The Impact of an Inflammatory Challenge and Dietary Omega-6 to Omega-3 Fatty Acid Ratios on Protein Deposition in Nursery Pigs
The objective of this experiment was to determine if decreasing the dietary omega (ω)-6 to ω-3 fatty acid ratio would affect protein deposition in nursery pigs during a prolonged E. coli lipopolysaccharide (LPS) inflammatory challenge. Twenty-four barrows were assigned to one of four treatment groups at 21 d of age (d 0). Treatments, arranged as a 2 x 2 factorial, were diets (10:1 and 5:1 ω-6:ω-3 plant based FA ratios) and challenge (LPS injection, ad lib intake; or saline injection, pair fed to match LPS injection intake levels). On d 15 and 18, pigs were injected with 15 µg/kg BW LPS in saline or saline alone. On d 21, 1.5 h post-feeding, pigs were given a flooding dose of 2H2O and at 2.5 h post-feeding received another LPS or saline injection. Following the final injection, pigs were slaughtered (5.5 h post-feeding). Liver, semi-tendinosus muscle and blood samples were collected, and the remaining carcass was ground and analyzed for N and DM. Whole carcass protein deposition was determined relative to an initial slaughter group of pigs. Liver, muscle and blood samples were analyzed for 2H2O enrichment to determine the fractional rate of protein synthesis (FSR) during final day of the LPS challenge. ADFI (d 0 to 15) was unaffected by diet (P>0.05); however 5:1 fed pigs tended to have higher ADG relative to the 10:1 fed pigs (28.8 vs 25.0 ± 1.4 g/d; P=0.06). Pigs consuming the 5:1 diet, regardless of challenge group, had higher whole body protein deposition rates for the 3 wk period relative to pigs consuming the 10:1 diet (87.8 g/d vs. 61.3 g/d; P=0.04). Similarly, 5:1 fed pigs tended to have increased FSR in the liver on the final day of the challenge relative to those consuming the 10:1 diet (8.55 % synthesized/h vs 6.16 %/h; P=0.08). There was no effect of LPS challenge on carcass composition, protein deposition rate or on liver or muscle FSR measured using 2H2O enrichment (P>0.05). Protein deposition measured over time and on the final challenge day (FSR) provided similar results. This experiment shows that altering the FA ratio in nursery pig diets can alter the efficiency by which the animal utilizes nutrients for growth, as evidenced by similar feed intakes but improved ADG and protein deposition rates.
Keywords: Swine, Omega-3, Protein Synthesis