Monozygotic bovine quadruplets
H. P. DONALD, W. S. BIGGAR and D. M. LOGAN Animal Breeding and Genetics Research Organisation, Edinburgh Received Io.v.5o ON the 27th January 1949, a Friesian type cow called Peggy, and belonging to Mr William Youngs of Sankence Farm, Aylsham, Norfolk, produced four bull calves. After undergoing considerable publicity for a few days, Peggy died, but the calves survived and were purchased by the Agricultural Research Council, and transferred to the Cattle Breeding Research Farm at Cold Norton in Staffordshire. These calves are remarkable, not only because quadruplets are unusual in cattle, but also because they were born alive, and were all of the same sex. Furthermore, they appear to be the first recorded set judged to be of monozygotic origin. A somewhat detailed account of them, therefore, appears desirable. Unfortunately, two of the calves died a few weeks after purchase, so that a comparison of late developing features became impossible. The evidence on which the diagnosis of one-egg origin is based is as follows. Except where otherwise noted, all remarks apply equally to all four calves.
Inheritance in Crosses of Jersey and Holstein-Friesian with Aberdeenangus Cattle. II. Color and White Spotting
The results of crossbreeding between self-colored black Aberdeen-Angus animals and fawn Jerseys, and also between black, or red Angus and black-and-white, or red-and-white Holstein-Friesians may be summarized as follows: 1. In the Jersey x Angus cross the black color of the Angus breed was almost completely dominant in F1 over the fawn color of the Jerseys. The young calves showed in some cases a considerable degree of fawning but darkened with increasing age, and most F1 animals became intense black at the age of maturity. In F2 segregation occurred but the gradation in color was rather continuous, ranging from solid black to dark Jersey fawn. If F2 animals with muzzle band and distinct fawning are considered as Jersey colored, and the others as black, a ratio of 13 black to 4 Jersey colored is obtained. Two out of 4 Jersey colored F2 animals were distinctly brindled. The results are explained on the assumption that most purebred Angus are homozygous for a gene E causing complete extension of black pigment over the body. The Jerseys carry a different gene, Bs, causing only a partial extension of black. Modifying genes may influence the level of pigmentation in animals with partial extension of black. The gene for brindling, Br, was apparently introduced to this cross from the Angus. 2. In the Holstein x Angus cross black-pigmented bulls and, in the majority of eases, red-pigmented cows were used: two Angus cows were, however, self black. In matings between red- and black-colored parents, black was completely dominant over red in the F1 generation. In the F2 clear out segregation occurred but the ratio of 24: black to 17 red is a poor fit to the expected 3:1 ratio (P≅0.02). Considering results from crosses between black and red breeds, reported by other investigators, however, the hypothesis of monohybrid segregation is adopted. 3. In the F1 generation of the Holstein x Angus cross self color is strongly but not completely dominant to white spotting. Many F1 animals have, however, a considerable amount of white on the underline, and they may also have some white on the hind feet and a small white star. In the Fa generation there is a range in the extension of pigment from self-colored to predominantly white. The range is not quite continuous, however, and the Fa animals can therefore be divided into two fairly distinct groups, one group resembling the Angus and the F1 generation, and the other spotted with a variation in the extension of pigment observed in the Holstein breed. The ratio of "self" colored to spotted is 33:10, which approximates closely the expected 3:1 ratio in a monohybrid segregation. The Angus breed is homozygous self-colored (SS) and the Holsteins are homozygous for a recessive gene for white spotting (s), the level of pigmentation (the amount of white) being influenced by an unknown number of modifying genes. In the spotted animals the pigment recedes in a fairly definite manner as the level of pigmentation decreases, primary and secondary breaks occurring between pigment centers. The presence of pigmented spots on the legs in some of the ss segregates may be explained on the assumption of a gene, Pl, for such pigmentation, which probably was brought in through the Angus breed. No evidence is found for the presence of a particular gene for inguinal white. In red-and-white animals the borderline between pigmented and white areas is, as a rule, much more irregular than is the case when the animals carry black pigment. This may be due to a physiological correlation between red pigment and pigment distribution. 4. Self-colored Mack animals have Mack muzzle and tongue. In spotted black-and-white animals the extension of black pigment on the tongue is correlated with the extension of black on the body. The ss segregates from the Holstein x Angus cross had invariably "fleshcolored" tongue. The muzzle color is black in animals carrying the gene for extension (E) or partial extension (Bs) of black when white spots do not invade this region of the head. In the red animals the muzzle is "fleshcolored" or carries red pigment. We have found no evidence for the assumption that either muzzle or tongue color is determined by particular genes.
Pattern Development in Mammals and Birds
The principal points of this paper may be summed up as follows: In mammals and birds that normally are completely pigmented, there are certain definite points of the body from which as centers the tendency to develop pigment in the epidermal structures may become less and less. Outward from each of these centers pigment formation spreads to include very definite areas which in wholly pigmented animals overlap slightly at their borders or are at least contiguous. 2. A reduction in the area covered by any of these primary patches results in a white mark at the line of junction of two contiguous color patches, where no pigment is produced. These white marks between the primary patches are spoken of as primary breaks. 3. Through a study of the breaks in pied individuals of domesticated species of mammals and birds, the boundaries of the primary patches have been determined. These are homologous in the two groups and subject to a certain amount of variation in different types. They are: a median crown patch un...