Effects of field infestations of gastrointestinal helminths and of the cattle tick (Boophilus microplus) on growth of three breeds of cattle

Abstract

Approximately equal numbers of Shorthorn x Hereford (British), Africander x British, and Brahman x British yearlings (all F3-F4 generations), totalling 117, were run together on one pasture. One-third of each breed type was dipped every 3 weeks to control ticks, one-third was given injectable tetramizole at the same intervals to control gastrointestinal helminths, and one-third was untreated. The estimated increases in gains in body weight in 27 weeks due to dipping were 10 kg (10%) in Africander cross and 3 kg (3%) in Brahman cross animals (neither significant), but 27 kg (46%) in Shorthorn–Herefords (P 0.001). Anthelmintic treatment increased gains by 22 kg (22%) in the Africander cross (P < 0.001), and 1 kg (1%) in the Brahman cross group (not significant), and 18 kg (30%) in the Shorthorn–Herefords (P < 0.01). The differential breed responses to the presence of ticks were accounted for by differences in the numbers of female ticks maturing. The Africander and Brahman cross animals carried a mean of 20–30 ticks per side ompared with75–100 on Shorthorn–Herefords, and had higher repeatability of counts on individual animals. The regression of weight gain on tick count between animals within infested groups was similar to that between infested and dipped groups. There was no breed difference in counts of helminth eggs in faeces. There were significant differences between animals but they were not correlated with weight gain. Tick burdens were moderately high. Helminth egg counts were low. In these circumstances and under the pasture conditions represented, tick resistance accounted for 40% of the superiority in growth of the Brahman cross or Africander cross over Shorthorn–Herefords, and tolerance of helminths accounted for none of the difference between Africander cross and Shorthorn–Herefords, for 25–40% of the difference between Brahman cross and Shorthorn–Herefords, and for more than the observed difference between Brahman and Africander crosses. The effects of both parasites on growth, and the importance of differential responses of breeds, are conditioned by environmental conditions, notably nutrition.

The effect of the control of endo- and ectoparasites on weight gains in crossbred cattle (Bos taurus taurus × Bos taurus indicus) in the central region of Brazil

“…In that study, a significant effect on weight gain for treatment AH was seen for all three years, but for AC treatment only in one, although the mean infestations in the control animals were 102, 326 and 180 hornflies/animal per year (Sanson et al, 2003). Seifert (1971) and Turner and Short (1972) studied European crosses Hereford×Shorthorn (HS) and F3 crossbreds Afrikander× Hereford× Shorthorn (AX) and Brahman×Hereford×Shorthorn (BX), all naturally infested with gastrointestinal nematodes and ticks, treated with a suppressive regime every 21 days for both types of parasite for one year after weaning. They observed that the treatments against endo-and ectoparasites were very effective for the weight gain of HS animals, with little effect on animals AX, and without effect on the BX animals.…”

Importance of adaptation and genotype × environment interactions in tropical beef breeding systems

“…The impact of each stressor on production and animal welfare is often multiplicative rather than additive, particularly when animals are already undergoing physiological stress such as lactation (e.g. Turner and Short, 1972;Turner, 1982;Frisch and Vercoe, 1984;Frisch and O'Neill, 1998). Under extensive production systems common in the (sub)tropics, it is generally not possible to control the stressors through management strategies alone.…”

Correlated responses to selection for cow fertility in a tropical beef herd

“…This effect, which can be attributed to lower energy reserves for milk production in previously wet dams, was not compensated for post weaning and, in fact, was exacerbated in males during the first period of rapid growth, as evident by the sex x PLS interaction on live-weight gain between 12 and 15 months of age (Table 1). This interaction probably arose because males, relative to females, have higher nutritional requirements for growth, are less resistant to parasites (Turner and Short, 1972), and had poorer nutrition in their paddock compared with that of the females.…”