Thirteen reference genes were investigated to determine their stability to be used as a housekeeping in gene expression studies in skeletal muscle of chickens. Five different algorithms were used for ranking of reference genes and results suggested that individual rankings of the genes differed among them. The stability of the expression of reference genes were validated using samples obtained from the Pectoralis major muscle in chicken. Samples were obtained from chickens in different development periods post hatch and under different nutritional diets. For gene expression calculation the ΔΔCt approach was applied to compare relative expression of pairs of genes within each of 52 samples when normalized to mitochondrially encoded cytochrome c oxidase II (MT-CO2) target gene. Our findings showed that hydroxymethylbilane synthase (HMBS) and hypoxanthine phosphoribosyl transferase 1 (HPRT1) are the most stable reference genes while transferrin receptor (TFRC) and beta-2-microglobulin (B2M) ranked as the least stable genes in the Pectoralis major muscle of chickens. Moreover, our results revealed that HMBS and HPRT1 gene expression did not change due to dietary variations and thus it is recommended for accurate normalization of RT-qPCR data in chicken Pectoralis major muscle.

Studies have shown that intramuscular adipogenesis and fibrogenesis may concomitantly occur in skeletal muscle of beef cattle. Thus, we hypothesized that the discrepancy of intramuscular fat content in beef from Nellore and Angus was associated with differences in intramuscular adipogenesis and fibrogenesis during the finishing phase. To test our hypothesis, longissimus muscle samples of Nellore (n = 6; BW = 372.5 ± 37.3 kg) and Angus (n = 6; BW = 382.8 ± 23.9 kg) cattle were collected for analysis of gene and protein expression, and quantification of intramuscular fat and collagen. Least-squares means were estimated for the effect of Breed and differences were considered at P ≤ 0.05. A greater intramuscular fat content was observed in skeletal muscle of Angus compared to Nellore cattle (P≤0.05). No differences were observed for mRNA expression of lipogenic and lipolytic markers ACC, FAS, FABP4, SERBP–1, CPT–2, LPL, and ACOX (P > 0.05) in skeletal muscle of Nellore and Angus cattle. Similarly, no differences were observed in mRNA expression of adipogenic markers Zfp423, PPARγ, and C/EBPα (P>0.05) However, a greater PPARγ protein content was observed in skeletal muscle of Angus compared to Nellore cattle (P≤0.05). A greater abundance of adipo/fibrogenic cells, evaluated by the PDGFRα content, was observed in skeletal muscle of Angus than Nellore cattle (P≤0.05). No differences in fibrogenesis were observed in skeletal muscle of Angus and Nellore cattle, which is in accordance with the lack of differences in intramuscular collagen content in beef from both breeds (P>0.05). These findings demonstrate that difference in intramuscular fat content is associated with a slightly enhanced adipogenesis in skeletal muscle of Angus compared to Nellore cattle, while no difference in fibrogenesis.

The efficiency of livestock production has been largely demanded by population growth, in addition to cost reduction, food safety, and quality. The biggest challenges for the meat industry are to produce good quality meat, which meets the global demand and causes less environmental impact as possible. One of the ways to reach those goals is to shorten the cycle of animal production.

We aimed to investigate the effects of maternal protein restriction during mid-gestation on the skeletal muscle composition of the offspring. In the restriction treatment (RES, n = 9), cows were fed a basal diet, while in the control (CON, n = 9) group cows received the same RES diet plus the protein supplement during mid-gestation (100–200d). Samples of Longissimus dorsi muscle were collected from the offspring at 30d and 450d postnatal. Muscle fiber number was found to be decreased as a result of maternal protein restriction and persisted throughout the offspring’s life (p < 0.01). The collagen content was enhanced (p < 0.05) due to maternal protein restriction at 30d. MHC2X mRNA expression tended to be higher (p = 0.08) in RES 30d offspring, however, no difference (p > 0.05) was found among treatments at 450d. Taken together, our results suggest that maternal protein restriction during mid-gestation has major and persistent effects by reducing muscle fiber formation and may slightly increase collagen accumulation in the skeletal muscle of the offspring. Although maternal protein restriction may alter the muscle fiber metabolism by favoring the establishment of a predominant glycolytic metabolism, the postnatal environment may be a determinant factor that establishes the different proportion of muscle fiber types.

