Pertanika4(2), 141-147(1981)

Iron Tolerance by the Young Pig as Influenced by the Dietary Status of Vitamin E and Selenium1 K.K. KUAN and E.FL MILLER2

Faculty of Veterinary Medicine and Animal Science Universiti Pertanian Malaysia Key words: pigs; iron; vitamin E; Selenium; iron toxicity. RINGKASAN Tiga percubaan untuk menentukan pengaruh vitamin E and selenium terhadap kesan-kesan feram apabila ianya diberi dalam makanan atau disuntikkan dalam otot, telah dijalankan dengan menggunakan 191 ekor babi. Anak-anak babi berumur tiga hari dari ibu babiyang telah diberi makanan kurang vitamin E dan selenium (Se) semasa bunting dan menyusu, tidak menunjukkan toleransi rendah apabila diberi suntikan 100 mg feram dextran. Keracunan feram tidak berlaku pada babi yang dicerai susu pada lima minggu dari ibu babi yang telah mendapat makanan kurang vitamin E-Se apabila babi tersebut diberi suntikan kedua dengan 100 mg feram dextran. Babi yang membesar sehingga peringkat berat badan pasaran yang diberi makanan kurang vitamin E-Se tidak menunjukkan kesan-kesan keracunan feram apabila ransum itu mengandungi feram sehingga 850 'parts per million* (ppm). Babi yang berumur 9 minggu yang, diberi suntikan 1000 mg feram dextran menunjukkan kenaikan paras feram serum yang lebih tinggi (P < 0.01 j jikalau dibandingkan dengan babi yang tidak disuntikan dengan galian itu. Tambahan pula, babi yang diberi makanan dengan tambahan vitamin E dan disuntik dengan 1000 mg feram dextran menunjukkan paras feram serum yang lebih tinggi (P < 0.01 j apabila dibandingkan dengan babi yang diberi makanan kurang vitamin E. Walaubagaimanapun, paras feram serum yang tinggi itu tidak membawa kesan-kesan buruk kepada babi itu. SUMMARY Three experiments using a total of 191 pigs, were conducted to determine the effects of iron, both oral supplementation and intramuscular injection in young pigs as influenced by dietary vitamin E and Selenium (Se). Piglets from sows on low vitamin E-Se gestation and lactation diets did not show any reduced tolerance to the standard dose of 100 mg iron from iron dextran when given at three days of age. Iron toxicosis was not produced when young pigs weaned at five weeks from sows on a low vitamin E-Se diet were given a second iron dextran injection of 100 mg iron. Pigs fed a low vitamin E-Se diet upto market weight did not exhibit any conclusive evidence of iron toxicity when their feed contained up to 850 ppm iron. When nine week old pigs were given an intramuscular injection of 1000 mg iron from iron dextran, there was a highly significant increase in serum iron levels; pigs on the vitamin E supplemented diets had significantly higher serum iron levels than those on the low vitamin E diet. However, the high serum-iron levels did not produce any noticeable ill effect on the animals. ing following the routine administration of iron to piglets (Behrens, 1957; Brag, 1958; Henrikson, 1962). Follow-up research (Arpi and Tollerz, 1965; Patterson et al, 1969 and Patterson et al, 1971) has indicated that vitamin E deficiency will render piglets more susceptible to the toxic effects of iron.

INTRODUCTION

One of the standard practices on the modern intensive pig farm is the administration of iron to piglets a few days after birth as a prophylatic measure against anemia. The supplementary provision of this element can be given either orally or in the form of an intramuscular injection although the latter is a superior method in terms of promoting maximum hemoglobin synthesis and in increasing weight gains (Wahlstrom et al, 1960). There have, however, been reports of iron poison-

The present research was undertaken to further investigate the iron tolerance of the vitamin E deficient young pig. Selenium deficiency may also render piglets more susceptible to the toxic

Part of M.S. Thesis submitted to Michigan State University. Dept. of Animal Husbandry, Michigan State University.

141

K. K. KUAN AND E. R. MILLER

animals were given a second intramuscular injection of 100 mg iron from iron dextran.

effects of iron. Selenium functions as a biological antioxidant as the essential component of glutathione peroxidase (Hoekstra et al.t 1973 and Scott and Noguchi, 1973).

