High levels of phosphorus good for bone quality in pigs

In this study male and female pigs were supplied with increasing dietary P levels from 50 to 130% of the present recommendations and determined growth performance, feed conversion and P retention in the body between 25 and 125 kg body weight.

In general this study indicates that present recommendations are adequate to maximise animal performance. A P content in the diet below requirements resulted in a lower daily gain and a less efficient feed utilisation. However, the P-retention in the body and the metacarpus bone ash content increased linearly to the highest diet P content of 130% of recommendations.

For future application, the researchers address that it is needed to define what level of bone ash is desirable in order to estimate what dietary P content is required. At low P levels the pigs give priority to muscle and lean tissue deposition above skeleton development. Consequently, growth performance is maximised at lower dietary P-levels at the expense of P-retention in the skeleton, bone ash content and bone strength.

In the study, boars realised a higher gain and more efficient feed utilisation than sows and had less lipid and more protein in their bodies. Boars did not show a higher whole body P content. Rather, at low dietary P level, body P-content was higher in sows. Hence, these results indicate that efficiency of P utilisation in pig farms can be based on the same standard whole body P-content for boars and sows.

[Source: Wageningen UR Livestock Research]