High Dietary Ca Research Articles

Interactions of Dietary Calcium with Toxic Levels of Lead and Zinc in Pigs

Twenty-four weanling Yorkshire pigs were used in a 2 x 2 x 2 factorial arrangement of treatments to determine their response to high levels of dietary lead (Pb) (1000 ppm) and zinc (Zn) (4000 ppm) (as lead acetate and zinc oxide), to investigate the influence of high dietary calcium (Ca) (1.1%) on the biochemical and morphological manifestations of Pb and Zn toxicity, and to determine the effect of excess Zn on Pb toxicity. Clinical signs of Pb toxicity included behavioral changes, lameness, and anorexia. Pb content of blood, soft tissues, and bone was increased markedly by 1000 ppm Pb in the diet during the 13-week experiment. Zn and Pb fed together, as compared with Pb alone, tended to increase Pb levels in blood, soft tissues, and bone and to enhance the toxic effects of Pb as shown by reduced weight gains, severe clinical signs, and pathological changes. High Ca reduced blood and bone Zn and Pb concentrations. The results indicate that high dietary Ca has a protective effect against the adverse effects of diet Pb and Zn, and that Zn aggravates Pb toxicity in growing pigs.

Interactions of Ca, P, Zn, and alkaline phosphatase in the chick. II. Effect of dietary Ca level.

Chicks were fed a semi-purified diet, containing 0.75% Ca, 0.5% inorganic phosphate (Pi), and 50 p.p.m. Zn, to 2 weeks of age. They were then divided into groups and fed the same diet with 0, 0.75, 1.50, 2.25, or 3.00% Ca, for 4 or 7 days before being killed. Plasma was analyzed for Ca, Pi, and Zn, and duodenal mucosa for Ca, Pi, Zn, Mn, and alkaline phosphatase (AP). The low Ca treatment decreased plasma and mucosa Ca and increased mucosa Zn, whereas the high Ca diets increased mucosa Ca and decreased mucosa Zn, plasma Pi, and mucosa AP activity. There was an overall positive correlation of AP with plasma and mucosa Zn, and plasma and mucosa Pi, and a negative overall correlation of AP with plasma and mucosa Ca. Mucosa Mn content did not seem to be related to the enzyme activity.

The Effect of Calcium Level of Diet on the Metabolism of Calcium, Phosphorus and Magnesium in Pregnant Rats

Metabolism of calcium, phosphorus and magnesium during pregnancy was investigated with 20 primigravida albino rats about 170g body weight of Wister Imamichi strain fed with diets containing Ca 0.534 and 1.077% respectively.The animals were divided into four groups (A, B, C and D), and in the early period of pregnancy, A and B group were fed with low-Ca diet and C and D group were fed high-Ca diet. In the middle period, A and D group fed with low, and B and C group with high, then in the last period A and B fed with high, and C and D with low Ca diet.In the early period, calcium retention increased with the amount of calcium intake, therefore the absorption and the utilization of calcium were better in high calcium groups. In the middle and last period, the absorption rate was decreased and the amount of calcium retention of group C was smaller than that of calcium requirement for growth of fetuses.It seemed that the calcium need to fetuses was removed from the calcium stored in mother rat during the early period of pregnancy.From these results, it is considered that high calcium feeding in the middle or in the last period of pregnancy have no effect on calcium utilization, therefore it is preferable to feed high calcium diet from the beginning of pregnancy.Absorption and utilization of phosphorus in diet are affected by it Ca/P ratio, and the rats of high-Ca group utilized P better than that of the low-Ca groupMetabolism of magnesium resembles to that of phosphorus, and high Ca/Mg ratio in diet seems to have good effect on magnesium utilization.

Intestinal Phytase and Alkaline Phosphatase of Chicks: Influence of Dietary Calcium, Inorganic and Phytate Phosphorus and Vitamin D3

AS indicated in reviews by Taylor (1965) and Nelson (1967) data are incomplete and often conflicting in regard to the influence of dietary factors on the extent to which chicks are able to utilize phytin phosphorus. Maddaiah et al. (1964) were unable to relate supplementation with dicalcium phosphate, or calcium or sodium phytates to intestinal phytase activity in the chick or the rat. Balance studies have shown (Pileggi et al., 1955) that in the rat high dietary Ca lowered phytate hydrolysis; vitamin D3 reversed this effect but the inorganic phosphorus liberated by the treatment was inadequate to prevent rickets. It has also been demonstrated that dietary vitamin D3 increases the level of phytase activity in both chicks and rats (Steenbock et al., 1953, for chicks and rats, Pileggi et al., 1955, and Roberts et al., 1961, for rats), especially when rachitogenic rations were fed. On the other hand, Spitzer et…

