WAUKESHA, Wis. (AP) – The 83-year-old dairy processor that closed abruptly in southeastern Wisconsin and left area schools scrambling for milk has filed for bankruptcy.  The private equity firm that bought Golden Guernsey in 2011 says it’s filed for Chapter 7 bankruptcy protection in Delaware bankruptcy court. OpenGate CEO Andrew Nikou said in a statement late Tuesday that pressure to lower prices, as well as nonnegotiable operating expenses led to the decision to close the plant in Waukesha.   The sudden closure over the weekend left more than 100 people without jobs and had schools working to line up new milk suppliers. State labor officials say OpenGate had not provided the 60-day notice for a plant closing as required by law.  The Milwaukee Journal Sentinel (http://bit.ly/VFRDpB ) reports Golden Guernsey was established in Milwaukee in 1930.

—      Information from: Milwaukee Journal Sentinel, http://www.jsonline.com