Supplementary materials for Calcium status of multiparous Holstein cows during early lactation and its association with the health and production of dairies in Antioquia, Colombia

This file contains data supporting forage and concentrate results reported in Graef et. al Calcium status of multiparous Holstein cows during early lactation and its association with the health and production of dairies in Antioquia, Colombia.
In Graef et. al, we found: Periparturient hypocalcemia in dairy cows is known to negatively affect health and milk production. The grazing-based dairy industry of Colombia is the fourth largest milk producer in Latin America and is rapidly growing. However, with renewed commitments to sustainable intensification, Colombia may be disproportionately affected by poor forage quality and periparturient diseases due to limited access to technology and infrastructure. The primary objective was to assess the incidence of subclinical hypocalcemia (SCH) across three commercial dairy farms in Antioquia, Colombia, and its association with milk production, disease, and culling. Multiparous Holstein cows (n = 136) were enrolled in a prospective cohort study design on 3 farms in Antioquia, Colombia, from July to December 2023. Serum concentrations of total calcium were analyzed prepartum, between 1 and 10 d before expected calving, and postpartum at 1, 2, 4, and 7 days in milk (DIM). Cows were assigned either as eucalcemic (EU) or SCH based on the mean total calcium serum concentration at 4 DIM in this study [EU > 2.40 mmol/L and SCH ≤ 2.40 mmol/L]. Milk production was recorded daily. The SAS MIXED procedure with repeated measures was used to analyze differences between EU and SCH cows and respective milk production. The incidence of SCH was 39%. Pre and postpartum blood total calcium were greater in EU than SCH (prepartum = 0.23 mmol/L, 95% CI 0.39 to 0.07 mmol/L; and postpartum = 0.37 mmol/L, 95% CI 0.45 to 0.29 mmol/L). Over time, EU cows had greater milk yields in the first 9 wk of lactation than SCH cows (1.43 kg/d; 95% CI 2.90 to 0.20 kg/d) without significant changes in risk to disease or culling (P ≥ 0.13). Overall, SCH is a prevalent challenge in grazing systems in Colombian dairy herds and may affect the production and may unduly impact disease, culling, and reproduction outcomes.