Portland-based ImmuCell Corp. has secured an additional $2 million in bank financing to complete the construction of its $20 million production facility for nisin, the active ingredient in a new animal health product for which it is seeking U.S. Food and Drug Administration approval.

Completing the facility is a required step for obtaining FDA approval. ImmuCell develops, manufactures and sells products designed to improve health and productivity in the dairy and beef industries.

In the first quarter of 2016, the company entered into an agreement with TD Bank to secure financing of $4.5 million to help fund the facility’s construction. On Wednesday, the amount of available financing was increased to $6.5 million, ImmuCell said in a news release.

The financing is secured by company assets. Currently, ImmuCell has the full $6.5 million available with no outstanding balance, the company said.

Nisin, the active ingredient in Mast Out, a natural treatment for mastitis, inflammation of breast tissue that can afflict lactating dairy cows. Existing antibiotic treatments render the milk unsalable temporarily, causing a loss of revenue to the farmers. However, with the FDA’s approval, milk from cows treated with Mast Out could be sold immediately, giving the product a competitive edge.

Construction on the pharmaceutical-grade facility began in fall 2016 with the help of tax increment financing from the city of Portland.