Field study on nematode resistance in Nelore-breed cattle

Abstract

The present study evaluated Nelore cattle with different degrees of resistance to natural infections by gastrointestinal nematodes. One hundred weaned male cattle, 11-12 months of age, were kept on the same pasture and evaluated from October 2003 to February 2004. Faecal and blood samples were collected for parasitological, haematological and immunological tests. In February 2004, the 10 most resistant and the 10 most susceptible animals were selected based on individual means of nematode faecal egg counts (FEC). Such animals were slaughtered for worm burden determination and nematode species identification. The repeatability estimates for FEC (AES.D.), log-transformed FEC and packed-cell volume (PCV) in all animals were 0.3 (AE0.05), 0.26 (AE0.04) and 0.42 (AE0.05), respectively. The resistant group showed lower FEC and worm burdens than the susceptible group (P < 0.05). There were no significant differences between groups regarding mean body weight, weight gain, PCV and total serum protein values (P > 0.05). The resistant group showed higher total serum IgE levels (P < 0.05) and higher mean eosinophil blood counts. However, the latter was statistically significant only 42 days after the beginning of the study. Nematodes Cooperia punctata and Haemonchus placei were predominant and the correlation between Cooperia and Haemonchus burdens was 0.64 (P < 0.05), which indicated that animals presenting increased numbers of one of those genera probably had increased numbers of the other. The current study provides further evidence of IgE active role in nematode immunity and suggests that total serum IgE level might serve as an additional marker to select Nelore cattle that are responsive to H. placei and C. punctata infections.

Emergence and the spread of the F200Y benzimidazole resistance mutation in Haemonchus contortus and Haemonchus placei from buffalo and cattle

“…These results suggested that F200Y (T A C) resistance mutation is likely to be present in many H. placei populations of buffalo and cattle. Previously benzimidazole resistance has been reported in H. placei in Brazil (Bricarello et al, 2007), Argentina (Anziani et al, 2004), USA (Gasbarre et al, 2009b; Gasbarre et al, 2009a) and north India (Yadav and Verma, 1997), but there is little information on its prevalence. These reports are based on faecal egg count reduction tests (FECRTs) to give an estimate of the benzimidazole resistance or susceptibility status of a parasite community as a whole, but cannot be used to assess the proportion of benzimidazole resistance worms in a particular population (Achi et al, 2003; Jacquiet et al, 1998).…”

IL‐10 and TGF‐β1 are associated with variations in fluke burdens following experimental fasciolosis in sheep

“…The immunological and clinical pathological parameters in both cohorts were then compared. The approach taken in this study, to compare the immunological responses in animal with a large disparity in burden is not unique and has been used previously as a first effort to address natural resistance in other parasite classes (34)(35)(36)(37). The variability observed here could have arisen from sources other than host resistance, in particular experimental variation.…”

Resistance of beef cattle of two genetic groups to ectoparasites and gastrointestinal nematodes in the state of São Paulo, Brazil

“…1), when the averages for the two genetic groups were very near each other. Various studies conducted in Brazil have shown there are no associations between the levels of infection by nematodes and PCV values (Nicolau et al, 2002;Bricarello et al, 2007;Oliveira et al, 2009). Although it was not possible to detect alterations in the PVCs of the animals, it is known that gastrointestinal nematode infections can have a negative impact on food intake, causing significant declines in herd productivity (Frisch, 1999;Frisch et al, 2000;Stromberg and Gasbarre, 2006).…”