Effect of Niacin Supplementation on the Concentration of Niacin in Rumen and Duodenal Digesta and in Whole Blood of Sheep

Abstract

Summary Niacin concentrations in rumen liquor, duodenal digesta and blood, and daily duodenal flow of niacin were measured in four wethers which were fed an oatstraw grain concentrate diet (with normal niacin content) or an oatstraw maize diet (with low niacin content). The effect of an intraruminal supplementation of 2 mmoles nicotinic acid (NIA) or nicotinamide (NAM) on concentrations of NIA and NAM in gastrointestinal contents and blood and on daily duodenal flow of NIA and NAM was studied. The animals were equipped with rumen fistula and duodenal re‐entrant cannulae. NIA concentration in strained rumen liquor was 384 and 264 nmol/ml and daily duodenal flow of niacin was 616 and 528 μmoles/d in animals fed normal or low niacin diet, respectively. Intraruminal administrations of 2 mmoles of NIA or NAM raised NIA concentration in strained rumen liquor for approximately 6 h. About 20% of the administered dose of NIA or NAM passed out of the rumen and resulted in a 41% increase in daily duodenal flow of niacin. The remaining 80% of the administered dose of NIA or NAM disappeared from rumen liquor without being washed out. Supplemented NAM was rapidly hydrolyzed to NIA and ammonia when administered into the rumen. NAM concentration in blood appeared to be unaffected by the dietary content of NIA or by niacin supplementation. The NIA concentration in strained rumen liquor was positively related with niacin content of the diet. Increases in duodenal flow of niacin had no marked effect on concentration of NAM in blood. It appeared that feeding diets with different NIA content affected apparent niacin synthesis in the rumen.

Niacin nutrition and rumen-protected niacin supplementation in dairy cows: an updated review

“…In the study by Zeitz et al (17) , plasma nicotinic acid concentration was below the detection limit (0•025 μg/l). Those results are in agreement with an earlier study by Kollenkirchen et al (20) who reported that only nicotinamide was present in the blood of sheep after nicotinic acid or nicotinamide supplementation. It is generally accepted that nicotinic acid is readily converted into NAD þ in the intestine and liver and then is cleaved to produce nicotinamide into blood for extrahepatic tissues (21) .…”

Niacin for dairy cattle: a review

“…The results of this study also lead to the conclusion that ruminal absorption could be excluded as a reason for observed differences in blood niacin content, because changes occurred after post-ruminal infusion. In other studies as well there was no obvious relationship between ruminal and blood niacin concentrations (12,36) .…”

“…There is disagreement about the existence of NA in blood. Whereas Campbell et al ( 12 ) found both vitamers, Kollenkirchen et al ( 36 ) stated that only NAM was present in the blood of sheep. In two studies, only values for NAM were named ( 37 , 38 ) .…”

“…In sheep, the NAM concentration of whole blood was not influenced by NA or NAM supplementation ( 36 ) . Hence the conclusion was drawn that concentrations in blood appeared to be unaffected by supplementation, even though the amount reaching the duodenum was increased.…”

Η Επίδραση Των Επιπέδων Ακετυλίωσης Και Μεθυλίωσης Των Ιστόνων Στη Ρύθμιση Του Βιολογικού Ρολογιού Των Θηλαστικών

“…Nonetheless, it has been shown that exogenous application of nicotinamide for nutritional, veterinary or medicinal purposes can increase the nicotinamide concentration within the body to levels close to those that were used in this study (Kollenkirchen et al, 1992;Erb et al, 1998). Apart from the potential effects to clock function, the ability of nicotinamide to abrogate a gene's response to the effects of dexamethasone and trichostatin A through an alternative mechanism, not related to sirtuins and to ADP-ribosylation is by itself of extreme importance.…”