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Diets containing methyl mercury and mercuric chloride were fed to rats with and without sodium selenite supplements. Effects of selenite-mercury interactions for both forms of mercury include enhancement of the growth rate over that observed on diets with comparable levels of mercury without selenite, altered tissue mercury levels, and altered percentage distribution of mercury among several tissues. In addition, selenite protected against mortality and neurotoxicity due to dietary methyl mercury. Possible mechanisms for the mercury-selenium interactions are discussed.

The sequence of ceruloplasmin development and limiting factors controlling this process in neonatal piglets was studied in a randomized block design. Guided by the change in serum ceruloplasmin levels, the liver copper concentrations of piglets fed copper-deficient and copper-supplemented diets were compared in three different periods. The plasma of piglets was devoid of both apo- and holo-ceruloplasmin at birth. The system responsible for the synthesis of apoceruloplasmin developed shortly after birth as indicated by a steady increase in serum ceruloplasmin activity during the first week without being affected by the diet. Copper apparently was not the limiting factor at this stage since very high concentrations of copper were found in the livers of newborn piglets. However, the liver copper was depleted quickly within 1 to 2 weeks and became the limiting factor if the diet was deficient in copper. The livers of these piglets were fractionated by differential centrifugation to compare the liver copper distribution in the two dietary groups with and without copper supplementation. The treatments did not affect the copper distribution on a percentage of total liver copper basis. However, fractionation study revealed that, unlike adult pig livers, about 70% to 80% of copper was present in the heavier particle fractions of piglet livers.

Purified diets containing sodium sulfate and DL-methionine as sole dietary sources of sulfur were fed to fistulated sheep. The effect of dietary sodium molybdate (50 ppm Mo) on the capacity of the rumen microorganisms to produce sulfide from either sulfate or methionine was assayed in the two sulfur diets. Dietary molybdenum significantly inhibited the production of sulfide from sulfate but enhanced significantly the production of sulfide from methionine. The inhibitory effect of molybdenum on sulfide production in vitro and the number of sulfide-producing bacteria present in the rumen of these sheep are discussed in considering the mechanism of the molybdate effect on sulfide production.

Colostrum-free newborn pigs were raised artificially to investigate the appearance of ceruloplasmin in the serum of piglets. The sensitivity of the p-phenylenediamine oxidase activity assay, commonly used as a measure of ceruloplasmin, has been increased 10-fold. Based on this activity, no evidence was found that this copper protein was present in the serum of baby pigs at birth, although some evidence was obtained that the protein moiety (apoceruloplasmin) was present. Holoceruloplasmin usually became detectable in the serum 10–15 hours after birth. Its concentration increased slowly at first and then at an accelerated rate. The ceruloplasmin in the sera of 2-3-day-old piglets was isolated and compared with that isolated from the serum of adults. Contrary to a previous report, the physical and chemical properties of ceruloplasmin synthesized during the first 3 days of life of the piglet showed no significant difference from that synthesized by the adult.

Neonatal serum protein patterns from unfed pigs were compared with serum from mature pigs. This yielded a profile of an immature serum protein pattern and a mature pattern. The capacity of 4 diets to augment and influence changes from the immature to the mature serum protein pattern was determined. It was found with pigs nursing the sow that there were not only rather intense and immediate changes in serum proteins, but also a continuous and rapid alteration toward the mature serum protein pattern. Pigs fed an amino acid milk had little ability to promote normal changes associated with this serum protein maturation. The observations of pigs fed cow’s milk and artificial milk were intermediate between the two extremes of those fed sow’s milk and amino acid milk. That is, in the first 4 to 7 days, little or no change was observed in the serum protein patterns; however, from then on, changes, similar to those seen in the pigs fed by the sow, started to occur, but at a slower rate. The ability of pigs having static, immature patterns was inferior to that of piglets having rapidly maturing patterns, in reacting to treatment.

1.Data from two crops (1948 and 1950) showed that phosphate fertilization doubled the yield of soybean forage and produced a plant (+ P) having a higher concentration of calcium and phosphorus but a lower leaf percentage, by weight, than the plants grown on soil not fertilized with phosphate (- P).2.A rabbit assay is described which was successfully employed in the study of the relative nutritive value of these crops. Rabbits fed diets containing the - P forage made smaller gains and had a lower level of inorganic phosphorus in the blood serum, and bones of greater fragility, than did those fed the diets containing the +P forage.3.A supplement of CaHPO4(M) added to the test diets not only eliminated the differences observed between the non-supplemented diets, but in addition the rabbits on the - PM forage diet gained more than those on the + PM forage diet. Data on the digestible nutrients of these diets and spectrographic analysis for 8 other elements offered no explanation for the last-observed difference.4.Phosphorus concentration and a factor not identified, but possibly associated with leafiness, were the principal differences found between soybean forages differentially fertilized with phosphate.

