Improvement in early bone development in broiler chicks.

摘要

Three studies were conducted to evaluate the effect of the different dietary levels of aminoacids, calcium and phosphorus and the carryover of maternal vitamin D source and level supplementation on the incidence of leg abnormalities. Increasing levels of lysine from 1.10% to 1.5% adjusted for ideal ratios were fed to broiler chickens in combination with four levels of calcium (0.5, 0.7, 0.90 and 1.1%) in a factorial arrangement. Birds fed lysine levels higher than 1.1% expressed better body weight. Feed intake was decreased by increasing the lysine level while feed conversion improved as lysine level increased. Increasing levels of Ca decreased feed intake. High levels of lysine were related to a higher incidence of TD. Ca levels equal or greater than the NRC (1994) recommendation were adequate for optimum bone mineralization.;In a second study, four levels of dietary cholecalciferol (0, 300, 600, 1200 and 2400 IU/kg) and two levels of 25-hydroxycholecalciferol (25-OH) (0 and 68 microg/kg) were evaluateds. 25-OH in plasma and egg yolk was higher as the cholecalciferol increased. When HyD was fed the level of 25-OH in plasma and egg yolk was higher than obtained when cholecalciferol was fed. Increasing levels of cholecalciferol nad 25-OH improved egg shell thickness, hen-day production and egg mass.;In a third study, the progeny of the hens from the second study was raised to evaluate the carryover effect of the maternal diet. Feed conversion and body weight improved as the cholecalciferol level increased and with the inclusion of HyD. Bone development of the progeny was improved with the addition of HyD in the maternal diet. The results confirmed the importance of the maternal vitamin D carryover for an adequate development of the progeny even three weeks post-hatch.