The firm went into receivership last week after suffering various losses over the last 12 months.
As reported by Farmers Guardian last week, Alltech was in talks with Keenan to acquire the business.
An Alltech spokesman said talks were still ongoing and there was ‘no further update’.
It is thought some of Keenan’s 222 staff - 176 of which are based in Ireland – have not been paid for six months.
A letter to Keenan creditors said: “All outstanding contracts or orders for the supply of goods and services are being reviewed.
“You should make deliveries or supplies to the company only at the request of the joint administrators or their staff.
“We confirm that any goods supplied or services delivered in accordance with this letter and with a purchase order number will be for the account of the company in administration.
"Any payments that are made (or goods that are supplied) to you are to be regarded as being strictly for the account of the joint administrators. They cannot be held or applied by you in reduction of any debts outstanding prior to administration.”