title: 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.
authors.affiliation: Sherbrooke Research and Development Centre, 2000 College, Sherbrooke, QC, Canada, J1M 0C8; Département des sciences animales, Université Laval, 2425 rue de l'Agriculture, Québec, Québec, Canada, G1V 0A6.
authors.forename: D S
authors.initials: DS
authors.lastname: Castagnino
authors.affiliation: Sherbrooke Research and Development Centre, 2000 College, Sherbrooke, QC, Canada, J1M 0C8; Département des sciences animales, Université Laval, 2425 rue de l'Agriculture, Québec, Québec, Canada, G1V 0A6.
authors.forename: M
authors.initials: M
authors.lastname: Seck
authors.affiliation: Sherbrooke Research and Development Centre, 2000 College, Sherbrooke, QC, Canada, J1M 0C8; Département des sciences animales, Université Laval, 2425 rue de l'Agriculture, Québec, Québec, Canada, G1V 0A6.
authors.forename: V
authors.initials: V
authors.lastname: Beaudet
authors.affiliation: Department of Animal Science, Michigan State University, East Lansing 48824-1225.
authors.forename: K L
authors.initials: KL
authors.lastname: Kammes
authors.affiliation: Department of Animal Science, Michigan State University, East Lansing 48824-1225.
authors.forename: J A Voelker
authors.initials: JAV
authors.lastname: Linton
authors.affiliation: Department of Animal Science, Michigan State University, East Lansing 48824-1225.
authors.forename: M S
authors.initials: MS
authors.lastname: Allen
authors.affiliation: Département des sciences animales, Université Laval, 2425 rue de l'Agriculture, Québec, Québec, Canada, G1V 0A6.
authors.forename: R
authors.initials: R
authors.lastname: Gervais
authors.affiliation: Département des sciences animales, Université Laval, 2425 rue de l'Agriculture, Québec, Québec, Canada, G1V 0A6.
authors.forename: P Y
authors.initials: PY
authors.lastname: Chouinard
authors.affiliation: Sherbrooke Research and Development Centre, 2000 College, Sherbrooke, QC, Canada, J1M 0C8. Electronic address: Christiane.Girard@agr.gc.ca.
authors.forename: C L
authors.initials: CL
authors.lastname: Girard
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle / Q000378:metabolism*; D004032:Diet / Q000662:veterinary; D007887:Fabaceae; D005260:Female; D007774:Lactation; D006109:Poaceae; D011897:Random Allocation; D012417:Rumen / Q000378:metabolism*; D014803:Vitamin B Complex / Q000378:metabolism*
chemical_list: D014803:Vitamin B Complex
keywords: B vitamin; apparent ruminal synthesis; dairy cow; forage family