Tick resistance in Sahiwal cattle.

Abstract

Animal Production in Australia TICK RESISTANCE IN SAHIWAL CATTLE D.C. NICOL*, F.R. EMMERSON** and A.R. LAING Bos indicus cross cattle are now widely used in the cattle tick (Boophilus microplus) infested areas of Queensland . Beef producers state tick resistance as the main reason for adopting these genotypes (Elder et al. 1979). While the Brahman is the most common source of Bos indicus genes, the Sahiwal and Africander are alternative sources. Much is known of the tick resistance of Brahman and Africander derived breeds (Utech et al. 1978a), but relatively little has been published on the Sahiwal and its crosses. At Brian Pastures Research Station, near Gayndah, Queensland, tickresistance of Sahiwal x British cross animals of different levels of Sahiwal infusion was assessed. Four groups of animals with previous exposure to ticks were infested once (in late summer) with c, 20,000 tick larvae. Numbers of engorging female ticks were counted on one side of each animal on days 18-22 following infestation. Resistance levels were calculated as the percentage of female larvae which failed to survive to maturity. Results are presented according to the method of Utech et al. (1978a) and given in Table 1. TABLE 1 Resistance (R) and frequency distribution of resistance to cattle tick in fcur groups of cattle of varying Sahiwal content P= Pregnant NP = Non Pregnant L= Lactating NL = Non Lactating f Means not followed by a common superscript differ significantly (P < 0.05). The resistance levels compare favourably with levels for Bos indicus and Bos indicus derived genotypes reported by Utech et al, (1978b), indicating that Sahiwal crosses would be at least as tick resistant as comparable Brahman crosses. In the absence of a non-pregnant, non-lactating group it would be unwise to draw any conclusions, however, it is reasonable to assume (Utech et al. 1978a) that both pregnancy and lactation stress lowered the resistance in females. We thank A. Jamieson for statistical assistance. ELDER, J.K., DUNWELL, G.H., EMMERSON, F.R., KEARNAN, J.F., WATERS, K.S., KNOTT, S.G., and MORRIS, R.S. (1979). Symposium on Ticks and Tickborne Diseases, Townsville, May 1979, editors M.C. Cooper and L.A.Y. Johnston. UTECH, K.B.W., SEIFERT, G.W., and WHARTON, R.H. (1978a). Aust. J. Agric. Res. 29: 411. UTECH,?.B.W., WHARTON, R.G., and KEER, J.D. (1978b). Aust. J. Agric. Res. 29:885. * Qld Dept Primary Industries, P.O. Box 1143, Bundaberg, Qld 4670. ** Qld Dept Primary Industries, P.O. Box 432, Maryborough, Ql'd 4650, T Qld Dept Primary Industries, 'Brian Pastures', Gayndah, Qld 4625. 616