Based on management records of 181 Japanese Black beef calves (93 females and 88 males), we evaluated birth weight, subsequent growth, and carcass traits of cattle related to the apparent thickness of the umbilical cord in Experiment (Exp.) 1. Generalized regression analyses showed that birth weight was significantly greater in calves with a visually thick umbilical cord (P = 0.002). In addition, the birth weight was positively related to daily gain during the fattening period (P < 0.001) as well as carcass weight (P < 0.001). In Exp. 2, we measured the thickness of the umbilical cord of 26 calves by use of a caliper. The measured umbilical cord thickness was also positively related to birth weight (r2 = 0.178, P = 0.03) by linear regression analyses. We further evaluated the involvement of vitamin E status in dams in birth weight and measured umbilical cord thickness of their calves using 26 dams and their calves (Exp. 2). Serum vitamin E levels of the dams at 10 days before expected parturition were positively related to birth weight (r2 = 0.213, P = 0.02) but not umbilical cord thickness of their calves. In Exp. 3, vitamin E was supplemented to 9 dams during the final 3 months of pregnancy (1 g/day/head α-tocopherol acetate). As the control group, additional vitamin E was not provided in 11 dams. The vitamin E supplementation tended to increase birth weight (P = 0.08) but did not affect umbilical cord thickness in their calves (P = 0.83). In Exp. 4, the umbilical cords in Exp. 2 and Exp. 3 were histologically analyzed. Morphological analysis of the sections stained with hematoxylin and eosin revealed that the umbilical cord lining epithelial cell density was similar, irrespective of the umbilical cord thickness, whereas the stromal cell density was decreased with increasing umbilical cord thickness (r2 = 0.769, P = 0.02) by linear regression analyses. Our data suggest that activation of stromal cells in the umbilical cord is responsible for the thickening of the umbilical cord. In addition, vitamin E can stimulate the intrauterine growth of the fetus without affecting umbilical cord thickness. The present study demonstrates umbilical cord thickness and maternal vitamin E status are crucial factors for the intrauterine growth of calves. Although birth weight is not solely determined by the umbilical cord thickness, a feeding program to thicken the umbilical cord could be useful for efficient beef production in Japanese Black beef cattle.
Itoyama et al. (Tue,) studied this question.