Selenium and Vitamin E Deficiency in Pigs

The effect of selenium (Se) and vitamin E (Vit. E) on reproductive performance, growth and health was studied in pigs. Two levels of Se were used, 0.03 and 0.06 nag per kg feed. The major component of the experimental diets was barley originating from soil which had formerly produced crops with a very low content of Se. Prior to seeding, the area was divided into 2 plots, 1 of which was treated with Se in the form of sodium selenite, 100 g Se per ha. The use of Se enriched fertilizer was an effective way of increasing the Se concentration of the grain. Thus the concentration of Se in the barley produced on the treated area was 5 times higher than in barley from the untreated one. Vit. E was added at a level of 30 i.u. per kg feed, and the concentrations were approx. 15 and 45 i.u. in the basal and experimental diets, respectively. The higher level of Se or Vit. E was not significantly associated with milk yield of the sow, litter size, birth weight or haemoglobin levels. However, there was a tendency to an increase in milk yield of the sows following additions of Se plus Vit. E, and litter size was slightly higher from sows which had received an addition of Vit. E. The concentration of Se and Vit. E was much higher in colostrum than in sow milk, and additions of dietary Se and Vit. E were associated with marked increases in the concentrations of these compounds in both colostrum and sow milk. There was a moderately improving effect of a high Se concentration in feed on growth rate and feed utilization. Low dietary levels of Se and Vit. E were followed by increased mortality rate in piglets; iron toxicity in connection with iron treatment was observed in piglets on low dietary Vit. E. Symptoms characteristic of PSE were not observed in the Se and Vit. E deficient pigs.     

Clinico-Pathologic Findings in Young Pigs Fed Different Levels of Selenium,Vitamin E and Antioxidant

A randomized, blocked 23 factorial experiment was conducted with 48 young pigs. The treatment factors were: 2 levels of selenium (55 and 115 µg/kg), 2 levels of vitamin E (3 and 53 mg/kg) and 2 levels of the antioxidant feed additive Ethoxyquin (0 and 150 mg/kg). All pigs were kept in single pens and fed ad libitum throughout the experimental period of 9 weeks, i.e. from 3 to 12 weeks of age. Plasma, heart, liver and muscle Se levels as well as whole blood glutathione peroxidase activity (EC 1.11.1.9 GSH-Px) were significantly higher in pigs given a dietary supplement of Se than in pigs given no supplement of Se (P ≤ 0.001). The Se-supplemented pigs showed a tendency to lower mean serum transaminase activity (ASAT and ALAT) than unsupplemented pigs, but the influence was significant (P ≤ 0.05) only for the ALAT activity. Blood vit. E levels were higher for pigs receiving a supplement of vit. E than for unsupplemented pigs (P ≤ 0.001), and so was the resistance of red blood cells against lipid peroxidation (ELP), as expressed by lower ELP values. There were no effects of Ethoxyquin supplementation on the biochemical variables included in the study. The histological examination of heart muscle showed that the score for changes was negatively influenced by both Se and vit. E supplement (P ≤ 0.001) and to some extent also by Ethoxyquin supplement (P ≤ 0.05). The histological picture of m. long dorsi was influenced only by the vit. E supplement (P ≤ 0.01). No histological changes were found in the liver in this study. There were inverse relationships between whole blood GSH-Px defluorescence time and blood Se, and between ELP and whole blood vit. E (P ≤ 0.001).     

Analysis of class II genes of the chicken MHC (B) by use of human DNA probes

Class II genes of the major histocompatibility complex (MHC) in the chicken have been investigated by Southern blot analysis using human cDNA probes for DQ , DQ , DR , and DR . Both probes but not the probes cross-hybridized well with chicken DNA. The results indicated that the probes hybridized with at least two genes in the chicken MHC and there was no clear indication of a DQ-DR subdivision of chicken class II genes. The possibility of using human probes for MHC typing in the chicken was tested by using two homozygous individuals for each of 20 different, serologically defined, MHC (B) haplotypes originating from the domestic breeds of White Leghorn and Rhode Island Red, or from Red Jungle Fowl (the wild ancestral form). Genomic DNA samples from these individuals were digested with any one of the Eco RI and Pvu II restriction enzymes and hybridized with the DR probe. Restriction fragment length polymorphism (RFLP) was obtained with Pvu II only, which resolved seven different RFLP types. There was an excellent correlation between these RFLP types and the serological B typing since the RFLP type was identical within each pair of homozygotes. In addition to this broad survey of many haplotypes, a more detailed comparison was carried out on ²¹-like haplotypes originating from different breeds. No differences in restriction fragment patterns among these haplotypes could be resolved using any of the restriction enzymes Bg 111, Eco RI, Hind III, Pst 1, Pvu II, and Taq I.     