The effect of supplements of vitamins other than A and D, 5% alfalfa and substitution of urea for casein in a purified diet developed for lambs was investigated. The complete diet contained casein, all the known vitamins, starch, glucose, fat, minerals and bicarbonates of sodium and potassium. Deletion of the vitamins other than A and D resulted in reduced gains. Addition of alfalfa had little or no effect on gains of lambs receiving casein diets. In the diets where urea was substituted for casein, alfalfa had a significant positive effect on gains of lambs. Samples of rumen fluid from lambs fed the urea-substituted diet without alfalfa had a significantly higher percentage of propionate and lower percentage of butyrate than the samples of rumen fluid taken from lambs fed the urea-alfalfa diet.

For approximately the first 36 hours of life, neonates of some species, e.g., piglets, are able to absorb large molecules from their intestines. The time when the piglet ceased absorbing large molecules (closure) was a function of feeding regimen. Closure activity was in sow's and cow's colostrum. A diet containing protein in a simple salt solution (either egg albumin, porcine albumin or procine γ-globulin) did not render the piglet's gut impermeable to large molecules. Nor was milk fat needed in the diet for closure to occur. A diet of boiled (essentially protein- and fat-free) cow's colostral whey engendered closure. Also, closure activity was in a dialyzate of cow's colostrum and in a dialyzate of non-fat dried milk solids. No activity was associated with synthetic milk salts, vitamins or sugars. Thus, closure is possible with a heat-stable, low molecular weight, protein- and fat-free fraction of milk; and activity is not dependent on the absorption of large molecules.

Investigations were conducted on the effect of supplementary Na+and K+bicarbonates (cations) and ad libitum versus controlled-feeding regimens on growth of lambs fed purified diets. Subsequent effects of the cation supplementation on lactic acid isomer production and VFA production were evaluated. Results indicated that the supplementary Na+and K+bicarbonates improved growth with the controlled-feeding regimen. Their presence had little or no effect on growth with the ad libitum regimen. Production of significantly greater levels of L (+) lactic acid than the D (-) isomer and a greater percentage of the total VFA production being propionate occurred with Na+and K+supplementation. Without the additional Na+and K+, the predominant lactate isomer was D (-) and the greater percentage of VFA's produced was acetate plus butyrate rather than propionate. L (+) and D (-) LDH activities were in agreement with the levels of the two lactate isomers produced in both diets. Evidence was obtained that interconversion of lactic acid isomers in the rumen may take place by action of L (+) and D (-) lactic acid dehydrogenases. Under the experimental conditions, little or no racemase activity was found.

Studies were conducted in which copper-deficiency and/or iron-deficiency anemias were produced in the chick. The initial effect of copper deficiency was a decrease in the number of erythrocytes, whereas the initial effect of iron deficiency was a decrease in the hemoglobin content of the erythrocytes. Copper deficiency decreased the feather pigmentation of the chick and reduced the heart cytochrome oxidase activity, and iron deficiency affected pigmentation only slightly and did not reduce cytochrome oxidase activity. The requirement of the chick for these two minerals is discussed.

Pigs were weaned at one, 4, 8 and 14 days to fortified cow’s milk and to an “amino acid” milk. Those weaned to cow’s milk at one day experienced a delay in the maturation of their serum protein profile, even though marked changes toward a mature serum profile already had begun. Their response in serum protein development resembled the latent response seen in pigs weaned at the time of birth to cow’s milk. Pigs weaned at one day to the amino acid milk showed an arrested immature serum protein profile and eventually died.

It has been demonstrated with agar and immunoelectrophoresis that the protein absorption mechanism operating within the first 36 hours of a piglet’s life is qualitatively nonselective. Proteins from such phylogenentically different sources as chickens and cows, as well as different kinds of proteins (albumins and globulins), were absorbed by the neonatal pig. The nonselective nature of this absorption mechanism was emphasized further by the fact that a synthetic, high-molecular-weight, blood plasma extender (polyvinylpyrrolidone) also was absorbed by the piglet during this initial phase.

