Calcium levels and calcium: available phosphorus ratios in diets for white egg layers from 42 to 58 weeks of age

Abstract

-The experiment was conducted to determine the nutritional requirement of calcium and the best calcium: available phosphorus ratio for commercial layers at the post-laying peak. A total of 324 Hy-Line W-36 laying hens were utilized in the period from 42 to 58 weeks of age, distributed in a completely randomized design in a 3 × 3 factorial arrangement, composed of three levels of calcium (39, 42 and 45 g/kg) and three calcium:phosphorus ratios (12.12:1; 10.53:1; and 9.30:1), totaling nine treatments with six replications and six birds per experimental unit. There was no significant effect from the calcium levels × calcium:phosphorus ratio interaction for any of the variables studied. The calcium levels and the calcium: phosphorus ratios did not affect the variables performance or egg and bone quality. At the evaluation of the calcium:phosphorus balance, as the levels of calcium of the diet were raised, the intake of calcium and phosphorus and the contents of mineral matter and calcium in the excreta increased linearly, and the retention of calcium by birds decreased linearly. With the reduction of the calcium:phosphorus ratios of the diet, intake, retention and excretion of phosphorus by layers increased. Diets containing calcium at 39 g/kg and a calcium:phosphorus ratio of 12.12:1, corresponding to an increase in calcium of 3.51 g/bird/day and available phosphorus of 289 mg/bird/day, meet the requirements of calcium and available phosphorus of white egg layers in the period from 42 to 58 weeks of age.

Calcium deposition in egg due to substitution of limestone by eggshell flour in feed of laying hens

“…Calcium of albumen dereased along with increased calcium of yolk. This result was different from the result of Pastore et al (2012) and Vargas-Rodríguez et al (2016) that Ca of the feed did not affect the deposition Ca in albumen.…”

Changes in serum calcium and phosphorus levels and their relationship to egg production in laying hens infected with velogenic Newcastle disease virus

“…Phosphorus may affect more biological systems than any other element. It is an important element in many body functions including bone formation, acid-base balance, metabolism of fat, carbohydrates, proteins and lipids, and in egg formation (Wideman 1987;Pastore et al 2012). In poultry, it has been reported that calcium and phosphorus can be affected by poultry vaccination and diseases (Fernandez et al 1994;Talebi 2006).…”

Effects on performance and eggshell quality of particle size of calcium sources in laying hens' diets with different Ca concentrations

“…the fact that 95 % of the shell is made up of calcium carbonate, an optimal supply of Ca to hens is the most important nutritional factor determining eggshell quality. Providing the layer with an optimal amount of Ca is crucial in order to ensure proper calcification of the eggshell; however, the results of several earlier experiments demonstrated that the published values for hens ' Ca requirements (NRC, 1994) were adequate for optimum shell formation and further increases in Ca dietary level above 3.6-3.9 % usually had no positive influence on eggshell quality indices (Leeson et al, 1993;Bar et al, 2002;Keshavarz, 2003;Valkonen et al, 2010;Pastore et al, 2012). The results of some studies have indicated, however, that replacing fine limestone with coarse limestone, which is characterised by prolonged retention times in the gizzard and is dissolved more slowly, thus supplying the hen more evenly with Ca (ensuring the maintenance of an adequate Ca blood level overnight, when the process of shell calcification is intensive), may positively influence eggshell quality (Guinotte and Nys, 1991;Pavlovski et al, 2003;Koreleski andŚwiątkiewicz, 2004;Lichovnikova, 2007).…”