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This study aimed to identify interactions between state of lactation (dry or early lactating) and immune responder group (low, medium, or high) for energy metabolism traits as well as metabolic and immunological traits in dairy cows. In early lactation, when the energy priority of cows shifts toward the mammary gland, the energy available to be partitioned toward the immune system may differ among individuals. The equilibrium between energy supply from feed, digestion, and body reserve mobilization and energy expenditure with milk, immune system, methane, and heat production is delicate in this stage. Seventeen Holstein cows entering their second to fifth lactation were kept under comparable feeding, housing, and management conditions and were studied from 14 ± 6 d before calving to 11 ± 3 d after calving. Feed intake, milk yield, body condition, blood metabolites, and cortisol as well as gaseous exchange in respiration chambers were measured. The latter was used to quantify methane emission and to calculate resting metabolic rate and heat production. Subsets of blood leukocytes and peripheral blood mononuclear cells (PBMC) were monitored. Activation and proliferation of the PBMC in response to the mitogen phytohemagglutinin ante- and postpartum were assessed using the oxygen consumption rate (24-h cell culture assay) and the 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide (MTT) assay (72-h cell culture assay). Cows were classified based on the in vitro proliferative response of the PBMC measured postpartum in low (n = 6), medium (n = 5), and high (n = 6) responders. We found no interaction of state of lactation with responder group for feed intake, milk yield, efficiency, metabolic traits, and immune cell activation ante- and postpartum. However, after calving, low-responder cows produced less methane per unit of body weight and per unit of energy-corrected milk compared with the other cows. This might be indicative of a low rumen fermentation intensity. Low responders might therefore suffer from a lower availability of digestible energy in early lactation and not be able to sustain the shift from immune cell activation to proliferation. If so, the selection of environmentally friendly low-methane emitters could promote phenotypes with a compromised immune response in the critical early lactation., (Copyright © 2020 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Inflammation of the uterus is associated with disturbed ovarian function and reduced reproductive performance in dairy cows. To investigate the influence of endometritis on the bovine corpus luteum, 8 heifers received intrauterine infusions with either phosphate-buffered saline (PBS; 9mL) or Escherichia coli lipopolysaccharide (LPS; 3µg/kg of body weight diluted in 9mL of PBS) at 6-h intervals from 12h before and until 9d after ovulation during 2 cycles in a random order (ovulation=d 1). An untreated cycle was examined before and after PBS and LPS cycles, and the mean values from both untreated cycles were used as control. In all cycles, blood sampling and ultrasonography of the ovaries were performed on d 0, 1, 2, 4, 6, 8, 9, 10, 12, 15, 18, and then every 2d until ovulation. Endometrial cells were collected for cytology and quantitative real-time reverse transcriptase PCR on d 0, 6, and 9, and on d 0 and 6, respectively, and luteal tissue was collected for quantitative real-time reverse transcriptase PCR on d 6 and 9. Both, PBS and LPS infusions induced subclinical endometritis, which was accompanied by increased endometrial mRNA abundance of proinflammatory cytokines IL1β, IL8, and tumor necrosis factor α. Additionally, LPS challenge induced premature luteolysis, which was characterized by increased plasma concentrations of PGF2α metabolite, decreased plasma progesterone concentrations, and reduced luteal size and blood flow compared with the control. The luteal mRNA expression of the LPS receptor TLR4, PGE synthase, and the apoptosis-related factor CASP3 were higher, and those of steroidogenic factors STAR and HSD3B, the PGF receptor, and the angiogenic factor VEGFA121 were lower after LPS challenge compared with the control. In conclusion, repeated intrauterine LPS infusions during the first 9d of the estrous cycle alter gene expression and shorten the lifespan of the bovine corpus luteum., (Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Data from various studies indicate that the ovarian function in dairy cows can be compromised during intramammary infections. Therefore, in this study, we investigated if an experimentally induced mastitis has an effect on corpus luteum (CL) function in 14 lactating cows. On d 9 of the estrous cycle (d 1=ovulation), cows received a single dose of 200 μg of Escherichia coli lipopolysaccharide (LPS; dissolved in 10 mL of NaCL; n=8) or 10 mL of saline (control; n=6) into one quarter of the mammary gland. Measurements included plasma cortisol, haptoglobin, and progesterone (P4) concentrations, as well as luteal size (LTA) and relative luteal blood flow (rLBF). Sampling was performed on d 1, 4, and 8. On d 9, the main examination day, sampling was performed immediately before (0 h), every 1h (or at 3-h intervals for LTA and rLBF) until 9 h, as well as 12 and 24 h after treatment. Thereafter, measurements were taken on d 12, 15, 18, and then every 2 d until ovulation. Luteal tissue was collected for biopsy 24 h before and 6 h after treatment. Quantitative real-time PCR was applied to assess mRNA expression of steroidogenic factors (STAR, HSD3B), caspase 3, toll-like receptors (TLR2, -4), tumor necrosis factor α (TNFA), and prostaglandin-related factors (PGES, PGFS, PTGFR). Intramammary LPS infusion caused considerable inflammatory responses in the treated udder quarters. No decrease in plasma P4 concentrations was noted after LPS-challenge, and P4 levels did not differ between LPS-treated and control cows. Furthermore, LTA and rLBF values were not decreased after LPS challenge compared with the values obtained immediately before treatment. However, LPS infusion increased plasma levels of cortisol and haptoglobin compared with the control group. In the CL, mRNA abundance of TLR2 and TNFA was increased in cows after LPS-challenge (but not in control cows), whereas TLR4, steroidogenic, and prostaglandin-related factors remained similar to the mRNA abundance before treatment. In conclusion, intramammary LPS challenge induces systemic inflammatory reactions which alter the luteal mRNA abundance of TLR2 and TNFA but does not induce lysis of the CL., (Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)