在以半纯化日粮饲养 20 公斤重的猪时，真钙比在石灰石和磷酸二钙中表观总肠道消化率更能增加钙的含量。
True is more additive than apparent total tract digestibility of calcium in limestone and dicalcium phosphate for twenty-kilogram pigs fed semipurified diets.
出版信息
J Anim Sci. 2017 Dec;95(12):5466-5473. doi: 10.2527/jas2017.1849.
Two experiments were conducted to determine the Ca digestibility of limestone and dicalcium phosphate (DCP) and if values for Ca digestibility are additive in mixed diets for pigs. In Exp. 1, 48 barrows with an average initial BW of 19.2 ± 1.1 kg were assigned to 1 of 6 dietary treatments in a 2 × 3 factorial arrangement of 2 Ca sources, including limestone or DCP, and 3 dietary Ca concentrations of 0.54, 0.74, or 0.94%. Diets were fed for a 5-d adjustment period followed by a total collection period of 5 d with chromic oxide and ferric oxide as markers to determine the initiation and termination of fecal collection, respectively. Results indicated that the increased dietary Ca concentration linearly increased ( < 0.01) Ca intake, digested Ca, and retained Ca but did not affect the apparent total tract digestibility (ATTD) of Ca or Ca retention of intake (%). The ATTD of P and P retention of intake were linearly increased ( < 0.05) as dietary Ca and P increased. In Exp. 2, 72 barrows with an average initial BW of 20.8 ± 1.3 kg were assigned to 1 of 9 dietary treatments in a 3 × 3 factorial arrangement of 3 Ca sources, including limestone, DCP, or the mixture of the 2 at a ratio of 1:1, and dietary Ca concentrations of 0.40, 0.50, or 0.60%. Feeding and sample collection procedures were as in Exp. 1. The results also showed that increased Ca concentration linearly increased ( < 0.001) Ca intake, fecal Ca output, and Ca absorbed but did not affect the ATTD of Ca within each Ca source. The average ATTD were 66.46, 70.34, and 69.32% for the limestone, DCP, and mixed diets, respectively. By regressing daily digested Ca against daily Ca intake, the true total tract digestibility (TTTD) of Ca was determined to be 70.06, 76.42, and 73.72% for the limestone, DCP, and mixed diets, respectively. The predicted TTTD for Ca in the mixed diets of limestone and DCP was calculated to be 72.67% based on the Ca contribution coefficient of 0.59 for limestone and 0.41 for DCP. The predicted Ca TTTD (72.67%) in the mixed diets was not different from the Ca TTTD (73.72%) determined using the regression method. It is concluded that although the ATTD of limestone and DCP were not affected by the Ca concentration in the diet, TTTD is recommended for evaluation of Ca digestibility because of its additivity in a mixed diet.
进行了两项实验，以确定石灰石和磷酸二钙 (DCP) 的钙消化率，以及在猪的混合日粮中钙消化率是否具有加性。在实验 1 中，48 头平均初始体重为 19.2 ± 1.1kg 的阉猪被分配到 6 种日粮处理中的 1 种，采用 2 种钙源（石灰石或 DCP）和 3 种日粮钙浓度（0.54、0.74 或 0.94%）的 2 × 3 因子排列。日粮饲喂 5 天进行调整期，然后用铬氧化物和三氧化二铁进行 5 天的总收集期，分别作为标记以确定粪便收集的开始和结束。结果表明，日粮钙浓度的增加线性增加（<0.01）钙的摄入量、消化钙和保留钙，但不影响钙的表观全肠道消化率（ATTD）或钙的摄入量保留（%）。随着日粮钙和磷的增加，磷的 ATTD 和磷的摄入量保留线性增加（<0.05）。在实验 2 中，72 头平均初始体重为 20.8 ± 1.3kg 的阉猪被分配到 9 种日粮处理中的 1 种，采用 3 种钙源（石灰石、DCP 或两者以 1:1 的比例混合）和 3 种日粮钙浓度（0.40、0.50 或 0.60%）的 3 × 3 因子排列。饲养和样品收集程序与实验 1 相同。结果还表明，钙浓度的增加线性增加（<0.001）钙的摄入量、粪便钙输出和钙吸收，但不影响每种钙源的钙的 ATTD。石灰石、DCP 和混合日粮的平均 ATTD 分别为 66.46%、70.34%和 69.32%。通过将每日消化钙与每日钙摄入量进行回归，确定钙的真实全肠道消化率（TTTD）分别为石灰石、DCP 和混合日粮的 70.06%、76.42%和 73.72%。基于石灰石的钙贡献系数为 0.59 和 DCP 的钙贡献系数为 0.41，计算出石灰石和 DCP 混合日粮中钙的预测 TTTD 为 72.67%。基于回归法确定的混合日粮中钙的预测 TTTD（72.67%）与 TTTD（73.72%）无差异。结论是，尽管日粮钙浓度不会影响石灰石和 DCP 的 ATTD，但由于其在混合日粮中的加性，建议使用 TTTD 来评估钙消化率。
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