A pilot study on in vitro solubility of phosphorus from mineral sources, feed ingredients and compound feed for pigs, poultry, dogs and cats

Abstract

Excess phosphorus (P) as seen in cat foods can have a negative effect on health (Dobenecker, Webel, Reese, & Kienzle, ; Pastoor, Klooster, Mathot, & Beynen, ). P surpluses may affect the environment, and economics in food producing animals, whereas marginal supply may impair performance and health. P can only be absorbed if it is soluble. Solubility of feed P in water and weak acid solution—as a precondition for absorption—was investigated in feed for dogs, cats, pigs and poultry. Different P containing mineral compounds (Ca(H2PO4)2, CaHPO4•2H2O, Ca4Na(PO4)3, KH2PO4, K4P2O7, NaH2PO4, Na5P3O10 (29 samples), as well as eight different ingredients such as wheat or meat, 64 compound feeds for pig and poultry, eight complete dry and 13 complete moist dog foods, 25 complete moist cat foods and 29 experimental diets were analysed for P solubility. Finely ground feeds were soaked in water or hydrochloric acid (0.4%) for 1 and 90 min. The samples were centrifuged and the supernatant was analysed for P (photometric vanadate molybdate method after wet ashing). The solubility of P from inorganic sources reflected the solubility of the main compound of the feed grade material. “organic” ingredients, such as fish meal or meat, showed a lower P solubility than inorganic sources. Most ingredients from animal origin (exception fish meal) had a higher P solubility than those from plant origin. When inorganic and “organic” P sources were mixed, the P solubility of the mixture reflected the P solubility and percentages of its compounds. In chicken, turkey and pig compound feed the percentage of acid soluble P increased with increasing P content. Pet moist food showed high percentages of water‐soluble P. The results show that the method is suitable to obtain data on water and acid solubility of P in feed and ingredients.

Comparisons of In Vitro and In Vivo Digestibility Assays for Phosphorus in Feline Diets and Associations with Dietary Nutrient Content

“…A preliminary study using a simple, in vitro method to assess the solubility of P present in mineral sources, food ingredients, and processed compound animal diets in water or weak acid following 1 and 90 min of stirring has introduced the possibility of using this type of method to predict soluble P salt contribution in diets . The results suggested that not only the source, processing, ingredient mixes, and concentration of P but also levels of calcium and other electrolytes present in diets may affect P solubility.…”

Phosphataufnahme durch auf dem deutschen Markt befindliche Alleinfutter und Nierendiäten für Hunde und Katzen

“…Genauso ist es nicht möglich, vom Rohproteingehalt im Futter auf die Menge an P sol1 zu schließen (R 2 = 0,000003). Dies hätte man eventuell vermuten können, da auch Fleisch eine gewisse Menge an hochlöslichem Phosphor enthält [27]. Zu den Phosphorquellen, die bereits nach 1 Minute in Wasser löslich und damit hoch verfügbar sind (P sol1 ), gehören Phosphatsalze wie z.…”

In Vivo Toxicity and In Vitro Solubility Assessment of Pre-Treated Struvite as a Potential Alternative Phosphorus Source in Animal Feed

“…Factors including transit and retention time, pH, and particle size may control the P solubility in the gastrointestinal tract [43]. Moreover, P from inorganic sources are more soluble in the acid medium than the P from plant materials [44]. The amount of P available for absorption is controlled by its sustained solubility in the gastrointestinal tract in animals [45].…”