Raisers believe that raising native chicken in free-range conditions is cheaper than semi-controlled conditions. However, the flock's health is threatened by the infections due to internal parasites. The presence of these organisms creates stress among the infected chickens and makes them vulnerable to other pathogens. Our field studies showed that the chicks aging two to three months old have a vast population of internal parasites. The roundworm (Ascaridia galli) was the prominent species among the parasites. This worm is the reason for having native chickens with bigger body sizes but has lighter live weight. Latter, the infections like chronic respiratory infections, infectious coryza, and others follow due to the lower immune response of the said chicken.

When do the internal parasites start to infect the chicken? The infections started as early as a few weeks old. The grazing behavior of chicks with their hen allows the former to acquire viable roundworm eggs either in grass, soil or even in contaminated equipment. Once it enters the gastrointestinal tract of the chicks, it will start to incubate and hatch. The conditions within the gastrointestinal tract favor the hatching of eggs and the growth of larvae of roundworms. It will take about three to four weeks to hatch. After hatching, it will take 35 days for the larvae to become sexually mature and begin to shed their eggs.

When is the best time to administer dewormers? Start to apply a dewormer as early as three to four weeks old and have it be done every two weeks. Possibly, select anthelmintics having ovicidal effects. The active compound within such a dewormer can lead the fertile eggs into unviable ones for hatching. Through these actions, the applied dewormer can cause death to larvae and the developing embryos in the eggs.