[Relation between vitamin E supply and the fertility of laying hens]

In 4 experiments with a total of 1296 laying hens it was ascertained that a laying hen requires 1 mg vitamin E/kg feed for egg production if the ration contains sufficient selenium and is not rich in multiply unsaturated fatty acids. For the fertilization of the eggs little more of this vitamin is required. There were close relations, however, between the amount of vitamin E supplement to the feed and the number of hatched chickens in % of the fertilized eggs. With the help of the experiments carried out so far the exact requirement could not yet be ascertained. Based on the results of our experiments we recommend 20 mg vitamin E/kg feed for breeding hens of the laying variant. There is a close relation between the vitamin E content of the feed and that of the yolk. A supplement of 7 or 14% resp. of vitamin-free sunflower oil decreases -in dependence on the vitamin E supplement-hatching in particular without diminishing the vitamin E content of the yolk. The vitamin E content of the yolk sac, however, was drastically reduced. The influence of polyene fatty acids in hatching is smaller when sunflower oil rich in vitamin E is supplemented. Vitamin-free sunflower oil has an influence on the vitamin content of the yolk, but it diminishes drastically the vitamin content of the yolk sac and, provided that vitamin E supply is low, prevents hatching.