Rectal temperature was taken at 0, 1,4 and 6 hours after the second iron injection, to determine whether there was an anaphylactic reaction.

MATERIALS AND METHODS

Three experiments were conducted to examine the pig's tolerance for iron as influenced by vitamin E and Se status.

Experiment 2. Effect of dietary iron supplementation to low vitamin E and vitamin E supplemented rations of young pigs.

General conduct of Experiments Experiment 1: Effect of a second iron injection on vitamin E - Se deficient pigs. A total of 127 piglets from 17 litters were used in this experiment. All litters were from sows fed a low vitamin E - Se ration throughout gestation and lactation (Table 1). At three days of age the piglets were given their first intramuscular injection of 100 mg iron from iron dextran. At five weeks of age, these pigs were weaned to a low vitamin E - Se starter ration (Table 1). Two days after weaning each litter was divided at random into two groups. Pigs in one group received an intramuscular injection of 34 I.U. of vitamin E plus 0.5 mg of Se, the other group served as a control. Two days after the vitamin E - Se injection, each group of animals was further divided into two sub-groups. One group of vitamin E - Se injected pigs and one group of non-injected

Forty-eight pigs from sows fed a low vitamin E - Se diet were used. The pigs were weaned at five weeks of age and allotted randomly by litter and weight into six groups of eight pigs per group. The feed provided following weaning and throughout the experimental period was a corn-soybean meal basal diet which contained about 0.05 ppm Se. (Table). The basal diet contained 345 ppm Fe. Additions of iron as ferrous sulphate (FeSO4 7H2O) and vitamin E as d-otocopheryl acetate to the basal diet were combined in a 3 X 2 factorial arrangement of treatments. The diets contained 345, 550 and 850 ppm iron and contained either a low level of vitamin E (none added) or were supplemented with 22 I.U. of vitamin E/kg of feed. The pigs had ad libitum access to feed and were weighed at weekly or fortnightly intervals. Blood for hematological studies and serum Fe analysis were collected at various intervals during the course of the experiment. Half of the animals

TABLE 1 Composition of diets Ingredients Ground corn Soybean meal Rolled oats Dried skin milk Sucrose Ground limestone Dicalcium phosphate Salt Vitamin trace-mineral premixa Antibiotic premixb

Gestation %

Lactation %

85.0

77.5 19.0

11.5

1.0 1.5 0.5 0.5

1.0 1.5 0.5 0.5

a

b

Grower %

51.45 20.0 10.0 10.0

78.75 18.0

5.0 1.0 0.8 0.5 1.0

_ 1.0

1.25 0.5 0.5

0.25 100.0

Analyses: Crude protein, % Selenium, ppm d-otocopherol, mg/kg

Starter %

100.0

100.0

100.0

13.2 0.04

16.1 0.05

19.5 0.09

16.0 0.05

7.6

7.4

7.8

7.5

Supplied the following/kg of diet: Vitamin A, 3,300 I.U., Vitamin D2, 660 I.U.;riboflavin, 3.3 mg;nicotinic acid, 17.6 mg; d-pantothenic acid, 13.2 mg; choline chloride, 110 mg; vitamin B12,.19.8 mg; zinc, 74.8 mg; manganese 37.4 mg; iodine, 2.7 mg; copper, 9.9 mg; iron, 59.4 mg.

Supplied to the ration 110 ppm chlortetracycline, 110 ppm sulfamethazine and 55 ppm penicillin. 142

IRON TOLERANCE OF YOUNG PIGS AND DIETARY STATUS OF VITAMIN E AND SELENIUM

1955). Blood samples were centrifuged for five minutes at 1000 rpm in an International Hematocrit centrifuge. 3. Iron level in the feeds was determined by a wet ash method. Feed samples were digested using concentrated nitric acid followed by concentrated perchloric acid. After cooling, samples were diluted to a constant weight with deionized distilled water and, iron concentration was then determined by atomic absorption spectrophotometry. Blood serum samples were precipitated with 20% trichloroacetic acid. The mixture was heated in a water bath at 90° for 15 minutes. Upon cooling, the mixture was centrifuged, the supernatant decanted into acid washed testtubes and iron concentration then determined by atomic absorption spectrophotometry. Liver, muscle and pancreas samples were homogenized and a weighed amount of the homogenate was digested and analyzed by the procedure followed for the feed samples.

