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The Ohio State University,6, Wooster 44691
Abstract
An experiment utilizing 198 first-and 77 second-litter sows evaluated the effects of five dietary Ca:P levels at two litter sizes (six to seven or 11 to 12 pigs/litter) over a 21-d lactation period for two parities. Lactation dietary P levels ranged from .50 to .90% in .10% increments with Ca concurrently increased in a 1.3:1 ratio using dicalcium phosphate and limestone as the inorganic mineral sources. A 14% protein, corn-soybean meal diet was formulated with .80% Ca and .60% P for gestation while lactation diets varied in their Ca and P contents. Randomly selected sows from each treatment group and parity were slaughtered with various bones collected for analyses. A counterpart set of nongravid gilts remained on trial and were slaughtered at the end of the two-parity period with bones collected. Sow dietary mineral level did not affect sow or pig performance, nor was there an interaction between dietary mineral level, parity or litter size nursed. Serum and milk Ca, P or Mg were unaffected by dietary Ca:P at 7 or 21 d of lactation, but milk Ca and P increased from parity I to II. Percent rib and vertebra bone ash decreased from parity I to II for sows nursing the larger litters; other bones were unresponsive to dietary mineral level. Femur thickness decreased from parity I to II but was not influenced by dietary Ca:P level. Bone-bending moment of the ribs, metacarpals and metatarsals were not influenced by diet, but a lower metacarpal bending moment was observed for sows nursing larger litters. All bones from nongravid females had higher percentage of bone ash, bending moment and shaft thicknesses when compared with reproducing sows. These results suggest that reproductive state (i.e., reproducing vs non-reproducing), litter size and parity affected sow Ca:P mineral skeletal reserves more than dietary Ca:P levels.
1 Salaries and research support provided by State and Federal Funds appropriated to the Ohio Agr. Res. and Dev. Center, The Ohio State Univ. Journal Article No. 209-85.
2 Partial research support provided by the Natl. Pork Producers Council.
3 Appreciation is expressed to the Wooster and Western Branch swine crews for management of experimental animals, Dr. F. L. Herum and P. Hiltner for technical advice, Dr. W. R. Harvey and B. Bishop for statistical analysis.
4 Present address: Dept. of Anim. Sci., Kansas State Univ., Manhattan, KS 66506.
5 Reprint requests to: Dept. of Anim. Sci., The Ohio State Univ. Columbus, OH 43210.
6 The Ohio Agr. Res. and Dev. Center, Wooster
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