Influence of feeding thermally peroxidized soybean oil on growth performance, digestibility, and gut integrity in growing pigs

Authors: LINDBLOM, STEPHANIE - Iowa State University; GABLER, NICHOLAS - Iowa State University; Kerr, Brian

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/8/2018
Publication Date: 3/6/2018
Publication URL: http://handle.nal.usda.gov/10113/5927845
Citation: Lindblom, S., Gabler, N., Kerr, B.J. 2018. Influence of feeding thermally peroxidized soybean oil on growth performance, digestibility, and gut integrity in growing pigs. Journal of Animal Science. 96(2):558-569. https://doi.org/10.1093/jas/sky004.

Interpretive Summary: Soybean oil and products derived from soybean oil, such as recycled restaurant grease, can be an important source of energy in swine feeding programs because they provide a concentrated source of energy compared to other commonly used feedstuffs. While the digestibility and caloric value of refined, deodorized, bleached soybean oil is well documented in swine, there is limited data on the impact of thermally processed (i.e., peroxidized) soybean oil on pig performance, energy and lipid digestibility, and gastrointestinal integrity in growing pigs. The current study was conducted to evaluate the effect of thermally processing soybean oil at 45C, 90C, and 180C on pig performance, energy and lipid digestibility, and gastrointestinal integrity in growing pigs compared to pigs fed unprocessed soybean oil. Data from this experiment indicate that the presence of lipid peroxidation products contained in the soybean oil thermally processed at 90C reduced pig gain, energy and lipid digestibility, and nitrogen balance, but appear to have no impact on gut permeability, compared to pigs fed unprocessed soybean oil. Processing soybean oil at either 45C or 180C had little impact on these same parameters. This information is important for nutritionists at universities, feed companies, and pig production facilities for the determination of the impact on pig performance and caloric value of thermally processed soybean oil in feed formulations, and provides a basis from which to assess their economic value.

Technical Abstract: Consumption of peroxidized oils has been shown to affect pig performance and oxidative status through the development of compounds which differ according to how oils are thermally processed. The objective of this study was to evaluate the effect of feeding varying degrees of peroxidized soybean oil (SO) on parameters of growth performance; lipid, N, and GE digestibility, gut integrity in growing pigs, and plasma Trp. Fifty-six barrows (25.3 ± 3.3 kg initial BW) were randomly assigned to 1 of 4 diets containing either 10% fresh SO (22.5oC) or thermally processed SO (45oC for 288 h, 90oC for 72 h, or 180oC for 6 h), each with an air infusion of 15 L/min. Peroxide values for the 22.5, 45, 90 and 180oC processed SO were 2.0, 96, 145, and 4.0 mEq/kg, respectively; 2,4-decadienal values for 22.5, 45, 90 and 180oC processed SO were 2.11,5.05, 547.62, and 323.57 mg/kg, respectively; and 4-hydroxynonenal concentrations of 0.05, 1.05, 39.46, and 25.71 mg/kg with increasing SO processing temperature. Pigs were individually housed and fed ad libitum for a 49 d period to determine the effects of SO peroxidation status on growth performance, including a metabolism period for assessing GE and N digestibility, and N retention. In vivo urinary lactulose to mannitol ratio was also assessed to evaluate potential changes in small intestinal integrity. Although there were no differences observed in ADFI (P = 0.19), ADG was decreased in pigs fed 90oC SO diet (P = 0.01), while G:F was increased (P = 0.02) in pigs fed 45oC SO diet compared to the other SO diets. Pigs fed the 90oC processed SO had the lowest (P = 0.01) DE as a % of GE, whereas ME as a % of DE was lowest (P = 0.05) in pigs fed the 180oC SO and 90oC SO followed by 45oC SO and fresh SO. Ether extract digestibility was lowest (P = 0.01) in pigs fed 90oC SO followed by pigs fed 180oC SO, 45oC SO, and fresh SO. The percent of N retained was greatest (P = 0.01) in pigs fed fresh SO followed by pigs fed 45oC SO, 180oC SO, and 90oC respectively. There were no differences observed among SO treatments for urinary lactulose to mannitol ratio (P = 0.60). Pigs fed SO processed at 90oC and 180oC had lower concentrations (P < 0.01) of serum Trp compared to pigs fed the 22.5oC and 45oC SO treatments. These results indicate that the presence of lipid peroxidation products contained in the 90oC SO diet reduce ADG, GE and ether extract digestibility, and N balance, but appear to have no impact on gut permeability.