DES MOINES, Iowa (AP) -- About 300 workers at Anderson Erickson Dairy in Des Moines went on strike after voting to reject the company's latest contract offer.

Des Moines Register reports (http://dmreg.co/ULRimt) Mike Klootwyk, the vice president of Teamsters Union Local 120, said the contract would have required workers to accept a pay freeze and to pay significantly more for health care insurance. Workers rejected it Sunday evening.

The company said the primary sticking point is the health care benefit. Union employees have two options, one which costs the employee nothing and the other $69 a month for an individual or family plan.

The company has proposed three options with employee costs from $15 to $35 a month for individuals and $45 to $105 a month for family plans, said Kim Peter, the company's director of marketing. She said the company has asked for salaries to remain the same.

Peter said the average compensation of an AE Dairy worker is just above $73,000 a year. That includes a wage of $53,477, company paid insurance premiums of $10,753, and pension contributions of $8,772.

The company has nearly 400 employees in Des Moines including the 300 union members, most of which work production lines and drive trucks to deliver the dairy's products.

"We are very eager to get back to the bargaining table with the Teamsters so that we can offer a balanced agreement that helps us remain competitive while continuing to provide good jobs and benefits for our employees including health care and pension," she said.

Several dozen picketers with "On Strike" signs on Monday walked around the dairy's building on the city's east side. The previous four-year contract expired in March, and the last negotiating sessions were held last month. Klootwyk says the union also remains willing to talk.

He did not immediately return a call Monday.

Anderson Erickson Dairy is a private family owned company based in Des Moines. Its current CEO is Miriam Erickson Brown, the granddaughter of Iver Erickson, who founded the company in 1930.

It makes and distributes milk, cottage cheese, ice cream yogurt and other milk products and fruit juices.

Copyright 2012 The Associated Press.