Date of this Version
An experiment was conducted to further define the vitamin B12 requirement of the 11- to 44- lb pig. Pigs (initial weight 11.20 lb) were fed one of six diets for a total of 35 days: 1)Negative control, common nursery diet with no added vitamin B12; 2) IX, common nursery diet with the addition of 100% the 1998 NRC-requirement for the 11- to 22- lb pig for vitamin B12 (7.94 µg/lb of diet), 4) 4X, common nursery diet with the addition of 400% the 1998 NRC-requirement for the 11- to 22- lb pig for vitamin B12 (31.75 µg/lb of diet); 5) 8X, common nursery diet with the addition of 800% the 1998 NRC requirement for the 11- to 22-lb for vitamin B12 (63.49 µg/lb of diet); and 6) 16X, common nursery diet with the addition of 1600% the 1998 NRC-requirement for the 11- to 22-lb pig for vitamin B12 (126.98 µg/lb of diet). Pig weights and feed disappearances were measured weekly to determine average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency (ADG/ADFI). Pigs were visually scored to assess any visual signs of vitamin B12 deficiencies on d 14, 21, 28, and 35. During Phase I, there was no growth or feed intake response to supplemental vitamin B12. During Phase II and the overall experimental period, there were no feed intake responses. During Phase II, there were quadratic responses of ADG (P<0.009) and feed efficiency responses (P<0.02) to supplemental vitamin B12. Overall (Phase I +II), there was a tendency for a linear growth response (P <0.1) and there was a quadratic feed efficiency response (P<0.02). There were no differences among groups based on visual assessment of vitamin B12 deficiencies. Based on these results the vitamin B12 requirement of the 11- to 22- lb pig is similar to that recommended by the 1998 NRC (7.94 µg/lb). However, the 22- to 44-lb pigs responded to vitamin B12 concentrations between 4 and 8 times that currently recommended by the 1998 NRC (6.8 µg/lb of diet). These data suggest that many pork producers are feeding vitamin B12 at concentrations well below those observed to maximize growth and feed efficiency. The data from this experiment should be used in the reassessment of the vitamin B12 requirement for weanling pigs.