Influence of Meal Frequency on Postprandial Variations in the Production and Absorption of Volatile Fatty Acids in the Digestive Tract of Conscious Pigs

Abstract

Five Large White pigs of 62.2 +/- 1.4 kg mean body weight were fitted with permanent catheters in the portal vein and carotid artery and with an electromagnetic flow probe around the portal vein to study the absorption of volatile fatty acids (VFA) by measuring the concentration of these metabolites in hourly blood samples, and by determining the portal blood flow rate for a period of 12 h after intake of a single 800-g meal (6% crude fiber) preceded by 12 or 24 h of fasting. The portal concentration of VFA mixture always highly exceeded the arterial concentration. The arterial concentrations of propionic, butyric, valeric and isovaleric acids were nearly null, accounting for an almost complete uptake of these VFA by the liver. Acetic acid also was taken up, but to a lesser extent. Total VFA absorption during 12 h was 64% higher (P less than .05) after 12 h (1,160 +/- 100 mmol/12 h) than after 24 h of preprandial fasting (740 +/- 83 mmol/12 h). It increased after the meal (P less than .05) from 82.3 +/- 7.8 mmol/h between the first and fourth hour to 107.8 +/- 7.5 mmol/h between the fifth and tenth hour when the preprandial fasting lasted 12 h; a nonsignificant increase also was found when fasting prior to the meal lasted 24 h. The composition of the VFA mixture was not modified by the length of preprandial fasting. With this type of diet there was a large predominance of acetic acid (52%) followed by propionic and butyric acids (36 and 8.5%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of the nature of carbohydrate intake on the absorption chronology of reducing sugars and volatile fatty acids in the pig

“…Leaving out one meal therefore depresses the basal VFA production rate (R6rat et al, 1987). However, this does not explain why the VFA absorption was poorer than in previous experiments performed after 24 h of fasting (R6rat et al, 1987;Yen et al, 1991 This divergence probably appeared because semi-synthetic diets were used in the present study, whereas R6rat et al (1987) (R6rat et al, 1984). These differences probably depend on how the diet affects the length of gastric emptying, on the hydrolysation speed of the molecules according to their complexity (starch vs maltose), and on the nature and amount of enzyme secretion (amylase vs maltase).…”

“…Significant amounts of these substances are used by the enterocytes for their own metabolic needs during transport (Ly, 1974;Imoto and Namioka, 1978a, b). Almost all of the propionic, butyric and valeric acids are taken up by the liver, which uses part of the acetic acid only (Giusi-P6rier et al, 1989;R6rat et al, 1987 (Heller and Kern, 1968). Although the amounts absorbed during the postprandial period are quite high (20-30 g within 8 h according to R6rat et al, 1978), it should be borne in mind that part of the lactic acid is produced by the metabolism of the gut wall along the gastrointestinal tract (Windmueller and Spaeth, 1978).…”

“…The production of VFA is followed by absorption, as indicated by their presence in the portal blood (Topping et al, 1985) and quantified by measuring portal-arterial concentration differences and blood flow in the portal vein (R6rat et al, 1985, 1987Yen et al, 1991 ).…”

Effect of adding sugar beet fibre and wheat bran to a starch diet on the absorption kinetics of glucose, amino-nitrogen and volatile fatty acids in the pig

“…The same was observed for the total amounts of volatile fatty acids absorbed within 12 h. In contrast, the adaptation period had no significant influence on the absorption of volatile fatty acids. This result was not in agreement with the data of a previous experiment [9] which showed a higher VFA absorption when the adaptation period was extended from 21 to [29]. A major fraction of acetic acid was also taken up by the liver since the concentration in the arterial blood was 2 to 4 times lower than in the portal blood according to sampling time, but a portion of it escapes liver metabolism by being taken up by peripheral tissues, particularly muscles [21].…”

“…The [29]. The subsequent increase in the portal concentration corresponded to the arrival of fresh residues at the level of the large intestine.…”