Models for estimating digesta passage kinetics in the gastrointestinal tract of the horse

Abstract

Fecal samples were collected to evaluate mathematical models to describe the kinetics of digesta passage in the segments of the equine gastrointestinal tract and to compare the passage kinetics of hay and oats. Four Norwegian Cold-blooded trotters (cecally cannulated, approximately 500 kg of BW) were fed Cr-mordanted hay and Yb-marked oats with their morning meal. The meal consisted of 2 kg of hay and 1 kg of oats processed as ground, pelleted, extruded, or micronized. Each horse was fed each type of oats on different days of collection, after a 5-d adaptation period, in a 4 x 4 Latin square design. Fecal samples were collected 5, 6, 7, 8, 9, 10, 11, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 48, and 52 h after administration of the marker dose. The samples were analyzed for Cr and Yb, and values were plotted using 1- and 2-compartment nonlinear passage models and an algebraic model. The 1-compartment G4 model and the 2-compartment G4G1 model showed an equally good fit to the observed excretion curves, based on low mean square error and SE. The excretion curves for hay (Cr) and oats (Yb) showed a striking similarity, and there seemed to be no difference in retention time between hay and oats in the horse. The mixing compartments in the horse are believed to be the cecum or both the cecum and the right ventral and dorsal segments of the colon, but further research in this area is needed to make a final conclusion.

The effect of dietary carbohydrate composition on apparent total tract digestibility, feed mean retention time, nitrogen and water balance in horses

“…Many factors influence the passage rate (van Weyenberg et al, 2006), and diet had an effect on TMRT in the present study with the HAY and SBP diets having a~5 h shorter TMRT than the BAR + SBP and BAR diets. The TMRT of the two barley diets were in accordance with previous studies Rosenfeld et al, 2006). There was no effect of partly substituting hay or barley with SBP on the TMRT, and similar results were found when lucerne silage was partly substituted with SBP (Murray et al, 2009).…”

“…The time-dependent one-compartment G4 model used in the present experiment has been described to fit excretion data well in other experiments, where different compartmental models have been discussed in detail (Moore-Colyer et al, 2003;Austbø and Volden, 2006;Rosenfeld et al, 2006). Many factors influence the passage rate (van Weyenberg et al, 2006), and diet had an effect on TMRT in the present study with the HAY and SBP diets having a~5 h shorter TMRT than the BAR + SBP and BAR diets.…”

“…Faecal Yb excretion curves were fitted to different nonlinear models describing a single age-dependent mixing compartment (Gamma distribution; Gn, n = 2 to 4) and a two-compartment model with an age-dependent first compartment and an age-independent second compartment (G4G1) using the NLIN procedure in SAS ® (Version 9.2, SAS Institute Inc., Cary, NC, USA) as described by Pond et al (1988) and Moore et al (1992). The two-compartment G4G1 model has previously been proposed as the best model to describe faecal excretion of markers compared with onecompartment (Gn; n = 1 to 4) and other two-compartment models (GnG1; n = 1 to 3) (Moore-Colyer et al, 2003;Rosenfeld et al, 2006), but in the present study the G4G1 model failed to converge in 6 out of the 16 faecal excretion data sets, and therefore only the one-compartment G2, G3 and G4 models were further evaluated. The following equations were used (Pond et al, 1988):…”

Carbon and nitrogen stable isotope turnover rates and diet–tissue discrimination in Florida manatees (Trichechus manatus latirostris)

“…Manatees use hindgut fermentation and have a passage rate through the digestive tract of 146-147 h (Lomolino and Ewel, 1984;Larkin et al, 2007). This rate is consistent with that of the dugong, another sirenian [145-166 h (Lanyon and Marsh, 1995)], but much slower than those of other large hindgut fermenters such as elephants [21-46 h (Rees, 1982)], horses [26-27 h (Rosenfeld et al, 2006)] and rhinoceros [61 h (Clauss et al, 2005)]. Manatees sampled in the present study were rescued for reasons including cold stress, entanglement and watercraft injuries.…”

The effect of very low food intake on digestive physiology and forage digestibility in horses

“…Relationship between the relative dry matter intake (r DMI in g dry matter/kg 0.75 /day) and the mean retention time ( MRT in h) of a particle marker ( C r) in ponies on two different hays and four different intake levels. Comparative data for horses from literature sources (Wolter et al., ; Orton et al., ,b; Suhartanto et al., ; Cuddeford et al., ; Todd et al., ; Yoder et al., ; Pagan et al., ; Drogoul et al., , ; Pearson et al., ; de Araújo Oliveira et al., ; Moore‐Colyer et al., ; Austbø and Volden, ; Pearson et al., ; Rosenfeld et al., ; Miyaji et al., ).…”