Vitamin B requirements and duodenal deliveries in lactating dairy cows: Organization of a limited literature

•A model to evaluate diets of dairy cows for vitamin B duodenal deliveries relative to requirements was created.•Requirements for each vitamin B were calculated factorially with the total requirement for each being the sum of its needs for maintenance, gestation and lactation.•The sequence of predicted vitamin B oversupply was biotin, niacin, cobalamine, riboflavin, pantothenic acid, vitamin B6, thiamine, folate.•Evaluation of published studies suggests that the only B vitamin which has consistently positively impacted performance of lactating dairy cows is folate.