Relationship of Body-Checked Eggs to Photoperiod and Breaking Strength

Abstract

Hisex hens (20 weeks of age) were housed one or three per 30.5 × 40.6 cm cage (Experiment 1). One half of the hens at each density received a constant 15-hr photoperiod (0500 to 2000 hr). The other half received a 15-hr photoperiod that was increased 15 min every 5 days to a maximum of 18 hr (0200 to 2000). Total feed consumption, egg production, egg weight, specific gravity, body checks, and time of oviposition were determined at various intervals throughout a 12-month period. Shell weight, thickness, and breaking strength were determined on normal and body-checked eggs paired for equal egg weight and specific gravity (Experiments 2 to 4).Hens housed three per cage laid 2.2 times as many body-checked eggs as hens housed one per cage. Hens receiving the 18-hr photoperiod laid 2.4 times as many body-checked eggs and laid significantly earlier in the day than hens receiving the 15-hr photoperiod. Hens receiving the 15-hr photoperiod had significantly greater egg specific gravity and significantly smaller eggs than hens receiving the 18-hr photoperiod. Hens housed one per cage and supplied the 18-hr photoperiod laid significantly more eggs than hens housed three per cage. Photoperiod had no significant influence on average 12-month egg production or feed consumption. Approximately 18% less force was required to break a body-checked egg than an egg not body-checked.It was concluded that photoperiod (18 and 15 hr) had little or on effect on production or feed consumption, but the shorter photoperiod significantly reduced the incidence of body-checked eggs by at least 50% and significantly increased egg specific gravity.