Bar, A., Institute of Animal Science, Agricultural Research Organization, Volcani Center, Bet Dagan, Israel, Institute of Animal Science, ARO, Volcani Center, POB 6, Bet Dagan 50250, Israel Razaphkovsky, V., Institute of Animal Science, Agricultural Research Organization, Volcani Center, Bet Dagan, Israel Vax, E., Institute of Animal Science, Agricultural Research Organization, Volcani Center, Bet Dagan, Israel
1. A series of 5 trials was conducted with 401- to 650-d-old Lohmann, Yafa (local breed with brown eggshells) and Yarkon (local breed with white eggshells) hens fed for 56 to 84 d with diets containing 25 to 50 g/kg calcium (Ca) and 4·5 to 7·6 g/kg phosphorus (P). 2. Increasing dietary Ca from 24-25 to 36-40 g/kg improved egg production, shell weight (SW) and shell thickness (ST), and decreased mortality. 3. Increasing dietary Ca to 48 to 50 g/kg did not affect egg production but increased SW and/or ST. In one out of the 4 trials, this effect was not significant, most likely because of the high shell quality of the eggs from the Yafa hens used for this trial. 4. Dietary P content of 4·5 g/kg (1·0 g/kg added inorganic P) appears to be sufficient for maintaining egg production and shell quality in aged laying hen given 36 to 40 g/kg Ca. 5. Increasing dietary Ca above 40 g/kg may require a higher dietary P content.
Re-evaluation of calcium and phosphorus requirements in aged laying hens
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Bar, A., Institute of Animal Science, Agricultural Research Organization, Volcani Center, Bet Dagan, Israel, Institute of Animal Science, ARO, Volcani Center, POB 6, Bet Dagan 50250, Israel Razaphkovsky, V., Institute of Animal Science, Agricultural Research Organization, Volcani Center, Bet Dagan, Israel Vax, E., Institute of Animal Science, Agricultural Research Organization, Volcani Center, Bet Dagan, Israel
Re-evaluation of calcium and phosphorus requirements in aged laying hens
1. A series of 5 trials was conducted with 401- to 650-d-old Lohmann, Yafa (local breed with brown eggshells) and Yarkon (local breed with white eggshells) hens fed for 56 to 84 d with diets containing 25 to 50 g/kg calcium (Ca) and 4·5 to 7·6 g/kg phosphorus (P). 2. Increasing dietary Ca from 24-25 to 36-40 g/kg improved egg production, shell weight (SW) and shell thickness (ST), and decreased mortality. 3. Increasing dietary Ca to 48 to 50 g/kg did not affect egg production but increased SW and/or ST. In one out of the 4 trials, this effect was not significant, most likely because of the high shell quality of the eggs from the Yafa hens used for this trial. 4. Dietary P content of 4·5 g/kg (1·0 g/kg added inorganic P) appears to be sufficient for maintaining egg production and shell quality in aged laying hen given 36 to 40 g/kg Ca. 5. Increasing dietary Ca above 40 g/kg may require a higher dietary P content.