Rate of passage of digesta in sheep

Abstract

1.Five sheep were given 400,625, 850, 1075 and 1300 g lucerne chaffid according to a 5 x 5 Latin square design to perturbate a mathematical model describing the rate of passage of digesta in terms of rate constants for the reticulo-rumen (k,) and caecum and proximal colon (ka), and a transit time (n) for the intestines. These values were obtained from the concentration curves of W r EDTA and 1r4Ce-14rPr (lO4Pr) excretion in faeces for comparison with similar measurements obtained directly.2. The retention times of markers in the reticulo-rumen, caecum and proximal colon and intestines all decreased by approximately 50 % as intakes were increased from 400 to 1300 g/d. For both markers, the direct and indirect measures of half-time in the reticula-rumen were essentially identical. The predicted (indirect) values for half times in the caecum and proximal colon were smaller than the direct values (P < 0405) but the correlations between them were significant (P < 0.01) for "Cr EDTA (r 066) and l4Vr (r 0.78). The direct measures of transit time were smaller (P < 0.025) by 5-10 a/. than the predicted values but correlations between them were significant (P < 0.01) for W r EDTA (r 0.91) and for lrrPr (r 0.93). Thus the model predicted the changes produced in the rate of passage of digesta and its usefulness and limitations are discussed. 3. With lr4Pr ,k, for the reticulo-rumen and TAka for the caecum and proximal colon were both positively correlated (P < 0-025) with the organic matter digestibilities. Ttk, decreased at half the rate of Ttkl with increasing intakes. This wcluld have favoured compensatory digestion in the large intestine.This experiment in pertubatian analysis was designed to evaluate further a mathematical model of digesta passage thiough the alimentary tract of the sheep. Grovum & Williams (1973~) showed that the rate of passage of digesta in sheep given either 800 g lucerne chaff or diets consisting of wheat and lucerne chaff could be described with an equation having as independent variables: the transit time of marker through the intestinal tract (TT), the half-time of marker in the reticulo-rumen (Tjk,) and the half-time of marker pertaining mainly to the caecum and proximal colon (Tik,).In the experiment now reported, the rate of passage of digesta through the gut was increased by increasing the level of food intake and values of TT, Tik,, and Tik, were compared with corresponding measurements made more directly. The biological relevance of these values for rate of passage was studied by relating them to the apparent digestibility of the food, the concentrations of volatile fatty acids (VFA) in the reticulo-rumen and the water content of the faeces. E X P E R I M E N T A L SheepThree Merino wethers (castrated males) (sheep nos. 1, 2 and 3) and two ewes (sheep nos. 4 and 5 ) with permanent rumen (Hecker, 1969) and abomasal (Jarrett, 1948) fistulas were 15 N U T 38

Calculation of fecal kinetics in horses fed hay or hay and concentrate.

“…second term (data not shown). Hence, these data did not support a two-compartment model (Brownell et al, 1968), such as those proposed for sheep and horses (Blaxter et al, 1956;Grovum and Williams, 1973;Bertone et al, 1989). The delay ( d, d ) was then represented by a decrease in time ( t) in the monoexponential equation:…”

“…Hay Concentrate b H&C c and exchanging mass(es) or compartment size(s), can be calculated from the shape of the response (compartmental analysis). Noncompartmental and compartmental analysis have been applied to marker studies in ruminants and horses (Blaxter et al, 1956;Grovum and Williams, 1973;Orton et al, 1985;Pond et al, 1988;Bertone et al, 1989). Our objective was to develop a simple, convenient, and mathematically correct method for estimating fecal kinetics in grazing animals, and the first step involved the testing of a marker model in the context of a digestion balance experiment done on stall-fed horses.…”

Retention times of small feed particles and of water in the gut of dairy goats fed at different levels of intake

“…mean particle size (1.06 mm) and slightly higher density (1.44 g/ml). Also GROVUM and WILLIAMS (1977) found significant correlations between the retention time of a solid phase marker ('44Pr) and the liquid phase marker (51CrEDTA) in different parts of the gastrointestinal tract. CASTLE (1956b) fed stained long hay and stained faecal fragments to growing goat kids.…”

“…As a consequence, the retention time post-rumen will be greatly aKKected by an increase in Keed DM intake. A niajor part o t the reduction in post-ruminal retention times with increasing feed intake was shown to be accounted for by the distal 80% of the large intestine (GROVUM and WILLIAMS 1977). However, also the transit time through the small intestine was markedly reduced.…”

Effet d'une restriction alimentaire sur le flux de matière organique et d'azote dans le tube digestif des caprins

“…La diminution du niveau d'ingestion entraîne une amélioration de l'utilisation des aliments dans le tube digestif (Grovum et Williams, 1977 …”