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|Title:||Cadmium-Induced Growth Depression and Cadmium Accumulation in Chicks as Influenced by Dietary Modifications|
|Author(s):||Rowland, Robert Dale|
|Department / Program:||Animal Science|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Subject(s):||Agriculture, Animal Culture and Nutrition|
|Abstract:||Nine experiments were conducted with week-old crossbred meat-type chicks to explore the effect of dietary nutrient balance upon the response of chicks to cadmium. When 1, 5, 10, 15, 20, 30, and 40 ppm of cadmium as cadmium chloride was added to corn-soya diets for two weeks, there was growth depression at 10 ppm and a dose-related increase in the cadmium content of kidneys and livers due to added cadmium. As the cadmium intake was increased, there was an increase in the percent of ingested cadmium retained in these two tissues.
Simultaneous decreases in dietary calcium, zinc, phosphorous, and manganese increased the growth sensitivity of chicks to added cadmium and increased cadmium retention without affecting growth when no cadmium was fed. When the diet was adjusted to be marginal in methionine and manganese, supplementing the diet with either of these nutrients did not influence growth or cadmium retention when cadmium was added to the diet. Added copper did not alleviate cadmium-induced growth depression, but increased cadmium retention. Supplemental zinc and levels of calcium above accepted requirments ameliorated cadmium-induced growth dpression and reduced the amount of cadmium retained in livers and kidneys.
Chicks depleted of vitamin D during the first week of life were found to be more growth-sensitive to 10 ppm of cadmium in subsequent 2-week assays. High levels of vitamin D reduced the growth depression and increased liver and kidney accumulation of cadmium in both depleted and undepleted chicks. When levels of calcium and vitamin D that were marginal for maintaining normal bone ash were fed, 10 ppm of added cadmium reduced tibia bone ash.
When D-depleted chicks were fed diets containing factored levels of vitamin D and calcium at marginal levels of zinc, chicks were found to be most growth-sensitive to 10 ppm added cadmium when the diet was marginal in absorbable calcium. When the calcium level of such diets was increased, growth was increased and cadmium retention decreased. In contrast, added vitamin D improved growth, but increased cadmium retention in the livers and kidneys.
When D-depleted chicks were fed factored levels of zinc (none and 112 ppm added), calcium (1.0 and 1.5%), vitamin D (200 and 1,000 IU/kg), and cadmium (none and 10 ppm), chick gains were maximized (18.2 grams/chick/day) at 112 zinc, 1.0% calcium, 1,000 IU vitamin D, and 10 ppm cadmium. Minimum gain (12.9 grams) was at no zinc, 1.5% calcium, 200 IU vitamin D, and 10 ppm cadmium.
With 10 ppm cadmium in the diet, both liver and kidney retention of cadmium (.556 and .492% of the cadmium ingested, respectively) was maximized with the no zinc, 1.0% calcium. and 1,000 IU vitamin D diet, and gain was 15.5 grams/chick/day. Cadmium retention was lowest (.216 and .203%, respectively) at 112 zinc, 1.5% calcium, and 200 IU of vitamin D, and gain was 17.4 grams/chick/day. Cadmium retention in livers and kidneys was reduced by 61 and 59%, respectively.
Regardless of calcium or vitamin D content of the diets, liver zinc was reduced by feeding 10 ppm added cadmium, but was restored to normal levels by adding 112 ppm zinc to the diets. Kidney zinc levels were less diet-sensitive, and kidney zinc concentrations were highest when both zinc and cadmium were added to the diets.
The results of these studies indicate that adjusting the levels of calcium, zinc, and vitamin D in the diets of broilers could influence the flow of cadmium into the human food chain.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1980.
|Date Available in IDEALS:||2014-12-13|