"It's just that there's been such a high rainfall for a reasonably long period that has created considerable grass growth. Farmers are not under any particular pressure to have stock processed. We believe the lambs are out there but it's very much dependent on the weather conditions," Mr Ogg said.
He hoped any shutdown, which would see workers laid off without pay, would be "relatively short".
"We're just playing it week by week at the moment and hoping that the stock supply will come right," he said.
Meat Workers Union North Island branch secretary Graham Cooke said seasonal shutdowns were normal "but in this situation it's very unseasonal".
"They [the workers] don't know from week to week whether they're going to have a pay packet," Mr Cooke said.
The lamb season traditionally ran from December to July, peaking from January to April, and it was similar for the beef season.
Seasonal shutdowns usually occurred, and were planned for by workers, during the spring, he said.
"That's the time that we would expect our workers to be laid off, not in January. We make money while the sun shines and it's only at a certain time of the year."
During the slower months, employers were obligated to pay workers a minimum gross weekly wage of $503.78, regardless of how many hours they worked.
"It just keeps them above the bread line," Mr Cooke said.
The situation was a reflection of an industry-wide push to casualise the workforce, he said.
"It's terrible, absolutely terrible. When the lambs don't run the employers don't help their employees out," he said.
The union representative said yesterday the mood lifted slightly when workers were told they had another week's employment.
"They're looking at rolling it [the shutdown] for another seven days and hopefully the stock numbers will pick up by then."