Effect of dietary calcium levels near the time of sexual maturity on water intake and excreta moisture content

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. Implications Protected-calcium supplementation can be used in practice for decreasing the breakage of eggs.

Adaptive response of broilers to dietary phosphorus and calcium restrictions

The aim of this study was to evaluate the capacity of chickens to adapt to and compensate for early dietary restriction of non-phytate P ( NPP: ) and/or Ca (10 to 21 d) in a later phase (22 to 35 d), and to determine whether compensatory processes depend on the P and Ca concentrations in the finisher diet. Four diets were formulated and fed to broilers from 10 to 21 d in order to generate birds with different mineral status: L₁ (0.6% Ca, 0.30% NPP), L₂ (0.6% Ca, 0.45% NPP), H₁ (1.0% Ca, 0.30% NPP), and H₂ (1.0% Ca, 0.45% NPP). On d 22, each group was divided into three groups which received a low (L, 0.48% Ca, 0.24% NPP), moderate (M, 0.70% Ca, 0.35% NPP), or high (H, 0.90% Ca, 0.35% NPP) finisher diet until 35 d, resulting in a total of 12 treatments. Lowering the Ca level enhanced apparent ileal digestibility of P (P AID) at 21 d especially with the high NPP level (Ca × NPP, P < 0.01). The lower bone mineralization observed at 21 d in broilers fed the L₁ diet compared to those fed the H₂ diet had disappeared by 35 d with long-term stimulation of the P AID with the low NPP level (P < 0.001). Although P AID and growth performance were improved in birds fed the L₁L compared to the L₁H and H₂H treatments, tibia characteristics tended to be lower in birds fed the L₁L compared to those fed the L₁H treatment. Birds fed the H₁M treatment had higher P AID, growth performance and tibia ash content than those fed the H₁H treatment. A significant increase in the mRNA levels of several genes encoding Ca and P transporters was observed at 35 d in birds fed the L₁ followed by the L diet compared to birds fed the L₁ followed by the M diet. In conclusion, chickens are able to adapt to early dietary changes in P and Ca through improvement of digestive efficiency in a later phase, and the extent of the compensation in terms of growth performance and bone mineralization depends on the P and Ca levels in the subsequent diet.