Twenty-four pregnant Nellore cows were randomly assigned into 2 feeding level groups (control [CTL]; fed 1.0 times the maintenance requirement; n = 12; and overnourished [ON]; fed at 1.5 times the maintenance requirement; n = 12) to evaluate effects of maternal overnutrition on fetal skeletal muscle development. Cows were slaughtered at 135, 190, and 240 d of gestation and samples of fetal LM were collected for analysis of mRNA expression analysis and for histological evaluation of collagen content and number of muscle cells. There was no interaction between gestational period and maternal nutrition for the variables evaluated (P > 0.05). The mRNA expression of Cadherin-associated protein, β 1 (β-catenin) tended to be greater in fetuses from ON cows (P = 0.08), while myogenic differentiation 1 (MyoD; P = 0.56), myogenin (MyoG; P = 0.70), and the number of muscle cells (P = 0.90) were not affected by maternal overnutrition. Gestational period did not affect the mRNA expression of β-catenin (P = 0.60) and MyoG (P = 0.21). The mRNA expression of MyoD tended to increase with days of gestation (P = 0.06). The mRNA expression of zinc finger protein 423 (Zfp423; P < 0.0001), C/EBPα (P = 0.01), and PPARγ (P < 0.0001) were enhanced in ON fetuses. No effects of days of gestation were observed for mRNA expression of Zfp423 (P = 0.75) and C/EBPα (P = 0.48). The mRNA expression of PPARγ in fetuses at 190 d of gestation tended to be greater than those at 135 and 240 d of gestation (P = 0.06). The mRNA expression of transforming growth factor β (TGF-β; P < 0.0001), collagen type III, α I (COL3A1; P < 0.0001), and collagen content (P = 0.01) were increased in ON fetuses. Gestational period did not affect the mRNA expression of collagen type I, α I (COL1A1; P = 0.65). The mRNA expression of COL3A1 (P = 0.09) in fetuses at 190 d of gestation tended to be greater than fetuses at 135 and 240 d of gestation. The mRNA expression of TGF-β in fetuses at 190 d of gestation was greater than in fetuses at 135 d of gestation (P = 0.03), and the values observed in fetuses at 240 d of gestation did not differ from the other gestational time points. The least value of collagen content (P = 0.01) was observed in fetuses at 135 d of gestation, and no differences were observed among the other gestational time points. These data shows that maternal overnutrition enhances fibrogenesis and likely adipogenesis without compromising myogenesis in fetal skeletal muscle of cattle.

This meta-analysis aimed to identify knowledge gaps in the scientific literature on future fetal-programming studies and to investigate the factors that determine the performance of beef cows and their offspring. A dataset composed of 35 publications was used. The prenatal diet, body weight (BW), average daily gain (ADG) during pregnancy, and calf sex were elicited as possible modulators of the beef cows and their offspring performance. Then, the correlations between these variables and the outcomes of interest were investigated. A mixed multiple linear regression procedure was used to evaluate the relationships between the responses and all the possible explanatory variables. A knowledge gap was observed in studies focused on zebu animals, with respect to the offspring sex and the consequences of prenatal nutrition in early pregnancy. The absence of studies considering the possible effects promoted by the interactions between the different stressors’ sources during pregnancy was also detected. A regression analysis showed that prenatal diets with higher levels of protein improved the ADG of pregnant beef cows and that heavier cows give birth to heavier calves. Variations in the BW at weaning were related to the BW at birth and calf sex. Therefore, this research reinforces the importance of monitoring the prenatal nutrition of beef cows.