Proteome basis for the biological variations in color and tenderness of longissimus thoracis muscle from beef cattle differing in growth rate and feeding regime.

The proteome basis for the biological variations in color and tenderness of longissimus thoracis muscle from ½ Angus (Bos taurus taurus) × ½ Nellore (Bos taurus indicus) crossbred steers was evaluated in a completely randomized experimental design consisting of four treatments (n = 9 per treatment): 1) feedlot finished, high growth rate (FH); 2) feedlot finished, low growth rate (FL); 3) pasture finished, high growth rate (PH); and 4) pasture finished, low growth rate (PL). The following comparisons were made to evaluate the effects of finishing systems and growth rates on muscle proteome: 1) FH × PL; 2) FL × PH; 3) FH × FL; and 4) PH × PL. Sixteen protein spots were differentially abundant among these comparisons (P ≤ 0.05), which were distinguished in two major clusters, energy metabolism- and muscle structure-related proteins that impacted glycolysis, carbon metabolism, amino acid biosynthesis and muscle contraction pathways (FDR ≤ 0.05). For FH × PL comparison, triosephosphate isomerase (TPI), phosphoglucomutase-1 (PGM1) and phosphoglycerate kinase 1 (PGK1) were overabundant in FH beef whereas troponin T (TNNT3), α-actin (ACTA1) and myosin regulatory light chain 2 (MYLPF) were overabundant in PL beef. For the FL × PH comparison, PGM1, phosphoglycerate mutase 2 (PGAM2) and annexin 2 (ANXA2) were overabundant in PH beef. For the FH × FL comparison, AMP deaminase (AMPD1) and serum albumin (ALB) were overabundant in FH beef whereas glycogen phosphorylase (PYGM) was overabundant in FL beef. For the PH × PL comparison, myoglobin (MB) was overabundant in PH beef whereas PYGM and MYLPF were overabundant in PL beef. In non-aged beef, L* was positively correlated with PGM1 (r = 0.54) while tenderness was negatively correlated with PGAM2 (r = -0.74) and ANXA2 (r = -0.60). In 7-d aged beef, color attributes (L*, a* and b*) were positively correlated with PGM1 (r = 0.67, 0.64 and 0.64, respectively) while tenderness was negatively correlated with TNNT3 (r = -0.57), PGK1 (r = -0.52) and MYLPF (r = -0.66). Therefore, finishing systems and growth rate affected the muscle proteome profile, which was related to beef color and tenderness. Additionally, these results suggest potential biomarkers for beef color (PGM1 and PGAM2) and tenderness (ANXA2, MYLPF, PGK1 and TNNT3).

Effect of different selenium sources and concentrations on glutathione peroxidase activity and cholesterol metabolism of beef cattle.

The objective of this study was to investigate the effects of different Se sources and concentrations on glutathione forms and cholesterol metabolism in beef cattle. Sixty-three Nellore bulls (412 ± 19 kg body weight (BW); 24 mo old) were randomly assigned to a completely randomized design in a 2 × 3 + 1 factorial arrangement (63 pens; one animal/pen) with two Se sources (sodium selenite, ING and Se-yeast, ORG), three concentrations (0.3, 0.9, and 2.7 mg supplemental Se/kg dry matter (DM)), and control treatment (without Se supplementation) fed for 90 d. Blood samples were collected on day 0, 28, 56, and 84. Muscle and liver samples were collected at harvest. Hepatic GSSG (P = 0.004), GSH/GSSG ratio (P = 0.030), and GSH-Px (P = 0.004) were affected by Se source × concentration interaction. Oxidized glutathione was higher in the ORG group vs. ING at concentration 2.7 mg supplemental Se/kg DM, but at 0.3 mg supplemental Se/kg DM the ING group was higher than ORG. The liver GSH-Px activity was higher in the ORG group vs. ING at concentration 0.9 and 2.7 mg supplemental Se/kg DM. The GSH/GSSG ratio was the highest in animals fed 0.3 mg supplemental Se/kg DM of ORG. Selenium liver concentration increased linearly with the supplemental Se concentration in the diet (y = 0.0583 + 0.4254x, R2 = 0.92, P < 0.0001), regardless of source. Total meat cholesterol was greater (P < 0.001) in CON (control) vs. SUP (supplemented, regardless source) group. The muscle GSH-Px activity was higher (P < 0.001) in SUP vs. CON and increased (P < 0.004) with increasing supplemental Se concentrations. There was an increase on very low-density lipoprotein (VLDL), glucose, and triglycerides in ORG vs. ING (P ≤ 0.035). In general, serum Se was higher (P < 0.001) in SUP vs. CON and increased with increasing supplemental Se concentration. Lastly, the 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGCR) concentration was lower (P = 0.002) in SUP (0.39 ng/mL) vs. CON (0.55 ng/mL). Selenium supplementation with different sources and concentrations has the potential to affect cholesterol metabolism by affecting GSH/GSSG ratio, GSH-Px, and the HMGCR.

