Effects of Gulf Coast ticks on blood composition and weights of pastured Hereford steers.

ABSTRACT

Studies conducted in 1975 and 1976 were made of lightweight Herefored steers, pastured on native grass pasture and infested with Gulf Coast ticks, Amblyomma maculatum Koch. The effects of tick infestations on the blood composition and weights of steers over an 8-week period were measured each year and compared to tick-free animals maintained similarly. By the end of the 8-week study infested animals averaged 8.21 kg less than control animals in 1975 and 12.42 kg less in 1976. Of the blood parameters measured significant decreases in Hb, and a lymphopenia, neutrophilia, and basophilia occurred in infested animals in 1975. In 1975 and 1976 after infestations began significant increases occurred in total serum protein, serum globulin, and plasma fibrinogen, and decreases occurred in the albumin/globulin ration of infested animals. Of the serum globulin fractions, only gamma globulin increased in infested animals in 1975 and alpha globulin in 1976. Also, during both years, decreases occurred over time in the number of ticks attaching.