Effect of cage tier and age on performance, egg quality and stress parameters of laying hens
This study was conducted to investigate the effects of cage tier and age on performance characteristics of layer hybrids, egg quality and some stress parameters. Ninety laying hens (hybrid ATAK-S) of similar bodyweights were used in the experiment. They were housed in three-tier conventional battery cages (bottom, middle and top) with 600 cm2/per bird. The experiment was conducted on hens from the age of 18 weeks to 42 weeks. Layers at the age of 18 weeks were randomly allocated to conventional three-tier battery cages with five replicates of six hens per treatment in a completely randomized design. In the bottom, middle and top tiers, 5% age of yield was observed as 151, 146 and 156 days, respectively; 50% age of yield was 162.4, 158.6 and 161.8 days; 5% yield age bodyweight (BW) as 1597.8, 1460.5 and 1599.2 g; 50% yield age BW as 1708.7, 1666.4 and 1671.7 g, respectively. The effects of cage tiers on week 42 BW, feed conversion ratio (FCR), tonic immobility (TI), egg weight (EW), egg yield (EY), and most external and internal quality traits of the hens’ eggs were found to be insignificant. Except for shape index (SI) and albumen pH, internal and external quality traits of eggs were significantly affected by age of the hens. In addition, there were significant effects of age on the FCR, EY, EW and oviposition time. The effects of cage tier on tonic immobility (TI) in week 42 and viability were found to be insignificant, but TI in week 30 was found to be significant. It can be concluded that cage tier did not have significant effects on egg yield, egg quality and indicators of stress parameters studied in the experiment. However, these parameters were affected by the age of the hens at the beginning of the laying period.
Keywords: Cage tiers, layer hybrids, hybrids age, egg quality