Influence of Rendement Napole (RN) genotype on growth performance and expression of metabolic genes in crossbred Ossabaw pigs fed different levels of dietary fat

Abstract Text: The study was conducted to investigate the effects of Rendement Napole (RN) genotype on growth performance and key metabolic markers in crossbred Ossabaw pigs fed diets with different levels of dietary fat. Thirty two crossbred Ossabaw pigs were used for the study with equal number of animals (n=16) belonging to either the wild type (WT, rn⁺/ rn⁺) or carrier (CAR, RN^-/ rn⁺) genotypes. Pigs in each genotype were divided into two dietary groups (n=8) and fed either a high fat (HF, 4026 kcal/kg ME) or low fat (LF, 3364 kcal/kg ME) diet for 12 weeks after which pigs were killed for gene expression analysis by RT-PCR. There was a significant diet X genotype interaction (P<0.05) for final BW, ADG and Gain: Feed. Wild type pigs on LF diet had lower final BW than WT pigs on HF diet. However, the final BW of carrier pigs was not affected by diet. Feed efficiency (Gain: Feed) and ADG were lower (P<0.05) in WT pigs on LF diet compared to WT pigs on HF diet and all carriers pigs, irrespective of their diets. There was a trend (P<0.08) for a higher feed consumption in pigs on the LF diet compared to HF. Backfat thickness was higher (P<0.01) in pigs on the HF diet vs. LF. Serum triglyceride was higher (0.62 vs. 0.33 mg/dL, P<0.01) in pigs on HF diet compared to those on LF. However, there was no effect of genotype on serum metabolite concentrations. Expression of carnitine palmitoyl transferase 1-alpha (CPT1α) was higher (P<0.05) in the longissimus dorsi (LD) and semitendinosus (STD) muscles of pigs on HF diet relative to those on LF diet. Acyl-CoA oxidase (ACO) was also elevated (P<0.05) in the liver of pigs on HF diet compared to those on the LF diet. Fatty acid synthase (FAS) was lower in the LD muscle, liver and mesenteric fat (P<0.05) of carrier pigs compared to WT. Overall, the RN genotype had no significant effects on the growth performance of crossbred Ossabaw pigs, but may result in suppression of fatty acid synthesis through downregulation of FAS.

Keywords: RN, Ossabaw pigs, growth performance, fatty acid metabolite