Objective: To assess the safety of 3 enterococci strains (LQ-R-16-1, FC-3-7 and FC-3-2) originating from milk in mice through 7-day acute oral toxicity test and 30-day feeding test. Methods: Kunming mice of clean grade were subjected to intragastric administration of different doses of enterococci and during the test, the mice were observed for changes in physical signs and daily weight gain; afterwards, they were anatomized to observe organ changes and bacterial translocation and calculate organ indices. Results: Acute toxicity and feeding tests exhibited no significant difference in daily weight gain or organ indices compared with the control group (P > 0.05), and after the 30-day feeding test bacterial translocation was found not to occur. Conclusion: Enterococci LQ-R-16-1, FC-3-7, FC-3-2 are safe to consume, having no toxic side effects.

Dairy cows show lower disease resistance with late pregnancy, calving, lactation and other physiological changes during the peripartum period. Subsequently, the cows are prone to many diseases such as hypocalcaemia (milk fever) after calving. In this paper, the pathogenesis, hazards, influencing factors and control principles of hypocalcemia in dairy cows during the peripartum period are summarized in order to provide theoretical references for the feeding and management of dairy cows.