The effect of anthelmintic treatment on the growth rate of beef calves following weaning

Abstract

The liveweight gains obtained from drenching 7–9 month-old weaner beef steer or heifer calves were examined over a period of nine years in 15 trials covering 10 localities in New Zealand. Treated groups received either thiabendazole or carnbendazole between weaning (autumn) and the following spring on 3–6 occasions, at intervals of 4–8 weeks. Similar untreated cattle were used as controls in all trials. The advantage in liveweight gain of groups treated with TBZ or CBZ ranged from 6.7 kg to 31.0 kg over controls. The trial periods ranged from 105 to 168 days. Faecal egg counts were low and clinical signs of parasitism were not apparent. Statistically significant improvement in liveweight of treated compared with control animals over the winter period were demonstrated in all trials, and in 9 out of 10 trials these could be justified economically based on live valuations, or returns at slaughter.

Keywords:

• Anthelmintic
• parasitism
• thiabendazole
• cambendazole
• beef cattle
• weaning
• liveweight
• growth rates
• drenching
• carcass weight