Endotoxin-induced changes in plasma mineral and vitamin levels in calves

Tumor necrosis factor-α-induced inflammatory responses in cattle

Tumor necrosis factor-alpha (TNF-α) is recognized as a cytokine because of its involvement in inflammation-mediated biological defense functions. Although TNF-α is primarily produced by macrophages, it is also produced by other cells, including lymphocytes, Kupffer cells, natural killer cells and adipocytes. While TNF-α has diverse immune system functions, including antitumor activity, antimicrobial activity and mediation of inflammation, it also regulates a number of physiological functions, including appetite, fever, energy metabolism and endocrine activity. Factors such as viruses, parasites, other cytokines, and endotoxins induce TNF-α production. In combination with other cytokines, TNF-α plays a clinically important role in cattle by mediating immune inflammatory responses such as mastitis and endotoxic shock. It has been reported that cytokines such as TNF-α are involved in metabolic disease such as acidosis. On the other hand, several data suggest that lactoferrin (LF) acts to prevent the release of a number of inflammatory mediators from various activated cells, and further suggest that the prophylactic effect of LF involves inhibition of cytokine production, including TNF-α, that are principal mediators of the inflammatory response leading to death from toxic shock. This review discusses the role of TNF-α in pathological conditions in cattle, including infections and metabolic diseases caused by perturbation of metabolism and endocrine functions.

Nutrition and mastitis

Increasing evidence presents a relationship between nutrition and mammary resistance to infection. The role of nutrition in mammary resistance has been best defined for antioxidants. To optimize this interaction, rations should be balanced and formulated for lactational stage. Although supplementation of nutrients with antioxidant function may enhance immune resistance against infections, therapeutic roles for nutritional management of clinical mastitis, as yet, are not well documented. The need to monitor herd antioxidant status as part of a mastitis control program is critical because (1) antioxidant supplementation improves mammary resistance to infectious disease during the most critical period for enhanced resistance, the dry and early postpartum periods; and (2) dry cows and heifers often are on a marginal plane of Se supplementation, particularly during periods of risk for mastitis and reproductive disorders. In areas where forages contain less than 0.1 ppm Se (dry matter) because of low soil availability, herds should be tested for Se status and, if found to be below optimum levels, increased dietary supplementation or sustained-release Se boluses should be considered. Similarly, vitamins A (or beta-carotene) and E status should be monitored in herds, especially confined herds receiving a large proportion of ensiled forages.