Young steers do not benefit from short term sequential grazing with lambs

The IFOAM – Organics International norms impose that ruminants must be grazed throughout the entire grazing season. This approach increases the exposure to pasture borne parasites and eventually increases the number of anthelmintic treatments, especially in young animals. According to the IFOAM norms, the use of synthetic allopathic veterinary drugs is allowed if preventive measures concerning pasture rotation and management have been exploited. Therefore, we examined the sequential grazing of steers and lambs as a preventive measure to control gastrointestinal nematodes in the steers indicated by weight gains and parasite egg excretion. Ten comparable pairs of steers and 5 groups of lambs were used for this study. The 5 lamb groups were assigned to 5 pairs of steers to establish the steer treatment groups. The remaining 5 pairs of steers served as control groups. Two pastures were subdivided into 15 plots. At each pasture change, the treatment steers changed their plots with the lambs, whereas the control steers only changed pasture, but not the assigned plot. The steers were 173±16 days old and had an average live weight of 171±15 kg at the start of the trial. The trial lasted for 105 days during summer 2018. The steers were weighted and sampled (faeces) at regular intervals during the 105 days and faecal egg count was determined at individual levels. Linear and generalised linear mixed effect models were applied using the software R. The model could not reveal significant differences of total body weight and daily weight gains of the steers between treatment and control. Even though gastrointestinal nematode egg excretion rose to a mean of 270±287 eggs per gram faeces in control steers compared to a mean of 140±70 eggs per gram faeces in treatment steers towards the end of the trial, no significant differences of EPG could be shown over the total trial period. We conclude that sequential grazing of steers and lambs does not improve the parasitological status of young steers. In the frame of Core Organic Cofund MIX-ENABLE.