In recent years, importance of alternative rearing systems has increased notably because of growing public concern against intensive rearing systems. Animal welfare laws have been established in some European countries with strict guidelines concerning the available area per bird in cage rearing systems; in some cases, the use of cages has been forbidden. Alternative rearing systems, such as furnished cages, semi-intensive and free range, have been introduced as substitutes for the currently used system (cage system). In intensive rearing systems, birds cannot fully express their intrinsic behaviors, such as walking, jumping, running, wing flapping, lying, dust bathing, sun bathing, scavenging and foraging. On the other hand, outdoor rearing systems are comfortable and welfare friendly where birds can walk and exercise freely. Present study was conducted at Layer Unit, Department of Poultry Production, UVAS, Ravi Campus Pattoki, to evaluate the effects of different rearing systems on production performance, blood biochemical profile and behavioral pattern in two commercial layers strains. A total of 150 pullets (18 wk old), 75 from each strain, were randomly allotted to 6 experimental groups in factorial arrangement under complete randomized design (CRD). Treatments consisted of 2 strains (Hy-line and Bovans) and 3 rearing systems (free range, semi-intensive and intensive). Each treatment was replicated 5 times with 5 birds per replicate. Production performance, blood biochemistry, immune response and behavioral parameters were studied. The collected data were analyzed through two-way ANOVA technique using PROC GLM in SAS 9.1 software. Treatment means were compared through Duncan’s Multiple Range test. Hy-line strain showed greater egg production, egg weight, antibody titers against IBV, more feather pecking and drinking behavior, whereas more feeding behavior was observed in Bovans strain. The results
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showed higher body weight, egg production, and egg weight, and more feeding, lying and aggressive behavior in intensive, and higher antibody titer against IBV under semi-intensive. However, free range rearing system showed more wing flapping, walking, jumping, litter pecking, feather pecking and dust bathing behavior, whereas standing and drinking behavior was found to be higher in both semi-intensive and intensive rearing systems. Interaction showed maximum body weight, blood glucose, triglycerides and antibody titer against IBV in Bovans under semi-intensive and intensive rearing systems, whereas egg production was found to be maximum in Hy-line under intensive rearing system. Interaction of strains and rearing systems, likewise, indicated variations in behavior pattern.