A. A. Kurnick

Phytic Acid Studies.

Summary Relative tendency of some metals to complex with phytic acid, and the influence of sodium phytate on the availability of zinc in chicks were studied. Of the metals studied, zinc appeared to form the most stable complex with phytic acid in the physiological pH ranges. Addition of sodium phytate (0.25%) to a low-zinc chick diet depressed growth rate presumably by binding zinc and rendering the element less available for growth. Therefore, the greater tendency exhibited by zinc to form a complex with phytic acid near physiological pH ranges would possibly explain the adverse effect of phytic acid on zinc metabolism.

Nature of intestinal phytase activity.

Summary Experiments were carried out with chicks, mature hens and weanling rats fed dicalcium phosphate, calcium phytate and sodium phytate as dietary phosphorus sources. Intestinal phytase activity measurements failed to show a significant difference in the activity of this enzyme due to the dietary treatments. The mature hen exhibited lower intestinal phytase activity than did the chick or the rat. The use of mixed substrates, employing sodium phytate and beta-glycerophosphate at equi-molar concentrations, failed to produce an increase in activity as compared to these substrates singly. These data indicated that the phytase activity may have been due to a non-specific phosphatase in the intestinal homogenates. The ratios of alkaline phosphatase to phytase activities in presence or absence of fluoride were the same. These data also point to the presence of only one enzyme system which hydrolyzed both sodium phytate and beta-glycerophosphate.

Effect of a minimal fluoride diet on rats.

Summary The feeding of a minimal fluoride (< 0.005 ppm F) diet for a 10-week period to weanling rats demonstrated significantly lower levels of bone fluoride compared to the control group receiving the minimal diet plus 2 ppm fluorine. Serum and liver enzymes activities were determined, and the only significant differences noted were an increase in serum isocitric dehydrogenase and a decrease in activity of this enzyme in the liver.

Ethoxyquin and egg yolk pigmentation.

Summary Three experiments have been conducted to evaluate the site of action and effectiveness of the antioxidant ethoxyquin on egg yolk pigmentation. Results of the first experiment conducted during a period of high ambient temperatures indicated an average improvement of 53.8% in yolk pigmentation due to the feeding of 125 ppm of the antioxidant in addition to dehydrated alfalfa meal in the diet of laying hens. In the absence of ethoxyquin, dietary loss of xanthophylls amounted to 24% and loss of betacarotene was 32%. The second experiment conducted during cooler weather resulted in an improvement of 21% in yolk pigmentation due to ethoxyquin feeding. Dietary losses of carotenoids in the second study were negligible. The result of the third experiment indicated approximately 10% of the xanthophylls were destroyed in vivo. This in vivo loss of xanthophyll pigments was prevented by either the feeding of 125 ppm ethoxyquin in the diet or administration of the antioxidant by capsule (50 mg, 3 times daily) or intramuscular injection (50 mg, 3 times daily).

Effect of Sterculia foetida oil on uptake of water by the avian egg yolk.

Summary The yolks of eggs from hens having a one-egg clutch average took up significantly more water than those from hens having 2-4 egg clutch sizes. Yolks from hens having 2, 3, and 4 egg clutch, sizes showed no significant differences in water uptake. Yolks from eggs stored overnight and from hens given Sterculia foetida oil were not significantly heavier and did not take up more water than eggs from hens given corn oil. However, when the eggs were stored one month the yolks from the hens fed Sterculia foetida oil increased 20% in weight and showed an 80% greater water uptake than those from the corn oil fed hens.