, and in a few cases sex was not recorded, the latter being stillbirths and abortions. In some instances the horned character of the dams was not known. These have been indicated in the table by a question mark. The bucks in both herds were polled except one of the Toggenburgs, which sired only I I kids. One Saanen buck evidently was homozygous for the polled condition, since all of the 66 kids which he sired out of both polled and horned does were polled. All hermaphrodites produced in the Beltsville herd, and their parents, were polled. Horns in goats are inherited as a simple recessive. Therefore, in matings between animals heterozygous for the polled condition, one quarter of the progeny should have horns. I n the Saanens the ratio was 219 polled: 63 horned; and in the Toggenburgs 255: 89. These numbers agree very well with expectation. Chi-square for the two herds combined is 1.203 with a corresponding P value of 0.548. I n deriving these values, chi-square is the sum of the chi-squares for each breed calculated separately, and P is caclulated for two degrees of freedom (the sum of one degree of freedom for each breed).