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

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.

The gastrointestinal tract provides the location for the digestion and absorption of nutrients. It has physical and chemical barriers to protect body from pathogens and toxins. Oxidative stress tends to weaken the physical and chemical barriers of the intestine, which in turn can lead to intestinal dysfunction. Fiber has been suggested to have beneficial effects on the intestine health of pigs. Revealing how fiber can maintain intestinal health is important for pig production. In the present research, we investigated the effect of fiber on the oxidative stress status and antioxidant content in the pig intestine. Our data revealed that a low-fiber diet contributed to oxidative stress in the pig intestine (jejunum). Pigs fed a high-fiber diet had less intestinal oxidative stress and grew heavier. Pigs fed a low-fiber diet may produce more antioxidants to cope with the increased oxidative stress in the intestine.

miR-145a-5p Promotes Myoblast Differentiation.

MicroRNAs are a class of 18-22-nucleotide noncoding RNAs that posttranscriptionally regulate gene expression and have been shown to play an important role during myoblast differentiation. In this study, we found that the expression of miR-145a-5p was gradually increased during C2C12 myoblast differentiation, and miR-145a-5p inhibitors or mimics significantly suppressed or promoted the relative expression of specific myogenesis related marker genes. Moreover, overexpression or inhibition of miR-145a-5p enhanced or repressed the expression of some special genes involved in the endogenous Wnt signaling pathway during C2C12 myoblast differentiation, including Wnt5a, LRP5, Axin2, and ß-catenin. These results indicated that miR-145a-5p might be considered as a new myogenic differentiation-associated microRNA that can promote C2C12 myoblast differentiation by enhancing genes related to myoblasts differentiation.

Effect of miR-143-3p on C2C12 myoblast differentiation.

MicroRNAs are a class of 18-22 nucleotide non-coding RNAs that modulate gene expression by associating with the 3' untranslated regions of mRNAs. A large number of microRNAs are involved in the regulation of myoblast differentiation, many of which remain undiscovered. In this study, we found that miR-143-3p was upregulated during C2C12 myoblast differentiation and over-expression of miR-143-3p significantly inhibited the relative expression levels of MyoD, MyoG, myf5, and MyHC genes, especially in the later stages of differentiation. In addition, miR-143-3p inhibited expression of genes involved in the endogenous Wnt signaling pathway during C2C12 myoblast differentiation, including Wnt5a, LRP5, Axin2, and ß-catenin. These results indicate that miR-143-3p represents a new myogenic differentiation-associated microRNA that can inhibit C2C12 myoblast differentiation, especially in the later stages of differentiation.

Estimation of Growth Curves and Suitable Slaughter Weight of the Liangshan Pig.

The Liangshan pig is a traditional Chinese small-sized breed; it has a relatively long feeding period and low meat production ability but superior meat quality. This study utilized three non-linear growth models (Von Bertalanffy, Gompertz, and logistic) to fit the growth curve of Liangshan pigs from an unselected, random-bred pig population and estimate the pigs most suitable slaughter weight. The growth development data at 20 time points of 275 Liangshan pigs (from birth to 250 d) were collected. To analyze the relative gene expression related to development, seven slaughter weight phases (50, 58, 66, 74, 82, 90, and 98 kg) (20 pigs per phase) were examined. We found that the Liangshan pig growth curve fit the typical S-curve well and that their growth turning point was 193.4 days at a weight of 62.5 kg, according to the best fit Von Bertalanffy model based on the goodness of fit criteria. Furthermore, we estimated that the most suitable slaughter weight was 62.5 to 74.9 kg based on the growth curve and the relative expression levels of growth-related genes.

Comparison of energy metabolism and meat quality among three pig breeds.

The objective of this study was to evaluate the effects of muscle-fibre types and hormones on glycolytic potential and meat quality traits and their association with glycolytic-related gene expression in three different altitude pig breeds. The pig breeds studied were the Tibetan pig (TP, high altitude), the Liang-Shan pig (LSP, middle altitude) and the Duroc×(Landrace×Yorkshire) cross (DLY, flatland). The results indicated that TP and LSP had better meat quality than DLY (P<0.01). The glycolytic potential (GP) increased in the order of TP