206 An Investigation into the Role of Dietary Essential Fatty Acids Ratios and Energy Level on Growth Performance, Inflammation, and Joint Health of Grow-finish Pigs

The objective of this study was to investigate the effects of dietary metabolizable energy level and the ratio of linoleic acid:linolenic acid (n6:n3) on the growth performance and inflammatory status of grow-finish pigs. A total of 240 growing pigs (BW = 41.5 ± 6.1 kg) were randomly assigned to either a high (3.55 Mcal/kg; HE) or low (3.29 Mcal/kg; LE) energy dietary treatment with a high (23:1) or low (12:1) n6:n3 in a 2 x 2 factorial design (n = 16). Diets were fed across three 28-day phases and were balanced for linoleic acid inclusion. Pigs were housed 4 pigs per pen. Blood samples were collected on weeks 1, 3, 6, and 12 of the study. Synovial fluid was collected from the hock joint on weeks 1 and 12 for inflammatory marker analysis. The pen was the experimental unit and data were analyzed as repeated measures using PROC MIXED (SAS 9.4) with energy, ratio, and the interaction as fixed effects. Compared to LE, pigs receiving HE had increased BW (P < 0.05) at d28 (73.0 vs. 69.9kg), d56 (105.0 vs. 100.7kg), and d84 (135.3 vs. 129.9kg). For the overall period, HE had increased ADG compared to LE (1.10 vs. 1.06kg; P < 0.05) and improved G:F (0.41 vs. 0.37; P < 0.05), while LE increased ADFI compared to HE (2.88 vs. 2.72kg; P < 0.05). There was no effect of ratio or energy ratio interaction for growth performance. C-reactive protein tended to be reduced in hock synovial fluid of pigs receiving LE (1854.3 vs. 2277.3ng/mL; P < 0.10). Across all treatments, CRP was reduced in the synovial fluid and plasma in week 12 compared to week 1 (P < 0.05). In conclusion, dietary n6:n3 ratio did not impact growth performance or CRP response regardless of energy level.