Effect of Dietary Linoleic Acid and Selenium on the Requirement of Vitamin E in Ducklings

Abstract

The effect of dietary linoleic acid and selenium on vitamin E requirement has been investigated. Groups of newly hatched, male Peking ducklings were kept for 4 weeks on diets containing increasing amounts of vitamin E (D α-tocopherol acetate). The dietary fat (35 cal%) consisted of lard (low linoleic acid content), tocopherol-free maize oil (high linoleic acid content) or natural maize oil. In addition to D α-tocopherol acetate, some groups received 0.1 mg selenium (Na₂SeO₃) per kg food. Vitamin E deficiency manifested itself by myopathy of all types of muscles. The skeletal muscles showed the typical hyaline degeneration. Necrocalcinosis was found in the muscular tissue of heart, gizzard and intestine. The lard diet needed 13.5 and the tocopherol-free maize oil diet 27 mg vitamin E/kg food to prevent myopathy; this is 86 and 172 mg D α-tocopherol per kg fat, respectively. For the natural maize oil, this requirement was amply covered by its own tocopherol content, while on lard diets all animals died within 3 weeks, showing severe myopathy when extra vitamin E had not been added. The increased vitamin E requirement of the animals on the tocopherol-free maize oil diet could be explained by their lower blood-tocopherol level, as compared with the lard group, at an equal dietary level of vitamin E. Selenium was found to be most effective in preventing myopathy (0.1 mg Se ≧ 20 mg D α-tocopherol acetate). The beneficial effect of selenium could not be explained by an increase of the plasma tocopherol level. Obviously, most animal fats are inadequate in vitamin E, whereas vegetable oils with a high linoleic acid content (sunflower, maize, safflower) must be considered as the natural sources of this vitamin. It is concluded, that a critical dietary E/PUFA ratio (intake of mg D •α-tocopherol, divided by the intake of polyunsaturated fatty acids in g) does not exist.

Linoleic Acid Intake and Vitamin E Requirement in Rats and Ducklings

“…In the small intestine, the tocopherol itself is formed from the acetate ester, and part of this tocopherol may be destroyed by the lipid peroxides already present in the food. 16 These considerations are summarized in FIGURE 9. A-B is the phase of EFA deficiency.…”

“…Newly hatched male Peking ducklings were given the diets indicated in TABLE 1 ; the type of fat used was lard or tocopherol-free maize oil. 16 After four weeks the surviving animals were killed by decapitation and examined for gross pathology; different organs were removed for microscopic examination. The same procedure was followed with animals that had died before the end of the experimental period.…”

Influence of Dietary Selenium on Performance, Tissue Selenium Content, and Plasma Concentrations of Selenium-Dependent Glutathione Peroxidase, Vitamin E, and Ascorbic Acid in Ducklings

“…A nutritional need for selenium has been demonstrated in ducks by several investigators (Jager, 1972;Yarrington et al, 1973;Moran et al, 1974;Hulstaert et al, 1976;Van Vleet, 1977). The experimental diets used in these studies were usually low in both selenium and vitamin E and were based on either torula yeast (Yarrington et al, 1973;Van Vleet, 1977), low-selenium casein (Hulstaert et al, 1976), or high-moisture corn .…”

“…Gross lesions included necrosis and mineralization of the muscles of the gizzard, intestine, and heart, and pale or white striated skeletal muscle. Exudative diathesis has been observed infrequently (Jager, 1972;Moran et al, 1975). In the above mentioned studies, supplementation of the basal diets with .1 to .2 ppm selenium (as sodium selenite, selenium dioxide, or selenomethionine) or 20 to 100 mg of DLalpha-tocopherol per kilogram prevented the appearance of clinical signs or lesions associated with feeding the unsupplemented diets.…”