Effects of dietary mineral manipulation on productive performance and eggshell quality in laying hens during the late laying period.

This study evaluated mineral-based dietary interventions as a strategy to mitigate the age-related decline in egg production and quality commonly observed in late-cycle Lohmann Selected Leghorn laying hens. A completely randomized design was used with 294 hens at 90 wk of age assigned to 7 dietary treatments for 56 d:(1) basal control diet; (2) basal diet supplemented with 4 g/kg MgO; (3) basal diet supplemented with 50 mg/kg MnSO4; (4) basal diet supplemented with 30 mg/kg ZnSO4; (5) basal diet supplemented with MgO, MnSO4, and ZnSO4 at the respective levels; (6) basal diet containing 25% less available P than the control; and (7) basal diet containing 15% more Ca than the control. Supplementation with Mg or Mn increased feed intake, whereas the combined Mg + Mn + Zn treatment reduced feed consumption (P ≤ 0.05). All dietary treatments improved feed conversion ratio throughout the experimental period, and increased egg production during 94-98 wk of age (P ≤ 0.05), with no effect on egg mass (P > 0.05). The high-Ca diet increased specific gravity and shell thickness, Mg supplementation increased shell weight, and Mn supplementation enhanced shell thickness (P ≤ 0.05). Zinc supplementation, alone or in combination with Mg and Mn, reduced the incidence of damaged eggs (P ≤ 0.05).Dietary treatments had no significant effect on internal egg quality traits (P > 0.05), with the sole exception of Haugh unit values, which were significantly higher in hens supplied the high-Ca diet (P ≤ 0.05). Overall, targeted mineral interventions, particularly increased dietary Ca and supplementation with Mg, Mn, or Zn, improved selected production and eggshell quality traits in aged laying hens.