To convert to dollars per hundredweight:
1 kilogram = 2.2046 pounds. So, take the payout ($8) divided by 2.2046 ($3.63 per pound of milk solids). There are 8.4 pounds of solids per hundredweight of milk. Therefore, $3.63x8.4 equals $30.482 per hundredweight.
I see no reason to convert the New Zealand dollars to U.S. dollars, unless the milk check is being sent to the U.S. All costs are local and therefore all milk checks are local.
Virtually, all cows are milked seasonally in New Zealand. The season for this payout began in July 2010 and will end in June 2011. consequently, the payout is still subject to change.