Metabolic and inflammatory responses reveal different adaptation to the transition period challenges in Holstein, Brown Swiss, and Simmental dairy cows

Twelve Holstein (HOL), 9 Brown Swiss (BRO), and 9 Simmental (SIM) dairy cows raised in the same barn and managed identically were enrolled to characterise the responses to the transition period. From -21 to 28 d from calving (DFC), body condition score (BCS) and milk yield were measured, and blood samples were collected to assess plasma biomarkers of metabolism, minerals, liver function, inflammation, and oxidative status. Compared with SIM, HOL and BRO had higher milk yield during the first week of lactation. HOL had the highest milk yield from the second to the fourth week and the lowest BCS at 28 DFC. SIM had the highest BCS and the highest plasma creatinine and P, reflecting a greater attitude to gain muscle mass. Compared with SIM, BRO and HOL had lower plasma fructosamine, indicating reduced glucose availability driven by lactose synthesis. SIM had the mildest acute phase response at the onset of lactation, as suggested by the lowest ceruloplasmin concentration. HOL had the highest cholesterol and paraoxonase concentrations, and the greatest interleukin-1 beta production by leukocytes following ex-vivo stimulation, suggesting that they had the quickest resolution of the acute phase response due to the fastest immune cell activation. BRO had the highest concentration of reactive oxygen metabolites, ceruloplasmin, bilirubin, glutamate-oxaloacetate transaminase, gamma-glutamyl transferase, and beta-hydroxybutyrate, and the lowest concentration of paraoxonase, reflecting the strongest activation of leukocytes and the most severe acute phase response. Together, these results highlight different metabolic and inflammatory conditions around calving in the three explored breeds.