Composição mineral da casca proteinada de soja para alimentação de ruminantes / Mineral composition of protein soybean hull for feeding ruminants

ABSTRACT

Background: The industrial by-products vary widely in the mineral composition, therefore is necessary to identify the composition of these products to determine if present risk of toxicity to animals. Heavy metals, once ingested, can accumulate in animal tissue, mainly in the liver, kidneys and muscles. Some elements such as arsenic, cadmium and mercury are often classified as toxic elements because their biological activities are linked to toxic reactions, although all chemical elements, whether metal or not, can be toxic to animals if consumed in amounts above the need of each animal or for a long period. The protein soybean hull (PSH) is the residue coming from the technological process of extraction of soy protein, with is originally called primary sludge. To this is added 50% soybean hull and dried, resulting in the product called protein soybean hull. This work was carried out in order to assess through mineral studies the nutritional potential of the protein soybean hull for feed sheep in replace soybean meal, because currently there is no available scientific studies on the effect of using protein soybean hull in the ruminant animals diet related to mineral metabolism. Materials, Methods & Results: For this, samples of soybean protein hull were collected from a benefited soy industry in different batches to evaluate the variability in mineral composition of experimental material. The samples of soybean protein hull were analyzed for, calcium, phosphorus, potassium, magnesium, sulfur, sodium, iron, manganese, zinc, copper, cobalt. It was also analyzed for fluorine, aluminum, arsenic, cadmium, lead, mercury and vanadium, minerals considered potentially toxic to feeding sheep. The mean values of Ca and P in PSH were 0.52% and 1.22% respectively. The average content of Mg found in the PSH was 0.19% and represents 63% of the amount of Mg present in soybean meal. The S content in CPS ranged from 0.22 to 0.29%, so the PSH is sufficient to meet the daily requirements of S for sheep in growing / finishing. The PSH showed high levels of Na (0.19%) and iron (16,414 mg / kg) and can cause problems of toxicity, if not provided in a balanced diet. However, the mean levels of Mn (40.29 mg / kg), Zn (61.07 mg / kg), Cu (14.29 mg / kg) and Co (1.15 mg / kg) were suitable for feeding sheep. Considered potentially toxic minerals to feeding sheep (F, Al, As, Cd, Pb, Hg and V), only the F and Al were detected, with values of 100 and 199.43 mg / kg, being within the limits considered toxic to sheep. Discussion: The industrial production process of protein soybean hull was homogeneous due to the small variation in the mineral levels analyzed in seven different batches. The P is an essential element in the diet of sheep that represents the greatest risk of environmental pollution, so the P content of the diet should be adequate for optimal animal performance with minimal environmental impact, but the greater concern in the PSH is related to the Ca P ratio, because this ratio was less than 11 (0,521,22) and may affect the absorption of Ca or P, if the diet was not balanced properly. The iron was the only mineral and perhaps the most limiting nutritional potential of the PSH, due to its high concentration may cause problems of toxicity in sheep. The concentration of other minerals is within the maximum tolerable level for sheep. The toxicity of Iron can be better evaluated in animal experiments. In PSH samples analyzed, minerals with direct toxic potential or accumulation (heavy metals) have no major problems, since most of them were not detected in the analysis.