Customers either don't know or aren't concerned about the practice, said Wang Jianhui, manager of the Kaiyuan Protein Feed company in the northern city of Shijiazhuang.
"We've been running the melamine feed business for about 15 years and receiving positive responses from our customers," Wang told The Associated Press in a telephone interview.
"Using the proper quantity of melamine will not harm the animals. Our products are very safe, for sure," Wang said.
Although apparently widely practiced in China, concern over the use of melamine arose only in March, after the U.S. recall of nearly 100 brands of pet food made with wheat gluten contaminated by the chemical. Adding melamine to food is illegal under American law, and China's government last week.
Adding melamine raises the nitrogen level of feed, making it appear that the feed is higher in protein without increasing its nutritional value. That makes it attractive to makers of feed for stock animals such as pigs, chickens, and fish, as well as companies that make prepared foods for household pets such as cats and dogs.
Despite Wang's claim of safety, pet food tainted with melamine apparently has resulted in kidney failure in an unknown number of cats and other animals across the United States.
Some pet food was also shipped to hog farms in several states for use as feed and was later discovered to have another ingredient, rice protein concentrate, imported from China that was also tainted with melamine.
The U.S. Food and Drug Administration has blocked wheat and rice gluten from Xuzhou Anying Biologic Technology Development Co. and Binzhou Futian Bio-technology Co. after melamine was found in samples taken from batches used to make pet food.
Although the FDA said there is no reason to believe the hogs pose any danger to humans, the quarantined swine will be euthanized and not sent markets, CBS' The Early Show's resident veterinarian, Dr. Debbye Turner reported.
China's government has said it will allow officials from the U.S. Food and Drug Administration to investigate melamine contamination.
Melamine is not considered a human health concern, but there is no scientific data on the health effects of melamine combined with the other compounds. Made from coal, the chemical is usually used in the making of plastics or fertilizer.