Dietary Conjugated Linoleic Acid and IGF-I Transgene Effects on Pork Quality.

Abstract

Transgenic (T) pigs produced with a fusion gene composed of avian skeletal α-actin regulatory sequences and cDNA encoding human IGF-I have exhibited increased lean tissue and less fat than normal (N) controls. While the use of T-pigs for meat production has not yet been approved, it is worthwhile to explore the quality of the meat from these pigs. Thirty pigs (14 T and 16 N siblings) were finished on a control (CO) growing-finishing diet or with added conjugated linoleic acid (CLA) to 120 kg. Carcass weight for N pigs was heavier (P<.01) than for T (92.5 vs 87.4 kg, respectively); however T loin eye area (38.1 cm2) was 16% larger than in N (32.5 cm2). Backfat thickness was lower (P<.05) for T-CLA-fed pigs (21.4 mm) than for N-CO, N-CLA and T-CO pigs (29.8, 27.5 and 27.0 mm, respectively). Although pH at 45 min was higher (P<.01) in N (6.10) compared to T (6.01), there were no differences detected in ultimate pH (N=5.65 vs T=5.59). CLA affected pH at 45 min (5.99 vs 6.13 for CO and CLA, respectively) but not ultimate pH (CO=5.58; CLA=5.66). Gene and diet effects on pork quality traits of ultimate pH, amount of purge after 21 d, cook yield and shear force values were not different. Shear force for N vs T (6.3 vs 5.8 kg) and for CO vs CLA (6.1 vs 5.9 kg) was not different. Malonaldehyde (TBARS) formation after 5 d fresh, 21 d fresh and 6 mo frozen storage was not influenced by gene or diet. CLA added to growing-finishing diet may help reduce carcass fatness. Based on the present study, the muscle hypertrophy induced by the IGF-I transgene has no detrimental effects on quality of meat as compared to control.