In remarks posted on the ministry Web site late Sunday, Minister Sun Zhengcai said that "very few batches of eggs from very few companies" contained the chemical melamine.
Calling them "isolated cases," he nevertheless said the Agriculture Ministry's departments "should pay high attention" to the feed quality to ensure the safety of eggs and other animal products, and protect farmers' interests.
Sun made the remarks during a trip to a farm in Dingxing county in northern Hebei Sunday.
Last week, four brands of Chinese eggs were found to be contaminated with melamine, and agriculture officials speculated that the cause was adulterated feed given to hens. No illnesses have been linked to melamine in eggs.
Other ministry officials have asserted that the practice of deliberately adding melamine to animal feed was widely practiced, signaling that melamine contamination may be more widespread than in just baby formula and dairy products.
Inspectors have destroyed 3,682 tons of animal feed that was tainted with the chemical. Commonly used in plastics and fertilizers, melamine is high in nitrogen, which registers as high protein levels in routine tests of food and feed.
Infant formula tainted with the chemical has been blamed for sickening tens of thousands of children and causing the deaths of four infants.
Though experts say at low levels it does not pose a risk to human health, higher concentrations of melamine harm the kidneys.
Over the weekend, Agriculture Ministry official Wang Zhicai said that inspection teams have descended on feed makers nationwide in a "punishment" campaign to ferret out those found using excessive amounts of the chemical melamine.
Among the 250,000 feed-makers and animal breeding farms inspected, inspectors found more than 500 engaged in illegal or questionable practices, with police further investigating 27 companies, Wang said. He likened the behavior of some of the companies to organized crime, calling them "black nests of gangsters."
China has struggled to appear responsive to a widening food scandal. In the nearly two months since the government first acknowledged that melamine contaminated the milk supply, the chemical has been detected in eggs, candy and other products. Its presence in feed raises fears about the safety of meat and fish.
A little more than a year ago, China vowed to minimize the use of melamine after it was found in pet food exports that killed dogs and cats in North America in 2007.