The metabolic rate, which is measured as the volume of oxygen consumption, increases dramatically after feeding. This increase in metabolic rate in response to digestion is referred to as "specific dynamic action" or SDA (Secor et al, 200).Within three hours of swallowing prey, the python's metabolic rate begins to rise. The metabolic rate peaks after 1-2 days of digestion and slowly decreases to fasting levels 4-16 days after eating as seen in the graph below. The average factorial increase in metabolic rate show on this graph is about 20 times the rate during fasting, but it has be recorded that the python's metabolic rate can increase as much as 44 times fasting levels (Secor and Diamond, 1998). In comparison, the largest increase in metabolic rate in mammals is seen in a galloping race horse at 45 times that of resting levels. However, this rate can only be sustained for a short period of time in a racehorse, while the python's metabolic rate remains elevated for about 2 weeks (Secor and Diamond, 1998).
Figure 1 used with permission of (Secor and Diamond, 1995)
The large increase in metabolic rate after digestion is due not only to the high amount of oxygen needed for digestion, but also the comparatively low amount of oxygen needed during periods of fasting. Therefore, the python can maintain a very low metabolic rate while fasting and then suddenly increase it's metabolic rate upon eating. It was also found that as the meal size increase so does the magnitude of the metabolic response, in that larger meals elicit bigger and longer increases in metabolic rate (Secor and Diamond, 1998).