Effect of Varying Calcium Intake on the Parameters of Calcium Metabolism in the Rat

Kinetic tracer techniques providing the data for a compartmental analysis were supplemented with Ca balance measurements to obtain the rates of Ca absorption, endogenous fecal excretion, exchangeable space and accretion rates. The effect of low and high Ca diets was measured in terms of the above-measured parameters of skeletal metabolism in rats. Varying the Ca intake had no effect on the size of the compartments in the model used. Further, while the accretion rate of Ca into bone was not affected by the dietary Ca level, the rate of feedback of Ca from bone was quite sensitive to the level of Ca in the diet. The low Ca diet resulted in an appreciable increase in the resorption rate of Ca from bone and a very low rate of apposition of Ca into bone. However, the high Ca diet resulted in a minimal resorption rate (actually a negative rate) and a large increase in the net deposition of Ca in the skeleton. The use of a mathematical model proved to be a useful framework against which the effects of various Ca intakes could be measured quantitatively.

Radiostrontium excretion in the feces of young rats following a diet rich in calcium

Young immature rats of both sexes were fed with a diet either high (1.95%) or low (0.31%) in Ca content. A s.c. injection of weightless90Sr results in a better excretion of radiostrontium with the faeces during feeding with high Ca diet. The retention of activity in the femori 30 days after injection is, in the same case, lower than by feeding with low Ca diet.

Diet-Induced Changes in the Exchange and Accretion of Radiostrontium by Rat Skeleton

The administration of stable Ca or Sr to decrease the retention of radiostrontium by skeletal tissue has been employed by a number of investigators with equivocal results. The experiments were based chiefly on the carrier effect, the dilution of radiostrontiuru with stable Sr or Ca adruinistered just prior to or immediately after the adrninistration of the radiostrontium. A different approach was used to decrease the Sr/sup 85/ retention. This procedure is based on the hypothesis that a monolayer of Sr salts will be bound to the reactive sites of binding on the surface of the inoramic bone crystal with greater force than will a subsequent layer of Sr salts, since Ca phosphate is less soluble than Sr phosphate. Accordingly, stable Sr was administered in the diet for periods ranging from 2 to 7 days prior to the injection of Sr/sup 85/. Similar use of stable Ca and Zr was also investigated. It was found that there was a decrease of 76% in the retention of Sr/sup 85/ in young growing rats receiving a high-Sr diet for 7 days, as compared with animals fed a stock diet. The decreased uptake of Sr/sup 85/ was reflected in a decrease of both themore » Sr exchange capacity and the Sr accretion rate of the skeleton. A high-Ca diet also produced a decrease in the Sr/sup 85/, but much less than a Sr diet, and a Zr sulfate-supplemented stock diet was a little more effective than the high-Ca diet. (auth)« less

Studies on the Relation between the Excretion of Sr and the Intake of Ca (Report 1)

This experiment was attempted to know how to prevent or reduce the effect of contamination by radioactive substances by fallout. There are many kind of radioactive substances in the fallout, and above all 90Sr and 137Cs seem to be most important.As it has been indicated that the behaviour of Sr in and out of our bodies is very close to that of Ca, the experiment on the relation between the Ca content of diet and the excretion of Sr was performed by using albino rats.Experimental: Adult albino rats weighing about 200g were subjected to this experiment, and they were divided into four groups, the Ist group was fed with a high Ca diet and the 2nd a low Ca diet during experimental period, and the 3rd was fed with these high and low Ca diets alternately for 6 days each during this experiment. 90Sr was injected into the abdominal cavity of the rat, 1.3μc per capita. The 4th group was fed by standard diet and 90Sr was injected together with relatively large amount of non-radioactive Sr.Results: The percentage of total excretion 90Sr during 24 days of the Ist, 2nd and 3rd groups were 15%, 8%, 14% respectively, and of the 4th group was about 25% during 18days. The amount of excretion of 90Sr of high Ca diet group was superior to that of the low Ca diet group, and that of the group non-active Sr injected was the highest of all.

