A study involving 0.2, 2 and 8 p.p.m. selenium and 8 or 15 p.p.m. arsenic additions to corn-soy, glucose-isolated soy and glucose-Torula yeast diets for laying type chickens was conducted to 62 weeks of age. Hens from the corn-soy diet were force molted and continued on treatment to 104 weeks of age.
Addition of 2 p.p.m. selenium to the corn-soy diet significantly (P < 0.01) increased hen-day production during a first year’s production cycle but resulted in only a slight improvement during a second year’s production under less crowded conditions. Poor production was obtained with the purified type diets. However, no significant improvement was noted with an 2 p.p.m. addition to the glucose-isolated soy diet or the glucose-Torula yeast diet.
Egg size was decreased when 8 p.p.m. selenium were added to any of the three diet types and in some cases with 2 p.p.m. No significant effects due to selenium supplementation were noted on shell thickness, Haugh units or egg fertility. Percent hatch of fertile eggs was significantly (P < 0.01) decreased when 8 p.p.m. selenium were added to any of the three diet types. Arsenic partly overcame the toxic effects to a greater extent with the yearling hens on the corn-soy diet.
Selenium supplements up to 2 p.p.m. to the purified-type diets containing 0.02 to 0.07 p.p.m. selenium resulted in tissue selenium contents of 0.5–0.9 p.p.m. These were comparable to those found in hens fed the unsupplemented corn-soy diet which contained 0.4 p.p.m. selenium. With the unsupplemented purified-type diets, tissue selenium levels were in the range of 0.06–0.4 p.p.m. Selenium deposition in eggs followed the same patterns as tissue selenium and did not increase with length of time the hens were fed the supplements. Within two weeks after supplementation was terminated, egg selenium levels were similar irrespective of previous dietary treatment.