Serum Vitamin B12 and Homocysteine Concentrations of Weanling Pigs Fed Increased Levels of Dietary Vitamin B12

University of Nebraska 2007 Swine Report. Data were published (2006 Nebraska Swine Report) in which wean- ling pigs (weaned 13- to 14-days) were fed graded levels of dietary vitamin B12 in a 35-day study (phase 1, day 0 to day 14; phase 2, day 14 to day 35). Dietary treat- ments included: NC, negative control, basal diet without supplemented vitamin B12; or the basal diet with the inclusion of 100% (1X, 7.94 g/lb), 200% (2X, 15.87 g/lb), 400% (4X, 31.75 g/lb), 800% (8X, 63.49 g/lb), or 1,600% (16X, 126.98 g/lb) of NRC requirements for the 11- to 22-lb pig. Throughout phase 1, there were no differences among treat- ments. During phase 2 and overall (phase 1 and phase 2), the inclusion of vitamin B12 resulted in a linear increase (P < 0.05) in ADG and ADFI. Sub- sequently (after the publication of the 2006 swine report), serum samples were analyzed for vitamin B12 and homocys- teine. On day 0, there were no differences in serum concentrations of vitamin B12 or homocysteine among treatments. On day 14 and 35, serum vitamin B12 and homocysteine concentrations increased linearly and quadratically (P < 0.05) to dietary B12 addition. The average daily change in homocysteine decreased linearly and quadratically (P < 0.05) to the inclusion of vitamin B12 in the diet. The average daily change in serum vita- min B12 increased linearly (P < 0.05) as the inclusion of vitamin B12 in the diet increased. Although there is confl icting growth data, the data from the analyses of serum metabolites suggests that the vitamin B12 requirement lies between the 1X and 4X treatments (7.94 g/lb and 31.75 g/lb, respectively) to prevent the accumulation of homocysteine. The responses of serum metabolites (vitamin B12 and homocysteine) are more sensitive to dietary B12 status compared to growth performance criteria.