Certain chemical parameters of the elements, copper, zinc, cadmium, and iron and the interactions of these elements were used to obtain insight on their absorption and utilization. Three experiments were conducted. In experiment 1, rats were subjected to a copper depletion pretreatment (pretreatment 1). Mice that received a normal diet in the pre-experimental period (pretreatment 2) were used in experiment 2, and both pretreatments were used with mice in experiment 3. Cadmium decreased gains and hemoglobin levels significantly in all experiments. With pretreatment 1, the combination of copper and zinc largely overcame the adverse effects of cadmium for rats and mice. In pretreatment 2, however, supplemental copper and zinc did not overcome the depressing effect of cadmium. Another pretreatment effect was observed with dietary cadmium. This element increased zinc concentrations in the liver and testes more markedly in pretreatment 2 than in pretreatment 1. Dietary zinc increased liver iron concentration in all cases.

The chemical similarities between copper, zinc, and cadmium led to the speculation that there existed a copper component of cadmium toxicity in addition to the previously shown zinc component. Cadmium was found to be toxic to chicks at dietary levels of 25 to 400 ppm in a copper- and iron-deficient diet. The toxicity resulted in a reduced growth rate, mortality, microcytic hypochromic anemia, and atony and elongation of the gizzard. The growth depression and gizzard abnormality were corrected by increased dietary zinc. The mortality was reversed by added copper indicating that the speculation which prompted the study was valid. Increased dietary iron partially corrected both the mortality and the growth depression, indicating a previously unsuspected iron component of cadmium toxicity.

Experiments were conducted to study the in vivo availability and movement of copper of a copper-molybdenum (Cu-Mo) complex. In baby pigs fed the Cu-Mo complex as the only copper supplement, serum copper levels were similar to those in pigs fed copper sulfate. However, the pigs receiving the Cu-Mo complex showed an increase in ceruloplasmin activity which was no greater than that in pigs fed a diet without supplemental copper. Tissue molybdenum concentrations were higher in pigs fed the Cu-Mo complex than in pigs fed an equal amount of molybdenum as the sodium salt. Conversely, tissue copper levels in the pigs fed the Cu-Mo complex were generally lower than those in pigs fed either copper sulfate or copper citrate plus sodium molybdate in equivalent amounts. In sheep given an intravenous injection of the Cu-Mo complex made from 64Cu and 99Mo, the rates of removal from the blood of the copper and molybdenum were equal, and this rate was more rapid than the removal of molybdenum when 99Mo was injected alone. Conversely, the rate of urinary excretion of molybdenum from the 64Cu-99Mo-injected sheep was slower than from the 99Mo-injected animal. These results support the hypothesis that copper bound in a Cu-Mo complex is biologically unavailable and indicate that such a complex can exist in vivo.

A series of experiments was conducted in an attempt to gain further insight into the biological interaction between copper and molybdenum. In sheep fed a purified, low copper diet containing varying levels of molybdenum and inorganic sulfate, anemia developed only in those animals receiving molybdenum. All these sheep showed a diminution of plasma copper as the trial progressed. High levels of dietary molybdenum did not significantly depress the induction of ceruloplasmin activity in chicks stressed with fowl typhoid. High levels of molybdenum in the incubation solution reduced the in vitro uptake of copper by rat liver and kidney slices. It was observed that CuSO4and Na2MoO4form a complex which precipitates in a near neutral solution. The ratio of copper to molybdenum in this complex was 4:3. The results of these studies were used to develop a hypothesis that molybdenum complexes with copper and that copper bound in this state is biologically inactive.

A study of the relative nutritive value of several foods grown at widely differing locations demonstrated the superiority for the growing rat of turnip greens grown at Blairsville, Ga. in two different years. Turnip greens grown at two other locations—Experiment, Ga. and Raleigh, N. C.—were equivalent in nutritive value and definitely inferior to the Blairsville greens. No difference was observed in the nutritive value of corn and cowpeas which were tested similarly.

