Dc. Willis et al., PHYSIOLOGICAL AND NUTRITIONAL RESPONSES OF STEERS INFESTED WITH VARYING DENSITIES OF AMBLYOMMA-AMERICANUM (ACARI, IXODIDAE), Journal of economic entomology, 88(6), 1995, pp. 1679-1683
The effects of varying densities of lone star tick, Amblyomma american
um (L.), on measured physiological parameters of beef cattle in a cont
rolled environment was determined. Steers were infested with either 0,
20, 60, or 120 pairs of adult ticks. Heart rate, respiration, rectal
temperature, fecal and urine excretions, and water and feed consumptio
n were monitored daily. Blood samples were taken every 3rd d to measur
e cortisol, total proteins, urea nitrogen, and glucose levels. Hematoc
rits were also taken at each blood sampling. Results showed that A. am
ericanum evoked elevated heart rates. The other measured physiological
and nutritional responses of parasitized steers were similar to the c
ontrol steers. These results suggest that tick densities were too low
to cause physiological stress under the conditions used in this study.
The methodology precluded detection of the parameters measured, A. am
ericanum does not affect the parameters measured, or that fluctuating
environmental parameters and varying host nutritional states may play
major roles in modulating the effect of A. americanum infestations on
cattle in nature.