This study aimed to investigate the effect of the supplementation of branched-chain amino acids (BCAAs) at different ratios in protein restriction diets on lipid metabolism in a finishing pig model. The BCAA supplementation (leucine/isoleucine/ valine = 2:1:1 and 2:1:2) ameliorated the poor growth performance and carcass characteristics, particularly high fat mass caused by a protein-restricted diet. Serum adiponectin increased while leptin decreased in BCAA diets in comparison to the 12% CP group. BCAA supplementation also increased the low-protein expression of AMPK and SIRT1 caused by protein restriction. The mRNA and protein levels of peroxisome proliferation-activated receptor-γ (PPARγ) and acetyl-CoA carboxylase (ACC) were highest in the protein-restricted group and lowered in the 2:1:1 or 2:1:2 group. In conclusion, BCAAs supplemented in an adequate ratio range of 2:1:1 to 2:1:2 (2:1:2 is recommended) in reduced protein diets could modulate lipid metabolism by accelerating the secretion of adipokines and fatty acid oxidation.

One digestibility and one performance experiments were conducted to investigate the effects of a feed enzyme of arabinoxylanase and arabinoxylanase plus protease on digestibility of nutrients, nitrogen (N) fl ow and performance of the growing pigs fed a maize-wheat bran-based diet or a maize-rice bran-based diet. In the digestion experiment, six Landrace × Large White × Chinese Black male pigs of approximately 20 kg initial body weight , fi tted with a simple T-cannula at the terminal ileum, were used to study dietary nutrient digestibility and nitrogen fl ow of the experimental diets. The six experimental diets were prepared in this study: maize-wheat bran diet, consists of maize, wheat bran, soyabean, of rapeseed meal, without feed enzyme supplementation (MWB); MWB supplemented with arabinoxylanase (A); MWB supplemented with arabinoxylanase plus protease (AP); maize-rice bran diet, consists of maize, rice bran, soyabean, rapeseed meal, without feed enzyme supplementation (MRB); MRB supplemented with arabinoxylanase (A); MRB supplemented with arabinoxylanase plus protease (AP). The MWB diet contained: %: soluble nonstrach polysaccharide (NSP) 0.8, insoluble NSP 19, crude protein 22, and 18.6 MJ/kg gross energy (GE), while the MRB diet contained, %, respectively: 0.5, 22, 21, and 18.9 MJ/kg GE. In the performance experiment, lasting 40 days, 60 pigs (30 gilts and 30 castrates) with body weight of 20.5±0.76 kg were randomly allocated to the six dietary treatments with a completely randomized design (5 gilts and 5 castrates per treatment). Feed and water were provided ad libitum. DIETS SUPPLEMENTED WITH ENZYME FOR PIGSThe results show there were no signifi cant differences in average daily gain (ADG) (P=0.09), feed gain ratio (F/G; P=0.09), ileal digestibility of nutrients (P=0.09) and N fl ow (P>0.08) between the MWB and MRB diet, although the crude fi bre level in the MRB diet had higher crude fi bre content (9.7 g/kg) than that the MWB diet. The dry matter intake (DMI) of the MWB diet was increased (P<0.05) by the enzyme A supplementation. The ADG and F/G of the pigs fed the MWB diet were improved (P<0.05) by either arabinoxylanase or arabinoxylanase plus protease supplementation. The ileal endogenous N excretion determined with enzymatic hydrolysed casein diet in this experiment was half higher than that calculated from the N-free diet. The ileal digestibility of soluble NSP fractions of the MWB and MRB diets were signifi cantly (P<0.05) increased by either enzyme arabinoxylanase or arabinoxylanase plus protease supplementation. There was no enzyme effect on insoluble NSP fraction digestibility. The results of this study suggest that NSP degrading enzyme do mainly reduce the negative nutritional effect of the soluble NSP in the small intestine of growing pigs.

BACKGROUND Pork is an important food for humans and improving the quality of pork is closely related to human health. This study was designed to investigate the effects of balanced branched‐chain amino acid (BCAA)‐supplemented protein‐restricted diets on meat quality, muscle fiber types, and intramuscular fat (IMF) in finishing pigs. RESULTS The results showed that, compared with the normal protein diet (160 g kg−1 crude protein), the reduced‐protein diet (120 g kg−1 crude protein) supplemented with BCAAs to the ratio of 2:1:2 not only had higher average daily gain (P < 0.05) and carcass weight (P < 0.05) but also improved meat tenderness and juiciness by decreasing shear force (P < 0.05) and increasing water‐holding capacity (P < 0.05). In particular, this treatment showed higher (P < 0.05) levels of phospho‐acetyl‐CoA carboxylase (P‐ACC) and peroxisome proliferation‐activated receptor‐γ (PPARγ), and lower (P < 0.05) levels of P‐adenosine 5‘‐monophosphate (AMP)‐activated protein kinase (P‐AMPK), increasing the composition of IMF and MyHC I (P < 0.05) in the longissimus dorsi muscle (LDM). In terms of health, this group increased eicosapentaenoic acid (EPA) (P < 0.01) and desirable hypocholesterolemic fatty acids (DHFA) (P < 0.05), and decreased atherogenicity (AI) (P < 0.01) and hypercholesterolemic saturated fatty acids (HSFA) (P < 0.05). CONCLUSION Our findings suggest a novel role for a balanced BCAA‐supplemented restricted protein (RP) diet in the epigenetic regulation of more tender and healthier pork by increasing IMF deposition and fiber type conversion, providing a cross‐regulatory molecular basis for revealing the nutritional regulation network of meat quality. © 2021 Society of Chemical Industry.

