Department of Animal Sciences, University of Illinois, Urbana, IL.
Division of Nutritional Sciences, University of Illinois, Urbana, IL.
J Anim Sci. 2019 Jul 30;97(8):3440-3450. doi: 10.1093/jas/skz176.
Two experiments were conducted to test the hypothesis that standardized total tract digestibility (STTD) of Ca and the response to microbial phytase is constant among different sources of Ca carbonate and that the STTD of Ca is constant among different sources of dicalcium phosphate (DCP) when fed to growing pigs. In Exp. 1, 80 pigs (initial BW: 19.0 ± 1.9 kg) were randomly allotted to 10 diets and 2 blocks with 4 pigs per diet in each block. Four sources of Ca carbonate were used, and each source was included in a diet without microbial phytase and a diet with microbial phytase (500 units/kg diet). Two Ca-free diets without or with microbial phytase were also formulated. Feed allowance was 2.7 times the maintenance energy requirement for ME and daily feed allotments were divided into 2 equal meals. The initial 4 d of each period were considered the adaptation period to the diets followed by 4 d of fecal collection using the marker-to-marker procedure. Pigs fed diets containing exogenous phytase had lower (P < 0.05) basal endogenous loss of Ca compared with pigs fed diets containing no phytase. There were no interactions between phytase and source of Ca carbonate. Values for STTD of Ca were greater (P < 0.05) for diets containing microbial phytase (77.3% to 85.4%) compared with diets without exogenous phytase (70.6% to 75.2%), and values for STTD of Ca differed (P < 0.05) among the 4 sources of Ca carbonate. In Exp. 2, 40 pigs (initial BW: 14.9 ± 1.3 kg) were allotted to a completely randomized design with 5 diets and 8 replicate pigs per diet. A basal diet in which all Ca was supplied by Ca carbonate was formulated. Three diets were formulated by adding 3 sources of DCP to the basal diet and a Ca-free diet was also used. Feeding and collection methods were as described for Exp. 1. Results indicated that values for STTD of Ca and ATTD of P were not different among diets, indicating that under the conditions of this experiment, the digestibility of Ca and P in DCP appears to be constant regardless of origin of DCP. In conclusion, use of microbial phytase reduces the basal endogenous loss of Ca and increases Ca digestibility in Ca carbonate. The STTD of Ca varies among sources of Ca carbonate, regardless of phytase inclusion, but that appears not to be the case for the STTD of Ca in different sources of DCP.
标准化总肠道消化率（STTD）的钙和微生物植酸酶的反应是恒定的不同来源的碳酸钙和钙的 STTD 是不同来源的磷酸二钙（DCP）时，生长猪。在实验 1 中，80 头猪（初始体重：19.0±1.9 公斤）被随机分配到 10 种饮食和 2 个块，每个块中有 4 种饮食。使用了 4 种不同来源的碳酸钙，并且每种来源都包含在没有微生物植酸酶的饮食和含有微生物植酸酶（500 单位/千克饮食）的饮食中。还配制了两种不含或含微生物植酸酶的钙自由饮食。饲料允许量是维持能量需求的 2.7 倍，ME 和每日饲料分配分为 2 等份。每个时期的最初 4 天被认为是适应饮食的适应期，然后使用标记到标记程序收集 4 天的粪便。与不含植酸酶的饮食相比，添加外源植酸酶的饮食中猪的基础内源钙损失较低（P<0.05）。植酸酶与碳酸钙来源之间没有相互作用。含有微生物植酸酶的饮食的钙 STTD 值较高（P<0.05）（77.3%至 85.4%），与不含外源植酸酶的饮食相比（70.6%至 75.2%），并且 4 种碳酸钙来源之间的钙 STTD 值存在差异（P<0.05）。在实验 2 中，40 头猪（初始体重：14.9±1.3 公斤）被分配到完全随机设计，有 5 种饮食和 8 种饮食中的 8 个重复猪。一种基础饮食，其中所有的钙都是由碳酸钙提供的。通过向基础饮食中添加 3 种来源的 DCP 来配制 3 种饮食，并且还使用了一种无钙饮食。饲养和收集方法如实验 1 所述。结果表明，饮食之间的钙 STTD 值和磷总可消化率（ATTD）没有差异，表明在本实验条件下，DCP 中的钙和磷的消化率似乎是恒定的，而与 DCP 的来源无关。总之，使用微生物植酸酶可减少基础内源钙的损失，并提高碳酸钙中钙的消化率。钙的 STTD 因碳酸钙来源而异，无论是否添加植酸酶，但在不同来源的 DCP 中，钙的 STTD 似乎并非如此。
