Leytem April B, Turner Benjamin L, Thacker P A
USDA-ARS, Northwest Irrigation and Soils Research Laboratory, 3793 N 3600 E, Kimberly, ID 83341, USA.
J Environ Qual. 2004 Nov-Dec;33(6):2380-3. doi: 10.2134/jeq2004.2380.
Including low-phytic-acid grains in swine diets can reduce P concentrations in manure, but the influence on manure P composition is relatively unknown. To address this we analyzed manure from swine fed one of four barley (Hordeum vulgare L.) varieties. The barley types consisted of wild-type barley (CDC bold, normal barley diet) and three low-phytic-acid mutant barleys that contained similar amounts of total P but less phytic acid. The phytic acid concentrations in the mutant barleys were reduced by 32% (M422), 59% (M635), and 97% (M955) compared with that in the wild-type barley, respectively. Phosphorus concentrations were approximately one-third less in manures from animals fed low-phytic-acid barleys compared with those fed the wild-type variety. Phytic acid constituted up to 55% of the P in feed, but only trace concentrations were detected in NaOH-EDTA extracts of all manures by solution (31)P nuclear magnetic resonance (NMR) spectroscopy. Phosphate was the major P fraction in the manures (86-94% extracted P), with small concentrations of pyrophosphate and simple phosphate monoesters also present. The latter originated mainly from the hydrolysis of phospholipids during extraction and analysis. These results suggest that phytic acid is hydrolyzed in swine, possibly in the hind gut by intestinal microflora before being excreted in feces, even though the animals have little phytase activity in the gut and derive little nutritional benefit from phytate P. We conclude that feeding low-phytic-acid grains reduces total manure P concentrations and the manure P is no more soluble than P generated from normal barley diets.
猪日粮中添加低植酸谷物可降低粪便中的磷含量，但对粪便磷组成的影响相对未知。为解决这一问题，我们分析了饲喂四种大麦（Hordeum vulgare L.）品种之一的猪的粪便。大麦类型包括野生型大麦（CDC bold，正常大麦日粮）和三种低植酸突变大麦，它们的总磷含量相似，但植酸含量较低。与野生型大麦相比，突变大麦中的植酸浓度分别降低了32%（M422）、59%（M635）和97%（M955）。与饲喂野生型品种的动物相比，饲喂低植酸大麦的动物粪便中的磷浓度约低三分之一。植酸在饲料中的磷含量中占比高达55%，但通过溶液（31）P核磁共振（NMR）光谱法在所有粪便的NaOH-EDTA提取物中仅检测到痕量浓度。磷酸盐是粪便中主要的磷组分（86-94%的提取磷），同时也存在少量的焦磷酸盐和简单磷酸单酯。后者主要源于提取和分析过程中磷脂的水解。这些结果表明，植酸在猪体内被水解，可能是在肠道微生物群的作用下在后肠中被水解，然后才随粪便排出，尽管动物肠道中的植酸酶活性很低，且从植酸磷中获得的营养益处很少。我们得出结论，饲喂低植酸谷物可降低粪便总磷浓度，且粪便中的磷溶解性并不比正常大麦日粮产生的磷更高。
