Mr Mitchell said at the moment there was no supply of pine kernels, as current stocks had been exhausted.
He had also seen an increased demand for high-quality hay baleage and high-protein feeds, to help ensure dairy herds kept producing milk.
"I have farmed on the West Coast for the best part of 25 years and been in the industry all my life, and I'd say this is the biggest event in terms of a summer dry I've seen."
Mr Mitchell said another area of concern was the danger current conditions posed to the health of farming families.
"Definitely a significant impact on farmer mental health, and that's something we all need to be aware of, the stresses which are being put on the family as a unit.
"Because most farms are run as a family unit, the impact we are seeing in terms of cash flow is significant."
He said the severity of the dry weather also varied across the Coast.
"There are areas on the Coast which are significantly worse than others. Murchison certainly has seen quite a bit of rain.
"But perhaps Tapawera didn't, and the Grey Valley and Rotomanu, Inchbody, those areas are still under severe pressure from moisture."
Mr Mitchell was working hard to impress upon farmers the importance of working out how many animals they could afford to feed, and which needed to be dried off.
"That's one thing I have been trying to get farms to do, is to sit down and see what it's costing them to feed their cows every day, and assess what the milk yield is.
"Each farmer has to individually do that assessment to see whether it's viable for them going forward to continue milking."
Mr Mitchell said decisions on stock levels needed to be taken now to ensure farmers had enough feed put by to cater for their animals in the spring.
"What we are doing is trying to ensure people aren't digging themselves a bigger hole ... this is a significant event and it needs to be treated as such."