Effect of reduced dietary level of available phosphorus on performance and bone parameters in growing pigs
A 3-wk experiment was conducted with growing pigs to investigate the effects of different dietary concentrations of available phosphorus (aP) on performance and bone parameters. Fifty-four growing pigs (19.5 ±1.11 kg BW) housed in groups of three per pen were randomly allotted to three experimental diets formulated to contain 0.23% (control), 0.17% and 0.11% aP. Feed and water were provided on an ad libitum basis throughout the experiment. Body weight and feed intake were measured on d 0, 7, 14, and 21. At the end of each wk, one pig per pen was sacrificed to obtain the third (MC3) and fourth (MC4) metacarpals for determining bone mineral density (BMD) and bone mineral content (BMC) using the Dual Energy X-ray Absorptiometry. The data were subjected to GLM procedure of Statistical Analysis System (SAS) and significant difference were accepted if P< 0.05. There was no effect of diet on performance in wk 1, however reducing aP in diet reduced (P < 0.05) ADG in wk 2 and 3. Pigs fed the diet with the aP content of 0.11% had the lowest (P < 0.05) BMD of MC3 compared with those fed the control or the intermediate aP content (0.17%) in wk 1 and 2 but not in wk 3. BMC in the MC3 was significantly lower (P < 0.05) in pigs fed diets with reduced aP(0.17% and 0.11%) in wk 1 and 3; but in wk 2 only lowest aP diet (0.11%) resulted in reduced BMC compared to control. In the MC4, BMD and BMC were not different among diets in wk 1. However, BMD was reduced in pigs fed lower aP diets (0.17% and 0.11%) in wk 2 (P < 0.05) and wk 3 (P < 0.001) compared with control. Similarly, BMC was reduced (P < 0.05) in lower aP diets in wk 2 and 3 compared to control. In conclusion, growing pigs are highly sensitive to dietary aP level as they displayed reduced ADG and bone parameters for low aP diets and these aP effects were profound when age increased.
Keywords: Phosphorus, Bone mineral density, Bone mineral content, Pig