Effects of phosphorus level and microbial phytase supplementation on the performance and bone mineralization in pigs

Influence of phosphorus level and soaking of food on phosphorus availability and performance in growing-finishing pigs

The effects of 1-h soaking of a pig diet based on wheat and barley with low (4·1 g P per kg) and high (6·8 g P per kg) total phosphorus (P) content on total tract apparent digestibility and performance in growing-finishing pigs were studied in a balance and a performance trial respectively. Phosphorus bound to inositol penta- and hexaphosphate (IP5-IP6) was reduced by proportionately 0·1 in the soaked food. Soaking numerically increased the apparent digestibility of P. The digestibility of P did not differ between the dry high P and the soaked low P. Excretion of P in urine was correlated (R2= 0·84) with the intake of digestible P. The average daily weight gain, final body weight and carcass weight were lower (P< 0·001), and the energy conversion ratio was higher (P< 0·001) in the dry low P treatment than in the other treatments. Pigs on the low P diets had lower levels of inorganic P in serum (P< 0·01) and slightly higher serum Ca values (P< 0·05) and there were no effects of soaking. The density of femur was lower (P< 0·01) in both the low P treatments than in the high P treatments, and soaking of the low P diet improved (P< 0·01) femur density. In conclusion, a 1-h soaking of pig food in water appears to be sufficient to improve P availability and growth performance.