A study was made to determine whether low serum copper and ceruloplasmin activity values of piglets were the result of insufficient copper or insufficient serum protein. Observations were made on naturally and artificially raised piglets. In the naturally raised piglets, serum copper and ceruloplasmin activity increased from very low values to approximately those of the adult pig in one week. Two litters of artificially raised pigs were subdivided into 3 groups, each of which was fed in one of 3 dietary sequences. Pigs fed in sequence A received a mineral water solution for the first 36 hours and thereafter received cow's milk fortified with iron and copper. Sequence B pigs received the mineral water for the first 36 hours also, and thereafter were fed cow's milk fortified with iron alone. Sequence C pigs received cow's colostrum for the first 36 hours and then cow's milk as those in sequence B. The results from the artificially raised piglets indicated: (a) that ceruloplasmin protein as measured by its activity was inducible by supplementary dietary copper; (b) that rate of synthesis of hemoglobin was increased by cow's colostrum; and (c) that one of the limiting factors with the piglet under the conditions of this experiment appeared to be source of protein in early postnatal life rather than iron and copper per se.

A series of experiments was conducted with rats to characterize further the effects of high dietary zinc (0.75%) on iron metabolism. It was found that the red blood cells from animals fed a diet high in zinc were irregularly shaped and microcytic and hypochromic. The osmotic fragility of the red blood cells from the zinc-fed rats was greater than that of the control rats. The zinc content of the blood of the former group was more than twice as high as that of the controls. Blood cells of rats fed the diet high in zinc had a life span (utilizing glycine-2-14C) one-third of that of the controls. By means of 55Fe studies, it was shown that iron incorporation into heme was not affected by zinc toxicity. 59Fe studies showed that the greater turnover of red blood cells for the animals fed the zinc-supplemented diet brought about a greater loss of red blood cell iron via the feces. From the results of this study and those of a previous report, a hypothesis was developed rationalizing the effects of zinc toxicity on iron metabolism.

A series of experiments was conducted to determine the nature of the effect of high zinc diets on iron metabolism. The rats used in all studies were fed a basal diet or the basal + 0.75% zinc. In the initial study radioisotope experiments with 59Fe were conducted to determine whether zinc was interfering with iron absorption. Results indicated that orally administered radioactive iron was absorbed equally by the 2 groups. Subsequent studies showed that the high zinc intake reduced both the amount of ferritin and the percentage of iron content of the ferritin present in the liver. In the next study, the livers of the experimental animals were partitioned and zinc analyses made on the liver fractions. Livers from animals receiving zinc showed that fraction III, the ferritin-containing fraction, was highest in zinc. Iron-induced ferritin synthesis studies showed that ferritin synthesis was not impaired by high dietary zinc. The hypothesis formulated from these studies was that zinc interferes with iron incorporation and release from ferritin.

Studies were conducted to determine whether both mercury and silver were antagonistic to copper in the nutrition of the chick. Although there was a statistical interaction between mercury and copper, it was not one of antagonism. Mercury did not reduce growth or increase mortality of copper-deficient chicks, but had both these effects when the diet was supplemented with copper. Silver was antagonistic to copper in that all the symptoms of copper deficiency were accentuated in the presence of silver and absence of copper. In the presence of copper, silver had no effect. These effects are explained on the basis of the similarities between the Ag++ion and the Cu++ion and the dissimilarities between the Hg++ion and either Cu+or Cu++ions.

The elastin content of the aortas of newly hatched chicks is approximately 5% of the wet weight of the aorta. When chicks were fed a diet containing 25 ppm copper, the elastin content increased to 12% by the seventeenth day. When the diet contained less than 1 ppm copper, the elastin content of the aorta increased more slowly and never equalled that of the control chicks. The addition of copper to 27-day-old copper-deficient chicks resulted in an increase in aortic elastin concentration to that of the control chicks by the sixteenth day of supplementation. Radio-isotope studies, using valine-1-C14to study the metabolism of elastin, revealed that this protein is relatively inert once formed. The results of these studies suggest that the lesion in copper deficiency affected the synthesis of elastin. Amino acid analysis of elastin from copper-deficient and control chicks revealed that the lysine concentration of the copper-deficient elastin was 3 times that of control elastin.

Studies of the effect of dietary vanadium revealed that 25 ppm vanadium added to a dry skim milk-glucose monohydrate diet was toxic to chicks as indicated by both depression of growth and mortality. Ammonium metavanadate and vanadyl sulfate were equally toxic. The addition of the essential trace elements, iron, copper, molybdenum, cobalt, zinc, and manganese to the basal diet did not affect the toxicity of vanadium. Scandium, titanium, and niobium, elements which resemble vanadium in many of their chemical and physical parameters, were not toxic when fed at 200 ppm nor did they influence the toxicity of vanadium. Radioisotope studies revealed that scandium and niobium were poorly absorbed or poorly retained compared to vanadium. EDTA completely prevented the toxicity of vanadium apparently by preventing its absorption from the intestinal tract. Ingested V48was found to be mainly concentrated in the bone and kidney of young chicks and in the kidney of adult rats.

