Abstract
In the past, efforts to improve the transition to lactation have focused largely on preventing infections and maximizing energy intake in transition cows, and these issues have generally been treated independently. New models, however, are emerging to explain the development of numerous transition disorders. A combination of insults, including social stress, negative energy balance, heat stress, endotoxin exposure, and oxidative stress may promote inflammation, suppress feed intake, and impair both metabolic and immune function during the transition period. These models suggest that transition cow management must be viewed holistically, because the cow’s environment, nutrition, and immune function interact in many complex ways. Fortunately, a number of practical approaches can be used to improve the overall health of transition cows, which can decrease the cull rate in early lactation and improve both productivity and reproductive success.
Highlights
A number of practical approaches can be used to improve the overall health of transition cows, which can decrease the cull rate in early lactation and improve both productivity and reproductive success.; Dairy Day, 2012, Kansas State University, Manhattan, KS, 2012; Dairy Research, 2012 is known as Dairy Day, 2012 Keywords Dairy Day, 2012; Kansas Agricultural Experiment Station contribution; no. 13-030-S; Report of progress (Kansas Agricultural Experiment Station and Cooperative Extension Service); 1075; Dairy cattle; Lactation; Health; Productivity; Reproduction Creative Commons License
Oxidative stress may play a key role in the poor immune function observed in transition cows, a hypothesis that is supported by numerous studies demonstrating beneficial effects of supplementing antioxidants in the transition period
Recent work showed that heat stress during the dry period decreased dry matter intake (DMI) during the week of calving by nearly 50%, decreased the function of immune cells after calving, and decreased peak milk production by more than 10 lb/day
Summary
Efforts to improve the transition to lactation have focused largely on preventing infections and maximizing energy intake in transition cows, and these issues have generally been treated independently. A combination of insults, including social stress, negative energy balance, heat stress, endotoxin exposure, and oxidative stress may promote inflammation, suppress feed intake, and impair both metabolic and immune function during the transition period These models suggest that transition cow management must be viewed holistically, because the cow’s environment, nutrition, and immune function interact in many complex ways. An inability of monocytes to utilize intracellular calcium for cell signaling is expected to dampen functional responses and the ability of these immune cells to fight pathogens Such findings may provide a physiological basis for the long-observed links between hypocalcemia and mastitis in transition cows. Infection, metabolic stress, and heat stress will be discussed as key sources of stress in the transition cow
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