Resumo

ENCALADA-MENA, Lisandro A. et al. Gastrointestinal nematode prevalence in dual purpose systems in the municipality of Escárcega, Campeche, Mexico. Agrociencia [online]. 2009, vol.43, n.6, pp.569-576. ISSN 2521-9766.

In tropical climates, nematodoses cause major economic losses and are of vital importance in dual purpose production systems because of the prevailing management conditions. This study determined the prevalence and intensity of infection by gastrointestinal nematodes (NGE) in nursing calves and the rate of infecting NGE larvae (L3) in pastures during three climatic seasons (dry, February to March; rainy, June to September; cold fronts ("nortes", October to January). The study was conducted from March 2006 to February 2007 on four dual purpose ranches with similar management, in Escárcega, Campeche, México. Two age groups were formed with 509 Bos indicus x Bos taurus calves: I (birth to four months) and II (four to seven months). Monthly, coproparasitoscopic examinations (McMaster) were conducted to determine number of eggs g^-1 feces (HPG) and coprocultures by group. The ranch pastures were sampled (W method), and the sedimentation technique for L3 was performed. The analysis of variance showed the effect of age on prevalence; group I and II averages were 62.31 % and 80.15 % (p<0.01). Low (61.40 %) infection intensity was found to be different (p<0.01) from medium and high (23.90 % and 14.69 %) intensities. Differences (p<0.01) in number of L3 were found among the seasons: dry, 21.25; rainy, 156.87; cold fronts (nortes), 117.81. The correlation between average precipitation and larva count in grass was 0.61. It is concluded that prevalence was not different among seasons of the year (p=0.105), but it was different between calf ages (p<0.01). During the rainy and cold front seasons, L3 counts on grass increased considerably, relative to the dry season. Identified as predominant was the genus Cooperia spp, followed by Haemonchus spp and Oesophagostomum sp. This information would help to plan de-worming calendars and pasture management in dual purpose systems.

Palavras-chave : Dual-purpose system; calves; gastrointestinal nematodes; prevalence.

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