Studies on the role of iron in zinc toxicity in chicks

The interaction of dietary iron and zinc was studied in chicks. Zinc was found to be more toxic in iron-deficient animals than iron-supplemented animals as measured by hemoglobin concentrations and growth. Analyses of the kidney and liver for iron and zinc were carried out. As the level of iron was increased from 0-1000 ppm supplementation, the concentration of liver zinc increased. The organ levels of iron were decreased as the dietary zinc levels were increased from 0-5000 ppm. Radioisotope studies using⁶⁵Zn revealed that the iron content of the diet did not affect absorption of zinc. Administration of the isotope, either in an intestinal segment or intravenously, resulted in more zinc being taken up by the liver in the iron supplemented animals. This was especially noted when the ratio of the isotope in liver to that in the blood was compared. Gel chromatography of kidney and liver homogenates revealed that iron deficiency resulted in less zinc being eluted in a volume characteristic of metallothionein compared to homogenates of organs from iron supplemented animals. The results indicate that iron-supplemented animals have a greater capacity for sequestering zinc on metallothionein than do iron-deficient animals. Conversely, iron-deficient chicks were more susceptible to the effects of zinc toxicity than are iron-adequate chicks.     

Growth, morphogenesis, and virulence of Candida albicans after oral inoculation in the germ-free and conventional chick

Balish, Edward (Syracuse University, Syracuse, N.Y.), and A. W. Phillips. Growth, morphogenesis, and virulence of Candida albicans after oral inoculation in the germ-free and conventional chick. J. Bacteriol. 91:1736-1743. 1966.-The effects of intestinal bacteria on the multiplication, morphogenesis, and infectivity of Candida albicans in the alimentary tract were investigated by comparing results obtained in germ-free and conventional chicks after oral inoculation. This challenge resulted in the establishment of large numbers of the pathogen in the alimentary tract of each group of chicks; these numbers were increased in crop contents from challenged bacteria-free chicks wherein hyphae predominated over the yeast form. These animals also had lesions of the crop epithelium containing numerous hyphae and few yeast-like forms. In contrast, challenged conventional chicks receiving an adequate diet displayed no evidence of infection. Their alimentary tract contained the yeast form of C. albicans; no hyphae were seen. Although we found bacterial inhibition of C. albicans multiplication in the alimentary tract, this in itself did not seem to explain the resistance to intestinal candidiasis in our conventional chicks. We argued that this resistance to infection was due chiefly to the prevention of hyphal development in C. albicans by intestinal bacteria. C. albicans in the gut of our conventional chicks resulted in some increase in numbers of enterococci in contents from the crop. Increased pH values in contents from the gut of germ-free chicks were not clearly related to infection after challenge. The E(h) of the above crop contents were only slightly decreased in the germ-free crop. Thus the E(h) did not appear to be involved in susceptibility to infection. Invasion of the blood stream and kidneys of conventional chicks by the yeast form of C. albicans occurred in challenged animals receiving a purified diet which had been radiation-sterilized and stored for 6 months at room temperature (25 C). Their growth rate decreased and they became moribund; no hyphae were observed in tissues or intestine of these animals. Challenged bacteria-free chicks receiving the same diet were resistant to the above invasion, although they had crop lesions containing hyphae as described. The resistance of these chicks to systemic invasion was attributed to absence of intestinal bacteria competing for low levels of vitamins in the stored diet. Germ-free chicks had decreased levels of serum gamma-globulin which increased after challenge, whereas this value was unchanged in conventional birds after challenge.     

Effects of chronic lead and cadmium exposure on blood pressure in occupationally exposed workers

Studies were carried out to determine the effect of dietary vanadium on chicks fed phosphorus deficient and control diets. Vanadium at 50 mg/kg of diet decreased growth of both control and deficient chicks. The high mortality among the phosphorus deficient chicks was significantly alleviated by the presence of vanadium. The increased relative ventricular weights found among the deficient chicks was also alleviated by the presence of dietary vanadium. Vanadium fed at 10 or 20 mg/kg diet did not reduce growth rate but significantly reduced mortality among chicks fed the deficient diet and decreased the relative ventricle weights. Time course studies revealed that chicks are hatched with high relative ventricular weights (.83% of body wt) and remain at that level among chicks fed the phosphorus deficient diet. The addition of vanadium or phosphate to the diet resulted in a progressive decrease in relative ventricular weights. The inclusion of vanadium in the diet resulted in increased serum phosphorus levels among the deficient chicks that may be related to the decrease in mortality and relative ventricle weights.     

