Proceedings of the New Zealand Society of Animal Production. 1995,
55: 211-213
Proceedings of the New Zealand Society of Animal Production. 1995,
55: 211-213
There were four farmlets, with paired units on dry and irrigated land (5 and 6.4 ha respectively) with mixed aged flocks of 60 or 80 ewes respectively. One flock on each pair of farmlets, termed treated flock, were treated with a continuous anthelmintic release bolus in March prior to mating and again 100 days later in June. The control flock of each pair was given an oral anthelmintic post-lambing in line with local farmer practice.
In March of both years faecal egg counts (FEC) were similar for all flocks and averaged between 40 and 160 eggs per gram (peg). For bolus treated flocks average FEC declined to 0 after treatment and remained below 32 peg until September. In contrast the control flocks had significantly higher (P<0.001) egg counts at levels of 50 to 600 epg throughout winter, but exhibited the classic periparturient peak in 1993 only. From October all flocks had similar FECís below 100 epg.
Lamb birthweights in September/August corrected for birth rank, birth rate, sex and year were 400g higher for bolus treated flocks but this result was not significant. Weight of lambs weaned per hectare was greater from the treated unit (P<0.05) by 11%.
These results show that anthelmintic treatment of ewes in autumn and winter by way of slow release bolus almost eliminated FEC output from ewes during pregnancy and early lactation and eliminated the expected spring rise in FEC of ewes associated with lambing. The benefits were greater lamb weight gains and elimination of the need for pre-weaning lamb drenching. The implications from on-farm drenching strategies, particularly in view of parasite resistance problems, is discussed.
Keywords: NZSAPAB; sheep, internal parasites; ewe; anthelmintic; albendazole; slow release; CRC; production; response
