Influence of cage feeding density on immune function in female striped hamsters

Abstract

The immune system plays a crucial role in protecting animals from the attack of pathogens and hence determines their survival. However, animals’ immunity is influenced by many environmental factors. Cage feeding density is one of the most important factors influencing immune function in animals. To test whether high cage feeding density would suppress animals’ immunity, female striped hamsters (Cricetulus barabensis) were divided into the One/Cage, Two/Cage, and Three/Cage groups. Phytohaemagglutinin (PHA) responses were higher in the One/Cage group than the other two groups, implying that cellular immunity was suppressed by high cage feeding density. The numbers of white blood cell (WBC) and lymphocytes (LYMF), the coagulation ability indicated by blood platelet count (PLT), mean platelet volume (MPV) and platelet distribution width (PDW) were the highest in the Three/Cage group among the three groups, implying the occurrence of the fight and injury in the high cage feeding density. Other immunological parameters including the masses of thymus and spleen, intermediate granulocytes (MID), neutrophil granulocytes (GRAN) were all not impacted by cage feeding density. Total body fat mass, the levels of blood glucose, leptin and corticosterone did not differ among the three groups, and these parameters were not correlated with PHA responses, WBC, LYMF, MID and GRAN except that LYMF was positively correlated with blood glucose levels, indicating that the changes in immunity might not be caused by the energy status and stress hormone in hamsters. Suppression of cellular immunity and the increase of WBCs, LYMF under high feeding density might help us to understand the adverse effect of high population density on animals’ survival in the wild. Our findings may also provide some useful information on animal welfare, laboratory animals preparation and wildlife management.