3 tips for broody hens Why drenching pregnant ewes
just before lambing isn’t the answer
If you’d like to try raising a clutch of chicks, a broody hen who refuses to get out of her nest for days at a time is your natural-born incubator. However, during the time she is sitting, she won’t be laying eggs for you. • Don’t put your most valuable fertile eggs under an untested broody – you need to make sure she’s reliable before you entrust her with valuable eggs. • You can buy fertile eggs (these are posted in the mail, quite safely) and this gives you the option of getting heritage breeds, or you can have a rooster. • If you are raising a clutch, remember you will be getting a 50-50 mix (or thereabouts) of males to females – are you prepared to keep the boys or raise them for meat, or to sell or euthanise them? Dumping birds is cruel and not permitted under the Animal Welfare Act.
Drenching pregnant ewes just before lambing is a long-held, popular belief. The theory is any sheep that are thin and not doing as well as others in the flock are suffering from parasites, and so pre-lambing drenching is a must.
That seemed to be backed up by research over the last 50 years, but scientists at Agresearch have now found that isn’t the case and that there are other issues far more likely to be the cause of thin ewes in late pregnancy.
It has just finished a review of all the on-farm trials conducted in New Zealand since the 1960s and discovered something interesting: there is no consistent benefit from drenching ewes around lambing time, no matter what method you use.
“That means that sometimes there is a measurable benefit and sometimes there isn’t,” says Agresearch parasitologist Dr Dave Leathwick. “But it’s a bit more complicated than that, because many of the trials didn’t actually measure all the variables necessary to make a proper decision on the benefits of treatment.”
His findings showed that over the period from pre-lambing to weaning, some ewes increase in condition, some lose condition and some stay the same.
“The proportions following this pattern were exactly the same whether the ewes were drenched or not, and the type of drench was irrelevant. We interpret these data as telling us that low body condition in ewes at this time of year is unlikely to be caused by worms. Even when skinny ewes are given a long-acting drench, many of them don’t improve in condition, and some lose condition.”
Work by Massey University suggests that thin ewes are more likely to be suffering from subclinical pneumonia and/or the long-term effects of facial eczema.
“While the causes of ill-thrift remain uncertain, it does appear worms are not important,” says Dr Leathwick. “If you try and solve an ill-thrift problem in your ewes by drenching you will probably fail.”
The best recipe to having healthy ewes at lambing? Get as many as possible to condition score 3 before lambing starts.
If you try to solve an illthrift problem in your ewes by drenching, you will probably fail.