Long Gully Station owner Denis Nyhon, of Tarras, said he had a winter contract to get 1000 lambs killed at a meatworks near Invercargill later this month.
Now he had to keep the lambs on his farm for longer than intended, due to a new drench product he had given them to treat internal parasites in his flock.
The delay was due to the Government extending the withholding period for sheep that were given certain batches of slow-release drench capsule product Bionic Plus Hogget.
Boehringer Ingelheim, the animal health company which distributes the capsules, has recalled the product.
New Zealand Food Safety deputy director general Vincent Arbuckle said the recall was being closely monitored by the Ministry for Primary Industries.
The recall involves about 219,000 capsules.
"The matter relates to the rate at which the product dissolves once consumed by animals, which renders it less effective."
There was no food safety risk, Mr Arbuckle said.
The ministry was informed by Boehringer Ingelheim about the issue three weeks ago.
Boehringer Ingelheim had contacted all veterinarian clinics stocking the capsules to stop sales, and all customers who had bought the product to stop usage.
"As part of this issue we have arranged for testing to establish a withholding period to ensure exported product meets trading requirements," Mr Arbuckle said.
"Testing to confirm this has now been completed, and we have established a withholding period of 154 days — up from the existing 126 days — will effectively manage residues.
"Affected farmers have been notified and the company is providing support."
A withholding period was the minimum period which must elapse between using a veterinary chemical product on a sheep and slaughtering it for human consumption.
Mr Nyhon said the extension of the withholding period had potential to be "an absolute disaster".
"It’s crucial for our management to get the lambs off our property."
He started using drench capsules for the first time this year, after being recommended the product.
Holding on to the flock would cost him financially because the sheep would need extra feed and would age, which could potentially cost him.
"They are winter contract lambs.
"If they cut their two teeth, then they’re no longer lambs and they’ll drop in value, $2 a kilo.
"There are quite a few implications."
Mr Nyhon said a Boehringer Ingelheim representative had told him the company would cover any costs associated with the issue.
Mr Nyhon said he had heard the problem was discovered after sheep given the capsules were dying due to a worm burden.
"The capsules weren’t doing the job but we haven’t had that problem.
"Our lambs don’t have a dag on them, they’re as clean as a whistle," he said.
Boehringer Ingelheim Animal Health New Zealand country manager Steve Rochester said the capsules had been distributed to about 40 veterinarian practices since last year.
The controlled-release capsules were manufactured by Argenta, in Auckland, and distributed by Boehringer Ingelheim to New Zealand veterinarians.
Animals treated this season with selected batches of Bionic Plus Hogget were advised not to be slaughtered for meat or offal, until further investigation was carried out.
"Through our veterinarian customers we have offered animal welfare support to affected farms by providing parasite control products for existing treated animals, as well as immediate financial relief for feed for hoggets destined for the meat market," Mr Rochester said.
"We realise this product recall is a disruption for our vets and their farmer customers during a busy time in the lambing season."
Boehringer Ingelheim was working with Argenta and the ministry to investigate the cause of the problem.
The following four batches of Bionic Plus Hogget were affected by the recall: 504829-2, 504830-1, 504831-1 and 504850-1.
No other Boehringer Ingelheim products were affected by the recall.
