NUTRITION problems - as a result of annual ryegrass toxicity and a bumper 2003 cropping season - are causing concern for some WA feedlot prime lamb producers and abattoirs.
In the southern wheatbelt regions, the level of ARGT is so high that lambs off ARGT pastures were only gaining 30-50 grams a day, compared to the normal rate of 260g-plus a day.
Hillside Abattoirs managing director, Peter Trefort, said ARGT had to be dealt with urgently.
"We believe it has a huge impact on feed conversion rates," Mr Trefort said.
He said the problem was first identified around seven years ago in finishing-diet pen trials with lambs from ARGT-affected regions.
On closer inspection, ARGT problems became evident, mainly liver damage to the stock.
"The livers in most cases can't be used for human consumption, and the carcass is a lot flatter," Mr Trefort said.
"We've even found liver damage in cattle."
Consequently, Hillside now sources the majority of their lambs from southern Wheatbelt areas where ARGT incidences are significantly lower.
"It is very dangerous buying lambs from ARGT-affected areas," he said.
"I believe it's an even bigger problem for ewes rearing lambs."
Meanwhile, other lamb producers are finding that their stock are not getting enough nutrients from their stubble feed.
York feedlot manager Scott Boyle recently had a vet take blood samples from lambs in his feedlot after concerns over sheep feed conversion rates and performance.
"What we've found in all the sheep was a very big deficiency in vitamin E and some in vitamin A," Mr Boyle said.
"Vitamin deficiency, like ARGT, also affects the feed conversion ratio."
He said the deficiency came down to the fact that 2003 was a very good cropping season.
Due to the bigger crops last season, most of the nutrients went into the grain heads, therefore the stubble nutrients were reduced significantly, Mr Boyle said.
He said late rains in the southern regions of the wheatbelt leached what little nutrients remained in the stubble.
Mr Boyle said lambs sourced from southern areas were not in the best condition before they even arrived at the feedlot.
"We have pulled about 720 lambs out of our feedlot this year, due to the fact that they're not doing well at all," he said.
"We've never had this problem, last year or the year before."
Mr Boyle said lambs taken out of the feedlot were put back into the paddock on a diet of high quality silage and lupins.
"Some are starting to come back slowly," he said. "But ones that were very deficient and had a big setback aren't coming along as well."
Mr Boyle said while the formulated pellets fed to the lambs contained the correct levels of nutrients, this year a specific drench had to be introduced to further supplement the diet of stock arriving in poor condition.
"We're getting a drench in from the eastern states and mixing it with our worm drench, and drenching every sheep that comes on to the property," he said.