Breeding Australian Illawarra Shorthorn cattle for resistance to Boophilus microplus. I. Factors affecting resistance

Abstract

Selection and breeding for tick resistance in an Australian Illawarra Shorthorn (AIS) herd was undertaken from 1966 to 1971. Mating of half the AIS herd with a Brahman bull in 1968–69 provided a comparison of tick resistance in selected Bos taurus and crossbred B. taurus x B. indicus cattle. Parent cows and their progeny were ranked for resistance to ticks, infestations of which were acquired as a result of grazing infested pastures, and from periodical artificial infestation with cohorts of c. 20,000 larvae of Boophilus microplus. Ranking and assessment of resistance levels were based on counts of semi-engorged female ticks on the right side. Parent cows selected for high resistance consistently carried fewer ticks than cows selected for low resistance. Mating of cattle selected for high resistance produced progeny that were significantly more resistant than the progeny of cattle selected for low resistance. However, the Brahman bull, which had slightly lower resistance than the AIS bull, produced progeny with higher resistance, even when mated with AIS COWS selected for low resistance. Pregnant cows were significantly less resistant than non-pregnant cows, and lactating cows were very much less resistant than non-lactating cows. Young cows were more resistant than older cows. Calves at foot carried fewer ticks than their dams when grazing infested pastures, but after weaning they were less resistant than their parents when resistance was determined from artificial infestations. Female calves carried fewer ticks than males on almost all occasions, but differences were not significant in winter. Significant seasonal changes in resistance were demonstrated in AIS and Brahman x AIS weaner and yearling cattle. All cattle were less resistant in winter. Changes were greatest in Brahman x AN females, on which the average numbers of female ticks that matured following artificial infestations in January 1970 (summer), July 1970 (winter) and January 1971 (summer) were 151, 1046 and 95 respectively.

Breeding strategies for tick resistance in tropical cattle: a sustainable approach for tick control

“…Contemporary group comparison reveals lighter colored animals are more resistant than dark colored ones (Gasparin et al 2007). Utech et al (1978) and Silva et al (2010) observed that females, pregnant cows and younger animals are more resistant when compare to their respective counterparts.…”

“…There is uniform agreement that Zebu cattle (Bos indicus) have, on average, greater tick resistance than either European cattle (Bos taurus) or African cattle (Utech et al 1978;Madalena et al 1990;Frisch and O'Neill 1998;Mwangi et al 1998;Wambura et al 1998;da Silva et al 2007). Immunological mediators induced by tick antigens introduced into host skin contribute to the itching sensation which stimulates grooming.…”

“…Natural disease resistance refers to the inherent capacity of an animal to resist disease when exposed to pathogens, without prior exposure or immunization (Adams and Templeton 1998). Utech et al (1978) defined tick resistance as the ability of cattle to limit the number of ticks that survive to maturity. Selection for disease resistance has been applied successfully in poultry, and opportunities are also being applied increasingly in pigs and sheep in some countries.…”

Tick Resistance and the Major Histocompatibility System

“…Tick resistance was assessed by placing a collar containing 20,000 viable tick tarvae on each animat's neck (Utech, Seifert and Wharton, 1978) for 4 h. The number of surviving female ticks, 4 5 mm to 8 mm in tength, present on one side of each animat, 20 days and 2t days after the challenge infestation, was counted independently by two people. The repeatability of tick counts within days was 0 97 for both days and the repeatability between the average count for each day was 0 89.…”

Parâmetros genéticos de temperamento e resistência de bovinos da raça Nelore ao carrapato Boophilus microplus e validação do uso de marcadores moleculares na seleção para essas características

“…Mesmo em animais da raça Brahman, cerca de 10% dos animais tem apenas moderada resistência aos carrapatos (UTECH et al, 1978). Portanto, ao invés de se usar animais de mediana resistência de raças resistentes, o ideal é utilizar os animais altamente resistentes para aumentar a resistência média de todos os indivíduos da população, de acordo com Martinez et al (2004).…”