Dietary supplementation with protected calcium effects production and egg quality of Hy-line brown laying hens

Context. Currently, the commonly used dietary calcium sources are not sufficiently bioavailable to be used for eggshell formation or bone health in laying hens. Protected calcium, a blend of calcium and medium-chain fatty acids with matrix coating, may exert an effective absorption and metabolism ability for calcium consumption in the laying hen. Aims. The present study was conducted to evaluate the effects of protected-calcium supplementation on egg production, egg quality, and serum calcium and phosphorus concentrations in laying hens. Methods. In total, 144 Hy-line brown laying hens (25 weeks old) were randomly allotted to three treatments (8 replicates with 6 hens, 1 hen per cage) in a 10-week trial. Treatments consisted of corn wheat soybean meal-based basal diet with limestone (coarse limestone : fine limestone = 50 : 50) as a calcium source (CON) or basal diet supplemented with 0.5% (P1) or 1% (P2) protected calcium in substitution for an equal quantity of coarse limestone. Data were statistically analysed using linear and quadratic contrast with the GLM procedure of SAS. Probability values of <0.05 indicate significance. Key results. At Weeks 31-33 and 35, the cracked-egg rates were lower in the P1 and P2 groups than in the CON group (P < 0.05; linear, P < 0.05) and, at Weeks 29 and 34, the cracked-egg rates in the P2 group were also significantly (P < 0.05) decreased. At Weeks 26, 30 and 32, the Haugh units in the P2 group were significantly (P < 0.05) higher than those in the CON group. In addition, eggshell strength was increased significantly (P < 0.05) in the P2 group at Weeks 26, 27 and 31-35. The serum calcium concentration of the P2 group was significantly (P < 0.05) greater than that of the CON group in the morning. Conclusions. In conclusion, a replacement of limestone with 1% protected calcium can increase eggshell quality.