Effects of high- and low-fiber diets on intestinal oxidative stress in growing-finishing pigs

Abstract

Feed is the most expensive facet of commercial pork production. In order to reduce feed costs, using high-fiber ingredients has become a common practice. Moderate levels of fiber can maintain intestinal physiological function and promote intestinal health. Oxidative stress is linked to impaired nutrient absorption and growth performance. This study investigated the effects of high-fiber (5.26% crude fiber) and low-fiber (2.46% crude fiber) diets on growth performance and intestinal oxidative stress parameters in growing-finishing pigs. Forty growing pigs with initial body weight (27.07 ± 1.26 kg) were randomly assigned to 2 treatment groups with 10 replicates of 2 pigs per pen. Pigs were weighed on day 35, 42, and 70. The feed intake was recorded daily to calculate growth performance parameters. On day 70, eight pigs in each treatment group were randomly selected and euthanized to obtain jejunum to measure oxidative stress status. Pigs fed a high-fiber diet were heavier than those fed a low-fiber diet on days 35, 42, and 70 (P < 0.05). During the whole feeding period, pigs fed a high-fiber diet had a higher average daily gain than those fed a low-fiber diet (P < 0.05). The low-fiber diet resulted in increased levels of malondialdehyde (P < 0.05) in the jejunum, suggesting that the low-fiber diet contributed to oxidative stress in the jejunum. The low-fiber diet also led to a significant increase in glutathione and oxidized glutathione levels (P < 0.05) in the jejunum, indicating that pigs fed a low-fiber diet needed to produce more antioxidant substances to cope with oxidative stress in the intestine. This was accompanied by a significant increase in the expression of glutathione synthesizing enzymes in the jejunum of the low-fiber group (P < 0.05). These results suggest that the high-fiber diet can improve growth performance and maintain intestinal health in growing-finishing pigs by reducing intestinal oxidative stress.

Keywords: fiber; growing-finishing pigs; growth performance; intestine; oxidative stress.

Figure 1.

Effect of fiber on glutathione levels and lipid peroxidation in the jejunum. Jejunal malondialdehyde (MDA) levels (a), reduced glutathione (GSH) (b), oxidized glutathione (GSSG) (c), and a ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG) (d) were measured in pigs fed a high-fiber (HF) or low-fiber (LF) diet. Results are expressed as mean ± SEM (n = 8 for each group). *P < 0.05 when compared with the value obtained from the HF group.

Figure 2.

Expression of glutathione synthesizing enzymes in the jejunum. Jejunal glumate-cysteine ligase catalytic subunit (Gclc) protein (a) and mRNA (b), glutamate-cysteine ligase modifier subunit (Gclm) protein (c) and mRNA (d), glutathione synthetase (GS) protein (e) and mRNA (f) were measured in pigs fed a high-fiber (HF) or low-fiber (LF) diet. Results are expressed as mean ± SEM (n = 4 to 8 for each group). *P < 0.05 when compared with the value obtained from the HF group.