Metabolic status is associated with the recovery of milk somatic cell count and milk secretion after lipopolysaccharide-induced mastitis in dairy cows

摘要

Infections of the mammary gland in dairy cows arecommonly accompanied by reduced milk productionand feed intake and poor milk quality. The metabolicstatus of early-lactating cows is known to affect immuneresponse to pathogens and imposed immune challenges.We investigated the extent to which metabolic statusbefore an intramammary lipopolysaccharide (LPS)challenge (LPS-CH) is associated with immune response,milk production, and feed intake and the recoverythereof. In 15 Holstein cows, weekly blood samplingand daily recording of dry matter intake, milk yield,milk composition, and body weight (to calculate energybalance) was started immediately after parturition. Inwk 4 after parturition, cows underwent an intramammaryLPS-CH (50 μg of LPS into 1 quarter). Blood andmilk samples were taken in parallel at 30- and 60-minintervals, respectively, until 10 h after the LPS application.Plasma concentrations of glucose, nonesterifiedfatty acids, β-hydroxybutyrate (BHB), cortisol, and insulinwere analyzed. In milk, serum albumin, IgG concentration,somatic cell count (SCC), and lactate dehydrogenase(LDH) activity were determined. Dry matterintake and milk yield were recorded for an additional 6d. Milk of the LPS-treated quarter was sampled at everymilking for 8 d after the challenge. Based on plasmaglucose concentrations in wk 1 to 4 after parturitionbefore the LPS-CH, cows were retrospectively groupedinto a high-glucose group (HG; 3.34–3.93 mmol/L, n= 7) and a low-glucose group (LG; 2.87–3.31 mmol/L,n = 8). Data were evaluated using mixed models withtime, group, and time × group interaction as fixed effectsand cow as repeated subject. Glucose was lowerand BHB was higher in LG compared with HG beforeLPS-CH, whereas dry matter intake, energy balance,and SCC did not differ. During LPS-CH, SCC and LDHincreased similarly in HG and LG, body temperatureincreased less in HG, and BHB and nonesterified fattyacids were higher in LG compared with HG. Dry matterintake declined in both groups during the day of theLPS-CH but recovered to prechallenge values faster inHG. Milk yield recovered within 2 d after the LPS-CHwith no differences in morning milkings, whereas eveningmilk yield increased faster in HG. During 8 d afterLPS-CH, SCC, LDH, IgG, and serum albumin in milkwere lower in HG compared with LG. In conclusion, thelevel of circulating glucose and BHB concentrations incows was associated with metabolic responses duringan LPS-CH as well as the recovery of udder health andperformance thereafter.