Effects of Cold Exposure on Performance and Skeletal Muscle Fiber in Weaned Piglets

Abstract

Low-temperature is one of the most significant risks for the animal industry. In light of this, the present study aimed to explore the effects of low-temperature on growth performance, nutrient digestibility, myofiber types and mitochondrial function in weaned piglets. A total of sixteen 21-day-old male Duroc × Landrace × Yorkshire (DLY) piglets were randomly divided into a control group (CON, 26 ± 1 °C) and a low-temperature group (LT, 15 ± 1 °C), with eight duplicate piglets in each group. The trial period lasted for 21 days. We showed that LT not only increased the ADFI (p < 0.05), as well as increasing the diarrhea incidence and diarrhea index of weaned piglets in the early stage of the experiment (p < 0.01), but it also decreased the apparent digestibility of crude protein (CP), organic matter (OM) and dry matter (DM) (p < 0.05). Meanwhile, in the LT group, the mRNA expression of MyHC IIa (p < 0.05) in longissimus dorsi muscle (LM) and MyHC I (p < 0.01) in psoas muscle (PM) were increased, while the mRNA expression of MyHC IIx in PM was decreased (p < 0.05). In addition, LT increased the mRNA expression of mitochondrial function-related genes citrate synthase (CS) and succinate dehydrogenase-b (SDHB) in LM, as well as increased the mRNA expression of CS (p < 0.05) and carnitine palmitoyl transferase-1b (CPT-1b) (p < 0.01) in PM. Furthermore, LT increased the T-AOC activity in serum and LM (p < 0.01), as well as increased the T-SOD activity in PM (p < 0.05). Taken together, these findings showed that low-temperature could negatively affect the growth performance and nutrient digestibility, but resulted in a shift toward oxidative muscle fibers, which may occur through mitochondrial function regulation.

Keywords: antioxidant capacity; cold exposure; growth performance; skeletal muscle fiber; weaned piglets.

Figure 1

Effects of low-temperature on the mRNA expression level of fiber type-related genes in (A) LM and (B) PM of weaned piglets. Results were the mean and standard errors. LM, longissimus dorsi muscle; PM, psoas muscle. * Mean values were significantly different between two groups (p < 0.05). ** Mean values were very significantly different between two groups (p < 0.01).

Figure 2

Effects of low-temperature on the mRNA expression level of mitochondrial function-related genes in (A) LM and (B) PM of weaned piglets. Results were the mean and standard errors. CS, citrate synthase; CPT-1b, carnitine palmitoyl transferase-1b; SDHB, succinate dehydrogenase-b; Nrf-1, nuclear respiratory factor 1. * Mean values were significantly different between two groups (p < 0.05). ** Mean values were very significantly different between two groups (p < 0.01).