Effects of Feeding Increasing Levels of Yerba Mate on Lamb Meat Quality and Antioxidant Activity.

The present study investigated the inclusion of yerba mate extract (YME) in the lamb's diet on meat quality traits, antioxidant activity, and shelf-life. Thirty-six lambs were distributed according to a block design with the following groups: control group without YME (0%) and three treatment groups with 1, 2, and 4% YME inclusion in the dry matter. The animals were fed these diets for 53 days. Samples were collected from the Longissimusthoracis (LT) muscle to analyze antioxidant activity and meat quality. Samples were placed on a counter display simulating a retail environment for 0, 3, and 6 days at 4 ± 2 °C. All data were analyzed using a MIXED model with orthogonal contrasts. Inclusion of 1 and 4% YME in the diet changed the yellow (b*) and the chroma (C*) of the meat (p ≤ 0.05). The pH, colour, thiobarbituric acid reactive substances, and carbonyl values were influenced by the retail display time for all the evaluated treatments (p ≤ 0.03). However, neither diet nor the retail display time influenced the oxidation of proteins or the antioxidant enzyme activities of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPX) and glutathione activity (GSH) in meat. Therefore, the inclusion of 4% YME showed positive results in the yellow and colour stability parameters of the meat without increasing the lipid peroxidation values or altering the normal meat quality parameters in lambs.

Liver proteomics unravel the metabolic pathways related to Feed Efficiency in beef cattle.

Improving nutrient utilization efficiency is essential for livestock, given the current scenario of increasing demand for animal protein and sustainable resource use. In this context, understanding the biology of feed efficiency (FE) in beef cattle allows the development of markers for identification and selection of best animals for animal production. Thus, 98 young Nellore bulls were evaluated for FE and at the end of the experiment liver samples from six High Feed Efficient (HFE) and six Low Feed Efficient (LFE) animals were collected for protein extraction, digestion and analysis by HPLC-MS/MS. Data were analyzed for differential abundant proteins (DAPs), protein networks, and functional enrichment. Serum endotoxin was also quantified. We found 42 DAPs and 3 protein networks significantly related to FE. The main pathways associated with FE were: microbial metabolism; biosynthesis of fatty acids, amino acids and vitamins; glycolysis/gluconeogenesis; xenobiotic metabolism and; antigen processing and presentation. Serum endotoxins were significantly higher in LFE animals supporting the results. Therefore, the findings presented here confirmed the altered hepatic metabolism and pronounced hepatic inflammation in LFE animals supporting that the increased bacterial load is at least in part responsible for the hepatic lesions and inflammation in LFE animals.

Proteome changes of beef in Nellore cattle with different genotypes for tenderness.

In the present study, 155 Nellore cattle were genotyped for the CAPN4751 and UOGCAST polymorphisms and phenotyped for shear force (SF) at 1, 7 and 14days aging. The effects of different genotypic combinations were evaluated on the Longissimus muscle proteomic profile using 2DE and mass spectrometry. A significant association was found between genotypes for UOGCAST and CAPN4751 and meat tenderness. The CC genotype for both markers was favorable for lesser shear force than TT. A total of 40 spots showed significant differential expression profiles (P<0.05), of which eight had a main effect for the CAPN4751 marker, 11 for UOGCAST, two for both markers, and 19 had interactions between markers, including myosin (MYL1, MYL2, MYLPF and MYL6B), actin (ACTA1 and CAPZß), troponin (TNNT1 and TNNT3) and heat shock proteins (HSPB6, HSPB1 and HSP70-2). The results demonstrated that UOGCAST and CAPN4751 genotypes led to variability on the expression of proteins that are involved in muscle metabolism, and consequently affect meat tenderness.