Characterization of milk yield, milk solids, MUN, BHB, and SCC in confined Chilean Holstein cows

We aimed to characterize milk yield, solids, urea, BHB, and SCC of Holstein cows maintained in confinement in Chile. We analyzed records from a DHIA that conducts monthly milk testing (Cooprinsem, Osorno). The analysis included 96,872 lactations from 90 dairies recorded between 2017 and 2023. The inclusion criterion was lactations with complete data for the first 9 mo of lactation (T1 to T9) from primiparous cows (n = 10,283) and multiparous cows (2 to 10 lactations, n = 21,144). The dairies were visited monthly, and all lactating cows were sampled
for their daily milk production (kg). A composite sample from all 4 quarters was collected for subsequent analysis using a milk analyzer (MilkoScan 7 RM, FOSS). Milk samples were analyzed for fat (%), protein (%), MUN (mg/dL), BHB (mmol/L), and SCC (× 1,000/mL). Descriptive statistics for the variables under study were generated using SAS. The peak of lactation occurred in T2 in multiparous cows and in T3 in primiparous cows. The MUN values were higher in primiparous than
in multiparous cows, suggesting that primiparous cows were overfed protein, perhaps due to the use of a single TMR in dairies in central Chile. Peak BHB concentrations occurred at T1 across parity groups, with primiparous cows exhibiting greater values than multiparous cows. SCC values were lower in primiparous cows, while multiparous cows had values greater than 200,000 in all the periods, indicating that multiparous cows exhibit a significant level of subclinical mastitis (Table 1). Copyright © 2026 Elsevier Inc.