Duration of feeding linseed diet influences expression of inflammation-related genes and growth performance of growing-finishing barrows

ABSTRACT

The aim of the study was to investigate the effects of dietary linseed (rich in n-3 PUFA) on expression of inflammation-related genes and on growth performance of growing-finishing barrows. Two isoenergetic and isonitrogenous diets were formulated, one as the basal diet and the other containing 10% linseed. Twenty-four Landrace × Yorkshire barrows weighing 35 ± 3.7 kg were randomly assigned to 1 of 4 treatment groups, with 6 pigs per group. During the entire experimental period of 90 d, these 4 groups of pigs were first fed the basal diet and then fed the linseed diet for 0, 30, 60, and 90 d before slaughter, respectively. Pig growth; messenger RNA (mRNA) expression of peroxisome proliferator-activated receptor-γ (PPARγ), IL-1β0, IL-6, and tumor necrosis factor-α (TNF-α); and plasma concentrations of the 3 proinflammatory cytokines were measured and analyzed. Average daily feed intake did not differ among treatment groups (P > 0.05), but ADG (P < 0.05) and G:F (P < 0.01) responded quadratically to the duration of linseed diet feeding, and pigs in the 60-d treatment group had the greatest ADG and G:F. The mRNA expression of PPARγ in loin muscle and spleen increased linearly (P < 0.01) with the duration of linseed diet feeding, whereas its expression in adipose tissue was not affected (P = 0.095). Tumor necrosis factor-α and IL-6 mRNA expression in muscle, adipose, and spleen, as well as serum concentration of TNF-α, decreased linearly (P < 0.01) with the duration of linseed diet feeding. Peroxisome proliferator-activated receptor-γ mRNA abundance was negatively correlated with IL-1β, IL-6, and TNF-α mRNA abundance both in muscle (R² = 0.63, P < 0.001) and in spleen (R² = 0.69, P < 0.001), and PPARγ mRNA expression in spleen (R² = 0.59, P < 0.01) and muscle (R² = 0.52, P < 0.05) was negatively correlated with serum TNF-α concentration. There were also significant quadratic relations between ADG and expression of PPARγ (P < 0.05) and splenic TNF-α (P < 0.05). These data suggest that intake of n-3 PUFA from the linseed diet led to significant decreases in the expression of proinflammatory cytokine genes, which may stimulate growth in growing-finishing barrows, at least in part, through a PPARγ-dependent mechanism.