罗伊氏乳酸杆菌LR1对猪蛋白消化酶基因表达、肌肉抗氧化指标及氨基酸组成的影响

试验旨在研究长期饲喂罗伊氏乳酸杆菌LR1（Lactobacillus reuteri 1）对猪胃及胰腺蛋白消化相关酶的基因表达、肌肉抗氧化指标及冰鲜肉氨基酸谱的影响。选用144头（杜×长×大）21日龄断奶仔猪（平均体重6.49 kg±0.04 kg），随机分为3组。对照组饲粮为基础饲粮，抗生素组饲粮为添加抗生素的基础饲粮（仔猪阶段添加100 mg/kg喹乙醇和75 mg/kg金霉素，生长肥育猪阶段添加75 mg/kg金霉素），LR1组饲粮为添加5×10¹⁰ CFU/kg LR1的基础饲粮，试验期175 d。结果表明：与对照组相比，①抗生素组猪胰腺中弹性蛋白酶的表达降低（P<0.05）；LR1组胃窦、胃贲门及胃底黏膜中胃蛋白酶A的表达提高（P<0.05），同时也高于抗生素组（P<0.05）。②抗生素组猪背最长肌（longissimus dorsis muscle，LDM）总抗氧化能力（total antioxidant capacity，T-AOC）及总超氧化物歧化酶（total superoxide dismutase，T-SOD）活力增加（P<0.05）；LR1不影响LDM中丙二醛（malondialdehyde，MDA）含量，T-AOC、T-SOD及谷胱甘肽过氧化物酶（glutathione peroxidase，GSH-Px）活力（P>0.05）。③饲粮添加抗生素及LR1不影响冰鲜肉水解氨基酸含量及组成（P>0.05）；抗生素组24 h冰鲜肉中甲硫氨酸（苦味氨基酸）含量、甜味氨基酸总量及游离氨基酸总量降低（P<0.05），而LR1降低24 h冰鲜肉中甲硫氨酸含量（P<0.05）；饲粮中添加抗生素及LR1均降低48 h冰鲜肉中甜味氨基酸、苦味氨基酸、必需氨基酸及总游离氨基酸（P<0.05），同时，抗生素组48 h冰鲜肉中鲜味氨基酸含量降低（P<0.05）。综上，与对照组相比，长期饲喂LR1可提高猪胃对蛋白质的消化功能，改善24 h冰鲜肉的风味；而长期饲喂抗生素降低猪胰腺的消化功能，提高肌肉抗氧化能力，但降低24及48 h冰鲜肉的风味。

Effect of Lactobacillus reuteri 1 on the Gene Expression of Protein Digestion-related Enzymes,Antioxidant Indexes and Amino Acids Composition of Muscle in Pigs

This experiment was conducted to study effects of long-term Lactobacillus reuteri 1 (LR1) on the expression of enzymes involved in protein digestion in pancreas and stomach,antioxidant capacity and amino acid profile of meat in pigs.A total of 144 cross-bred (Duroc×Landrace×Yorkshire) weaned piglets (average body weight 6.49 kg±0.04 kg) at 21 days were randomly assigned to 3 groups.The diet in control groups was basal diet,the diet in antibiotic group was basal diet supplemented with antibiotics (100 mg/kg olaquindox plus 75 mg/kg aureomycin for weaned piglets,and 75 mg/kg aureomycin for growing and finishing pigs),and the diet in LR1 group was basal diet supplemented with 5×10¹⁰ CFU/kg LR1.The experiment lasted for 175 days.The results showed as follows:① Antibiotics decreased the expression of elastase in pancreas compared to control (P<0.05),LR1 increased pepsinogen A in antrum,cardia and fundus of stomach in pigs compared to control and antibiotics (P<0.05).② Compared to control group,antibiotics increased activities of total axtioxidant capacity (T-AOC) and total superoxide dismutase (T-SOD) in longissimus dorsis muscle (LDM) (P<0.05).LR1 did not affect malondialdehyde (MDA) content,activities of T-AOC、SOD and glutathione peroxidase (GSH-Px)in LDM of pigs (P>0.05).③ Both antibiotics and LR1 did not affect significantly total amino acids profile following hydrolysis (P>0.05).Antibiotics decreased free methionine (bitter amino acids),total content of sweet amino acids and free amino acids compared to chilled fresh pork at 24 h in contron group (P<0.05),and LR1 decreased methionine (P<0.05).Antibiotics and LR1 decreased the content of sweet,bitter,essential amino acids and total free amino acids (P<0.05),additionally,antibiotics decreased the content of flavor amino acids of chilled fresh pork at 48 h (P<0.05).In conclusion,long-term LR1 improved digestive function of protein in stomach and flavor of chilled fresh pork at 24 h of pigs.Long-term antibiotics decreased digestive function of pancreas,improved antioxidant capacity of muscle,but decreased flavor of chilled fresh pork at 24 h and 48 h of pigs.