Background Mastitis is the most frequent diseases for transition cows. Identification of potential biomarkers for diagnosis of mastitis is important for its prevention. Thus, this study was conducted to investigate blood variables related to lipid metabolism, oxidative stress and inflammation, and serum variables that are related to health in postpartum cows. Results Seventy-six healthy Holstein dairy cows at week 4 before calving were selected to collect blood samples from weeks − 4 to 4 weekly relative to calving, respectively. Milk yield and composition were recorded weekly. According to the cut-off of somatic cell counts (SCC) for diagnosis of mastitis, 33 cows with SCC ≥ 500,000 cells ml− 1, 20 cows with 200,000 cells ≤ SCC < 500,000 cells ml− 1, and 23 cows with SCC < 200,000 cells ml− 1 were defined as high, middle, and low SCC, respectively. Serum concentrations of β-hydroxybutyrate were higher (P < 0.01) during all weeks, and non-esterified fatty acids were higher in high SCC than in low SCC cows from weeks − 3 to 2 relative to calving. Higher serum concentrations of superoxide dismutase (P < 0.01) and lower malondialdehyde levels (P < 0.01) in low SCC than in high SCC cows indicate that the latter suffered from oxidative stress. The difference analysis of the three groups suggested that none of the above-mentioned variables can be used as potential prognostic candidates. On the other hand, high SCC cows exhibited higher blood neutrophil to lymphocyte ratio (NLR, P < 0.01) and platelet to lymphocyte ratio (PLR, P < 0.01) than low SCC cows, with a higher NLR (P < 0.01) in middle SCC than in low SCC cows. The high SCC cows had lower levels of anti-inflammatory factors including IL-10 (P = 0.05), but higher levels of proinflammatory factors such as IL-6 (P < 0.01), TNF-α (P < 0.05), and PSGL-1 (P < 0.01) than low SCC cows. Conclusions The significantly different NLR and PLR pre-partum between the middle and low SCC cows suggest their prognostic potential for postpartum mastitis risk.

The objective of this study was to evaluate the effects of rumen-protected betaine supplementation on performance of postpartum dairy cows and immunity of newborn calves. Twenty-four multiparous Holstein dairy cows were randomly divided into the control (CON, n = 12) and rumen-protected betaine (BET, n = 12) groups after blocking by parity and milk yield during the previous lactation cycle. The cows were fed a basal total mixed ration diet without BET (CON) or with BET at 20 g/d per cow (BET) from four weeks before expected calving to six weeks postpartum. The results showed that betaine supplementation had no effect on dry matter intake and milk yield of the cows. The BET cows tended to increase feed efficiency (energy-corrected milk/dry matter intake) and body weight loss postpartum compared to the CON cows. The plasma β-hydroxybutyrate concentrations of the BET cows were greater at d seven after calving than those of the CON cows. Moreover, compared to the CON calves, the BET calves had greater plasma total protein and globulin concentrations. The plasma glucose concentrations of the BET calves tended to decrease relative to CON cows. In conclusion, rumen-protected betaine supplementation from four weeks before expected calving tended to increase fat mobilization of postpartum dairy cows, and might improve the immunity of newborn calves.

The current study was conducted to analyze the functions of blood neutrophils in transition cows and their association with postpartum mastitis risk as indicated by somatic cell counts (SCCs) in milk. Seventy-six healthy Holstein dairy cows were monitored from Week 4 prepartum to Week 4 postpartum. Five dairy cows with low SCCs (38 ± 6.0 × 103/mL) and five with high SCCs (3,753 ± 570.0 × 103/mL) were selected based on milk SCCs during the first three weeks of lactation. At Week 1 pre- and postpartum, serum samples were obtained from each cow to measure neutrophil extracellular trap (NET)-related variables, and blood neutrophils were collected for transcriptome analysis by RNA sequencing. The serum concentration of NETs was significantly higher (P &lt; 0.05) in cows with high SCCs than in cows with low SCCs (36.5 ± 2.92 vs. 18.4 ± 1.73 ng/mL). The transcriptomic analysis revealed that the transcriptome differences in neutrophils between high- and low-SCC cows were mainly in cell cycle-related pathways (42.6%), including the cell cycle, DNA damage, and chromosomal conformation, at Week 1 prepartum. The hub genes of these pathways were mainly involved in both the cell cycle and NETosis. These results indicated that the formation of NETs in the blood of transition dairy cows was different between cows with low and high SCCs, which may be used as a potential indicator for the prognosis of postpartum mastitis risk and management strategies of perinatal dairy cows.

Background Mastitis is one of the most frequent diseases for transition cows, causing significant economic losses. Identification of potential biomarkers for diagnosis of mastitis is important for its prevention. Thus, this study was conducted to investigate alterations in blood inflammatory cells and serum variables that are related to health in postpartum cows. Results Seventy-six healthy Holstein dairy cows at week 4 before calving were selected. Blood samples were collected at weeks -4, -3, -2, -1, 1, 2, 3 and 4 relative to calving, respectively. Milk yield and composition were recorded weekly. According to the cutoff of somatic cell counts (SCC) for diagnosis of mastitis, 33 cows with SCC ≥ 500,000 ml -1 , 22 cows with 200,000 ≤ SCC < 500,000 ml -1 , and 23 cows with SCC < 200,000 ml -1 were defined as high, middle, and low SCC, respectively. Serum concentrations of β-hydroxybutyrate were higher ( P < 0.01) during all weeks, and non-esterified fatty acids were elevated from weeks -3 to 2 relative to calving in high SCC cows compared to low SCC cows. Higher serum concentrations of superoxide dismutase ( P < 0.01) and lower malondialdehyde levels ( P < 0.01) in low SCC than in high SCC cows indicate that the latter suffered from oxidative stress. In addition, high SCC cows exhibited higher blood neutrophil to lymphocyte ratio (NLR, P < 0.01) and platelet to lymphocyte ratio (PLR, P < 0.01) than low SCC cows, with a higher NLR ( P < 0.01) in middle SCC than in low SCC cows. The high SCC cows had lower levels of anti-inflammatory factors including IL-10 ( P = 0.05), CD4 ( P < 0.01) and CD8 ( P < 0.01), but higher levels of proinflammatory factors such as IL-6 ( P < 0.01), TNF-α ( P < 0.05), and PSGL-1 ( P < 0.01) than low SCC cows, leading to the elevated NLR and PLR in high SCC cows. Conclusions The significantly different NLR and PLR pre-partum between the middle and low SCC cows suggest their prognostic potential for postpartum mastitis risk