Studies on the role of iron in the reversal of cadmium toxicity in chicks

Studies were conducted to determine the effect of dietary iron (Fe) levels ranging from a deficiency to an excess on the toxicity of cadmium (Cd) in chicks. In Fe-deficient animals, cadmium was found to be more toxic than in Fe supplemented animals as measured by growth. The liver Cd burdens were increased significantly in the presence of dietary Fe supplementation, and there was a significant Cd−Fe interaction in the Cd concentration of the kidney, indicating that iron deficiency increased the concentration of Cd in the kidneys of those chicks receiving this element. Cd tended to reduce the Fe concentration in both the liver and kidney. The absorption of Cd as measured by the amount of¹⁰⁹Cd that disappeared from an isolated duodenal segment in one h was not affected by the Fe content of the diet, but the amount of isotope appearing in the liver compared to the amount present in the blood was increased in the Fe supplemented chicks. Separation of the Cd binding ligands by column chromatography revealed that more of the Cd in the liver, but not the kidney, was associated with ligands which eluted in a column volume that contained metallothionein in those chicks receiving Fe than in the livers from Fe deficient animals. The inverse relationship between the amount of Cd bound to the metallothionein containing fraction and toxicity may be related causally. Paper No. 10538 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC 27695-7601. The use of trade names in this publication does not imply endorsement by the NC Agricultural Research Service of the products named nor criticism of similar ones not mentioned.     

Veterinary genetics and selection]

The article comprises the data on the genetic potentials of New-Hampshire cocks determined on the basis of the resistance of their offspring to the artificial infection with Salmonella gallinarum. It is shown that different cocks differ significantly from one another in their genetic potentials with respect to the resistance to Salm. gallinarum. Since the method of artificial infection can not be practiced always, it is proposed by the author to characterize the genetic potentials of animals by means of determination of the non-specific resistance index of the specimens tested.     

Dietary betaine accumulates in the liver and intestinal tissue and stabilizes the intestinal epithelial structure in healthy and coccidia-infected broiler chicks

The aim of this experiment was to study the patterns of betaine accumulation into intestinal tissue, liver and plasma of broiler chicks with or without coccidial infection. The chicks were raised on a corn-based, low-betaine diet with or without 1000 ppm betaine supplementation and with or without intestinal microparasite (Eimeria maxima) challenge to the age of 21 days. Plasma, liver, intestinal tissue and digesta of non-challenged (NC) birds and plasma and intestinal tissue of coccidiosis challenged (CC) birds were analysed for betaine content. NC birds were also analyzed for homocysteine in plasma and S-adenosylmethionine (S-AM) in liver. The jejunal epithelium was histologically examined for the presence of coccidia and the crypt-villus ratio was measured. Dietary betaine supplementation decreased the plasma homocysteine concentration but had no effect on liver S-AM of NC birds. The data suggest that chicks on a low-betaine diet accumulate betaine into the intestinal tissue. When the diet was supplemented with betaine, betaine accumulated heavily into liver and to a lesser degree into intestinal tissue. The concentration of betaine in jejunal and ileal digesta was low suggesting that dietary betaine was mainly absorbed from the proximal small intestine. The coccidial challenge decreased the concentration of betaine in the liver, but greatly increased that in the intestinal tissue. The crypt-villus ratio was decreased by the dietary betaine supplementation in healthy and challenged chicks, suggesting that dietary betaine both protects the jejunal villi against coccidial infection and also stabilizes the mucosal structure in healthy broiler chicks. These results support our earlier findings suggesting that betaine is likely to act as an important intestinal osmolyte in broiler chicks.     

Hemochromatosis and the enigma of misplaced iron: Implications for infectious disease and survival

The mystery surrounding the apparent lack of iron within the macrophages of individuals with hereditary hemochromatosis, a condition of excessive uptake of dietary iron, has yet to be fully explained. We have suggested that iron deficiency of macrophages in people with hereditary hemochromatosis mutations is associated with increased resistance to infection by Yersinia and other intracellular pathogens, a selection pressure resulting in unusually high current population frequencies of hereditary hemochromatosis mutations. Such selection pressure has been called Epidemic Pathogenic Selection (EPS). In support of the theory of EPS, a considerable number of virulent species of bacteria multiply mainly in iron-rich macrophages of their mammalian hosts. Among these fastidious pathogens are strains of Chlamydia, Coxiella, Francisella, Legionella, Mycobacterium, Salmonella and Yersinia. Iron deficiency of macrophages of persons with hereditary hemochromatosis gene mutations may result in increased resistance to members of these bacterial pathogens. People with genes that result in hereditary hemochromatosis may be protected against coronary artery disease associated with Chlamydia and Coxiella infection in the absence of iron overload. In the clinical setting, when a patient appears to be iron deficient, the reason for this should be carefully evaluated. Iron supplementation may adversely affect the health of individuals who have mounted an acute phase response to infection, injury or stress, or who carry genes predisposing them to iron overload disorders.     

