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Title: EFFECTS OF DIETARY CONJUGATED LINOLEIC ACID ON GROWTH AND BODY COMPOSITION OF CONTROL AND IGF-I TRANSGENIC PIGS

Author
item Mitchell, Alva
item PURSEL, VERNON - ARS, RETIRED
item Elsasser, Theodore
item McMurtry, John
item BEE, G. - SWISS FEDERAL STATION

Submitted to: Animal Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/26/2005
Publication Date: 10/1/2005
Citation: Mitchell, A.D., Pursel, V.G., Elsasser, T.H., McMurtry, J.P., Bee, G. 2005. Effects of dietary conjugated linoleic acid on growth and body composition of control and IGF-I. Animal Research. 54:5.

Interpretive Summary: Both dietary conjugated linoleic acid (CLA) and presence of the IGF-I transgene are reported to alter the fat:lean content of pigs. The purpose of this study was to compare the growth and body composition of control and IGF-I transgenic pigs in response to dietary CLA. During growth from 60 to 110 kg, the transgenic pigs gained less fat and more lean than did the control pigs and control pigs fed the diet containing CLA gained less fat and more lean than did those fed a diet without added CLA. However, dietary CLA did not influence the fat or lean gain in the transgenic pigs. There were only minor differences in bone growth. Overall, the effects of CLA were less than those of the IGF-I transgene on body or carcass composition, however during the treatment period from 60 to 110 kg, the effects were similar.

Technical Abstract: Both dietary conjugated linoleic acid (CLA) and presence of the IGF-I transgene are reported to alter the fat:lean content of pigs. The purpose of this study was to compare the growth and body composition of control and IGF-I transgenic pigs in response to dietary CLA. Transgenic (T) pigs expressing IGF-I gene and sibling control (C) progeny were produced by mating two half-sib G-1 transgenic boars to non-transgenic gilts. At 60 kg each pig was scanned by dual-energy X-ray absorptiometry (DXA) for body composition analysis, then placed on an 18% crude protein diet containing either 2% corn oil (CO diet) or 1.2% CO plus 0.8% CLA. Thus, the four genotype-diet combinations were: C-CO (n=25), C-CLA (n=25), T-CO (n=24), and T-CLA (n=23). Each pig was scanned again at 110 kg. All pigs were slaughtered at 120 kg and the right half-carcass was scanned by DXA. Results of the DXA scan at 60 kg revealed that the TG pigs were less fat (15.0%) than the C pigs (18.8, P<0.05). During growth from 60 to 110 kg, the tissue gain for the C-CO, C-CLA, TG-CO, and TG-CLA groups consisted of 16.6, 14.5, 13.2, and 13.0 kg of fat (P<0.05, C-CO vs C-CLA and C vs TG); and 30.6, 32.6, 33.7, and 33.8 kg of lean (P<0.05, C-CO vs C-CLA and C vs TG), respectively. There were only minor differences in bone growth. For the same groups, chemical analysis of the half-carcass revealed 29.2, 27.1, 23.8, and 22.8% fat (P<0.05 for C-CO vs. C-CLA and C vs. TG), respectively. Overall, the effects of CLA were less than those of TG on body or carcass composition, however during the treatment period from 60 to 110 kg, the effects were similar. TG pigs did not respond to CLA as much as did control pigs.