Studies on the Relation between the Excretion of Sr and the Intake of Ca (Report 2)

In continuance to the previous report, the relation between Ca intake and 90Sr excretion was investigated with young albino rats.Experimental: 16 immature albino rats weighing about 70g were subjected to this experiment, and they were divided into two groups.The 1st group was fed with a high Ca diet (506mg%) and the 2nd group on a low Ca diet (86mg%). Radioisotope was administered by the single shot method i. e., only 90Sr was injected into the abdominal cavity of the rats, 1μc per capita.After the injection, urine and feces of the rats were collected every two days during the first 10days, thereafter both were collected occasionally. Ten days after the injection, a tip part of the tail of each rat was cut off for the estimation of retained amount of RI in bones, 60-65days after the injection the rats were killed and the one side hind leg, incisor were taken off for determination of deposit activity in hard tissue.Results: The amount of 90Sr excreted by the rats fed on the high Ca diet were higher than that of the low Ca fed group.The retained amount of 90Sr in hard tissue, especially, in the teeth was larger in the low Ca group than that of the high Ca group.

Part III THE ACCERETION AND RESORPTION OF CALCIUM IN THE SKELETON

SummaryA method is described for the determination of digestive juices Ca, based on the continuous ingestion of Ca45 with stable Ca in the food. The true absorption of Ca can next be estimated.In the adult rat the digestive juices Ca was found to be in the range of 6.4 to 27.6 mg daily. The variability was considerable. When a number of consecutive periods were averaged in four vitamin D free rats, the variability was about ±15 per cent of the mean value of 11.2 mg Ca daily.Variations in serum Ca concentrations influence the digestive juices Ca as expected. When ionized Ca was calculated, a straight line relation was found between the ionized Ca and the amount of digestive juices Ca.Variations in the amount of food eaten resulted in proportional variations in the digestive juices Ca in rats supplied with vitamin D. In vitamin D free rats, variations in voluntary food consumption resulted in corresponding changes in the secretion of Ca with the digestive juices, not, however, to the same extent as in the rats supplemented with vitamin D.The method was found to be applicable with small errors only when the speed of Ca absorption was low, Serious errors may readily occur when the rate of Ca absorption is high or when high Ca diets are used.Some experiments in which the isotope was administered in a single dose by stomach tube revealed the serious weakness of such a procedure in contrast to the continuous feeding administration.Long‐term balance experiments were carried out to study the accumulation of Sr90 in rats with a constant level of Sr90 in their diet. Four groups were taken into experiment at different ages on a diet with 0.25 per cent Ca. A fifth group received a high Ca diet (0.71 per cent). The rats were kept in the experiment for 50 to 103 days.In the youngest group of rats the net absorption of Ca was nearly complete. The rats on the 0.71 per cent Ca diet did not absorb more Ca than rats of comparable age on the 0.25 per cent diet. The Ca absorption decreased with increasing age of the rats, as expected.Sr90 in faeces increased in the course of the experiments; the initial figures for faecal excretion in each experiment were definitely correlated to the efficiency of Ca absorption. An increase in the level of Ca in the diet resulted in a proportional depression of Sr90 absorption.The Observed Ratio (absorption) was calculated from the figures for net absorption of Ca and Sr90. Corrections have also been made for the secretion of Ca and Sr90 with the digestive juices. The O.R. (absorption) was found to be very high in the youngest rats, which is explained by the very high utilization of dietary Ca in the rats on the 0.25 per cent Ca diets.The urinary level of Ca was low in all the experiments. Sr90 in the urine remained within ten per cent of the intake in practically dl observations. There was a correlation between Sr90 absorbed and the urinary excretion. Within a given experiment, the Sr90 level in the urine became constant from the very early periods.The ratio of Sr90 in serum became constant after about eight days in young rats on continuous ingestion of Sr90.The Sr90/Ca ratio in the body was calculated at the end of each metabolic period. The resulting curves show a peak after approximately 33 days on the Sr90 diet. Next, some decrease followed, due to absorptive and urinary discrimination. The highest ratios for Sr90/Ca (body/diet) were found in the youngest rats, corresponding to the highest rates of absorption and the smallest body pool of Ca. The ratio of Sr90/Ca in the body was reduced in proportion to the increase of Ca in the diet.Following discontinuation of Sr90 ingestion, the faecal excretion was about twice as high as the urinary elimination.The figures for Ca and Ca45 retention were used in a calculation of the rate of bone accretion and resorption. The plasma Ca specific activity was constant in the periods used. The calculation rested on the presumption that the specific activity of Ca in accreted bone equals the specific activity of Ca in the plasma. In the first approximation zero specific activity of resorbed Ca was somewhat erroneously assumed. However a calculation with the aid of a set of figures for the specific activity of resorbed Ca results in: a) that accretion and resorption show a parallel increase, and b) gives a fairly good estimate of the probable size of the two variables under various experimental conditions. Experiments with vitamin D indicate that the vitamin acts primarily by increasing Ca absorption and bone accretion.