caa a22 4500 39756953X CHVBK 20180308164837.0 cr unu---uuuuu 161202e199610 xx s 000 0 eng 10.3382/ps.0751227 doi (NATIONALLICENCE)oxford-10.3382/ps.0751227 KESHAVARZ K. Department of Animal Science, Cornell University, Ithaca, New York 14853 The Effect of Different Levels of Vitamin C and Cholecalciferol with Adequate or Marginal Levels of Dietary Calcium on Performance and Eggshell Quality of Laying Hens [Elektronische Daten] [K. KESHAVARZ] Three experiments were conducted to determine whether shell quality, bone mineralization, and other production traits could be improved by adding vitamin C (ascorbic acid) to laying hen diets. The period of each experiment was 12 wk. Experiment 1 consisted of a 2 × 2 × 3 factorial design with two levels of Ca (2.8 and 3.8%), two levels of cholecalciferol (vitamin D3; 2,200 and 4,400 IU/kg diet), and three levels of vitamin C (0, 125, and 250 ppm). Experiment 2 consisted of a 2 × 3 × 2 factorial design with two levels of Ca (2.8 and 3.8%), three levels of vitamin D3 (250, 500, and 2,000 IU/kg diet), and two levels of vitamin C (0 and 250 ppm). Experiment 3 consisted of a 2 × 4 factorial design with two sources of vitamin D3 (12.5 μg vitamin D3/kg diet or 12.5 μg 25-OH-D3/kg diet) and four levels of vitamin C (0, 250, 500, and 1,000 ppm). Calcium level was kept constant at 3.5% for all the diets in Experiment 3. Production performance was not influenced by dietary treatments in Experiment 1. In Experiment 2, feed conversion was improved (P < 0.05) due to increasing the dietary Ca, and egg weight and egg size were increased (P < 0.05) due to adding 250 ppm vitamin C to the diet. In Experiment 3, albumen quality was increased by the addition of 1,000 ppm vitamin C to the diet. Egg specific gravity was increased in Experiments 1 and 2 only, due to increasing the Ca level (P < 0.05). In Experiment 2, increasing the Ca level and increasing the vitamin D3 level from 250 to 2,000 ppm reduced (P < 0.05) the number of cracked eggs, but incidence of cracked eggs was increased with the addition of 250 ppm vitamin C to the diet. In Experiment 1, plasma level of l,25(OH)2D3 was greater (P < 0.05) for hens fed 2.8 than 3.8% Ca, but blood acid-base balance was not influenced by dietary regimens. Bone ash was not influenced by dietary treatments in any of the experiments. The data indicated that a supplemental level of vitamin C had no beneficial effects on shell quality and bone mineralization under the conditions of the current experiments. © 1996 Poultry Science Association, Inc. Metabolism and Nutrition nationallicence calcium nationallicence cholecalciferol nationallicence 25-hydroxycholecalciferol nationallicence vitamin C nationallicence shell quality nationallicence Poultry Science Oxford University Press 75/10(1996-10), 1227-1235 0032-5791 75:10<1227 1996 75 ps https://doi.org/10.3382/ps.0751227 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.3382/ps.0751227 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- KESHAVARZ K. Department of Animal Science, Cornell University, Ithaca, New York 14853 NATIONALLICENCE 773 0- Poultry Science Oxford University Press 75/10(1996-10), 1227-1235 0032-5791 75:10<1227 1996 75 ps Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford