Digestibility of energy and caloric value in nursery pigs fed commercially available lipids

Authors: Kerr, Brian; CURRY, SHELBY - Oak Ridge Institute For Science And Education (ORISE); LINDBLOM, STEPHANIE - Iowa State University

Submitted to: Applied Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/9/2019
Publication Date: 6/1/2019
Citation: Kerr, B.J., Curry, S.M., Lindblom, S.C. 2019. Digestibility of energy and caloric value in nursery pigs fed commercially available lipids. Applied Animal Science. 35:291-297. https://doi.org/10.15232/aas.2018-01835.
DOI: https://doi.org/10.15232/aas.2018-01835

Interpretive Summary: Various refined, crude, and recycled lipids, depending upon their costs, can be used 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 has been documented in swine, there is limited data on the lipid digestibility and energy evaluation of many other fat and oil sources. The current study was conducted to evaluate the digestibility energy content of various lipids and to develop an equation to predict the digestible energy of a fat or oil based on its chemical composition. The digestible energy content of the fats and oils used differed by 1,900 kcal/kg lipid, with a best fit prediction generated based on a lipid’s free fatty acid, palmitic acid, stearic acid, unsaturation index, and iodine value. Data from this experiment provided empirical data on the digestible energy levels of ten different lipid samples and indicates that a lipid’s free fatty acid, palmitic acid, stearic acid, unsaturation index, and iodine value are important in predicting its caloric value to a growing pig. This information is important for nutritionists at universities, feed companies, and pig production facilities for the determination of the energy value of commonly used lipids in feed formulations, and provides a basis from which to assess their economic value.

Technical Abstract: The apparent total tract GE digestibility and DE value of 10 lipid sources were assessed using 480 nursery pigs which were weaned at 24 d of age and fed a common starter diet for 7 d prior to being fed either a basal diet or 1 of the 10 different lipid sources for an additional 28 d. Lipids were added to the diet at 7.13% in place of the basal diet, and all diets were pelleted and offered ad libitum. A fecal sample was collected on d 25 from 2 pigs per pen and pooled for subsequent analysis. All diets contained titanium dioxide to determine apparent total tract digestibility of GE by the indirect method and to determine the DE content of each lipid source using the difference procedure. The DE for butter fat, canola oil, coconut oil, fish oil, flaxseed oil, lard, olive oil, palm oil, soybean oil, and tallow was 8,911, 9,474, 9,380, 9,464, 8,584, 8,648, 9,606, 8,304, 9,979, 8,071 kcal/kg respectively. Using these values and the chemical composition of each lipid, the best fit equation was calculated to be: DE, kcal/kg = 10,267 – (110.3 × FFA, %) – 41.8 × C16:0, %) – (39.7 × C18:0, %) – (98.0 × U:S ratio) + (6.4 × IV), SE = 164, R2 = 0.97, P = 0.01. The DE values determined in the current study were approximately 12% greater than the values predicted based on published prediction equation, indicating an increased effort is needed to refine prediction equations to more accurately predict the caloric value of lipids to growing swine. In conclusion, these results indicate that the DE of lipid sources can vary greatly depending upon their FA composition which consequently affects pig performance.