Research conducted at Purdue University shows that genetically modified proteins cannot be detected in meat from hogs fed Bt corn. In addition, growth performance and carcass characteristics are similar between hogs fed Bt and non-Bt corn.
One hundred eighty pigs (Dekalb 45 by EB) were weaned at 12 to 16 days and housed in a SEW nursery for five weeks. At 66 lb. and 62 days of age, they were moved to a curtain-sided grow-finish barn and allowed to acclimate for 10 days.
The pigs were blocked by weight and sex and housed six pigs/pen. All had ad lib access to a one-hole, self feeder and nipple waterer.
Three diets were fed, including the isogenic control, non-GMO parent corn hybrid; the transgenic Bt corn hybrid; or commingled non-transgenic corn of different varieties.
All diets were formulated to meet or exceed requirements of the NRC. Four phases were set, with changes after four weeks on phases 1 and 2 and two weeks for phase 3. Phase 4 was fed from week 11 to market.
Weights and feed intake were measured every two weeks to monitor average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency (F:G). The hogs were marketed at 266 lb.
Carcass measurements included hot carcass weight, carcass length, backfat at last rib and last lumbar vertebrae, 10th rib backfat and loin eye area. Color, marbling and firmness were also tested.
Corn type did not affect ADG, ADFI or F:G in any of the phases.
Pigs fed the conventional commingled corn had heavier carcasses and higher dressing percentages. Corn had no effect on calculated percent lean. Pigs fed the isogenic control corn had greater backfat depths at the 10th and last rib and the P2 location.
Corn treatment also affected subjective marbling scores, with pigs fed commingled corn having lower marbling than the Bt or isogenic control corn.
To test if the Bt (Cry1aB or Shrunken-2 genes) protein was present in the meat, DNA was extracted from 12 loins of the Bt-fed pigs and 12 loins from the isogenic control pigs. Southern blot analysis of PCR was used and none of the DNA samples were positive for the Bt genes.
For more information, visit www.ansc.purdue.edu/swine/swineday/sday00/psd07-2000.html. 
Researchers: Tom Weber, Brian Richert, Purdue University. Contact Weber at (765) 496-6840 or email [email protected]