Effect of antinutritive factors in the feed (phytic acid, nonstarch polysaccharides) and kind of trace element forms (inorganic vs organic) was presented on the basis of literature review. Phytic acid, through formation of indigestible complexes with microelements, significantly decreases its utilization by the organism. Also non-starch polysaccharides showed of ten similar influence. Organic forms of trace elements generally are characterized by higher bioavailability than their inorganic forms.
When native and microbial phytases are included in the diets of monogastric animals there is a considerable improvement in phosphorus absorption from plant fodder, and thus, an ensuing reduction in the requirement for phosphorus in mineral form. Phytase may significantly diminish the amount of this mineral excreted in faeces and thereby reduce environmental pollution. Additionally, when added to the diets of monogastries, it not only improves the utilization of phosphorus, calcium and other minerals from the gastro-intestinal tract but also increases the digestibility of amino acids and fat.
On the basis of own research and literature the content of manganese in seeds of three lupin species (yellow, narrow-leafed and white) was discussed. White lupin seeds contained manganese at the amount exceeding several times its content typical to other leguminous plants. Contents of Mn in the seeds of Polish white lupin cultivars and strains ranged within 134-1452mg/kg Mn. Ten out of thirteen samples contained less that 700 mg/kg Mn, and in eight samples the Mn content was below 500 mg/kg. In an experiment on rats fed the diet including 30% lupin seeds containing approximately 1000 mg/kg manganese, the Mn dose increased to 330 mg did not negatively affect the feed intake nor utilisation of protein. This was due to a low bioavailability of manganese from lupin seeds, much lower than that of manganese carbonate. Following the analysis of animal nutrition requirements results of the experiments on pigs and poultry, and the review of permissible manganese content in animal feeds in the legislation of other countries, it was concluded that an excessive amount of manganese may sporadically limit the use of white lupin seeds for animal feed production in Poland. It was shown that lupine seeds for feed should not contain more than 900 mg/kg Mn. At 20-25% share of lupine seeds in feed mixture and provided 30 mg/kg Mn content in cereal grain, the content of manganese in feed mixtures should not exceed 250 mg/kg.