Submitted to: Comparative Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/8/2003
Publication Date: 1/1/2004
Citation: Wray-Cahen, D., Fernandez-Figares, I., Virtanen, E., Steele, N.C., Caperna, T.J. 2004. Betaine improves growth but does not induce whole body or hepatic palmitate oxidation in swine (sus scrofa domestica). Comparative Biochemistry and Physiology. Jan;137(1):131-40. Interpretive Summary: Betaine is a feed ingredient derived as a byproduct from sugar beet processing and has potential to reduce body fat in pigs. This study addressed whether the feeding of betaine could impact upon growth and fat metabolism by increasing the rate that lipids are oxidized in the whole body and liver tissue. Growing pigs were fitted with indwelling catheters, maintained in metabolism crates for two weeks and fed standard diets with or without added betaine. Blood and expired respiratory gas were collected to analyze the distribution and metabolism of a stable isotope of palmitae, a long chain fatty acid, by mass spectrometry. Pigs fed betaine for one week grew faster and more efficiently than control pigs, however no differences were observed in the uptake or utilization of palmitate in the betaine-fed pigs. In addition, liver cells were isolated from pigs, cultured for four days and maintained in the presence of media containing betaine. Palmitate oxidation was also evaluated by mass spectrometry. Betaine did not enhance the rate of palmitate oxidation in cultured pig liver cells. These data suggest that while betaine enhances growth and decreases fat deposition it is likely that the mode of action is by decreasing the rate of synthesis of fats rather than by enhancing the rate of lipid breakdown.
Technical Abstract: Dietary betaine can reduce carcass fat in growing pigs. We explored the effects of betaine on growth and on in vivo and in vitro fatty acid oxidation. Growing pigs were housed in metabolism crates and fed diets containing either 0% (control), 0.125% or 0.5% betaine at 80% of ad libitum energy intake. Fatty acid oxidation was measured during intravenous infusions of 1-13C-palmitate and in porcine hepatocytes incubated in the presence or absence of betaine and carnitine. CO2 and palmitate isotopic enrichments were determined by mass spectrometry. Pigs consuming 0.125 and 0.5% betaine had growth rates that were 38 and 12% greater than controls, respectively. Feed:gain ratios were also improved in pigs receiving betaine. Fasting increased palmitate oxidation rates by 7-8 fold (P<0.01), but betaine had no effect in either the fed or fasted state (P>0.1). For hepatocytes, carnitine, but not betaine enhanced palmitate oxidation. Betaine had no effect on plasma non-esterified fatty acids or urea nitrogen. Under the conditions in this study, dietary betaine markedly improved animal growth rates, but had no apparent effect on either whole body or hepatic fatty acid oxidation. These data suggest that the reduction in adipose accretion must be via a mechanism other than oxidation.