from each group were bled and bleeding was done on the same animals at each subsequent bleeding. Blood was taken from the anterior vena cava. The period of the experiment was 126 days, after which the pigs were slaughtered. Samples of liver, pancreas and flank muscle were collected from each animal for iron analysis. Experiment 3: Effects of a large dose of iron given intramuscularly to young pigs deficient in vitamin E and Se. Sixteen pigs were used in this study. Eight were weaned from sows fed a low .vitamin E - Se gestation and lactation ration, while the other eight were from sows whose diet had been supplemented with 22 I.U. of vitamin E/kg of diet. All 16 pigs received their first iron dextran injection (100 mg of iron) at three days of age. At nine weeks of age, each group of animals was again divided into two sub-groups. One sub-group from each of the two main groups received a second iron dextran injection intramuscularly at a dose of 1000 mg Fe. The animals were observed for signs of toxicity following the administration of the massive dose of iron.

Statistical analysis

The data for experiment 2 and 3 were analyzed for statistical differences by the f-test of Snedecor (1950). Individual treatment values were compared by the Duncan's (Bliss, 1967) multiple range test.

Blood was collected prior to the administration of the massive dose of iron and then at one day and again at one week after the iron treatment for hemoglobin, hematocrit and serum iron determinations.

RESULTS AND DISCUSSION

Experiment 1 The feeding of a vitamin E - Se deficient diet alone to sows did not produce piglets with reduced tolerance to iron dextran. When three-day old piglets from these sows were injected with 100 mg iron dextran these animals did not exhibit any signs or symptoms of iron toxicity. Pigs given a second intramuscular injection of 100 mg iron from iron

Analytical procedures 1. Hemoglobin was determined by the cyanmethemoglobin method of Crosby et aL, (1954). A Coleman Junior II spectrophotometer was used for optical density determinations. 2. Hematocrit was determined by the microcapillary tube method (McGovern et aL,

TABLE 2 Average rectal temperatures, °C, after a second intramuscular iron injection Vit. E - Se inj.a Iron inj.

+

+ +

39.1 39.6 39.5 39.3

39.1 39.5 39.4 39.4

+

-

Time Ohour 1 hour 4 hours 6 hours

39.0 39.4 39.5 39.3

intramuscular injection of 34 I.U. vitamin E + 0.5 mg Se intramuscular injection of 100 m e iron from iron dextran 143

39.1 1 39.5 39.7 39.4

K. K. KUAN AND E. R. MILLER

dextran, four days after weaning to a low vitamin E - Se starter diet, also did not develop any reduced iron tolerance. One half of the experimental pigs had received a vitamin E - Se injection (34 I.U. vitamin E + 0.5 mg Se) two days prior to the iron injection, irrespective of whether the animals had been previously treated with vitamin E - Se injection or not, there was no evidence of iron toxicity. Rectal temperatures taken at 0, 1, 4 and 6 hours following the second iron injection were all normal with no evidence of anaphylaxis for any of the treatments (Table 2).

Experiment 2 Pig performance data are presented in Table 3. Average daily gains during the growing period tended to increase with increasing levels of iron in pigs fed low vitamin E diets and decreased with increasing levels of iron on high vitamin E diets. Treatment average daily gains did not differ significantly during the finishing period or when the entire study was taken into consideration. Similarly there were only small differences among treatments in daily feed consumption or gain/feed ratios. The decrease in daily gains during the growing period with increasing levels of iron on the high vitamin E diet was rather unexpected. One possible explanation of the results is that a high level of vitamin E is somehow incompatible with a high iron level. The exact mode of incompatibility (if it exists) cannot be explained without further investigation.

The results of this study appear to be contradictory to those of Lannek et ah, (1962) and Patterson et ai, (1969). Both groups of workers obtained piglets that were hypersensitive to the toxic effects of iron by feeding gestating sows a low vitamin E diet. It is important however, to point out that in both the above mentioned studies, the oil and grain portions of the experimental diets were subjected to oxidizing conditions by heating. This increased the peroxide value of the diet and further aggravated the low vitamin E situation. In the present study no polyunsaturated fatty acids were added to the experimental diets and the peroxide level were not increased by heat treatment.

There was a significant (P