"They defecate far more because their innards are in a mess," Mr Farrer said.
As well as clearing up digestive problems, the VitaBee feed supplement makes bees more productive, calmer and easier to work with, he said.
"It probably increases brood by 50 per cent or more. If you have more brood, you have more bees collecting honey. The best is to have a hive of 60,000 bees, with 30,000 raring to go to pick up honey."
VitaBee has been on the market for two weeks, and is selling to commercial apiaries. It's fed to bees mixed with sugar syrup - their usual food.
Mr Farrer has been trying the product on his bees for 10 months. He wondered if it would contaminate honey, and last summer found it didn't. It has also met the Australia New Zealand Food Standards Code.
Wanganui company Vita Power already makes nutritional supplements for cattle, horses, sheep and pets. They contain fat- and water-soluble vitamins that improve the creatures' digestion.
It was honey bees swarming around the remains of a supplement for dogs that started Mr Palamountain thinking about the new product. He noticed how much they liked it and mentioned this to Massey University Professor Brian Wilkinson, who has worked with him for years on formulas for nutritional supplements.
It took about a year for Mr Wilkinson to come up with the right formula for bees.
The ingredients are a secret, but the product label lists many vitamins, selenium, whey and yeast. VitaPower formulas for other animals include garlic, brewer's yeast and molasses. Mr Palamountain said the bee mixture was similar.
His company has also worked with Professor Wilkinson and Quantum Laboratories to produce a farm health package that includes fertiliser as well as animal feed supplements.
His next challenge is to reduce the climate-changing gas emitted by farm animals.
