THE EFFECT OF THE STRESS OF WEANING AND TRANSPORT ON WHITE BLOOD CELL PATTERNS AND FIBRINOGEN CONCENTRATION OF BEEF CALVES OF DIFFERENT GENOTYPES

Abstract

The response to the stressors of weaning and transport of four distinct genotypes of beef calves, kept under the same management and environmental conditions from conception to weaning, were measured to determine the effect of genotype on stress responses when all other factors associated with the farm of origin were held constant. Genotype had no effect (P > 0.10) on total leukocyte count during weaning, transport or during the post-transit period. Weaning resulted in a decrease (P < 0.05) in total leukocyte numbers, while transport increased (P < 0.05) the number of leukocytes. Fibrinogen concentration was highly variable among and within genotypes but in general, assembly and transit resulted in an increase (P < 0.05) in fibrinogen concentration. Bos indicus calves had higher (P < 0.05) concentrations of fibrinogen during weaning, assembly and transit. In conclusion, genotype of the calf did not alter the fibrinogen concentration, the number of leukocytes or the distribution of the leukocyte population as the result of weaning or transit. Key words: Cattle, stress, leukocyte, fibrinogen