Mr Hodgson is the Australian Wool Innovation (AWI) sheep specialist and he was speaking at the first of the spring field days to be held across eastern Australia.

"We just want woolgrowers to understand the basic characteristics they should be looking for when breeding Merino sheep," he said.

"We are not taking away from professional sheep classers, but if the sheep breeder goes away from these days with a greater understanding of what the sheep classer is doing, then we have done a great service for the wool industry."

Mr Hodgson said the sheep can't be built.

"You have to work with what you've got," he told his audience.

"Size is important, but there is a cut-off point."

He admitted it wasn't a point he could identify but said it would depend on many factors including preference of the breeder, type of country the sheep run on and the bloodline of the rams sourced.

"There has to be balance," Mr Hodgson reiterated.

"You have to ask yourself ... is that big ewe going to give me a comparatively greater return than one and half ewes a bit smaller."

It all comes down to working with your country.

"I would think a two and half year ewe, bare shorn should weigh around 75-80 kilograms," he said.

"But I think it more important to have your maiden ewes at 40kg, that it is the weight which will trigger the ovulation in the ewe."

But he did point out, in the context of current super prices for surplus ewes, if you have a good weaning percentage and those young ewes are well grown, then there is an extra profit in having the bigger sheep.

Mr Hodgson said he looks for width through the chest for doability, and he doesn't want a sheep that is over long.

"She takes too long to feed, they are inefficient converters of available feed," he said.

"Again it all comes back to that magic word ... balance."

Mr Hodgson also emphasized the care needed for the sire battery.

"The rams are an expensive part of your flock so look after them," he said.

"I would suggest you shear them twice a year, and drench and innoculate when ever you think of it."

It is a lot easy to keep a ram healthy, than to find him dead in the corner of the paddock.

"Shorn rams are that much more active, and you increase their longevity," he said.

"You have made a big investment in your rams, and the extra shearing will be better than losing a few."

Mr Hodgson also noted the effect flystrike has on the fertility of the ram.

"Flystrike as big as a twenty-cent piece will render the ram infertile for six weeks," he said.

"Once a sheep become struck their temperature goes up.

"The ewe stops growing her wool, but the ram goes into complete lockdown with lack of sperm production."

Shearing twice a year will help alleviate that problem in your rams, Mr Hodgson said.