Prediction of Loin, Belly and Jowl IV Based on Diet Composition Verses Daily Fatty Acid Intake
Iodine value product (IVP) is commonly used to predict carcass fat iodine value (CIV). However, when higher fat diets are employed, IVP tends to emphasize the quantity of fat in the diet more than the composition of that fat. The objective of this experiment was to compare the effectiveness in predicting CIV by IVP versus individual fatty acid content in the diet or their daily intake. Forty-two gilts and 21 barrows (PIC 337 × C22/29) with an average initial weight of 77.8 ± 0.38 kg were allotted based on sex and weight across 7 treatments: a control diet with no added fat, and 6 diets containing either 3 or 6% of tallow, choice white grease, or corn oil. Pigs were individually housed to measure daily fatty acid intake. Adipose samples were collected from the jowl, loin, and belly at harvest (d 55). Of all the fatty acid intakes measured, only increased linoleic acid intake (LAI) generated a strong coefficient of determination in a positive correlation with CIV (CIV = 60.58 + (0.121× LAI/d (g)); R2 = 0.611; P < 0.05; Root MSE = 3.24). Comparison of IVP of the experimental diets was approximately equal (CIV = 58.10 + (0.215 × IVP); R2 = 0.93; P < 0.05; Root MSE = 1.45) to the treatment means of LAI (CIV = 58.57 + (0.139 × linoleic acid intake/d (g)); R2 = 0.94; P < 0.05; Root MSE = 1.37) as a predictor of CIV. Under the conditions of this experiment, a CIV standard of 74 g/100 g can be met by limiting LAI to less than 111 g/d. Linoleic acid is clearly the fatty acid that most affects CIV.