Short communication: Serum osteoprotegerin concentrations in periparturient dairy cows

Abstract

Dairy cows experience hypocalcemia at the onset of lactation; however, the contribution of bone metabolism to circulating Ca concentrations during the periparturient period is not well understood. Osteoprotegerin (OPG) protects against loss of skeletal mass by regulating osteoclastogenesis. We previously reported that the bone resorption increased around parturition in dairy cows from the perspective of bone markers in blood. The aim of this study was to explore osteoclastic bone resorption in periparturient dairy cows by measuring changes in serum OPG concentrations around calving. The OPG concentrations were evaluated in primiparous (n = 9) and multiparous (n = 9) cows at 21 d precalving and over 5 d after calving. Based on mixed model analyses, the multiparous cows had a higher serum OPG concentration than primiparous cows at precalving and exhibited a significant decline in serum OPG and Ca concentrations after calving. In contrast to multiparous cows, primiparous cows did not exhibit these changes. Therefore, we hypothesized that multiparous cows preserve their bone mineral content during late pregnancy and activate the osteoclastic bone resorption after calving. Based on our serum OPG data, we identified the different periparturient osteoclastic bone resorption patterns in healthy primiparous and multiparous dairy cows.

Prepartum measurement of serum biomarkers reflecting osteoclastic and osteoblastic bone metabolism for predicting the risk of milk fever in dairy cows

“…Specifically, the Ca concentration in multiparous cows with more than three lactations (M3 group) was lower than that in heifers (NP group) and other cows with one or two lactations (PP and M2 groups). These observations are in line with previous findings showing increased severity of parturient hypocalcaemia with advanced parity (Kim et al ., 2010; Hatate et al ., 2018, 2020; Megahed et al ., 2018; Chiba et al ., 2020 b ), supporting the long-held hypotheses that elderly parturient cows tend to have disturbed Ca homoeostasis due to rapid leakage of large amounts of Ca into the colostrum (Martín-Tereso and Verstegen, 2011; Megahed et al ., 2018) and an age-related inability to promptly mobilise Ca from bone and the gastrointestinal tract (Ramberg et al ., 1984; Yamagishi et al ., 2006; Martín-Tereso and Verstegen, 2011; Hatate et al ., 2018, 2020). The cumulative milk yield during the 5-d postcalving period was lower in the NP than other groups.…”

“…Serum TRAP5b activity had moderate associations with parity and age, whereas the A/T ratio had a moderate association with parity. The serum Ca concentration in parturient cows tends to be higher in younger animals (Kim et al ., 2010; Hatate et al ., 2018, 2020; Megahed et al ., 2018). Circulating ALP3 and TRAP5b activities are lower as parity advances (Kim et al ., 2010; Hatate et al ., 2020; Chiba et al ., 2020 b ).…”

“…Circulating TRAP5b activity in dairy cows increased commencing 1 week prepartum and was maintained at this level up to a few days postpartum (Devkota et al ., 2015). Multiparous cows had a higher serum OPG concentration than late-pregnant heifers at 21 d precalving, indicating that older cows may preserve their bone mineral content during late pregnancy (Hatate et al ., 2018, 2020). Our pilot study, using the data of cows recruited from several experiments (Hatate et al ., 2020), showed that the decrease in the ratio of OPG and TRAP5b (O/T ratio) towards calving was less pronounced in MF cows compared to cows without MF.…”