Study On Phosphorus Requirement Of Growing Pigs Weighing From30to60kg

30three-way crossbred (Duroc×Landrace×Yorkshire) pigs were conducted to investigate the effects of different phosphorus levels of diet with0.55%calcium content on growth performance, biochemical indexes in serum and tibia quality of growing pigs, and to estimate the requirement of dietary phosphorus for growing pigs weighing from30to60kg. Completely randomized design was adopted and a total of30experimental pigs with similar body weight (32.12±0.49kg) were randomly allotted into5treatments with6repetitions in each treatment and1pig in each repetition. Pigs were fed diet with five different levels of phosphorus (0.38%、0.43%、0.48%、0.53%、0.58%) randomly in a single factorial arrangement. At the end of the research, all of experimental pigs were imbibed blood in the jugular, and three pigs were selected randomly to butcher according to the standard abatage technology from each group, and collected samples at the same time. The prepare trial period was7d, and the trial period was28d. The results indicated that:1The effects of different dietary phosphorus levels on growth performance of growing pigs were extremely significant (P<0.01). Pigs produced the higher average daily gain and feed reward fed diet with0.53%phosphorus content than0.38%and0.43%(P<0.01); There was a strong quadratic curve relationship between average daily gain and phosphorus levels in diet, as well as ADFI, and with phosphorus levels in diet decreasing, the two indicators showed a trend that increased first and decreased then.When the phosphorus levels was0.53%, growing pigs showed a better growth performance.2The differences of serum phosphorus concentration were extremely significant (P<0.01), so as the serum calcium concentration (P<0.01), while significant for serum alkaline phosphatase (AKP) activity (P<0.05) and not significant for insulin-like growth factor Ⅰ(IGF-Ⅰ)(P>0.05); Serum phosphorus concentration, serum calcium concentration and alkaline phosphatase activity showed a quadratic curve variation, increasing first and decreasing then, with phosphorus levels in diet decreasing.3Length of tibia, dry fat-free weight of tibia, the percentage of dry fat-free tibia ash, the percentage of tibia ash phosphorus and the percentage of tibia ash calcium showed a quadratic curve variation that meaned increased first and decreased then with increased dietary phosphorus from0.38%to0.53%, but the differences among the5treatments were not significant (P>0.05). The indexes above reached maximum at0.53%dietary phosphorus; dry fat-free weight of tibia of growing pigs offered0.53%phosphorus diet was higher than diet offered0.38%phosphorus (P<0.05), and the differences of dry fat-free weight of tibia between any other treatment groups were not significant(P<0.05).Taking the results above into account, the requirement of phosphorus for growing pigs weighing from30to60kg is0.53%in diet.