Good to Know: Baseline Data on Feed Intake, Fecal Pellet Output and Intestinal Transit Time in Guinea Pig as a Frequently Used Model in Gastrointestinal Research

Abstract

Guinea pigs are a traditional and frequently used species in gastrointestinal research. Comprehensive knowledge of basic parameters connected with their intestinal function, such as feed intake, fecal pellet output and gastrointestinal transit time, is important for evaluating results from basic gastrointestinal research that may be applied to practical problems in human and veterinary medicine, for example, when establishing diagnostic tools. Our study revealed that over a 24-h period, single-housed guinea pigs showed a continual but day-accentuated feeding activity, consuming 57% of the total feed during the light period, with pronounced peaks of feed intake during the beginning and end of the light period. This was mirrored by fecal pellet output during the light period and almost no defecation during the dark period, while potential coprophagy not measured in this study needs to be considered. A highly comparable feeding activity was recorded in pair-housed guinea pigs, with 60% of overall feed intake within the light period, indicating that such differences in housing conditions did not influence guinea pigs' feeding behavior. Intestinal transit time was successfully recorded by oral administration of carmine red and counted 5 h on average. Hence, this study provides important information on the basic functional parameters of guinea pigs' gastrointestinal tract physiology.

Keywords: carmine red; fecal pellet output; feeding pattern; gastroenterology; guinea pig; intestinal transit time.

Figure 1

Fecal pellet output (FPO) aligned with feed intake (FI) in single-housed guinea pigs during 24-h recording period. n = 4; means ± SD. Times on the x axis indicate end time for each hour (e.g., 14:00: values measured between 13:00 and 14:00). Dark gray box indicates values measured during the dark period.

Figure 2

Feed intake (FI) in guinea pigs during 24 h recording period under single-housing (a) and pair-housing (b) conditions. n = 6; means ± SD. Times on the x axis indicate end time for each hour (e.g., 14:00: values measured between 13:00 and 14:00). Dark gray boxes indicate values measured during the dark period.

Figure 3

Comparison of feed intake (FI) in single-housed (a) and pair-housed (b) guinea pigs during light and dark periods. n = 10 (panel a) and n = 6 (panel b); means ± SD. Paired t-test, * p < 0.05, *** p < 0.001.