Note: [] Address for correspondence: Department of Physiological
Sciences, Faculty of Veterinary Medicine, Warsaw Agricultural University,
Nowoursynowska 159, 02-776 Warszawa, Poland. Tel.: +48 22 843 90 61, exr.11507;
Fax: +48 22 847 24 52; E-mail: [email protected]
Abstract: Bone mineralization was studied in rats. Animals were divided into
three feeding groups: LCP – diet with 13.5% crude protein in DM (5% of
gluten, 10% of casein), HCP – diet with 21.2% CP in DM (8% of gluten, 10%
of casein), and LSM – diet based on grain meals and meat-bone meal (21%
CP in DM). After 28 days feeding, animals were euthanased by cervical
dislocation and femur bones were collected, weighed and kept frozen until
analyses. Diets with 21% protein (HCP, LSM) significantly increased weight of
femur bones. Despite of the substantially higher ash level (7.1%) in the LSM
diet than in the LCP diet (3.4%), rats of both groups had the similar bone
concentration of Ca (15.7 ± 1.1 vs. 17.4 ± 1.1 g/kg) and Zn
(178.7 ± 7.9 vs. 173.0 ± 8.5 mg/kg). However bone density in LSM
rats was significantly higher than in LCP ones. Although rats fed HCP diet had
intermediate bone density, the bone concentration of Ca (11.4 ± 0.5
g/kg) and Zn (145.1 ± 2.9 mg/kg) was significantly lower, than in
animals fed LCP and LSM diets. This was related to the very wide
protein/calcium (37:1 g/g) and protein/zinc (5.3:1 g/mg) ratios in HCP diet.
Those ratios were narrowest in the LSM diet: 16.2:1 (CP/Ca) and 2.6:1 (CP/Zn).
It can be conluded that protein/mineral ratio in a diet is a very important
factor in bone development, besides dietary protein and ash contents
itselves.
Keywords: bone density, protein, calcium, zinc, rat
Journal: BioFactors, vol. 22, no. 1-4, pp. 25-28, 2004
