| Abstract: | Evidence is reviewed that indicates Ni is an essential element for the chick, rat, pig, sheep and goat. Although a number of possible functions for Ni have been proposed based on in vitro and in vivo studies, the physiological role of Ni in the mammalian or avian system is presently unknown. Rumen bacterial urease has been shown to be a Ni-dependent enzyme and Ni is a component of factor F430 present in methanogenic bacteria. Nickel can interact or influence the metabolism of a number of minerals. Interactions of Ni and Fe, Zn and Cu are discussed. The requirement for Ni is low (50 to 60 ppb) in chicks fed semipurified diets. Insufficient data are available to estimate the Ni requirement of swine. In ruminants, the Ni requirement appears to be higher than that for other animal species. Nickel supplementation to practical diets has increased gain, feed efficiency and ruminal urease activity in ruminants, but performance results have been inconsistent. Level of crude protein and urea are two factors that influence ruminant responses to dietary Ni. The greatest responses have been observed in ruminants fed low protein diets. Little is known concerning levels, forms and bioavailability of Ni in different feedstuffs. Nickel is homeostatically controlled in the animal's body and high levels of Ni are required to cause toxicity. |
