Decreased resistance of Bos taurus cattle on a diet supplemented with whole cotton seed to the tick Boophilus microplus (Canestrini)

Resistance to the tick B. microplus was compared in Bos taurus steers fed hay (low fat (LF) diet) with those fed hay supplemented with whole cotton seeds (high fat (CS) diet) which made them hyperlipideamic. The mean number of adult female ticks maturing from the same artificial doses of larvae was about 2.7 times higher on animals fed the CS diet than on animals fed the LF diet. In both dietary groups the effect of ticks: (a) depressed packed-cell volume, plasma cholesterol and phospholipid levels, serum albumin levels, serum alkaline phosphatase (EC 3.1.3.1) and amylase (EC 3.2.1.1) activities, and monocyte count; (b) increased the serum level of γ-globulin and eosinophil count. Animals on the LF diet responded to tick infestation with an increase in the number of circulating lymphocytes and a decrease in the neutrophil count. In contrast, the lower tick resistance in hyperlipidaemic animals on the CS diet was associated with a decrease in the number of lymphocytes.