Quantitation of the Bioenergetics of a Tuberculosis Infection in Chicks

Interaction of an avian tuberculosis infection with a known metabolizable energy yield of dietary corn oil in chicks was used to quantitate total host energy expenditure necessitated by the infectious process. Three trials in which two doses of inoculum were used resulted in mild and severe involvements. Trial 1 (mild) indicated that 6% and trials 2 and 3 (severe) that 96 and 93% of the energy supplied by known quantities of corn oil were utilized by the tuberculosis process. In the birds given the low level of inoculum, the degree of tuberculosis involvement, as measured by increased liver size, was correlated with increased total quantities of hepatic ribonucleic acid, monoglycerides, free fatty acids, free cholesterol, and glucose. All of these effects were observed prior to manifestations of clinical symptoms or failure of the chicks to consume all food offered.     

Interaction Between Aflatoxicosis and a Natural Infection of Chickens with Salmonella

Broiler chicks with a natural congenital infection of Salmonella worthington required a lower concentration of dietary aflatoxin (0.625 mug/g) to depress growth than uninfected chicks (2.50 mug/g).     

Serum and liver zinc,copper, and iron in chicks infected withEimeria acervulina orEimeria tenella

Two-wk-old broiler chicks were inoculated via crop intubation withEimeria acervulina at two doses: 10⁵ or 10⁶ sporulated oocysts/bird or withEimeria tenella at a dose of 10⁵ sporulated oocysts/bird. Serum and liver samples were collected on days 3 and 6 post-inoculation (PI). There were no significant changes in serum or liver zinc, copper, and iron concentrations in any of the infected groups by 3 d PI. However, on d 6, PI serum protein was significantly reduced in all of the infected groups compared to their pair-fed controls. The chicks infected withE. tennella had significantly reduced serum zinc (1.20 vs 1.77 μg/mL) and iron (0.44 vs 1.28 μg/mL) concentrations and significantly elevated serum copper (0.28 vs 0.17 μg/mL) and ceruloplasmin levels (20.33 vs 11.11 μg/mL) compared to their pair-fed counterparts. Those chicks infected withE. acervulina (10⁶ oocysts/bird) exhibited significantly reduced serum iron concentration by 6 days PI (0.90 vs 1.14 μg/mL). Liver zinc was significantly increased in the chicks infected withE. tenella (349 vs 113 μg/g dry liver wt), as was copper (24 vs 19 μg/g), whereas liver iron concentration was significantly reduced (172 vs 243 μg/g) compared to pair-fed controls. At both dose levels, the chicks infected withE. acervulina exhibited a significant reduction in liver iron by 6 d PI. Hepatic cytosol metals generally reflected whole tissue levels. Metallothionein (MT)-bound zinc was significantly elevated in the chicks infected withE. tenella. Iron bound to a high molecular weight, heat-stable protein fraction (presumably cytoplasmic ferritin) was significantly reduced in chicks infected withE. acervulina, as well as those infected withE. tenella. Collectively, the changes in serum zinc, copper, and iron concentrations, as well as the changes in hepatic zinc and MT-zinc concentrations in the chicks infected withE. tenella were similar to changes evoked during an acute phase response to infection. It is possible that a secondary bacterial infection or inflammation stemming from erosion of the lining of the cecum may play a role in the response of trace element metabolism to theE. tenella infection. Mentions of a trademarkr, proprietary product or specific equipment does not consitute a guarantee or warranty by the US Department of Agriculture and does not imply its approval to the exclusion of other products.     

Deferoxamine increases the susceptibility of beta-thalassemic, iron-overloaded mice to infection with Listeria monocytogenes.

The effect of the iron chelator deferoxamine (DFO) on resistance to infection with Listeria monocytogenes in mice with a condition analogous to human beta-thalassemia was studied. Intraperitoneal injection of 10 mg DFO resulted in significantly increased mortality when given one, three and six days before infection with L. monocytogenes (for all three time points, p less than 0.02). There were no significant differences in hematocrit, plasma iron, or splenic iron content between the two groups of mice during these time periods. In addition, splenic counts of L. monocytogenes were not significantly higher in DFO-treated compared to saline-treated mice three days after infection. Moreover, background C57Bl/6J mice were not more susceptible to Listeria infection after receiving DFO than were saline-treated controls. In conclusion, acute administration of DFO increases the susceptibility of beta-thalassemic mice to L. monocytogenes. The effect is not seen in background mice and suggests that DFO increases susceptibility to Listeria infection only in animals with iron overload.     

