Nitrate Toxicity in Dairy Heifers. 3. Endocrine Responses to Nitrate Ingestion during Pregnancy

Abstract

An investigation was conducted to gain information concerning the effects of nitrate on anterior pituitary and thyroid function in dairy heifers fed 0, 440, and 660 mg nitrate ion/kg body weight under conditions of management and feeding practices recommended for dairy cattle. Pituitaries from nitrate-fed heifers were heavier and contained a slightly higher concentration of growth hormone than those from control heifers. Nitrate did not adversely affect the thyrotropic, adrenocorticotropic, or gonadotropic activity of the pituitary glands. Barely sublethal levels of nitrate did not increase thyroid gland weights or acinar cell heights. Continuous feeding of sublethal levels of nitrate to dairy heifers, under the conditions of this study, did not produce a syndrome of chronic nitrate toxicosis characterized by thyroid dysfunction. © 1965, American Dairy Science Association. All rights reserved.