Effect of housing environment and hen strain on egg production and egg quality as well as cloacal and eggshell microbiology in laying hens

This study was conducted to determine the effect of housing environment and laying hen strain on performance, egg quality, and microbiology of the cloaca and eggshell. A total of 1,152 Hy-Line Brown (HB) and Hy-Line W-36 White Leghorn (W-36) hens were used. All hens were kept in conventional cages (CC) from 18 to 32 wk of age and then moved to either enriched colony cages (EC) or free-range (FR) pens or continued in CC. Hens were randomly allocated into a 2 pound 3 factorial arrangement of 2 laying hen strains (brown and white) and 3 housing environments (CC, EC, and FR) in a split plot in time (hen age) design. The experiment was conducted from 32 to 85 wk of age. The experiment was divided into 2 phases: early phase (32 -51 wk of age) and late phase (52-85 wk of age). A 3 way interaction was observed for hen day egg production (HDEP) among housing environments, hen strain, and bird age in the early phase (P = 0.004) as well as in the late phase (P < 0.0001). In both of the phases, HDEP was higher in CC and FR than in EC. Hy-Line W-36 hens raised in EC had the lowest HDEP compared to other treatments. A 3-way interaction was observed for feed intake (FI; P = 0.017) and feed conversion ratio (FCR) in the late phase (P < 0.0001). The lowest FI and highest FCR were observed in EC for W-36 hens. Free-range hens performed in-between for eggshell quality when compared to CC and EC while HB had better egg quality than W-36. Freerange hens had higher cloacal bacterial counts for aerobes, anaerobes, and coliforms than CC and EC. Higher eggshell bacterial contamination was observed in eggs from FR versus eggs from CC and EC. These results indicate that both housing environment and laying hen strain affect performance and egg quality as well as cloacal and eggshell microbiology. Further studies should be conducted to determine food safety and economic impacts when using different hen strains and housing environments.