Response of renal calcium-binding protein independence of kidney vitamin D hydroxylation

Dietary calcium and dietary phosphorus restriction were studied in chicks fed either cholecalciferol or 1α-hydroxycholecalciferol. Intestinal calcium absorption and calcium-binding protein of 1α-hydroxycholecalciferol-treated chicks remained unchanged under dietary calcium restriction, but increased under dietary phosphorus restriction. Kidney calcium-binding protein was not altered by dietary calcium restriction in chicks treated with either cholecalciferol or 1α-hydroxycholecalciferol, but increased under dietary phosphorus restriction independent of the vitamin D source. In contrast to the intestine, calcium-binding activity of the kidney was found to be poorly related to the calcium-binding protein concentration. It is suggested that kidney calcium-binding protein is regulated by a mechanism different from that of intestinal calcium-binding protein, and that its concentration in renal tissue is related to renal calcium excretion or plasma calcium level.     

The effect of Helicobacter pylori infection and dietary iron deficiency on host iron homeostasis: a study in mice

BACKGROUND: Helicobacter pylori, which requires iron to survive, may cause host iron deficiency by directly competing with the host for available iron or by impairing iron uptake as a consequence of atrophy-associated gastric hypochlorhydria. The aim of this study was to examine the effect of H. pylori infection and dietary iron deficiency on host iron homeostasis in a mouse model. MATERIALS AND METHODS: H. pylori SS1-infected and uninfected C57BL/6 mice, fed either a normal diet or an iron-deficient diet, were assessed for iron status and infection-associated gastritis over a 30-week period. RESULTS: After 10 weeks, serum ferritin values were higher in H. pylori-infected mice than in uninfected controls, irrespective of dietary iron intake (p = .04). The infection-related increase in body iron stores persisted in the iron-replete mice but diminished over time in mice with restricted dietary iron intake (p < .0001). At 30 weeks serum ferritin levels were lower in these animals (p = .063). No significant difference in bacterial numbers was detected at the 30-week time point (p > .05) and the histological changes observed were consistently associated with infection (p < .01) and not with the iron status of the mice (p = .771). CONCLUSIONS: Infection with H. pylori did not cause iron deficiency in iron-replete mice. However, diminished iron stores in mice as a result of limited dietary iron intake were further lowered by concurrent infection, thus indicating that H. pylori competes successfully with the host for available iron.     

Effect of dietary factors upon the resistance of albino mice to experimental infection with Mycobacterium tuberculosis

Layton, Herbert W. (Northwestern University Medical School, Chicago, Ill.), and Guy P. Youmans. Effect of dietary factors upon the resistance of albino mice to experimental infection with Mycobacterium tuberculosis. J. Bacteriol. 90:958-964. 1965.-Each of the major nutritional components of a synthetic diet was quantitatively altered to determine its effect upon the resistance of albino mice to infection with Mycobacterium tuberculosis. The animals were challenged after the first 2 weeks of feeding, and the percentage that survived acute death was determined statistically. The level of protein which provided the greatest percentage of survival was 30%; increases or decreases from this level were detrimental. The optimal fat level was found to be 5% for either corn oil or coconut oil. Survival decreased when greater amounts of oil were added, and this effect was especially marked for 40% coconut oil. Vitamin A enhanced survival when increased from the normal level of 20,000 units per kg of diet to 160,000 units, but further increases were harmful. An amount of 75 g/kg of a vitamin B complex mixture afforded optimal resistance, but 25-g shifts in either direction lowered this resistance. Vitamin K-free diets resulted in high levels of survival, and addition of the vitamin resulted in proportional decreases in resistance.     

