Short communication: Temporal changes in the skin morphology of dairy cows during the periparturient period

Management of dairy cow productivity requires monitoring of their nutritional status by visual observation. It has been suggested that changes in hair coat appearance are among the indicators of nutritional state in dairy cows. Temporal changes in the skin morphology in cows, however, have not been reported. In this study, we examined the changes in the skin of dairy cows that occur during the peripartum period. Seven pluriparous cows were used. Skin samples were collected at 28 d before the due date and 28 d and 56 d after calving for morphological examination. Hair follicle width was 108.8 ± 5.9 µm (±SD) in the dry period, 95.5 ± 5.5 µm at 28 d after calving, and 104.2 ± 5.3 µm at 56 d postpartum. The percentages of anagen hair follicles during these 3 periods were 41.4 ± 3.4, 18.5 ± 3.4, and 32.3 ± 3.3%, respectively. The corresponding sebaceous gland sizes were 8,362.0 ± 707.6, 7,800.0 ± 831.4, and 9,186.8 ± 962.6 µm², respectively. Hair follicle width was positively correlated with percentage of anagen hair follicles. The thickness of epidermal and proliferation rate of epidermal cell were also correlated. However, the hair follicle width, sebaceous gland size and cell proliferation rate, and thickness and proliferation rate of epidermal cells did not show any marked changes.