Drought-related Animal Health Issues
At the time of writing, we hope the drought may have been broken. Only time will tell, but whether or not it has ended, its effect will unfortunately be with us for some time.
If we don't get further showers and at frequent intervals, then there will be inadequate early autumn pasture growth, so ewes will in many cases be joining at low body weights. Conception rates and lambing percentage are therefore likely to be down next year. Interestingly, I have sometimes seen better than average lambings on some properties in the spring following a drought because farmers have been forced to supplementary feed the ewes and have done this well. A drought-affected ewe given good supplementary feed is often better off than a ewe in an average year which, although in reasonable condition, is losing weight when she goes to the ram.
Another positive effect of the drought is that parasite survival and contamination of pasture is low, fly strike is hardly a problem (less dags and less fleece rot) and footrot by and large self-cures.
However, sheep forced to graze very short pasture for extended periods will suffer excessive tooth wear. Some farmers may find a higher percentage of culling is required in the next few years because of this.
Whatever supplementary feed is given, let stock adjust to it gradually. More often than not one form of feed has to be replaced by another, so make any change gradual. We frequently see evidence of too rapid a change, eg grain overload, scouring, and laminitis.
If the drought breaks in the next month, watch for a massive parasite larval release from dungpats and parasitism in young stock of all species. Contamination of short, green pasture and ingestion of larvae as stock graze is likely to be high. If possible, continue supplementary feeding or sacrifice paddocks until at least 3 cm of pasture returns. There will be a tendency to graze pasture in the recovery phase too soon.
Watch for fly. If using flytraps, keep them well baited and move with susceptible mobs of sheep.
Be aware of the possibility of nitrate poisoning, especially on crops that have come away well after the drought. Get them tested before grazing. Also, ensure hoggets have been vaccinated against pulpy kidney. A good autumn will be dangerous for unvaccinated animals.
If stock have been grazed off the property, ensure they get their quarantine drench immediately on returning. One doesn't want to introduce resistance or further drench resistance. Other considerations are lice and footrot.
If stock have been grazed on liver fluke country, eg the West Coast, make sure all stock get a good liver fluke treatment once they return. The east coast is still relatively free of flukes and we don't want that incidence to increase.
If we don't learn anything from this drought experience then we are fools. Looking around I see some farmers who have coped a lot better than others. Those that are surviving are the ones that either made early destocking decisions or have been well prepared for such an event, having good reserves of supplementary feed-in particular silage.
Peter Anderson
Veterinarian
Marlborough
Contact for Enquiries
Manager
North Island Regions
Sector Performance Policy
MAF Policy
Hamilton
NEW ZEALAND
Phone: +64 7 957 8313
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