Vitarich has shut its poultry farm in Candaba town in Pampanga as a necessary precaution after the country confirmed its first avian flu outbreak.
The government, through the Department of Agriculture, said last week it would cull 200,000 chickens, quails and ducks after detecting an avian flu outbreak at a farm in San Luis also in Pampanga.
Vitarich shares were down 5.88 percent to P1.92 at the end of trading Monday.
The firm has yet to assess the financial impact of the outbreak.
It reported, however, a healthy first semester this year, with income growing 129 percent year-on-year to P93.3 million.
The firm said gross profit saw a 31-percent increase from last year, driven by higher chicken prices and improved efficiencies in its poultry operations.