Dietary calcium and zinc effects in unilaterally neutron irradiated swine

The importance of zinc in animal nutrition has been increasingly recognized in recent years. Numerous experiments have demonstrated that this trace element is an important constituent of rations for swine, poultry, ruminants, and some data are available on humans. No information was found regarding the metabolism of stable zinc and radiozinc in tissues of neutron irradiated swine. It has been widely demonstrated that a calcium and zinc relationship exists and that an inadequate amount of zinc in the diet has induced growth retardation and parakeratosis in swine (Lewis et al., 1956), as well as a health problem in cattle, goats, and chickens. Zinc is known to be a constituent of a number of metalloenzymes (Orten, 1966 and Vallee, 1959 referred to by Prasad, 1967). These include: carbonic anhydrase, pancreatic carboxypeptidase, liver, and yeast alcohol dehydrogenase, alkaline phosphatase, malic dehydrogenase, and glutamic and lactic dehydrogenase. In addition zinc increases the activity of a number of other enzymes apparently as a "cofactor" in a nonspecific manner. The gross and histological features of swine skin resemble that of the human, and the radiosensitivity of the pig is within the range estimated for man. Hence, investigations using X-ray and mixed neutron-gamma irradiated swine have been conducted. Since neutron irradiation can produce changes in the animal body, this work was initiated to study: (1) the excretion and retention of radiozinc and stable zinc in the organs of neutron irradiated swine fed different levels of calcium and zinc; and (2) to observe any gross and/or histological changes caused by neutron exposure.