Studies on the Hoof Quality of the Japanese Breeds of Cattle

It is a well-known fact that the hoof of cattle play's an important role when cattle are used as work animal. The fundamental research on hoof, however, has not been performed extensively, so far as the author is aware. The author has carried out studies on the hoof quality for the purpose of improving the utilization capacity of draft and work cattle. In testing the resisting power of hoof to the load, tensile test (Plate 9,19) as well as abrasion test (Plate 9,20) were employed, and four breeds of Japanese cattle, namely, Japanese Black Breed, Japanese Brown Breed, Misima Cattle (Japanese Native Cattle) and Japanese Polled Breed were used. It was found that the hardness of hoof quality had varieties, and also had a close relation to the structure of the tissue of hoof. Though the properties of horn-tubea in the horny capsule of hoof seems to correlate with the physical properties as hardness and resilience of it, there is no experimental proof. The present studies are the results obtained from careful observations on the various aspects of hoof quality with special reference to the horn-tubes. (1) The horn-tubes exist in the middle layer of hoof's wall and in the sole of hoof. The middle layer of hoof is divided into three equal parts, i. e., a, b and c. The part a is innermost and the part c is outermost (Fig.1). The resurts of observation of the horn-tubes are summarize! as follows: (a) Toe: the horn-tubes of part a are oval in shape and the horn-tubes which are located near to part b are larger than those which are located apart from it. It shows that both central cells of horn-tubes and horn-tube cells of part a are young and soft (Platc6.1&2). The horn-tubes of part b are round or oval in shape and large in size. The horn-tube cells develop fully and their central cells are vacuolated(Plate 6,3&4). The horn-tubes of part c are long ellipse in shape, the horn-tube cells and central cells degenerate at the region near to outer layer of wall (Plate fi,5&6). (b) Side wall: the horn-tubes of part a are oval in shape and small in size, the horn-tube cells in the region near to horn lamina are young and soft (Plate 7,7). The horn-tubes of part b are round in shape and medium in size, they are in full growth but they are smaller than those in the toe(Plate7,8). The horn-tubes of part c are oval in shape and degenerate in the region near to outer layer of wall. (c) Quarters: the horn-tubes of part a are seen to be immature and soft (Plate 7,9). The horn-tubes of partb are round in shape and develop fully, but the central cells are not vacuolated(Plate7,10). The horn-tubes of part c are not so small as the horn-tubes in the region near to the outer layer of wall (Plate 7,11) . (d) Inner wall: the horn-tubes of part a are oval in shape and are seen to be active(Plate 7,12). The horn-tubes of part b are oval in shape and develop fully, some of their central cells are vacuolated(Plate 8.13&16). The horn-tubes of part c do not degenerate so much as the the horn-tubes in the region near to the outer layer of wall, and their central cells do not degenerate and are seen to be active (Plate8,14&15). (e) Sole of wall: the horn-tubes are round in shape and soft, they are not seen distinctly (Plate 8,17). (2) The horn-tubes in the hoof wall have close relation with the hardness of the hoof, that is, the resilient hoof has large horn-tubes and large horn-tube cells, as well (Plate 10,25). The less resilient hoof has smaller horn-tubes and smaller central cells, these central cells are not active (Plate 9,23). From the fact that there can be oberved, under microscope, many horn-tubes in the hard hoof as shown in Plate 9,21 which shows a transverse section of hoof, the magnitude being ×100, the hardness of the hoof quality can be determined by number of horn-tubes. (3) From the results of observations in the Misima Cattle and the Japanese Polled Breed, it was considered that the number of horn-tubes was determined by quantitative hereditary factors. The authour presumably concludes that 3 incomplete dominant facters (A_1A_2A_3) concern with the number of horn-tubes. Heterozygous Fj is assumed as A_1a_1A_2a_2A_8a_8 in its genetic constitution and Fo shows as if the segregation of trihybrid (Figs.4～6). (4) The growth of calves accompanies with the growth of horn-tubes, that is, as the calves become bigger the hoof grows to become larger and the horn-tubes also attain their larger size. It is about 18 months of age when the horn-tubes attain their full growth ( Plate 12,37～42). (5) The characteristics of hoof are influenced by not only heredity but also environment. The horn-tubes of cattle in Karst-district are hard and the angle of horn-tube is large, on the other hand, the horn-tubes of cattle kept in the stall to be, fattened are swollen and soft, and the angle of horn-tube is small. (6) The differences of characteristics of hoof among various breeds were examined: (a) The horn-tubes of Holstein-Friesian Cattle are softer than that of the Japanese Breed of Cattle (Plate 14.53&54). (b) The horn-tubet of the Misima Cattle resemble to those of the Japanese Black Breed, but the horn-tubes of the former are a little finer than those of the latter (Plate 14,49). (c) The horn-tubes of the Japanese Brown Breed are larger and softer than those of the Japanese Black Breed (Plate 14,51) . (d) The horn-tubes of the Japanese Polled Breed are quite similar to those of the Japanese Brown Breed (Plate 14,52). (7) When the hoof is oild the abrasion of hoof becomes slight, and this is due to the fact that the oil protects it from the abrasion and promotes the resiliency, permeating into tissue of hoof, especially into horn-tubes. At the beginning of the labor in the puddy field, the abrasion of the hoof is very slow, but the abrasion of the hoof gradu- ally increases as the labor-hour is prolonged. When cattle are loaded with heavy goods on their back, the abrasion of hoof occurs strrnger than when non-loaded, hut the difference between them is rather insignificant (Figs. 1O～11).