Resistance of cattle to cattle tick, Boophilus microplus. II. The inheritance of resistance to experimental infestation

Abstract

Fifty-nine quarter-bred Zebu steers sired by six half-bred Zebu bulls were exposed to four infestations of 40,000 larval ticks at 7–11 week intervals, followed in another 7 weeks by a paddock infestation.

All developed a strong resistance to artificial infestations with cattle ticks by the third infestation.

There was no sire difference at the first infestation and a zero heritability estimate for tick resistance. At the fourth infestation there was a heritability of 28%, which increased to 42% at the fifth infestation. Female tick weights, egg-laying ability of ticks. and viability of eggs laid appeared to be affected by sires. Heritabilities of these characters are discussed.