In pig farming the main reason for anaemia is iron deficiency. From the composition of sow's milk and the feed supplements eaten by the piglet it was deduced that deficiency of copper and vitamins of the B group does not occur under conditions in the Netherlands. Giving iron to the sow during pregnancy does not increase the piglet's liver storage of iron or its blood haemoglobin content at birth. Iron must therefore be given directly to the piglet either orally or parenterally. As injections can cause muscle damage the best method of iron intake for the piglet's physiology is orally. With the oral method the absorption rate of iron from the intestines is important. In experiments many iron compounds, both organic and inorganic, were given to piglets but the published results showed no agreement for blood values and weight gain.
In our experiments we examined the influence of fumaric and succinic acid on the uptake of iron from the intestines and on the use of iron in the haemoproteides. These two organic acids were chosen because Brise & Hallberg (1962) found that more iron was recovered in the erythrocytes with iron succinate than with iron sulphate which is used in man; iron fumarate is widely used for pigs. Famaric and succinic acids are both intermediates in the Krebs cycle and components for certain iron-protein compounds. Our experiments were done with piglets weaned two days after birth and with rats weaned as soon as possible. Rats and piglets were then made anaemic with feeds low in iron (table 7 and 8).
After the depletion period the effects of iron and the organic acids of piglets were studied in two 22 factorial experiments. The amounts of iron and organic acids used for the weaned piglets are given in table 5. Iron and organic acid in the same ratio was used for the rats. There were 16 piglets for each experiment and they were housed individually. In the experiment with succinic acid 16 rats were used; in the other experiment 20.
A more practical trial was done with compost using only 16 pigs. After the depletion period the effect of 10 g of compost was studied with and without the addition of 250 mg extra iron as iron sulphate. 10 g compost contained 280 mg of iron, which is about the same amount as the iron given as iron sulphate.
The correlation between blood values of 121 breeding sows and their litters three weeks after farrowing was investigated.
With 96 fattening pigs individually-housed the correlation between haemoglobin content and cell volume on one hand and weight gain and feed conversion on the other, was studied.
In the experiments with fumaric and succinic: acid, the haemoglobin content, blood volume and number of erythrocytes were determined weekly in the rats and the piglets. From these values, the mean cell volume (mcv), the mean cell haemoglobin concentration (mchc) and the mean cell haemoglobin (mch) were calculated. At the end of each experiment the myoglobin content of certain muscles, total iron binding capacity, plasma iron, iron content of liver, spleen and kidney were analysed. The protoporphyrin content of the erythrocytes was also determined. The amount of haemoglobin present in each piglet or rat was calculated from live weight and haemoglobin content.
In the experiment with succinic acid and in the experiment with fumaric acid the number of erythrocytes (rbc) of the rats increased significantly two weeks after the first treatment (tables 10, 11 and 25, 26).
In both experiments the mean cell volume of the erythrocytes was smaller. In experiments with rats three weeks after first treatment no difference was found in the blood values. With these organic acids the rats recovered quickly. No positive effect was observed in the piglets with succinic acid or fumaric acid (tables 16, 17 and 31, 32). However, the effect of iron was clear in both rats and piglets.
From the blood values - the haemoglobin content, the cell volume, the number of erythrocytes, the mean cell haemoglobin concentration of the erythrocytes, the mean cell volume and the mean cell haemoglobin - the differences between the groups with and without extra iron were significant.
This was also seen from the iron content of the liver, spleen and kidneys. In all experiments with piglets the plasma iron content of the blood was very low, and there was a large standard deviation. The total iron binding capacity of the plasma was sometimes different for the animals with extra iron and for those without. There was seldom any difference in the myoglobin content if extra iron was given. Calculations were made of the amount of haemoglobin of the animal and the percentage of extra iron present in the blood after completing the experiments. More than 25 % of the extra applied iron should have been present in the haemoglobin of the piglets (table 48) and the rats. This percentage was less than 1 % in the liver of the piglets.
In spleen and kidneys a little more iron was found for the piglets with extra iron. The extra applied iron was considerably lower than 1 % in these organs.
In the experiment with 10 g compost applied with and without iron the effect of this small amount of compost on the anaemic piglets was noticeable. The effect of 250 mg of iron given as iron sulphate was more obvious although the compost and the iron sulphate contain about the same amount of iron. Iron from iron sulphate is absorbed better than iron from compost.
No important correlations between the values of the sows and the pigs of these sows were found from observations of the sows and their litters (table 46).
The blood values of the fattening pigs at the beginning of the mashing period compared with the results in the first two months of the fattening period were of no importance. The differences in blood values between the pigs were not very large and all values were within the normal physiological boundaries.