Effect of lymphoid Leukosis virus on performance of layer hens and the identification of infected chickens by tests on Meconia

Abstract

SUMMARYThe effect of subclinical infection with lymphoid leukosis virus (LLV) on the productivity traits of layer hens was investigated. In hens that shed gs-antigen of LLV to albumen, onset of sexual maturity was delayed by a mean of 11 days and the number of eggs laid was reducedby 68 per hen up to 75 weeks of age. Shedding hens laid on average 2 g lighter eggs and of lesser specific gravity. Thirty-four % less chickens were obtained in the reproduction programmes from LLV-shedders in comparison with non-shedders. LLV had no significant effect on fertility and hatchability. Reduced egg-related performance was only directly related to LLV-shedding and dams' shedding status had no effect on the egg-related performance of their LLV-free progeny. Dams' shedding status, however, correlated with higher mortality (10% higher) among their progeny. The percentage of non-layers was also higher in progeny of LLV-shedders. Meconia were highly suitable samples for identifying both transmitting dams and infected chickens but only if the test for infectious virus was performed. ELISA on meconia was less reliable than the test for virus and therefore is not recommended for the detection of residual of infected chickens in the flocks selected for reduced gs-antigen shedding.

A novel Bursin-like peptide as a potential virus inhibitor and immunity regulator in SPF chickens infected with recombinant ALV

“…A multitude of important viruses including ALVs [14], IBDV, avian reovirus, Marek’s disease virus (MDV), hemorrhagic enteritis virus [15] and avian reticuloen-dotheliosis virus (REV) [4] have been implicated in avian immunosuppression. Until now, there are limited reports of the in vivo or in vitro action of naturally-occurring substances and heterosynthetic immunomodulators in chickens infected with viruses causing immune-suppression.…”

Avian Viruses that Impact Table Egg Production

“…ALV is the type species of the genus Alpharetrovirus within Retroviridae family [ 119 ]. ALV shedding into the eggs was associated with lower egg production, delayed onset of laying, small-sized eggs, thin-shell eggs, and reduced hatchability compared with non-shedding hens [ 120 , 121 ]. Moreover, strains of chickens demonstrated a major impact on the rate of virus shedding and, consequently, production traits [ 120 ].…”