Submitted to: Journal of Dairy Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/10/1998
Publication Date: N/A
Citation: Interpretive Summary: Nitric oxide is a gas produced in cells in the body which helps kill bacteria and viruses in the cells of the body. Nitric oxide produced in excess, however, is toxic and can kill normal cells. In this study, we showed that during the first month after birth, immune cells from milk replacer-fed calves produced very high levels of nitric oxide when compared to adult cows. We also showed that production of nitric oxide by immune cells from calves decreased and was similar to production by immune cells from adults when optimal amounts of vitamins A and E were present in the milk replacer. The greater production of nitric oxide by a newborn calf during the first month after birth may be indicative of the immaturity of its immune system and, if sustained, might be detrimental. Conceivably, manipulation of dietary levels of vitamins A and E might play an important role in the maturation of this response to one more typical of adult cattle. An anticipated benefit would be an optimization of immune function and increase resistance to infectious disease.
Technical Abstract: Optimal production of nitric oxide by phagocytic leukocytes is required for microbial killing and signal transduction, whereas excessive production is toxic to cells. Because the neonatal immune system is frequently less efficient than that of the adult, and fat-soluble vitamins modulate immune function in a variety of animal species, this study evaluated the effects of dietary vitamin A and E on the in vitro capacity of blood mononuclear leukocytes from calves to produce nitric oxide. Milk replacer-fed calves received 100 IU/d of vitamin E as d-alpha-tocopherol or d-alpha-tocopheryl acetate and either 0, 1700, 34,000 or 68,000 IU/d of vitamin A. Leukocytes from 1-wk-old calves produced less nitric oxide and were less responsive to stimuli than older calves, a possible consequence suppressive factor present in the ingested colostrum or in the circulation at birth. Relative to adult leukocytes, leukocytes from calves produced greater amounts of nitric oxide. Nitric oxide production by calves fed d-alpha-tocopherol and either 1700 or 34,000 IU/d of vitamin A was less than calves in other groups and more typical of production by leukocytes from cows. The greater production of nitric oxide by calf leukocytes may be typical of the immature neonatal immune system. Dietary vitamin A and vitamin E appear to affect the maturation of this response towards one more typical of the adult.