The choice of the calcium (Ca) source in pig diets and the addition of formic acid may affect the gastrointestinal inositol phosphate (InsP) degradation and thereby, phosphorus (P) digestibility in pigs. This study assessed the effects of different Ca sources (Ca carbonate, Ca formate), exogenous phytase, and chemical acidification on InsP degradation, nutrient digestion and retention, blood metabolites, and microbiota composition in growing pigs. In a randomized design, eight ileal-cannulated barrows (24 kg initial BW) were fed five diets containing Ca formate or Ca carbonate as the only mineral Ca addition, with or without 1,500 FTU/kg of an exogenous hybrid 6-phytase. A fifth diet was composed of Ca carbonate with phytase but with 8 g formic acid/kg diet. No mineral P was added to the diets. Prececal InsP6 disappearance and P digestibility were lower (P ≤ 0.032) in pigs fed diets containing Ca formate. In the presence of exogenous phytase, InsP5 and InsP4 concentrations in the ileal digesta were lower (P≤0.019) with Ca carbonate than Ca formate. The addition of formic acid to Ca carbonate with phytase diet resulted in greater (P = 0.027) prececal InsP6 disappearance (87 vs 80%), lower (P = 0.001) InsP5 concentration, and greater (P ≤ 0.031) InsP2 and myo-inositol concentrations in the ileal digesta. Prececal P digestibility was greater (P = 0.004) with the addition of formic acid compared to Ca carbonate with phytase alone. Prececal amino acid (AA) digestibility of some AA was greater with Ca formate compared to Ca carbonate but only in diets with phytase (P ≤ 0.048). The addition of formic acid to the diet with Ca carbonate and phytase increased (P ≤ 0.006) the prececal AA digestibility of most indispensable AA. Exogenous phytase affected more microbial genera in the feces when Ca formate was used compared to Ca carbonate. In the ileal digesta, the Ca carbonate diet supplemented with formic acid and phytase led to a similar microbial community as the Ca formate diets. In conclusion, Ca formate reduced prececal InsP6 degradation and P digestibility, but might be of advantage in regard to prececal AA digestibility in pigs compared to Ca carbonate when exogenous phytase is added. The addition of formic acid to Ca carbonate with phytase, however, resulted in greater InsP6 disappearance, P and AA digestibility values, and changed ileal microbiota composition compared to Ca carbonate with phytase alone.

中文翻译：

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日粮钙源、外源植酸酶和甲酸对生长猪磷酸肌醇降解、矿物质和氨基酸消化率以及微生物群的影响


猪日粮中钙（Ca）来源的选择和甲酸的添加可能会影响胃肠道磷酸肌醇（InsP）的降解，从而影响猪对磷（P）的消化率。本研究评估了不同钙源（碳酸钙、甲酸钙）、外源植酸酶和化学酸化对生长猪 InsP 降解、营养物质消化和保留、血液代谢物和微生物群组成的影响。在一项随机设计中，八头回肠插管的阉猪（初始体重 24 公斤）被喂食五种含有甲酸钙或碳酸钙作为唯一矿物质钙添加物的日粮，并添加或不添加 1,500 FTU/kg 的外源混合 6-植酸酶。第五种日粮由碳酸钙和植酸酶组成，但每千克日粮含有 8 克甲酸。日粮中未添加矿物质 P。饲喂含有甲酸钙日粮的猪的前盲肠 InsP6 消失和磷消化率较低 (P ≤ 0.032)。在存在外源植酸酶的情况下，碳酸钙回肠食糜中的 InsP5 和 InsP4 浓度低于甲酸钙 (P≤0.019)。在植酸酶饮食的碳酸钙中添加甲酸导致盲肠前 InsP6 消失量更大（P = 0.027）（87% vs 80%），InsP5 浓度更低（P = 0.001），InsP2 和肌醇含量更高（P ≤ 0.031）回肠食糜中的浓度。与单独使用植酸酶的碳酸钙相比，添加甲酸的前盲肠 P 消化率更高 (P = 0.004)。与碳酸钙相比，甲酸钙对某些 AA 的盲肠前氨基酸 (AA) 消化率更高，但仅限于含有植酸酶的日粮中 (P ≤ 0.048)。在含有碳酸钙和植酸酶的日粮中添加甲酸可增加（P≤0.006）大多数不可缺少的 AA 的盲肠前 AA 消化率。 与碳酸钙相比，使用甲酸钙时，外源植酸酶影响粪便中更多的微生物属。在回肠食糜中，补充有甲酸和植酸酶的碳酸钙日粮产生了与甲酸钙日粮相似的微生物群落。总之，甲酸钙降低了盲肠前 InsP6 降解和磷消化率，但当添加外源植酸酶时，与碳酸钙相比，甲酸钙可能在猪盲肠前 AA 消化率方面具有优势。然而，与单独使用植酸酶的碳酸钙相比，在碳酸钙和植酸酶中添加甲酸会导致更大的 InsP6 消失、P 和 AA 消化率值，并改变回肠微生物群组成。