Effects of Body Mass, Meal Size, Fast Length, and Temperature on Specific Dynamic Action in the Timber Rattlesnake (Crotalus horridus)

Abstract

Detailed analysis of animal energy budgets requires information on the cost of digestion (specific dynamic action [SDA]), which can represent a significant proportion of ingested energy (up to 30% in infrequent feeders). We studied the effects of snake mass, temperature (25 degrees and 30 degrees C), fasting time (1 and 5 mo), and prey size (10%-50% of snake mass) on SDA in 26 timber rattlesnakes (Crotalus horridus). We used flow-through respirometry to measure hourly CO(2) production rates (VCO2) for 1 d before and up to 17 d after feeding. Crotalus horridus, like previously studied viperids and boids, show large and ecologically relevant increases in metabolism due to feeding. Depending on treatment and individual, VCO2 increased to 2.8-11.8 times the resting metabolic rate within 12-45 h postfeeding and decreased to baseline within 4.3-15.4 d. Significant effects of snake mass, meal mass, and fast length were detected. Increased temperature decreased the time required to complete the process but had little effect on total energy expended on SDA. Energy expended on SDA increased with increasing fast length, snake mass, and prey mass. Considering all of our data, we found that a simple allometric relationship explained 96.7% of the variation in total CO(2) production during SDA. Calculations suggest that energy devoted to SDA may approach 20% of the total annual energy budget of snakes in nature. Discrepancies between our data and some previous studies draw attention to the fact that the measurement, expression, and analysis of SDA may be sensitive to several methodological and statistical assumptions.

Juvenile salmon with high standard metabolic rates have higher energy costs but can process meals faster

“…The effect of meal size on subsequent oxygen consumption rates of salmon was similar to that often observed in other animals (Secor 2009): larger meals produced a higher peak elevation and magnitude of SDA; a longer time to reach the peak oxygen consumption; and a longer duration of SDA response. Such trends occur in various species of fishes (Beamish 1974;Jobling & Davies 1980;Boyce & Clarke 1997) and other poikilotherms including snakes ( Toledo et al 2003;Zaidan & Beaupre 2003) and salamanders (Secor & Boehm 2006). More interesting were the differences in the relationship between SMR and SDA among individual salmon.…”

“…It is well established that the height and magnitude of SDA relate directly to the meal size ( Jobling & Davies 1980;Secor & Diamond 1997;Zaidan & Beaupre 2003;Secor 2009), but there is no information on whether SDA for a given meal varies within species as a function of individual traits such as SMR. Here we explore this area, in particular testing the hypothesis that SMR is directly related to the speed and size of the SDA response.…”

Meal size effects on the postprandial metabolic response of Bothrops alternatus (Serpentes: Viperidae)

“…metabolic rates measured during digestion (HAILEY & DAVIES 1987, WANG et al 2003, ZAIDAN & BEAUPRE 2003, the reaching of this meal-size metabolic ceiling during digestion is probably modulated by temperature (TOLEDO et al 2003).…”

Fuel switching and energy partitioning during the postprandial metabolic response in the ball python (Python regius)

“…Of course, complete documentation of SDA, i.e. until MR returns to the SMR level, may reach much higher values (McCue, 2006;McCue, 2007a;McCue, 2007b;McCue et al, 2005;Overgaard et al, 1999;Secor and Diamond, 1997;Wang et al, 2001;Zaidan and Beaupre, 2003).…”

“…At the extreme, maximum values of 44 times standard metabolic rate (SMR) have been reported for SDA in Burmese python (Secor and Diamond, 1997;Secor and Diamond, 1998). However, the amplitude and the duration of SDA are modulated by the amount of food, the temperature, the time since last feeding and the food composition (Dorcas et al, 1997;McConnachie and Alexander, 2004;Secor and Diamond, 1997;Tattersall et al, 2004;Toeldo et al, 2003;Zaidan and Beaupre, 2003) and, generally, SDA reaches peak values of 10-17 times SMR (SMR at 30°C) maintained for 2-10days (Großmann and Starck, 2006;Ott and Secor, 2007;Secor and Diamond, 2000).…”