Feeding low energy and high fibre diets increases the concentraction of linoleic acid and iodine value in pork

The objective of the present work was to determine the effect of feeding a high energy, low fiber (HELF) or a low energy, high fiber (LEHF) diet on the fatty acid composition and iodine value in pigs. Barrows (n = 76) and gilts (n = 81) were used (LRFI (42 HELF and 41 LEHF; HRFI: 39 HELF and 35 LEHF). Pigs were randomly assigned to mixed line and sex within pens, with 6 pens on the HELF diet (3.32 Mcal ME/kg; 9.5% NDF) and 6 pens on the LEHF diet (2.87 Mcal ME/kg; 25.9% NDF). Pigs were slaughtered (2 groups) at a mean BW of 128.4 ± 8.0 kg. Samples were placed in re-sealable plastic bags and held at 4ºC for 2 d and then frozen at - 20ºC until analysis.

Feeding the HELF diet resulted in a greater adipose tissue IV (P < 0.01; 72.63 vs. 68.74) as a result of a greater percentage of C18:2n6c (P < 0.01; 16.34% vs. 13.76%), C18:3n3 (P < 0.01; 0.85% vs. 0.60%), and a lower percentage of C16:1 (P < 0.01; 1.57% vs. 1.70%) and C18:1n9c (P < 0.05; 43.29% vs. 44.63%). Line selection had no effect on IV (P > 0.05), however the percentage of C16:1 was greater in adipose tissue from animals of the LRFI line (P < 0.01; 1.73% vs. 1.54%). Within the LRFI line, gilts had adipose tissue with greater IV and C18:2 than adipose tissue from barrows (P = 0.01). Within each sex, pigs fed the LEHF diet had a greater percentage of C18:2n6c (P < 0.05) in their adipose tissue and greater IV (P < 0.01) than adipose from HELF fed pigs. Adipose tissue from LRFI pigs fed the HELF diet had a greater percentage of C18:3n6.

Regardless of selection for efficiency, feeding pigs diets low in energy and high in fiber resulted in an increase in carcass fat iodine value.