Abstract
This study examined the effects of dietary Eucommia ulmoides leaf extract (ELE) supplements on carcass traits and lipid metabolism in growing–finishing pigs. A total of 144 crossbred (Duroc × Landrace × Yorkshire) piglets with an average initial weight of 10.11 ± 0.03 kg were randomly allotted to four treatment groups, each with six replicates and six piglets per replicate. Each group of pigs was fed a basal diet or a diet supplemented with increasing levels of ELE (0.1, 0.2, or 0.3%). The results showed that adding ELE had no negative effect on the growth performance of pigs. Dietary supplements of 0.1% ELE significantly increased carcass weight (p < 0.01), dressing percentage (p < 0.01), carcass length (p < 0.05), and eye muscle area (p < 0.05). Compared with the control group, a 0.2% ELE supplement significantly increased (p < 0.01) the levels of adiponectin, insulin-like growth factor 1, and hormone-sensitive lipase and lipoprotein lipase activity in the serum. Histological examination showed that ELE inhibited fat deposition in the backfat tissue. Lipid metabolism-related biochemical indices and mRNA expression levels were improved after supplementing diets with ELE. Moreover, all three levels of ELE dramatically upregulated (p < 0.05) the protein levels of p-AMPK-α and p-ACC. In summary, adding ELE to pig diets could improve the carcass traits of growing–finishing pigs and exert a lipid-lowering effect by activating the AMPK-ACC pathway and regulating mRNA expression levels related to lipid metabolism. Supplementing the diet with 0.1–0.2% ELE is the optimal range to reduce fat deposition in pig backfat tissue.
Highlights
Obesity is becoming one of the most important health problems in several countries, affecting scores of people, as it increases the risk of various diseases, such as fatty liver, diabetes, and coronary heart disease [1]
Over the whole period of the experiment, average daily feed intake (ADFI) was higher (p < 0.05) in the 0.1% Eucommia ulmoides leaf extracts (ELE) group than in the 0.3% group, but there were no observable change in average daily gain (ADG) or feed to gain (F/G) among the different treatments
Growth performance directly affects the meat growth performance of growing–finishing pigs, affecting the economic return. These results showed that supplementing pig diets with different levels of ELE had no significant effect on ADG, ADFI, or F/G in piglets, which was consistent with a previous study [9]
Summary
Obesity is becoming one of the most important health problems in several countries, affecting scores of people, as it increases the risk of various diseases, such as fatty liver, diabetes, and coronary heart disease [1]. An antiobesity effect of Eucommia ulmoides has been supported by an increasing number of studies. Eucommia ulmoides promoted the recovery of lipid metabolism disorders caused by a high-fat diet in rats [4]. Eucommia ulmoides is widely distributed in China, with a high annual yield [6]. Studies into the potential of Eucommia ulmoides as a feed supplement in Chinese herbal medicine have been gradually developed. Previous studies focused on the effects of Eucommia ulmoides leaf and its extracts on growth performance and antioxidant activity in pigs [9,10,11]. At present, there are few studies on the effect of Eucommia ulmoides leaf extracts (ELE) on lipid metabolism in growing–finishing pigs, and the optimal supplement level is unknown. Since there are many similarities between pigs and humans in terms of structure and function, the effect of ELE as a dietary supplement in pigs can be used as a model for the study of human nutrition and metabolism [12]
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