Quite the opposite effect
If NZ had a 'credible' case of foot and mouth, then any agricultural based company would be decimated within a day or two for two reasons:
1. They would be required to write off all inventory, as it would be unsaleable
2. As most sensible exporters carry FX cover on either sales and/or inventory in store or on the water to markets, if the currency collapsed, they would have to SELL that cover into a collapsing NZD FX market, as the inventory being covered no longer has any value, i.e., the company is effectively suddenly VERY long NZD. Crystalised losses would be horrendous.
other factors to account for are:
most of these company's are poorly capitalised, with high debt levels. The Banks would want their money back immediately. No chance. The 'assets' comprise of inventory and specialised slaughter plants, which would be idle within days, and unsaleable. Staff redundancies would add further costs to the disaster.
Admittedly, one could argue PGW are not directly affected by such an outbreak, but the impact would nevertheless be quite severe, by having a large proportion of their customer base decimated.
quite frankly, it's simply a scenario we don't even want to contemplate ever befalling this country.
discl: been there as a risk manager through two 'scares' in last 25 years
but you are right, some smart-arse bank FX traders would immediately take advantage of the currency, but, their Corporate lending dept would take a hammering