Porcine focal symmetrical poliomyelomalacia: test for an interaction between dietary selenium and niacin.

Experiments were conducted to test the hypothesis that dietary supplementation with nicotinamide would retard or eliminate the signs of selenium induced porcine focal symmetrical poliomyelomalacia (PFSP). Mixed-sex feeder pigs, approximately five weeks old, were divided into four groups and daily received, by oral capsule, the following treatments: no supplementation (control); 2.86 mg sodium selenite per kg body wt (selenium only); 44 mg nicotinamide per kg body wt (niacin only); or both the niacin and selenium (niacin + selenium). Over the ten day treatment body weights and behavior scores were recorded, as well as collection of fluid (blood, serum, urine) samples. Upon death, tissue samples (kidney, liver, brain, spinal cord and muscle) were obtained. All of these samples were analyzed for total selenium and bioactive niacin compounds. After gross pathological analysis, 11 samples from specific brain and spinal cord regions were taken for fixation and processing for histological analysis by light microscopy. The selenium only group showed behavior signs related to PFSP after two days of treatment with the average time of death at 6.5 days. Tissue levels of selenium were elevated and histological analyses established the expected lesions of PFSP. No disorders were noted in the control and niacin only groups. The niacin + selenium groups had slightly retarded changes in behavior scores (first differences from controls on day 4) but their mean day of death (7.5 days of treatment) did not differ from that of the selenium only groups. Histological analyses of these tissues revealed similar lesions to the selenium only group, but they may have been of lesser magnitude. The data were consistent with, but only partially supportive of, the above hypothesis.

Hepatic neoplastic nodules, adenofibrosis, and cholangiocarcinomas in male Fisher 344 rats fed corn naturally contaminated with Fusarium moniliforme.

Twelve male Fisher 344 rats were fed corn naturally contaminated with Fusarium moniliforme. This corn sample was obtained from feed being fed horses during an outbreak of leukoencephalomalacia. All rats necropsied from 123 to 176 days post feeding had multiple hepatic nodules and pale depressed hepatic areas. Histological examination revealed multiple hepatic neoplastic nodules and large areas of adenofibrosis and cholangiocarcinomas. The corn only diet was deficient in many nutrients including choline and methionine. Aflatoxins at a level of greater than 0.9 p.p.b. were not detected. A discussion is presented regarding the significance of these lesions and possible relationship to the contaminating fungus and the choline, methionine deficient diet.