Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Abstract Only
Publication Acceptance Date: 2/1/2003
Publication Date: 3/14/2003
Citation: Fiorotto, M.L., Khan, A.S., Cummings, K.K., Draghia-Akli, R. 2003. Administration of a plasmid expressing growth hormone-releasing hormone (GHRH) augments lean mass gain in pigs [abstract]. The Federation of American Societies for Experimental Biology Conference. Part I, 17(4):A700. Interpretive Summary: Not Necessary for an Abstract
Technical Abstract: A major limitation to the widespread use of somatotropin (ST) for swine production is the lack of an economically feasible method of administration. We developed a method of intramuscular gene delivery that results in the constitutive, ectopic production of GHRH. Growth of barrows (6/ group) administered at 10 d of age with a single intramuscular injection of the plasmid [0 (control), 0.1, 1.0, or 3.0 mg/pig] was compared with growth of pST-injected pigs [0.15 mg/(kg.d)]. Body composition was measured by DEXA at the start and end of the study, 8 weeks later. Control and plasmid-treated pigs were pair-fed to the pST-treated group which was fed a high protein (24%) diet at 8% of their body weight daily. The growth response of the plasmid-injected pigs was not influenced by dose. Average daily gain of pST-treated pigs was greater than that of plasmid-injected pigs, which was greater than that of controls (490 +/- 18, 438 +/- 9, and 399 +/- 13 g/d, respectively; P<0.05). Total fat gain was similar among groups (56 +/- 2, 60 +/- 1, and 64 +/- 3 g/d, respectively). The variations in weight gain reflected differences in the gain of lean mass (435 +/- 19, 378 +/- 6, and 336 +/- 13 g/d, respectively; P<0.05); the fat to lean ratio was 0.13 +/- 0.01, 0.16 +/- 0.01, and 0.19 +/- 0.01, respectively (P<0.05). Thus, a single GHRH plasmid dose improved feed efficiency and lean gain compared to untreated pigs, a response comparable to that of pigs injected with daily doses of pST.