Apparent ruminal synthesis of B vitamins in lactating dairy cows fed diets with different forage-to-concentrate ratios

Abstract

Effects of the forage-to-concentrate ratio on apparent ruminal synthesis of thiamine, riboflavin, niacin, vitamin B, folates, and vitamin B were evaluated in an experiment using 14 ruminally and duodenally cannulated Holstein cows. The experiment was a crossover design with two 15-d treatment periods and a 14-d preliminary period in which cows were fed a diet intermediate in composition between the treatment diets. Treatments were diets containing low-forage (44.8% forage, 32.8% starch, 24.4% neutral detergent fiber) or high-forage (61.4% forage, 22.5% starch, 30.7% neutral detergent fiber) concentrations. Both diets were formulated with different proportions of the same ingredients. Concentrations of B vitamins were analyzed in feed and duodenal digesta. Apparent ruminal synthesis of each B vitamin was calculated as the duodenal flow minus the intake. The high-forage diet had the highest concentrations of riboflavin, niacin, vitamin B, and folates, whereas the low-forage diet had the highest thiamine concentration. Vitamin B in the diets was under the level of detection. Consequently, despite a reduction in dry matter intake when the cows were fed the high-forage diet, increasing dietary forage concentration increased or tended to increase intakes of riboflavin, niacin, and vitamin B but reduced thiamine and folate intakes. Increasing dietary forage concentration reduced apparent ruminal degradation of thiamine and apparent ruminal synthesis of riboflavin, niacin, and folates and increased ruminal degradation of vitamin B, but had no effect on ruminal synthesis of vitamin B. As a consequence, increasing the forage-to-concentrate ratio had no effect on the amounts of thiamine, riboflavin, and vitamin B reaching the small intestine but decreased the amounts of niacin, vitamin B, and folates available for absorption. Apparent ruminal syntheses of riboflavin, niacin, folates, and vitamin B were correlated positively with the amount of starch digested in the rumen and duodenal flow of microbial N, whereas these correlations were negative for thiamine. Apparent ruminal syntheses of thiamine and vitamin B were negatively correlated with their respective intakes, whereas folate intake was positively correlated with its synthesis in the rumen.

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

“…In the last decade, several studies also investigated the influence of different types of feed on the ARS of niacin (Table 2). Niehoff et al (14) observed that ARS of niacin was less in cows fed the low concentrate diet compared with the high or medium concentrate diet, which is consistent with the findings of Seck et al (7) In addition, the diet with high niacin content (9,12) would likely result in negative ARS of niacin. Especially, 98•5 % of supplementary nicotinamide (15) and 88-94 % of supplementary nicotinic acid (14) disappeared in the rumen, resulting in a greater negative ARS of niacin.…”

“…In above-mentioned studies, the difference in half-life time could be another reason for the different content in blood of two niacin vitamers as the blood samples were collected before feeding. However, Campbell et al (24) reported that concentrations of plasma nicotinic acid and plasma (7) ; Schwab et al (8) ; Beaudet et al (9) Alfalfa silage 21•6-291•0 Seck et al (7) ; Castagnino et al (10) ; Castagnino et al (11,12) Orchardgrass silage 52•4-81•7 Castagnino et al (10) ; Castagnino et al (11,12) Grass hay 12•1 Schwab et al (8) Alfalfa hay 34•0-70•2 Schwab et al (8) ; Beaudet et al (9) Wheat straw 46•6 Beaudet et al (9) Soyabean hulls 44•6-228•9 Schwab et al (8) ; Beaudet et al (9) Maize 7•0-30•2 Seck et al (7) ; Schwab et al (8) ; Castagnino et al (10) ; Castagnino et al (11,12) Barley 36•9 Schwab et al (8) Beet pulp 36•9 Beaudet et al (9) Soyabean meal 34•5-58•4 Seck et al (7) ; Schwab et al (8) ; Beaudet et al (9) ; Castagnino et al (10) ; Castagnino et al (11,12) Blood meal 45•2-56•3 Schwab et al (8) ; Castagnino et al (11) nicotinamide did not differ over time in 11 h after 12 g/d of free nicotinic acid or nicotinamide supplementation. Thus, further research are required to clarify the kinetics of niacin, especially RPN, in ruminants.…”

“…The niacin content of forage is highly variable, and the niacin content of grains seems relatively low ( Table 1). The daily intake of niacin in dairy cows is largely dependent on feed intake and diet composition, varying from 325 to 4434 mg/d as reported by various researchers in different studies (7)(8)(9)(10)(11) . In addition to the niacin supplied from feed, ruminants can synthesise niacin from tryptophan and quinolinic acid.…”

Thiamine status, metabolism and application in dairy cows: a review

“…The effect of dietary carbohydrates on thiamine concentration may be due to its influence on rumen fermentation and the microbial community. Castagnino et al (27) and Seck et al (28) reported a positive correlation between ruminal pH and thiamine AS. The impact of pH on thiamine status may be related to the increasing thiaminase production at low ruminal pH, since pH values below 5•8 (31) are optimal for thiaminase-producing bacteria (C. sporogenes and a few species of Bacillus; Brent & Bartley (32) ), as a result, thiamine degradation by microbial thiaminase increased.…”

“…Schwab et al (7) reported that the average ruminal thiamine AS in lactating dairy cows is 50•6 mg/d, which is similar to the value of 51•7 mg/d reported by Breves et al (2) and >26•0 mg/d reported by Santschi et al (29) . In the recent studies by Beaudet et al (23) , Castagnino et al (27) and Seck et al (28) , the ruminal thiamine AS was negative (from −39•8 to 0•8 mg/d), which they hypothesised was due to thiamine destruction by thiaminase enzymes or degradation by the ruminal microflora. Based on the above studies, we can conclude that dietary Castagnino et al (22) , Schwab et al (7) , Beaudet et al (23) Grass hay 0•89-1•49 Schwab et al (7) , Beaudet et al (23) Maize silage 0•57-1•37 Schwab et al (7) , Beaudet et al (23)…”