Abstract

SUAREZ, V.H; VINABAL, A.E; BASSANETTI, A  and  BIANCHI, M.I. Epidemiología y efecto de las parasitosis internas en la recría bovina en la región del pastizal serrano del noroeste argentino (NOA). RIA. Rev. investig. agropecu. [online]. 2017, vol.43, n.1, pp.59-66. ISSN 1669-2314.

The aim of this work was to study the epidemiology and the harmful effect of gastrointestinal nematodes (GINs) on replacement heifers in the mountain grassland region of northwestern Argentina (NOA). For this purpose, during the periods A (July 2013 to June 2014) and B (April 2014 to November 2015) weaned calves were monitored. Calves were divided into three groups: CTM (calves treated monthly with 200 mcg/kg moxidectin), CUT (calves treated at the start of the assay as usually done in the dairy farm, with 10 mg/kg albendazol for group A and 200 mcg/kg doramectin in B) and NTC: calves not receiving any anthelmintic treatment. Eggs per gram of feces (epg) were counted and feces mix cultures were performed for genus differentiation. Live weight gain (LWG) was recorded. Differences among groups were compared using least squares test. The highest epg count in weaned calves was observed in mid-winter, decreasing in spring and then increasing in late summer in yearling heifers. The genera Haemonchus, Cooperia and Ostertagia prevailed in moderately infested animals, although Trichostrongylus and Oesophagostomum were also present throughout the observation period. During period A, there were significant differences (P<0.05) in total LWG among groups (CTM: 102.4 kg; CUT: 94.0 kg; NTC: 86.6 kg). During period B, differences among groups were significantly (P<0.0002) higher (CTM: 43.1 kg; CUT: 29.9 kg; NTC: 26.9 kg). The present study showed a post-weaning winter peak in epg and another peak at the end of summer, and a negative effect of GINs on LWG, even in moderately infected calves.

Keywords : Cattle; Gastrointestinal nematodes; Epidemiology; Northwestern Argentina.

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