Effects of forage family on apparent ruminal synthesis of B vitamins in lactating dairy cows

Abstract

Effects of forage family (legume vs. grass) on apparent ruminal synthesis (ARS) and postruminal supply of B vitamins were evaluated in 2 experiments. Diets containing either alfalfa (AL) or orchardgrass (OG) silages as the sole forage were offered to ruminally and duodenally cannulated lactating Holstein cows in crossover design experiments. Experiment 1 compared diets containing AL and OG [~23% forage neutral detergent fiber (NDF) and ~27% total NDF] offered to 8 cows in two 15-d treatment periods. Experiment 2 compared diets containing AL and OG (~25% forage NDF and ~30% total NDF) offered to 13 cows in two 18-d treatment periods. Thiamin, riboflavin, niacin, vitamin B6, folates, and vitamin B12 were analyzed in feeds and duodenal digesta. Apparent ruminal synthesis was calculated as the duodenal flow of each vitamin minus its intake. Forage family affected B vitamin intakes, duodenal flow, and ARS. In both experiments, AL diets increased vitamin B6 and decreased folate intakes. In experiment 1, riboflavin and niacin intakes were greater with the OG diet, whereas in experiment 2 thiamin intake was greater but riboflavin intake was smaller with the OG diet. In spite of the low contribution of either silage to the dietary folate content, folate intake was greater with OG diets than AL due to the difference in soybean meal contribution between diets. Niacin and folate ARS were not affected by the forage family. Duodenal microbial nitrogen flow was positively correlated with ARS of riboflavin, niacin, vitamin B6, folates, and vitamin B12, but tended to be negatively correlated with thiamin ARS. Apparent ruminal synthesis of folates and vitamin B12 appear to be related to microbial biomass activity. Changes in nutrient composition of the diets likely affected the microbial population in the rumen and their B vitamin metabolism.

High-concentrate diets based on forages harvested at different maturity stages affect ruminal synthesis of B vitamins in lactating dairy cows

“…The negative correlation observed between riboflavin ARS and ruminally digested true OM supports this suggestion (Table 5). In our study, riboflavin ARS varied from −49.6 to 16.8 mg/kg DMI, and were similar to values reported by Castagnino et al (2016;−21.1 to 18.4 mg/kg DMI); it was negatively correlated with riboflavin Castagnino, Kammes, Allen, Gervais, Chouinard and Girard intake. Data calculated from Miller et al (1986), Santschi et al (2005a) and Schwab et al (2006) have all shown positive ARS (6.25, 13.48 and 11.67 mg for riboflavin/kg DMI, respectively).…”

“…With AL diets, thiamin ARS was in the same range (around −0.75 mg/kg DMI) as reported by Miller et al (1986;−1.19 mg/kg DMI) and Castagnino et al (2016;−1.20 mg/kg DMI). Thiamin destruction could be partially explained by the presence of thiaminases in the rumen as suggested by Edwin and Jackman (1982).…”

“…Data calculated from Miller et al (1986), Santschi et al (2005a) and Schwab et al (2006) have all shown positive ARS (6.25, 13.48 and 11.67 mg for riboflavin/kg DMI, respectively). However, on average, in Castagnino et al (2016) and the present studies, riboflavin intake (mg/day) and DF (mg/kg DMI) were 18-and threefold greater, respectively, than reported in literature cited above. Maturity of OG at harvest had no effect on niacin intake, DF and ARS.…”

“…Concentrations of B vitamins in feed and duodenal digesta were analyzed at the Sherbrooke Research and Development Centre (Agriculture and Agri-Food Canada, Sherbrooke, QC, Canada). Thiamin, riboflavin, niacin and vitamin B 6 were quantified by HPLC (Varian ProStar, Lake Forest, CA, USA) equipped with a solvent delivery system (model 210), an autosampler (model 410) and a fluorescence detection system (model 363) as described by Castagnino et al (2016). Folates were determined with a microbiological microtiter plate test (VitaFast ® Folic Acid; R-Biopharm Inc., Marshall, MI, USA) and vitamin B 12 was analyzed by radioassay (SimulTRAC-S Vitamin B 12 (Co 57 )/Folate (I 125 ); MP Biomedicals, Solon, OH, USA) as described by Castagnino et al (2016).…”

“…Thiamin, riboflavin, niacin and vitamin B 6 were quantified by HPLC (Varian ProStar, Lake Forest, CA, USA) equipped with a solvent delivery system (model 210), an autosampler (model 410) and a fluorescence detection system (model 363) as described by Castagnino et al (2016). Folates were determined with a microbiological microtiter plate test (VitaFast ® Folic Acid; R-Biopharm Inc., Marshall, MI, USA) and vitamin B 12 was analyzed by radioassay (SimulTRAC-S Vitamin B 12 (Co 57 )/Folate (I 125 ); MP Biomedicals, Solon, OH, USA) as described by Castagnino et al (2016). Cobalt concentration in experimental diets was determined by atomic absorption spectrometry with flame stoichiometric air-acetylene at 240.7 nm based on an adaptation of the method of Bellanger (1988).…”