This study established a model of mineral element homeostatic imbalance and examined the respiratory burst function of peripheral blood neutrophils and inflammatory and antioxidant indicators before and after the imbalance in sheep. The results showed that after an EDTA injection, the number of activated neutrophils in the peripheral blood was significantly higher than that in the control group (p < 0.01). In addition, the serum IL-6 level was significantly increased (p < 0.05) and matrix metalloproteinase 7 (MMP7) was inhibited (p < 0.05), but returned to a normal level one week after the injection. Tissue inhibitor of metalloproteinase 1 (TIMP1) levels were consistently higher after the injection and significantly higher than in the control group (p < 0.05). CuZn-SOD, TNOS activity, serum creatinine and urea nitrogen levels were significantly higher than before the injection (p < 0.05). Combining the results of previous studies, the EDTA injection altered the metabolism and transcription of peripheral blood neutrophils. These changes enhance the respiratory burst function of neutrophils and alter the status of inflammatory and antioxidant indicators such as IL-6 and CuZn-SOD.

The DHI data is crucial for monitoring the udder health of dairy cows during the breeding process. This study aimed to investigate the factors influencing milk production in dairy cows throughout this period. We analyzed DHI data from Holstein dairy cows in the Heilongjiang region, alongside the incidence of mastitis. The findings revealed that high-yielding cows demonstrated significantly higher peak milk yield days, peak milk yield, urea nitrogen levels, 305-day milk yield, and persistency (p < 0.0001) compared to their low-yielding counterparts. Conversely, high-yielding cows exhibited lower protein rates, fat-to-protein ratios, and milk fat rates (p < 0.0001). Additionally, the somatic cell count (SCC) in high-yielding cows was significantly lower than that in low-yielding cows (p < 0.0001). The multivariate linear regression analysis of the DHI data indicated that parity was the primary determinant affecting both milk yield and SCC. Statistical analysis of cows with clinical mastitis revealed that those experiencing a single episode of clinical mastitis during the lactation period were predominantly in their first and second parities, while recurrent cases were primarily observed in the second and third parities. These results suggest that as the number of lactations increases, the SCC also rises, reflecting the cumulative impact of parity on the udder health of dairy cows.

Mammary glands in cows are highly dynamic, making genomic stability particularly crucial. Continuous lactation and self-renewal of these glands are primary contributors to genomic instability. Results: We employed transcriptomic and proteomic methods to analyze the expressional characteristics in the mammary glands of cows with varying levels of milk production. Our findings indicated differences in relevant pathways, including DNA damage repair and apoptosis, which are influenced by increasing parity. Notably, ATR protein levels in the mammary glands of low-yield dairy cows were reduced. Following in vitro silencing of ATR, β-galactosidase content increased in aging mammary epithelial cells, with cell cycle arrest in the G2 and S phases. Secretory phenotypes associated with aging, including IL-6, IL-10, IL-1β, INF-γ, and IL-2, were elevated, along with increased TNF-α content. The expressions of DNA repair-related proteins, including PIG3, PARP1, and Cleaved caspase3, were upregulated, and SP1 expression was decreased. Furthermore, the expressions of cytochrome C and BAK increased, and ATR silencing inhibited mTOR and STAT5 lactation signaling pathways, resulting in elevated STAT3 protein levels associated with mammary gland degeneration. Conclusions: This study emphasizes the significance of the ATR protein in the mammary glands of dairy cows, contributing valuable insights into maintaining their health and presenting a novel perspective on strategies to enhance their lifespan.