The Influences Of Chronic Cold And Heat Stress On Maintenance Behavior And The Immunity Function Of Holstein Cows

The purpose of this experiment was to understand the influences of chronic cold and heat stress on the maintenance behavior and the immunity function of Holstein cows in Inner Mongolia. 15 Holstein cows, the gravida(about 4 years old), healthily were used in this experiment. On the basis of lactation period, cows were classified three groups, which were prelactation period (A).midlactation period (B) and later lactation period(C), respectively, each group was five heads. The whole year was divided into four periods. Taking summer (June-August) as the chronic heat stress period, autumn (September-November) as non-stress period, winter (December-February) as the chronic cold stress period. By using the naked eye, the maintenance behavior of cows were observed; By using haemacytometer, white, lymphoid and monocyte cell count were completed; By using the flowcytometer, the surface market (CD3) of T lymphocyte cell, the surface market (CD21) of B lymphocyte cell and surface market (CD14) of monocyte cell in peripheral blood were analysed. Passing the analysis of the Se, Glutathione-SH peroxidase (GSH-Px), Triiodothyronine (T₃), Tetraiodothyronine (T₄), Adrenocorticotropic hormone (ACTH) and Cortisol (Cort) in the serum, studied influence of chronic cold and heat stress on maintenance behavior and the immunity function of cows. The results showed as follows:Compared with non-stress period, standing time was shorten while lying time was increased in chronic stress period; the ruminating time was shorten, times of drinking water, evacuating and frequency of respiration were increased in chronic heat stress period; but the ruminating time and evacuating was increased, times of drinking water and frequency of respiration were reduced in chronic cold stress period. This experiment can initially think which Standing, Ruminating, Drinking water, Evacuating and Respiration were sensitive maintenance behavioral index in chronic cold and heat stress period.Compared with non-stress period, the white cell, Lymphoid cell and monocyte cell count were obviously lower in chronic stress period; CD21⁺% was notable lower (P<0.05), CD3⁺% and CD14⁺% were lower (P>0.05), this showed the immunity...