This study was carried out to determine the digestible phosphorus requirement for growing swine. Seventy crossbred swine (35 castrated males and 35 females), with initial weight of 29.72±1.52 kg were distributed in a completely randomized design with five treatments, seven replicates and two animals (one male and one female) per experimental unit. The experiment lasted 21 days. The treatments were composed of diets formulated with corn and soybean meal, supplemented with dicalcium phosphate, corresponding to five levels of digestible phosphorus (0.19; 0.25; 0.30; 0.35 and 0.40%). For each phosphorus level, limestone was added to maintain the calcium:phosphorus ratio constant. The increase in digestible phosphorus influenced feed intake and weigh gain quadratically, and the maximum values for those parameters were obtained with the levels of 0.32 and 0.31% digestible phosphorus, respectively. There was no effect of digestible phosphorus levels on the feed:gain ratio. The ashes and calcium contents analyzed in the metatarsi were not influenced by digestible phosphorus levels, while the phosphorus content in bone showed linear response. The requirement of digestible phosphorus for pigs fed diets based on corn and soybean meal is 0.31%, corresponding to a daily intake of 5.87 g digestible phosphorus.
calcium and phosphorus; requirements; true digestibility
