The what, why, and physiologic cost of leaky gut syndrome

Abstract

Heat stress and metabolic maladaptation to lactation (ketosis) are 2 economically devastating hurdles to profitability. These stressors affect herds of all sizes and almost every dairy region in the world. The biology of heat stress and ketosis has been studied for almost a half century, but the negative impacts of both are as evident today as they were 30 years ago. Our recent discoveries suggest that endotoxin is the common culprit in both disorders and the intestine appears to be the etiological origin of both metabolic disorders. Endotoxin stimulates the immune system and activated leukocytes switch their metabolism away from oxidative phosphorylation to rely more on aerobic glycolysis. In multiple species, we estimate that immune activation consumes about 0.45 g glucose/lb (1 g/kg) BW0.75 or about 0.9 lb (2 kg) glucose/day in an adult lactating dairy cow. Thus, an activated immune system reprioritizes nutrient partitioning away from the synthesis of economically valuable products.