Impact of dietary fat intake on carcass iodine value and pork fat quality

Abstract

<p>The study between dietary fat intake and pork fat composition is not novel or new. However, details of this relationship are not characterized enough to meet pork carcass fat quality standards. The objective was to more precisely define the relationship between dietary fatty acid intake and pork carcass fat composition. Our hypothesis was that pork carcass fat composition will be highly reflective of fatty acid intake, resulting in daily fatty acid intake proving to be an accurate predictor of pork fat composition. Experiment 1 used 42 gilts and 21 barrows allotted to 7 treatments: 3% and 6% of each of tallow (TAL; iodine value (IV) = 41.9), choice white grease (CWG; IV = 66.5) or corn oil (CO; IV = 123.1), plus a control (CNTR) diet based on corn and soybean meal with no added fat. Carcass lipid IV was elevated by increasing the degree of unsaturation of the dietary fat source (TAL = 66.8, CWG = 70.3, CO = 76.3; P < 0.001). Among fatty acids measured, only linoleic acid intake presented a reasonable coefficient of determination (R2 = 0.61). Measured iodine value product was of approximately equal effectiveness as linoleic acid intake as a predictor of carcass IV (R2 = 0.93 vs. R2 = 0.94). Experiment two used fifty individually housed pigs allotted to 10 treatments arranged as a 3 X 3 plus factorial for an 82 d experiment as follows: 3 dietary fat withdrawal times prior to slaughter (21, 42 or 63d) by 3 dietary fat sources (5% animal-vegetable blend (AV; IV = 90.7), 2.5% corn oil (2.5% CO; IV = 122.7) or 5% corn oil (5% CO), plus a control diet with no added fat (CNTR) fed throughout the duration of trial. At market (d82) increasing the withdrawal of dietary fat further away from market significantly decreased 18:2 and carcass IV (P < 0.01). Dietary 5% CO resulted in the greatest 18:2 concentrations, followed by 2.5% CO; 5% AV resulted in the lowest 18:2 levels (P < 0.01). In conclusion, limiting linoleic acid intake in daily consumption or before harvest is key to lowering carcass IV.</p>