| Summary: | The current data provide estimates of the flow of nitrogen (N), calcium (Ca) and phosphorus (P) in Shaver White layers housed under conventional cage (CC) and enriched cage (EC) systems from 19 to 63 wks of age. The experiment was conducted at the University of Manitoba poultry unit. Both feed disappearance (P < 0.01) (92.5 vs. 95.0 ± 0.6 g/hen/d, DM basis) and manure output (P < 0.01) (79.8 vs. 91.3 ± 1.2 g/hen/d, fresh basis and 27.0 vs. 28.1 ± 0.2 g/hen/d, DM basis) were lower in hens housed in EC compared to CC. Manure DM was 34.1 and 31.0 ± 0.3% for EC and CC, respectively. Feed conversion ratio; body weight; and egg production, weight and mass were not significantly different between the two systems. Although there was no difference in the overall manure N (EC: 1.94 vs. CC: 1.96 ± 0.02 g/hen/d, respectively), N balance was greater (P < 0.05) for the CC compared to EC system (85.0 vs. 30.2 ± 13.6 mg/hen/d, respectively). Lower (P < 0.01) Ca and P excretions were observed in EC (Ca: 2.11 vs. 2.29 ± 0.04 and P: 0.619 vs. 0.643 ± 0.005 g/hen/d) compared to CC. Overall egg N output was similar between the systems. Although lower Ca deposition (P < 0.0001) (2.07 vs. 2.13 ± 0.01 g/hen/d) and output (P < 0.05) (38.3 vs. 38.8 ± 0.15 mg/g egg) were noted in eggs from EC compared to CC, shell quality measurements were not different between the two systems. In addition, Ca outputs in eggs expressed as a proportion of Ca intake in both systems were similar (56.5 vs. 56.6 ± 0.51). Although overall mean P retention (-7.22 vs. -7.45 ± 0.71% P intake) was not different between the two groups of hens, Ca retention was higher (P < 0.05) in EC than CC hens (-1.37 vs. -4.76 ± 0.89% Ca intake, respectively). In addition to providing environmental enrichment and maintaining the production performance to the levels of those achieved by CC systems, EC may also help in reducing Ca and P excretions and improving their efficiency of utilization.
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