Department of Animal Sciences, University of Illinois at Urbana-Champaign, IL 61801, USA.
Department of Poultry Science, University of Arkansas at Fayetteville, AR 72701, USA.
Poult Sci. 2024 Nov;103(11):104226. doi: 10.1016/j.psj.2024.104226. Epub 2024 Aug 22.
Three experiments were conducted to determine effect of feeding 5 commercial limestones varying in solubility (88-97%), mean particle size (500-700 microns), and geographical origin on Ca bioavailability and digestibility in commercial broiler and crossbred chickens. In Experiment 1, both crossbred and commercial chickens were used to measure the effect of dietary Ca level on tibia bone ash to develop a slope-ratio Ca bioavailability assay. Chickens were fed diets that contained Ca levels ranging from 0.20% to 0.95% from 9 to 22 d-of-age. Regressions of bone ash (mg/tibia and %) on supplemental Ca intake yielded large linear responses in both types of chickens in Experiment 1. In Experiment 2, relative bioavailability of Ca in 5 limestones using bone ash as primary response criterion was determined. Thirteen diets were fed to commercial Ross 308 male broilers which were either a Ca-deficient diet (0.30% Ca) or that diet supplemented 0.15 or 0.30% Ca from either reagent grade calcium carbonate (RCaCO) or 1 of the 5 commercial limestones from 9 to 22 d-of-age. Bioavailability of Ca in limestones relative to RCaCO was determined using multiple linear regression of bone ash (mg/tibia and %) on supplemental Ca intake, which yielded slope-ratio relative Ca bioavailability values ranging from 90% to 106% in Experiment 2. In Experiment 3, apparent ileal digestibility (AID) and apparent total tract retention (TTR) of Ca in broiler chickens was measured for the 5 limestones using corn-based diets. The AID and TTR of Ca at 21 d-of-age were low and variable with a range of 20 to 34% for AID of Ca and 12 to 31% for TTR of Ca. Results from these studies indicate that a slope-ratio bone ash assay with either crossbred or modern commercial chickens can be used to measure relative bioavailability of Ca in limestones and there were few consistent differences in relative Ca bioavailability, AID of Ca, and TTR of Ca among 5 commercial limestones evaluated herein.
进行了三项实验，以确定饲喂 5 种不同溶解度（88-97%）、平均粒径（500-700 微米）和地理来源的商业石灰对商业肉鸡和杂交鸡钙生物利用度和消化率的影响。在实验 1 中，使用杂交鸡和商业鸡来测量饲粮钙水平对胫骨骨灰的影响，以开发斜率比钙生物利用度测定法。鸡从 9 日龄到 22 日龄饲喂含有 0.20%至 0.95%钙的饲粮。在实验 1 中，两种类型的鸡的骨灰（mg/胫骨和%）与补充钙摄入量的回归均呈较大的线性反应。在实验 2 中，使用骨灰作为主要反应标准，确定了 5 种石灰中钙的相对生物利用度。13 种饲粮饲喂 9 日龄至 22 日龄的商业罗斯 308 雄性肉鸡，饲粮为钙缺乏饲粮（0.30%钙）或该饲粮从试剂级碳酸钙（RCaCO）或 5 种商业石灰中的 1 种补充 0.15%或 0.30%钙。使用补充钙摄入量的线性回归，确定了石灰中钙相对于 RCaCO 的生物利用度，得出斜率比相对钙生物利用度值在实验 2 中为 90%至 106%。在实验 3 中，使用基于玉米的饲粮测量了 5 种石灰在肉鸡中的回肠表观消化率（AID）和全肠道表观保留率（TTR）。21 日龄时钙的 AID 和 TTR 较低且变化较大，钙 AID 范围为 20%至 34%，钙 TTR 范围为 12%至 31%。这些研究结果表明，使用杂交鸡或现代商业鸡的斜率比骨灰测定法可用于测量石灰中钙的相对生物利用度，并且在所评估的 5 种商业石灰中，钙的相对生物利用度、钙的 AID 和钙的 TTR 之间几乎没有一致的差异。
