Department of Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, 2-11, Inada, Obihiro, Hokkaido, Japan; United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu, Japan.
Field Center of Animal Science and Agriculture, Obihiro University of Agriculture and Veterinary Medicine, 2-11, Inada, Obihiro, Hokkaido, Japan.
Res Vet Sci. 2020 Aug;131:301-305. doi: 10.1016/j.rvsc.2020.05.009. Epub 2020 May 15.
Osteoprotegerin (OPG) inhibits osteoclast (OC) differentiation. TRAP5b (tartrate-resistant acid phosphatase 5b) secreted by OCs reflects the numbers of mature OCs. This study assessed these OC-related markers around parturition in cows of different parities and in cows with milk fever (MF). The blood OPG and TRAP5b concentrations, as well as the ratio of OPG to TRAP5b (O/T), were measured beginning 3 weeks before (-21 d) and over a few days after calving in 49 Holstein Friesian cows at first (n = 8), second (n = 17), third (n = 12), and fourth or greater (n = 12) parities. The ratio of O/T at -21 d to O/T at calving (PreCOT) was also calculated. In the third and greater parities, seven cows developed MF (non-MF, n = 17). Regardless of the development of MF, the serum OPG started to decline in the last week of gestation only in the cows entering the second lactation, while the blood TRAP5b increased at calving in all cows. O/T decreased toward parturition only in multiparous cows. The decrease in O/T at caving was less pronounced in MF cows. PreCOT was negatively correlated with lactation number only in multiparous cows (n = 41, ρ = -0.50, P < .01). This study implied that OC differentiation toward calving was tapered in cows with advanced parities, and these indexes predict the risk of MF.
骨保护素（OPG）抑制破骨细胞（OC）分化。OC 分泌的抗酒石酸酸性磷酸酶 5b（TRAP5b）反映成熟 OC 的数量。本研究评估了不同胎次奶牛和乳热（MF）奶牛在分娩前后的这些 OC 相关标志物。在荷斯坦弗里生奶牛 49 头中，于分娩前 3 周（-21 d）开始，在分娩后几天内测量血液 OPG 和 TRAP5b 浓度，以及 OPG 与 TRAP5b 的比值（O/T），首次分娩（n = 8），第二次（n = 17），第三次（n = 12）和第四次或更多（n = 12）。还计算了-21 d 时的 O/T 与分娩时的 O/T 比值（PreCOT）。在第三胎及以上胎次中，7 头奶牛发生 MF（非 MF，n = 17）。无论是否发生 MF，血清 OPG 仅在进入第二次泌乳的奶牛的妊娠最后一周开始下降，而所有奶牛在分娩时血液 TRAP5b 增加。只有在多胎奶牛中，O/T 才会在接近分娩时下降。MF 奶牛在分娩时 O/T 的下降不那么明显。仅在多胎奶牛（n = 41，ρ = -0.50，P <.01）中，PreCOT 与泌乳次数呈负相关。本研究表明，在胎次较高的奶牛中，OC 向分娩的分化逐渐减少，这些指标预测了 MF 的风险。