Dietary cadmium effect on iron metabolism in chickens

A control group of 1-day-old chicks, fed on commercial food, were compared with different experimental lots that had all received a supplement of 100 ppm Cd. The hematocrit, hemoglobin and ceruloplasmin concentrations, and metal contents (Fe, Cu, Zn, Cd) in plasma and in the liver were determined after either 4 or 9 weeks of treatment. The intestinal iron absorption and their ferrokinetics were also studied in 10-week-old Cd-fed chicks. The anemia-producing effect of cadmium was already evident after the second week of treatment. The iron supplement (oral or injected) corrected the anemia, but did not correct the depression of growth effect. Plasma iron was not affected, but the liver stores were reduced by 50%. Neither the plasma copper and ceruloplasmin, nor the copper content in liver, were affected. Zinc in the liver increased significantly (P<0.05). No statistical differences in plasma iron turnover were observed between the control and Cd-fed chicks, but the red blood cell utilization was higher (P<0.01) in Cd-fed groups. The intestinal iron absorption was clearly reduced (P<0.001) where cadmium was presented in the perfusion fluid “in vivo” experiments. This suggested that cadmium reduced the iron liver stores through its effect on intestinal iron absorption. However, it also seems that it did not interfere in iron mobilization, since the plasma iron was unaffected and the Cd-fed chicks presented increased plasma iron after estrogen administration. The indirect effect of cadmium on copper metabolism is uncertain.     

Effect of diet change on the behavior of chicks of an egg-laying strain

Injurious pecking has serious welfare consequences in flocks of hens kept for egg laying, especially when loose-housed. Frequent diet change is a significant risk for injurious pecking; how the mechanics of diet change influence pecking behavior is unknown. This study investigated the effect of diet change on the behavior of chicks from a laying strain. The study included a 3-week familiarity phase: 18 chick pairs received unflavored feed (Experiment 1); 18 pairs received orange oil-flavored (Experiment 2). All chicks participated in a dietary preference test (P); a diet change (DC); or a control group (C), 6 scenarios. All P chicks preferred unflavored feed. In Experiment 1, DC involved change from unflavored to orange-flavored; Experiment 2, orange- flavored to unflavored. Compared with controls, Experiment 2 DC chicks exhibited few behavioral differences; Experiment 1 DC chicks exhibited increased behavioral event rates on Days 1 and 7. They pecked significantly longer at their environment; by Day 7, they showed significantly more beak activity. There was little evidence of dietary neophobia. Change from more preferred to less preferred feed led to increased activity and redirected pecking behavior.     

Protective effects of supplemental vitamin E against infection.

Vitamin E supplementation (dl-alpha-tocopheryl acetate except where noted) in excess of requirement significantly increased humoral immune response or disease resistance. Mice immunized with sheep red blood cells or tetanus toxoid and fed the supplemental vitamin demonstrated increased plaque-forming cells (PFC) and hemagglutinin (HA) titers. A vitamin E deficiency resulted in decreased PFC and little IgG which was partially corrected by N,N-diphenyl-p-phenylenediamine but not as effectively as by vitamin E. Hens immunized with Brucella abortus and fed different levels of the vitamin produced chicks with increased passive immunity; a biphasic antibody response to the level of the vitamin fed was noted. Vitamin E fed to nonimmunized hens was found to significantly increase the primary immune response of their immunized chicks. Feeding dl-alpha-tocopheryl acetate to guinea pigs immunized with Venezuelan equine encephalomyelitis virus resulted in no increased immunity. Injecting this form of the vitamin resulted in severe tissue reaction. However, injecting dl-alpha-tocopheryl significantly improved hemagglutinin inhibition titers. Chicks and turkeys infected with Escherichia coli and fed supplemental vitamin E had reduced mortality and increased HA titers. Sheep fed vitamin E and challenged with Chlamydia had improved weight gains and no detectable Chlamydia.     

Pathogenicity of Salmonella gallinarum After Metabolic Injury by Freezing

Freezing (-75 C) and storage (-20 C) of a cell suspension of Salmonella gallinarum resulted in a heterogeneous population of dead, metabolically injured, and unharmed cells. Injured cells constituted as much as 40% of those surviving freezing and storage for 1 day. Replica plating of frozen and thawed cells indicated metabolic injury was repairable and not a stable mutation. Penicillin was used to increase the ratio of injured to uninjured cells from a frozen and thawed cell suspension. Pathogenicity was evaluated by observing per cent mortality after injecting injured or uninjured cells into separate sets of chicks. Mortality differences between wholly uninjured and predominantly injured populations were small and consistent (5% level) with a hypothesis of no difference.     

Implication of iron in seizure syndrome of mutant chicks (Gallus domesticus)

1. An investigation was made of systemic iron in paroxysmal (px) chicks. 2. Serum transferrin levels in px chicks are greatly increased (P less than 0.05) over control levels, but iron-binding capacity is decreased (P less than 0.05). 3. The delayed (by 10 days) increase in px hemoglobin (P less than 0.01) may be due to the general debilitation seen in px syndrome. 4. An attempt to determine brain iron showed no deposits comparable to mammalian brain iron distribution, but this was consistent with inability of others to locate iron in adult chicken brain tissue.