Veterinary Parasitology 175 (2011) 135–140 Contents lists available at ScienceDirect Veterinary Parasitology journal homepage: www.elsevier.com/locate/vetpar Performance of second-season grazing cattle following different levels of parasite control in their first grazing season A. Larsson, A. Uggla, P.J. Waller, J. Höglund ∗ Department of Biomedicine and Veterinary Public Health, Section for Parasitology (SWEPAR), Swedish University of Agricultural Sciences, SE 751 89 Uppsala, Sweden article info Article history: Received 29 June 2010 Received in revised form 13 August 2010 Accepted 15 September 2010 Keywords: Cattle Nematoda Coccidia Weight gain Performance Second grazing season Gastrointestinal parasitic infection Ostertagia ostertagi Dictyocaulus viviparus Eimeria alabamensis abstract A 3-year grazing trial was performed during 2003–2005 on a commercial steer-producing farm in Sweden to study performance of second-season grazing (SSG) cattle following dif- ferent levels of parasite exposure during their first grazing season. Initially, groups of 10 first-season grazing (FSG) cattle were each year assigned to four parasite control strategies: (1) turn-out onto pasture that during the previous year was grazed by SSG cattle, followed by a mid-July move to aftermath, (2) supplementation with concentrate and roughage for 4 weeks after turn-out, (3) no treatment, or (4) anthelmintic treatment (injectable doramectin) every fourth week. All animals were set stocked, except for those in group one. Next spring and following housing the cattle were turned out for their second grazing season onto approximately 25 ha communal pasturelands as a common mob. Weighing, faecal sampling and blood collection were performed at turn-out and then every 4 weeks for the 20-week grazing season. Faecal samples were also collected on day 10 after turn- out for detection of coccidian oocysts. Antibodies to Dictyocaulus viviparus were analysed at the time of their second housing period, and when elevated levels were recorded, stored serum samples from seropositive animals were analysed retrospectively. Results showed early-season weight losses of up to 47 kg in the SSG cattle. However, faecal egg counts were generally low and there was no correlation between SSG performance and treatment his- tory as FSG cattle. Still, cumulative egg counts were significantly higher in animals that had been treated with anthelmintic as FSG cattle but serum pepsinogen concentrations showed no significant differences and the output of Eimeria alabamensis oocysts seldom exceeded 10,000 oocysts per gram faeces. Antibodies to D. viviparus were observed from July 2004 and from June 2005 but not in 2003. In 2004 and 2005, 64% and 83% of the animals, respec- tively, were seropositive for D. viviparus. It is concluded that weight gain penalties resulting from different levels of parasite infections the first grazing season remained during the sec- ond grazing season in 2004 and 2005 but no differences in weight gain could be identified in SSG cattle that had experienced different parasite control measures during their first grazing season. This was under conditions where the level of pasture infectivity was low to moderate during the second grazing period. However, D. viviparus was demonstrated in SSG animals during the two last years of the study and was an important confounding factor. © 2010 Elsevier B.V. All rights reserved. ∗ Corresponding author. Tel.: +46 18 67 41 56; fax: +46 18 67 43 04. E-mail address: Johan.Hoglund@bvf.slu.se (J. Höglund). 1. Introduction The economic significance of parasite infections in graz- ing cattle is widely recognized (Corwin, 1997). Most studies refer to cattle in their first grazing season simply because 0304-4017/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.vetpar.2010.09.018