Body weight suppression in broilers naturally infected with avian leukosis virus subgroup J

Broiler progeny were hatched from avian leukosis virus (ALV)-negative and ALV subgroup J (ALV-J)-positive breeders. ALV-J infection in progeny was identified by p27 antigen capture enzyme-linked immunosorbent assay and reverse transcriptase-polymerase chain reaction specific for ALV-J performed on serum or plasma samples obtained at hatch. Hatch weights did not differ between ALV-negative broilers and ALV-J-positive broilers. Body weights of ALV-J-positive broilers were 64.4% of those of ALV-negative broilers at 1 wk of age. At 8 wk of age, weights of broilers with congenital ALV-J infection were still only 63.8% of those of ALV-negative broilers. No other concurrent pathogen was detected in either group of broilers. These findings indicate that congenital ALV-J infection is associated with significant weight suppression in broilers in the absence of other pathogens.