title: Calcium digestibility studies utilizing acid-insoluble ash measurements.
abstract: Laying hens were individually fed diets providing daily calcium intakes ranging from 2.0 to 4.5 g from two sources of limestone. Silica (washed sand) was added to the diets as filler for hens with less than 4.5 g of daily calcium intake. The calcium digestibility data were obtained both by the total collection (TC) method and b y using acid-insoluble ash (AIA) as an indicator. Source effect was not significant (P greater than .7) within each method tested, and data were pooled for analysis. The calcium digestibility values obtained by the TC method for hens with intake of 2.0, 2.5, 3.0, 3.5, 4.0, and 4.5 g daily were 59.16, 57.31, 54.29, 50.99, 44.63, and 41.76%, respectively. The AIA method consistently yielded higher digestibility values: 73.0, 65.36, 61.78, 54.19, 45.76, and 42.0%. The differences in calcium digestibility values between the two methods were linearly related to the levels of silica consumption (P less than .05).
authors.affiliation: Department of Animal Science, University of Minnesota, St. Paul 55108.
authors.forename: T K
authors.initials: TK
authors.lastname: Cheng
authors.forename: C N
authors.initials: CN
authors.lastname: Coon
mesh_terms: D000821:Animal Feed; D000818:Animals; D002136:Calcium, Dietary / Q000008:administration & dosage / Q000378:metabolism*; D002645:Chickens / Q000378:metabolism*; D004063:Digestion; D005260:Female; D012822:Silicon Dioxide / Q000008:administration & dosage
chemical_list: D002136:Calcium, Dietary; D012822:Silicon Dioxide