The Chinese research team’s objective was to compare muscle fiber characteristics, the profiles and related gene expression of amino acids and fatty acids and the metabolic regulation of these compounds in pigs fed either a control diet, an antibiotic-containing diet, or a diet with Lactobacillus reuteri (LR1) supplementation.
The composition of amino acids and fatty acids are crucial indicators of pork quality (Wood et al., 2008; Yin et al., 2017), but nothing is known of the effects of antibiotics or probiotics on these or muscle fiber characteristics in pork, they added.
The authors said, to their knowledge, there has been no other comprehensive evaluation of the effects of antibiotics and probiotics on profiles of muscle amino acids and fatty acids in pork.
Previous work, such as Wang et all, 2016, has suggested that LR1 can exhibit probiotic properties for growth performance and alleviate diarrhea in piglets. The researchers said, however, that in addition to direct effects on pig health, it is important to consider the effects of different treatments on the properties of produced meat as consumers are increasingly concerned about food quality.
“Consumers are increasingly demanding high-quality, healthier, safer, and tastier meat. Studies have reported dietary antibiotics can negatively influence pork quality (Frank et al., 1997; Wen, Jia, Li, & Wang, 2010), while feeding probiotics can improve meat quality and present an alternative to antibiotics as growth promoters (Dowarah, Verma, Agarwal, & Singh, 2018; Suo et al., 2012). The present results support previous findings that dietary antibiotics decreased meat quality.”
Methodology used
A total of 144 cross-bred male piglets were weaned at 21 days and were randomly assigned to control, antibiotic and probiotic treatments, outlined the team.
There were eight replicate pens each with 6 piglets per treatment.
The control diets were based on the National Research Council (NRC, 2012), were formulated to meet the requirement of pigs during six stages of growth, they reported.
For the antibiotic treatment, these control diets were supplemented with olaquindox (100 mg/kg) plus aureomycin (75 mg/kg) for weaned piglets, and just supplemented with aureomycin (75 mg/kg) for growing and finishing pigs.
In the probiotic treatment, the diets were supplemented with freeze-dried LR1 (5 × 1010 CFU/kg) throughout.
Pigs had free access to drinking water and feed throughout the 175 day long-trial period.
Daily feed intake, initial and final body weight of pigs were recorded to evaluate average daily gain (ADG), average daily feed intake (ADFI) and the feed to gain ratio (F/G).
Key findings
The team said the results indicated that both LR1 and antibiotics increased body weight of piglets at day 42, but the slight increases after long-term feeding were not significant at slaughter.
They saw that LR1 improved pork quality compared to antibiotics by decreasing drip loss and shear force, increasing inosinic acid and glutamic acid that may improve flavor, and altering muscle fiber characteristics.
They said the antibiotics decreased pork quality by increasing drip loss, shear force, and altering myofiber characteristics including diameter, cross-sectional area and myosin heavy chain isoforms compared to LR1.
“Pigs fed antibiotics had lower muscle contents of free glutamic acid, inosinic acid, and higher glutamine compared to pigs fed the controls and LR1 diets. Furthermore, antibiotics decreased free isoleucine, leucine, methionine in LT compared to the control.
“Compared to antibiotics, LR1 likely improved protein synthesis by modulating expression of amino acid transport and ribosomal protein S6 kinase 1 (S6K1) genes, and altered fatty acid profile by regulating metabolic pathways,” they concluded.
Source: Meat Science
Title: Effect of long-term dietary probiotic Lactobacillus reuteri 1 or antibiotics on meat quality, muscular amino acids and fatty acids in pigs
DOI: https://doi.org/10.1016/j.meatsci.2020.108234
Authors : Z Tian, Y Cui, H Lu, G Wang, X Ma