Date of this Version
An experiment was conducted to assess the responsiveness of weanling pigs to an antibiotic-like compound (Mecadox®) and vitamin B12. Pigs (initial weight 11.3 lb) were fed one of four diets for a total of 35 days: 1) Negative control, common nursery diet with no added Mecadox® or vitamin12; 2) Mecadox®, common nursery diet with 50 g/ton added Mecadox®; 3)B12 common nursery diet with 36.28 µg/lb added vitamin B12. Pig weights and feed disappearance 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 potential vitamin B12 deficiencies on d 14, 21, 28, and 35. No Mecadox® x vitamin B12 interactions were observed. During Phase I, pigs fed Mecadox® had greater (P<0.02) ADG and a greater ADFI (P<0.003) compared to pigs not fed Mecadox®. During Phase II and overall, pigs fed vitamin B12 had a greater ADG (P<0.003), ADFI (P<0.04), and improved feed efficiency (P<0.02 and P<0.03, respectively) compared to pigs not fed diets containing B12. During Phase II, pigs fed Mecadox® had a greater ADFI (P<0.02) compared to pigs not fed Mecadox®. For the overall experimental period, pigs fed Mecadox® had a greater (P<0.02) ADG and ADFI (P<0.04) versus pigs which were not fed Mecadox®. During Phase II and the overall experimental period, pigs fed Mecadox® had lower feed efficiencies (P<0.02 and P<0.04, respectively) than those not fed diets containing supplemental Mecadox®. There were no differences among groups for visual assessment of B-vitamin deficiencies. Vitamin B12 may be a partial alternative to Mecadox® for 22- to 44-lb pigs. The vitamin B12 requirement of the 22- to 44-lb pig may be greater than the current NRC requirement recommendation.