Effect of Various Feed Phosphates on Biochemical Indices of Blood and Mineral Composition of Bones in Finishing Pigs

The aim of this study was to evaluate the effect of three different chemical feed phosphates on the blood biochemical indicators and the content of main minerals of bones in finishing pigs. Over a period of 85 days of fattening, monocalcium (MCP, Finnish product), dicalcium (DCP, Polish product) and calcium-sodium (CSP, Russian product) phosphates were used in fattener feeding. The feeding was based on standard mixtures of starter, grower and finisher type. Dicalcium phosphate was produced according to the new, pro-ecological technology based on phosphoric acid. The content of Ca, Na, P, solubility of P in citric acid, and the concentration of undesirable substances (As, Cd, F, Hg and Pb) were determined in feed phosphates. At the end of the fattening period, blood was collected from 36 finishing pigs (12 from each group) and the following biochemical indicators were determined in the serum: enzymatic activity of aspartate aminotransferase (AST), alanine aminotransferase (ALT), γ-glutamyltransferase (GGT), creatine kinase (CK), lactic dehydrogenase (LDH), lactic acid (LA); the concentration of total protein, albumins, glucose, urea, creatinine, content of triglycerides, cholesterol and its high density lipoproteins (HDL) and low density lipoproteins (LDL) fractions, and mineral components concentration (Ca, Cl, Cu, Fe, K, Mg, Na, P, Zn). Basic macroelement content (Ca, Mg, P) was determined in the thigh bones from 30 pigs (10 from each group). Significant differences (p < 0.05) between groups were observed only in some biochemical indicators, i.e. CK, LDH and LA. The highest content of Ca, Mg and P was found in the bones of pigs fed mixtures supplemented with DCP which indicates improved bioavailability of main macroelements from that phosphate. Feed supplements, fatteners, blood serum, bone composition Cereal grain, i.e. the main source of phosphorus, is the basic fodder in pig feeding. In cereal grain, phosphorus is present in the form of sparingly available phytates. The introduction of formulation containing an exogenous microbiological phytase to feeding mixtures is a common way of improving phosphorus availability from phytic compounds (Krasucki and Grela 1997; Radcliffe et al. 1999; Steiner et al. 2006). Such procedure may considerably reduce the amount of phosphorus expelled in faeces which is important in terms of environmental protection. However, the amount of phosphorus available in feed of plant origin, even with the addition of microbiological phytase does not fulfill the demands of intensively growing pigs, and supplementation of the feeding dose with additional 30%-50% mineral phosphorus is necessary (Fandrejewski 1997). Mono-, di-, and tricalcium, calcium-sodium, sodium-calcium-magnesium and ammonium phosphates are available on the fodder market. The production of dicalcium phosphate (DCP) using a new pro-ecological method has been recently introduced in Poland (Hoffmann et al. 2008). ACTA VET. BRNO 2010, 79:355–361; doi:10.2754/avb201079030355 Address for correspondence: Prof. Dr hab. Zbigniew Dobrzański Department of Animal Hygiene and Environment, Faculty of Biology and Animal Science, University of Environmental and Life Sciences, Chelmonskiego 38c, 51-630 Wroclaw, Poland Phone/fax : +48 71 32 05 865 Fax: +48 71 3205 866 E-mail: [email protected] http://www.vfu.cz/acta-vet/actavet.htm The apparent digestibility of phosphorus in these phosphates is often extremely variable, from 51 to 90%, and depends mainly on the technology of production used and the purity of the phosphoric acid employed (Eckhout and Paepe 1997; Poulsen 2007; Gołębiowska et al. 2008). The aim of the present study was to evaluate the effect of three different feed phosphates including DCP produced using the new method, on the blood biochemical indicators and the content of the main minerals in bones of finishing pigs. Materials and Methods Animals and feeding Experimental fattening was conducted at the Experimental Animal Feeding Plant in Gorzyń that belongs to the Poznan University of Life Sciences, Poland. The study was conducted on 60 piglets (originating from Large Polish White × Polish Landrace crossbred sows and Hampshire × Pietrain crossbred boars) of an average initial body mass of 20 kg. The animals were divided into 3 groups of 20 individuals each, according to the rule of analogues. The fattening lasted 85 days, i.e. until the body mass reached about 110 kg. The division of piglets into 3 feeding groups followed from the contribution of phosphates analysed in mixtures used during the experimental fattening: group 1 (control) – mixtures with monocalcium phosphate (MCP); group 2 – mixtures with dicalcium phosphate (DCP); group 3 – mixtures with calcium-sodium phosphate (CSP). The contribution of particular feed phosphates resulted from the optimisation of P content in the mixtures. It was assumed that mineral phosphorus makes up 30% of the demand for total phosphorus. The contribution of phosphorus in the three mixtures used was as follows: MCP 0.57 – 0.73%, DCP 0.70 – 0.89%, and CSP 0.72 – 0.92%. The nutritional value of starter, grower and finisher mixtures, with mineral components, is presented in Table 1. Feed phosphates Three kinds of phosphates were used in the experiment: monocalcium (MCP, Finnish product), calcium-sodium (CSP, Russian product) and dicalcium (DCP, Polish product). Dicalcium phosphorus was produced from calcium oxide and calcium carbonate, using concentrated phosphoric acid as the phosphorus source. The product obtained in a direct chemical reaction between phosphoric acid and calcium was a phosphoric acid salt with the following chemical formula: CaHPO4 × 2H2O. The technology applied was non-scrap and non-sewage autothermal technology using the heat of the reaction to dry the product. Because of the lack of direct drying with gases, the final product thus obtained did not contain any harmful organic substances (Hoffmann and Hoffmann 2009). Within the chemical assessment of phosphates, the following were determined: the content of Ca, total P, P soluble in 2% citric acid, and the content of undesirable substances such as As, Cd, F, Hg and Pb. The analyses were conducted in a specialist chemical laboratory at the Institute of Inorganic Technology and Mineral Fertilizers in Wroclaw University of Technology using mandatory chemical methods (AOAC 1990). 356 Table 1. Nutritional values of “starter”, “grower” and “finisher” mixtures Feed materials Units Mixture Starter Grower Finisher In 1 kg of a mixture: Net energy Kcal 234