title: Zinc-65 absorption and tissue distribution in two- and six-month-old holstein calves and lactating cows.
abstract: Holstein calves and cows in first lactation were fed a low-zinc (16.6 ppm) experimental diet. Zinc-65 absorption and tissue distribution were determined following a single oral tracer dose of zinc-65 given 14 days prior to sacrifice. Net zinc-65 absorptions for the cows and 2- and 6-mo-old calves were 53.4, 49.7 and 47.2% of the dose. Tissue zinc-65 content, adjusted for body weight and zinc-65 of milk of the cows was not significantly different from that of either age calves in 13 of 20 comparable tissues. Greatest differences in tissue zinc-65 were in tibia and rib with the 6-mo-old group highest and cows lowest. Lactation represents a major homoeostatic demand for zinc, and the intestinal absorptive ability of adult cattle remains responsive to physiological need.
mesh_terms: D000018:Abomasum / Q000032:analysis; D000284:Administration, Oral; D000367:Age Factors; D000821:Animal Feed; D000818:Animals; D001923:Brain Chemistry; D002417:Cattle / Q000378:metabolism* / Q000502:physiology; D005243:Feces / Q000032:analysis; D005260:Female; D007421:Intestine, Small / Q000032:analysis; D007668:Kidney / Q000032:analysis; D007774:Lactation; D008099:Liver / Q000032:analysis; D008297:Male; D009132:Muscles / Q000032:analysis; D009206:Myocardium / Q000032:analysis; D010179:Pancreas / Q000032:analysis; D011247:Pregnancy; D011868:Radioisotopes; D012272:Ribs / Q000032:analysis; D012417:Rumen / Q000032:analysis; D012867:Skin / Q000032:analysis; D013977:Tibia / Q000032:analysis; D015032:Zinc / Q000008:administration & dosage / Q000378:metabolism*; D015033:Zinc Isotopes
chemical_list: D011868:Radioisotopes; D015033:Zinc Isotopes; D015032:Zinc