Sixty Duroc × Large White × Landrace pigs with an average initial BW of 77.1 ± 1.3 kg were used to investigate the effects of dietary supplementation with arginine and glutamic acid on growth performance, carcass traits, and meat quality in growing-finishing pigs. The animals were randomly assigned to 1 of 5 treatment groups (12 pigs/group, male:female ratio 1:1). The pigs in the control group were fed a basal diet (basal diet group), and those in the experimental groups were fed the basal diet supplemented with 2.05% -alanine (isonitrogenous group), 1.0% -arginine (Arg group), 1% glutamic acid + 1.44% -alanine (Glu group), or 1.0% -arginine + 1.0% glutamic acid (Arg+Glu group). After a 60-d period of supplementation, growth performance, carcass traits, and meat quality were evaluated. The results showed no significant differences ( > 0.05) in growth performance and carcass traits of the pigs in the Arg group relative to the basal diet group; however, the longissimus dorsi (LD) muscle and back fat showed a decrease ( < 0.05) in the percentage of SFA. In the Glu group, the final BW, phase 1 (d 1 to 30) and phase 2 (d 31 to 60) ADFI, and average back fat thickness of the pigs decreased ( < 0.05) by 7.14%, 23.43%, 8.03%, and 33.88%, respectively, when compared with the basal diet group. Dietary Arg+Glu supplementation had no effect ( > 0.05) on the final BW, phase 2 ADFI, and average daily weight gain in pigs but decreased ( < 0.05) their phase 1 ADFI, average back fat thickness, and percentage of SFA in the LD muscle and back fat, and increased ( < 0.05) the i.m. fat (IMF) content of the LD and biceps femoris muscles when compared with the basal diet group. Furthermore, a 16% decrease in yellowness (b* value; < 0.05) was observed in the Arg+Glu group pigs when compared with the isonitrogenous group. These findings suggest that dietary supplementation with both Arg and Glu beneficially increases the IMF deposition and improves the meat color and fatty acid composition without affecting growth performance and s.c. fat in pigs, providing a novel strategy to enhance meat quality in growing-finishing pigs.

Chlorogenic acid (CGA), as one of the richest polyphenol compounds in nature, has broad applications in many fields due to its various biological properties. However, initial data on the effects of dietary CGA on protein synthesis and related basal metabolic activity has rarely been reported. The current study is aimed at (1) determining whether dietary CGA supplementation improves the growth performance and carcass traits, (2) assessing whether dietary CGA alters the free amino acid profile, and (3) verifying whether dietary CGA promotes muscle protein synthesis in finishing pigs. Thirty-two (Large × White × Landrace) finishing barrows with an average initial body weight of 71.89 ± 0.92  kg were randomly allotted to 4 groups and fed diets supplemented with 0, 0.02%, 0.04%, and 0.08% CGA, respectively. The results indicated that, compared with the control group, dietary supplementation with 0.04% CGA slightly stimulated the growth performance of pigs, whereas no significant correlation was noted between the dietary CGA levels and animal growth ( P > 0.05 ). Furthermore, the carcass traits of pigs were improved by 0.04% dietary CGA ( P < 0.01 ). In addition, dietary CGA significantly improved the serum free amino acid profiles of pigs ( P < 0.01 ), while 0.04% dietary CGA promoted more amino acids to translocate to skeletal muscles ( P < 0.05 ). The relative mRNA expression levels of SNAT2 in both longissimus dorsi (LD) and biceps femoris (BF) muscles were augmented in the 0.02% and 0.04% groups ( P < 0.05 ), and the LAT1 mRNA expression in the BF muscle was elevated in the 0.02% group ( P < 0.05 ). We also found that dietary CGA supplementation at the levels of 0.04% or 0.08% promoted the expression of p-Akt and activated the mTOR-S6K1-4EBP1 axis in the LD muscle ( P < 0.05 ). Besides, the MAFbx mRNA abundance in the 0.02% and 0.04% groups was significantly lower ( P < 0.05 ). Our results revealed that dietary supplementation with CGA of 0.04% improved the free amino acid profile and enhanced muscle protein biosynthesis in the LD muscle in finishing pigs.