title: Dietary phosphorus concentrations related to breaking load and chemical bone properties in heifers.
abstract: Effects of dietary P on breaking load and chemical properties of bone were evaluated in growing beef heifers. Initially, 14 weaned Angus heifers received ad libitum a low P diet (.10% P dry basis) for 270 d. Heifers were subsequently randomly allotted into two groups (7 heifers/group) and received ad libitum either .12 or .20% P (dry basis). The experimental endpoint was 245 d of the treatment phase for nonpregnant and 3 wk postpartum for pregnant heifers. Results indicate that chemical and physical properties of bovine bones are sensitive to dietary P. Mineralization of rib bones was less at .12% P (dry basis). Rib bone density (g/cm3) and mineral content expressed on a per unit volume basis (mg/cm3) were the most sensitive parameters measured. Breaking load results of 12th ribs also indicated a greater amount of mineral present in heifers receiving .20% P (153.8 vs. 114.3 kg). Vertebral bone density and mineral concentrations on a per unit volume basis were also sensitive to dietary P and clearly ranked the two dietary P amounts, whereas percentage of bone ash or mineral concentration expressed on an ash basis did not.
authors.affiliation: Animal Science Department, University of Florida, Gainesville 32611-0691.
authors.forename: S N
authors.initials: SN
authors.lastname: Williams
authors.forename: L A
authors.initials: LA
authors.lastname: Lawrence
authors.forename: L R
authors.initials: LR
authors.lastname: McDowell
authors.forename: A C
authors.initials: AC
authors.lastname: Warnick
authors.forename: N S
authors.initials: NS
authors.lastname: Wilkinson
mesh_terms: D000818:Animals; D015519:Bone Density; D001846:Bone Development; D001842:Bone and Bones / Q000032:analysis / Q000187:drug effects* / Q000502:physiology; D002118:Calcium / Q000032:analysis; D002417:Cattle / Q000502:physiology*; D004032:Diet; D005260:Female; D008274:Magnesium / Q000032:analysis; D010758:Phosphorus / Q000008:administration & dosage / Q000032:analysis / Q000494:pharmacology*; D011897:Random Allocation
chemical_list: D010758:Phosphorus; D008274:Magnesium; D002118:Calcium