Grazing management studies with Australian cashmere goats. 4. Cobalt supplementation and intestinal parasite burdens in sheep and goats in south-eastern Queensland

Abstract

A flock of 32 weaner wether sheep (Border Leicester x Merino) and 32 weaner male goats (Australian cashmere) were grazed (37 animals/ha) on a common pasture of N-fertilised pangola grass from early March until June. One half of each group (16 animals) was supplemented with cobalt, and one half of each of these groups (8 animals) was dosed with approximately 500 infective helminth larvae at 2-week intervals throughout the trial. The final treatment was a drenching regime for one half (4 animals) of each of the above groups, levamisole (Nilverm) at 0, 2, 4 and 7 weeks and rafoxanide (Ranide) at 2-week intervals thereafter. There was no significant effect (P>0.05) of either cobalt supplementation or dosing with larvae on liveweight change, parasite egg concentrations in faeces or daily parasite egg excretion. Sheep gained significantly (P<0.05) more weight (50 g/day) than goats (31 g/day) in the first 7 weeks, and sheep also responded significantly (P<0.05) to drenching in this period whilst goats did not. In the second 8 week period, goats and sheep lost weight at a similar rate (-11 g/day), and both sheep and goats responded significantly (P<0.05) to drenching. The drenching program significantly (P<0.05) decreased faecal egg counts in sheep but not in goats. Undrenched sheep generally had higher concentrations of eggs in faeces than did undrenched goats, and with the exception of 1 sampling period, sheep also excreted significantly (P<0.05) more faecal eggs daily than goats. Undrenched sheep had significantly (P<0.05) lower haemoglobin concentrations in blood (82 gL) than drenched sheep (97 g/L). Undrenched goats also had lower blood haemoglobin concentrations (88 g/L) than did drenched goats (92 g/L). Cobalt supplementation did not exacerbate intestinal parasite burdens in either sheep or goats, and whilst goats did not appear to be more susceptible to intestinal parasites than sheep, the drenching strategies used for sheep were not effective in these goats.