The determination of the digestibility of the components of the cellulosic micelle has shown that the α-cellulose and pentosan constituents are digested unequally, with the micellular pentosans of alfalfa being less digestible than the alfalfa α-cellulose and the reverse situation being true with fescue; hence the micelle can not be considered a nutritive entity in these two forages. Thus the greater characterization of the carbohydrate fraction by micelle isolation may not be warranted. The digestibility of the total pentosans, accounting for 16.68 and 10.77% of the dry matter in fescue and alfalfa, respectively, when compared with the digestibility of the α-cellulose within species, was not different, suggesting that the combination of these two could result in a biologically meaningful partitioning of forages.

At birth, piglets had less immunoelectrophoretically identifiable serum proteins than the adult sow. Neonatal pig serum was different also in that it contained a serum protein not detectable in serum from a mature pig. The appearance and disappearance of serum proteins from birth to maturity occurred at fairly predictable times regardless of diet.

Estimates of the life span of the erythrocytes of three sheep were made using methylene-labeled C14glycine. The results obtained showed life spans of 131, 157, and 150 days which exceeded by approximately threefold previous estimates in which indirect techniques were used. The effect of the magnitude of erythrocyte life span on iron metabolism studies involving estimation of “physiological iron requirement” for maintenance is discussed.

The tallow from sheep fed purified diets contained less stearate and more oleate than tallow from either sheep fed haygrain diets or grazing animals. In some instances, the altered fatty acid distribution was sufficient to result in a tallow that was a liquid at room temperature. It is probable that less hydrogenation of unsaturated fatty acids was carried out by the rumen microorganisms of the sheep fed the purified diet, because the stearate level of the lipid of the rumen contents was appreciably less than that of the hayfed animals. A high content of transacids in the dietary fat resulted in high levels of transacids in the sheep tallow irrespective of the remainder of the diet, indicating the resistance of the transisomers to hydrogenation by the rumen flora.

Hemoglobin and weight-gain data from three experiments indicate that the minimum iron requirement of baby pigs, fed fortified cows’ milk, up to 60 days of age was approximately 60 ppm of the dry matter intake. Estimates of the synthesized hemoglobin, made from these data and radioactivity data, indicate that utilization of the iron at the minimum requirement level was approximately 30%. Making baby pigs anemic (about 6 gm Hb/100 ml blood) by depleting them of iron before initiating iron feeding did not increase iron utilization. Specific activity data of blood, liver, spleen, kidney and bone marrow suggested that at the critical end of iron deficiency, tissue iron needs took precedence over hemoglobin iron need. Once this minimum tissue need was met, however, absorbed iron appeared to be incorporated directly into hemoglobin without equilibrating with tissue iron.

The in vivoand in vitroincorporation of C14-labeled bicarbonate and acetate-2-C14into the ruminal volatile fatty acids of sheep receiving purified diets was studied. In the bicarbonate-CO2studies, most of the incorporated label was found in propionate and the specific activity of valerate exceeded that of either acetate or butyrate in all cases. A difference in incorporation rates between the sheep receiving diet 1 (Na plus K) and the sheep fed diet 1 was suggested and the addition of sodium and potassium bicarbonates to the diet enhanced C14O2incorporation into the fatty acids in the in vitrostudies. A product-precursor type relationship between acetate and butyrate was encountered in the in vivoexperiments and this relationship received additional support from the fatty acid analyses. Here again, the presence of the supplementary sodiumand potassium bicarbonates enhanced the incorporation of C14. Volatile fatty acid analyses revealed relatively higher levels of propionate in the rumen fluid of the sheep receiving diet 1 (Na plus K) than observed in rumen fluid from the sheep fed diet 1.

Young rats were fed purified diets containing high levels of zinc (0.75 and 1.0%) in the presence and absence of various combinations of copper, iron, vitamin and liver extract supplements. Under these conditions effects of zinc toxicity on growth, hemoglobin formation, liver copper and iron levels, and heart cytochrome oxidase activity were observed in several experiments.