Seymour police investigating the theft of nearly 400 lambs

It's believed to be one of Victoria's biggest livestock thefts and the victim, Kevin Butler, says the government needs to tighten regulations governing ear tags.

Mr Butler said 381 head of lambs had been "spirited away without a trace".

"I had 1800 sheep, close to the road, in pretty remarkable paddocks of feed, including 1600 lambs," he said.

"When I started counting them, I found I was missing 381 lambs."

He said he had scoured all his paddocks

"You blame yourself of course, you are looking for what you may have done, you may have left a gate open, or missed some," he said.

"I cried, because of all the work I had done - I have 134 paddocks, and I shift my stock every day, the lambs were in great order."

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The stock was stolen between December 11 to January 4.

Mr Butler called for a tightening of legislation governing electronic ear tags.

"Anyone with a Property Identification Code (PIC) can over-order on ear tags and put them in stolen stock," he said.

"The government needs to look at a system where one in every 100 tags has some sort of satellite surveillance."

He said he had no idea as to how the sheep were stolen.

"They were very easy to muster because I have small paddocks, I guess I was inviting trouble, by having them close to the road," he said.

"It's beyond the police, these guys have the police well and truly outsmarted - we can't blame the police".

He said there also needed to be a crackdown on the number of tags released, to more closely match the number of sheep actually on a property.

It would be too hard to write a statutory declaration, every time you had to replace an ear tag.

"Clearly we have a problem and we don't have any answer - there is no way any of the stolen sheep are found, or come back," he said.

Investigating officer Detective Senior Constable Geordie Thomas, Mitchell Criminal Investigation Unit, said the police were putting substantial resources towards catching the thieves.

"These numbers are outside what we normally see," Senior Constable Thomas said.

"We have spoken to Kevin and all the neighbours and got information on how the farm runs."

He said police had no suspects, at this stage.

"You are talking a four-decker truck and a substantial amount of time to round up that amount of sheep and load them," Senior Constable Thomas said.

"You are going to have to have some pretty well-trained dogs and experienced thieves, to pull that off."

The investigation was tailored towards who would have those sorts of resources and training to carry out such an offence.

Senior Constable Thomas said he had been in the Seymour area for six months and it was the biggest livestock theft in the area since had been there.

"This is definitely one that has raised the eyebrows," he said.

Victorian Farmers Federation Livestock group president Scott Young said trying to get recognition for stolen stock had been a high priority for the organisation for several years.

"We are trying to work with the police and government to get more recognition of farm crime," Mr Young said.

"There is a concern about who is doing these crimes and the ease with which they seem to be getting away with it.

"There has to be a harsher penalty for these crimes."

Mr Young said there needed to be greater collaboration between farmers, agents and the general public to identify thieves and raise awareness.

Victoria's Farm Crime Co-ordination Unit head Inspector Paul Hargreaves said members of the public needed to speak up.

"Silence is not going to solve anything for us - quite often people reflect after a crime and say 'I saw this vehicle, in this location, but I didn't think to report it - yes, it did seem a little bit suspicious to me," Inspector Hargreaves said.

"What we are asking is if you see something like that, jot down the rego and take a couple of minutes to ring it through."

Agriculture Victoria has been contacted for comment.

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