Effects of grouping of piglets on plasma cortisol concentration, lymphocyte blastogenesis and phagocytic function of monocytes in peripheral blood and on intradermal response to pytohaemagglutinin.

摘要

At 63 days of age, 4 specific-pathogen-free (SPF) piglets from a litter of 8 piglets (Group A) were moved to the pen where a litter of 4 (SPF) piglets (Group B) were housed and were reared together for 13 days. The remaining 4 piglets of the litterof 8 piglets were not moved but reared for 13 days as controls. After grouping, all piglets of Group B violently attacked the piglets of Group A and bit their shoulders and ears for 2 h. Plasma cortisol concentration 2 h after grouping was significantlyhigher than 3 days before grouping. Cortisol concentrations decreased to base-line levels 24 h after grouping. No significant difference in plasma cortisol concentration was observed between Groups A and B. The number of total and differential leukocyteswas almost the same throughout the experiment. In Group B, the proliferative responses of peripheral blood mononuclear cells induced with the mitogens phytohaemagglutinin (PHA) and pokeweed mitogen in vitro were significantly decreased on the third dayafter grouping compared with those 3 days before grouping. The intradermal response to PHA in vivo and the phagocytic function of monocytes was significantly reduced in all piglets until 14 days after grouping. In control piglets, a slight increase of plasma cortisol was also found, and the suppression of intradermal response to PHA was observed for 13 days. It is suggested that grouping puts piglets under stress and suppresses the functions of lymphocytes and monocytes for at least 13 days after grouping.