Effects of Dietary Nitrite on the Chick: Growth, Liver Vitamin A Stores and Thyroid Weight

Abstract

Experiments were conducted to determine the effect of 0.4% dietary nitrite (as potassium nitrite) on growth, vitamin A status and thyroid gland weight of chicks. Nitrite depressed growth under ad libitum feeding conditions regardless of whether vitamin A was administered orally or by intramuscular injection. However, when feed intake between nitrite and non-nitrite fed chicks was equalized a depression in growth was observed only in chicks receiving the vitamin A-free ration containing nitrite. Liver vitamin A levels were low in chicks fed the various levels of vitamin A or carotene along with nitrite. However, when high levels of vitamin A were injected, which were equivalent to levels fed, liver vitamin A concentration was relatively high in nitrite-fed chicks. Thyroid gland hypertrophy was observed in chicks receiving nitrite and was largely overcome by intramuscular injection of massive does of vitamin A. Nitrite increased chick mortality rate but specific vitamin A deficiency symptoms were not observed. The data suggest that nitrite depresses growth of chicks primarily by reducing feed consumption. In addition, these data indicate that the influence of nitrite on feed intake and consequent growth of the chick resides in some other physiological processes than those in which either vitamin A or the thyroid gland, or both, are critically involved.