Conclusions We have historically increased the dietary mineral levels of high producing sows above that indicated by the NRC (1998) requirements. Our results would suggest that there is a great deal to learn about the mineral needs of sows and to simply increase these levels may be in error. For example, it appears that a dietary level of 1.0% Ca when fed during the entire gestation may be responsible for lowering the litter sizes of sows. Yet it is also clear that the sow has a high requirement for calcium and phosphorus during the latter portion of gestation as well as throughout lactation. Although research has not been done to investigate the phase feeding of minerals to sows, our results suggest that this may need to be pursued. The trace mineral needs of reproducing sows are of concern. The use of organic trace minerals has been shown in our studies to increase litter size when compared with inorganic salts. Which trace mineral precipitated this response is not known, but our data suggest that the response is not solely due to selenium. The period of gestation where this benefit occurs and the optimum dietary level are currently unknown. The needs for trace minerals appear to be high, particularly during lactation. Our results indicate that sows of high productivity may be unable to meet trace mineral needs in a 21-day lactation period. Consequently, higher supplemental levels appear to be warranted, however research to prove this hypothesis is currently incomplete. |
Mahan, D. C. and J. C. Peters. 2004. Long-term effects of dietary organic and inorganic selenium sources and levels on reproducing sows and their progeny. J. Anim. Sci. 82:1343-1358.
Peters, J. C. and D. C. Mahan. In press. Effects of dietary organic and inorganic trace minerals at various levels fed to reproducing sow over six parities on reproductive performance. J. Anim. Sci. (submitted).
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