EFFECTS OF DIETARY CONCENTRATION AND SOURCE OF FIBER ON THE APPARENT ABSORPTION OF MINERALS BY PIGS

Four metabolism trials each involving 12 entire male pigs of an approx imate initial weight of 45 kg were conducted to determine the effects of the proportion and the source of dietary fibre on the apparent abso rption (AA) of calcium (Ca), phosphorus (P), magnesium (Mg), sodium (N a) and potassium (K). The materials used to provide the dietary fibre were: soya-bean hulls, pea (Pisum sativum) hulls, maize hulls and oat hulls. Increasing levels of each of the above-mentioned materials that would provide 69, 151, 249 or 367 g of neutral detergent fibre (NDF) were added to a constant daily allowance of a semi-synthetic diet and measurements of the total faecal output over a 10 day period were made . Increasing the proportion of fibre in the diet failed to produce any significant effects on the AA of Ca, P and Mg. Source of fibre also a ppeared not to be a major factor in influencing the AA of these minera ls. The AA of Na and K was significantly reduced (P<0.001) by the high NDF content in the diets. The extent of this reduction differed (P<0. 001) among NDF sources indicating that the chemical composition of fib re in terms of acid detergent libre (ADF), NDF, lignin, cellulose, hem i-cellulose and perhaps pectin content is an important factor relating to its effects on mineral utilization.