Female chickens were fed graded levels of sodium selenite to determine at what level a selenium toxicity occurred. In the first experiment a basal diet was supplemented with 0, 0.1, 1.0, 3.0, and 5.0 ppm of selenium. These levels had no effect on egg production, egg weight or fertility of the eggs. Hatchability of fertile eggs was significantly decreased by 5 ppm of dietary selenium. In the second experiment a basal diet was supplemented with 0, 5.0, 7.0, and 9.0 ppm of selenium. Egg weight and hatchability were significantly decreased by 7 and 9 ppm, and egg production was decreased by 9 ppm of selenium in the diet. When selenite was added to the diet, there was a lag of 2 to 3 weeks before the selenium content of the egg reflected the content of the diet. As long as the selenium content of the diet remained the same, egg selenium remained the same. When selenium was no longer supplemented, egg selenium content decreased. Two weeks after cessation of selenite supplementation, egg selenium was markedly reduced. Four weeks after cessation of selenite supplementation, egg selenium levels approached those of birds fed a basal diet continuously.

Maternal thyroid status was altered by means of diet to determine its effect on functional properties of turkey eggshells. Hens were fed a control diet (CON), the CON diet containing .5 ppm triiodothyronine (T3), the CON diet containing 2.1 ppm iodine as potassium iodide (KI) or the CON diet containing .1% thiouracil (THIO). Feeding T3 decreased plasma thyroxine but elevated plasma T3 concentrations compared to CON. The KI diet had no effect on plasma thyroid hormone concentrations, but feeding THIO depressed plasma thyroxine with no effect on T3, resulting in an elevated ratio of the two hormones compared to the CON ratio. Feeding KI decreased egg volume and T3 increased egg density compared to CON, but no effects on egg weight, surface area, width, or length were noted. Dietary T3 depressed eggshell water vapor conductance compared to CON. Dietary iodine resulted in thinner eggshells with fewer pores than the CON, whereas THIO caused significantly more pores in eggshells than CON but had no effects on shell thickness. Dietary KI had no effects on maternal plasma thyroid hormone concentrations, suggesting that the effects were due to iodine availability rather than to thyroid hormones. It is concluded that the availability of iodine to turkey breeder hens may influence eggshell characteristics.

Broiler breeders were fed CGA -72662 ( Larvadex ) at dosages of 0, 30, 300, and 3000 mg/kg (ppm) diet in a standard breeder diet from 25 to 65 weeks of age. The 3000 ppm level was reduced stepwise to 1000 ppm from 25 to 27 weeks due to a significant increase in male and female mortality. Feed consumption did not differ significantly due to treatment. However, birds fed 300 ppm exhibited significantly improved feed conversion and increased egg production on a hen-day basis compared to those fed 0 and 30 ppm with the 1000 ppm level intermediate. On an egg per hen-housed basis, birds fed 300 ppm produced significantly more eggs than those fed 0 ppm with 30 ppm intermediate. Hens fed 1000 ppm produced significantly fewer eggs than all other treatments due to higher initial mortality. Body weight gains for males and females among treatments were similar. Mortality was significantly greater at 1000 ppm than for all other treatments. Egg specific gravity at 50 and 60 weeks was not affected significantly by any treatment. Egg weight, when compared to the 0 ppm level, was decreased significantly at the 1000 ppm level at 50 weeks and by both 300 and 1000 ppm levels at 60 weeks. Egg shell weight was not affected significantly at 50 weeks, but was decreased significantly by both 300 and 1000 ppm Larvadex at 60 weeks. There were no significant effects due to treatment level on fertility, early deads , pipped eggs, hatchability of fertile eggs, or hatchability of eggs set.(ABSTRACT TRUNCATED AT 250 WORDS)

Hens were fed a diet low in selenium made up mostly of corn and torula yeast. Egg production and hatchability increased significantly when selenium was supplemented, while the percentage of infertile eggs and early dead embryos decreased. Anemia also resulted from the deficiency. A total of .05 mg. selenium per kg. (.04 from the basal diet plus .01 supplemental) was adequate to prevent signs of deficiency in a diet which contained no supplemental vitamin E or antioxidant. In a second experiment the anemia was classified as macrocytic.

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