The uptake of applied selenium by agricultural plants

Summary Elemental selenium and a series of selenites and selenates were applied in pot and field experiments. With the elemental selenium a small increase in concentration in the plants was found in both kinds of experiments with red clover, lucerne, mustard, andsugar beet as test plants, but not with barley. In the second year an increase in the concentration in the plants was found in lucerne only (field experiment). In a pot experiment eight successive cuts of clover all had nearly the same content. All the selenites had the same effect on the concentration in the plants, and the concentration in the eight cuts of clover decreased with time at the same rate for all six selenites irrespective of solubility. The decrease was about a factor of six. In the field the effect of K₂SeO₃ in the second year was reduced by 50 to 80 per cent. Also the selenates gave the same concentration in plants independently of the solubility. But the concentration was 20–50 times that obtained with selenites, and the decrease in the effect with time was greater. In the eight clover cuts the effect of selenate decreased four times as much as the effect of selenite. In the field the effect of K₂SeO₄ decreased more from the first to the second year than the effect of BaSeO₄. During a two years field experiment with mustard the total uptake as a percentage of the added selenium was 0.01% of Se°, 4% of K₂SeO₃ and 30% of K₂SeO₄ and BaSeO₄. With lucerne, barley and sugar beet the uptake was one third of this or less. Determinations of water-extractable selenium in profiles from the field in the autumn showed no increase succeeding the addition of K₂SeO₄ in the spring while the addition of BaSeO₄ increased the extractable amount in both autumns. Addition of five times more selenite increased the water-extractable as well as the total soil selenium in the upper 25 cm, and the increase in total Se was also present in the second autumn.     

Improvement of selenium status of pasture crops

Selenium was applied to pasture crops in a field experiment (1) by foliar application of 10 g Se/ha as selenite in the spring, (2) or by 5 g Se/ha in the spring plus 5 g in early August, (3) as selenite-enriched calcium ammonium nitrate (CAN) at 4 g Se/ha after each cut, and (4) as 4 g Se after every second cut. The experiment covered 2 yr. The results showed that applying 4 g Se in CAN/ha five times and spraying with 10 g Se/ha were efficient and safe measures to raise the average Se concentrations from about 0.04 ppm to 0.06-0.1 ppm. The yield of dry matter was lower in 1981 than in 1980 and consequently the Se concentrations were higher. Dividing the foliar application of 10 g Se/ha into two applications increased the efficiency considerably.     

Comparison of selenium treatments of crops in the field

Field experiments with spring and winter barley and ryegrass were carried out to compare the effect of fertilizers enriched with selenate or selenite with foliar application on the selenium (Se) concentrations in the crops. Application of about 20 g Se/ha given as selenate or about 100 g as selenite in a PK fertilizer and about 5 g Se/ha sprayed on the plants increased the Se-concentrations from insufficient levels to levels that met the animal nutritional requirement. Ryegrass obtained sufficient Se concentrations at lower levels of added Se than did the barley. Toxic concentrations did not occur. The choice of method thus depends on the farming practice in the individual cases.     

Loss of selenium in drying and storage of agronomic plant species

Summary In two experiments with Se⁷⁵, loss of selenium from agricultural species was noted during both drying and storage. The loss of selenium during drying was to some extent overshadowed by the influence of self-absorption caused by the water in the fresh material. The results showed that even plant material of non-indicator plantslose volatile selenium at drying temperatures of 60°C or higher, and in some cases even at temperatures below 60°C. The results also showed that storage as briquettes gives the lowest storage loss of selenium.