Fetal Programming and Its Effects on Meat Quality of Nellore Bulls.

This work aimed to evaluate the effects of prenatal nutritional stimulation at different pregnancy stages on carcass traits and meat quality in bovine progeny. For this purpose, 63 Nellore bulls, born from cows submitted to three nutritional plans, were used: not programmed (NP), which did not receive protein supplementation; partially programmed (PP), which had protein-energy supplementation (0.3% of mean body weight of each batch) only in the final third of pregnancy; and full programming (FP), which received supplementation (0.3% of mean body weight of each batch) throughout pregnancy. The averages of parameters were submitted to the ANOVA, and the supplementation periods, which were different when p value < 0.05, were compared. Carcass weights and rib eye area (REA) did not differ between treatments (p > 0.05), but subcutaneous fat thickness (SFT) showed a tendency (p = 0.08) between groups. For lipids and marbling, no differences were found (p > 0.05). In the analyses of maturation time and shelf life, no difference was observed between treatments. However, there was a tendency between treatments at 14 days of maturation time for cooking loss (CL) (p = 0.08). Treatments did not affect shear force in the progenies (p > 0.05). Fetal programming had no effect on the meat quality of Nellore bulls.

Genetic parameters associated with meat quality of Nellore cattle at different anatomical points of longissimus: Brazilian standards.

The present study estimated genetic parameters and evaluated the genetic and phenotypic correlations between meat quality characteristics of Nellore cattle evaluated at different anatomical points of the longissimus. Data from 1329 Nellore young bulls were used to evaluate, in the 5th and 12th ribs, marbling score (MAR), shear force (SF), cooking weight losses (CWL) and intramuscular fat (IMF). In addition, the subcutaneous fat thickness was measured at the 12th rib (SFT12) and between the last lumbar and the first sacral vertebrae (SFTLR), in the separation of loin and round. Results yielded moderate heritability coefficients for evaluated characteristics, except CWL. High genetic correlations (0.61) were found between measurements of SFT12 and SFTLR. MAR, IMF and SF were evaluated at the 5th and 12th rib. Meat quality and subcutaneous fat thickness measured at different anatomical points of the longissimus are genetically correlated and can be used in genetic selection programs to improve meat quality characteristics in Nellore cattle.

Predicting the shear value and intramuscular fat in meat from Nellore cattle using Vis-NIR spectroscopy.

Visible and near-infrared spectroscopy (Vis-NIRS) was tested for its effectiveness in predicting intramuscular fat (IMF) and WBSF in Nellore steers. Beef samples from longissimus thoracis, aged for either 2 or 7 days, had their spectra collected for wavelengths ranging from 400 to 1395 nm. Partial least squares regression models were developed for each trait. Determination coefficients of calibration models for WBSF ranged from 0.17 to 0.53. Considering WBSF in samples aged for 2 days, Vis-NIR correctly classified 100% of tough samples (>45 N), but wrongly classified all tender samples (≤45 N) as tough. Determination coefficients of calibration models for IMF ranged from 0.12 to 0.14. Vis-NIRS is a useful tool for identifying tough beef, but it is less effective in predicting tender samples and IMF. Additional studies are necessary to generate more robust models for the prediction of intramuscular fat in intact meat samples of Nellore cattle.

Shear force analysis by core location in Longissimus steaks from Nellore cattle using hyperspectral images - A feasibility study.

Industry requires non-destructive real-time methods for quality control of meat in order to improve production efficiency and meet consumer expectations. Near Infrared Hyperspectral Images were used for tenderness evaluation of Nellore beef and the construction of tenderness distribution maps. To investigate whether the selection of the region of interest (ROI) in the image at the exact location where the shear force core was collected improves tenderness prediction and classification models, 50 samples from Longissimus muscle were imaged (1000-2500 nm) and shear force were measured (Warner-Bratzler). The data were analyzed by chemometric techniques (Partial Least Squares together with discriminant analysis - PLS-DA). Classification models using local ROI presented better performance than the ROI models of the whole sample (external validation sensitivity for the tough class = 33% and 70%, respectively), but none could be considered as successful model. However, the more general model had better performance in the tenderness distribution maps, with 72% of predicted images correctly classified.

Phosphofructokinase and mitochondria partially explain the high ultimate pH of broiler pectoralis major muscle.

During postmortem metabolism, muscle pH gradually declines to reach an ultimate pH near 5.6 across most meat species. Yet, broiler pectoralis major (P. major) muscle generates meat with high ultimate pH (pH ∼ 5.9). For better understanding of the underlying mechanism responsible for this phenomenon, we evaluated the involvement of breast muscle chilling on the extent of postmortem metabolism. Broiler breast muscles were either subjected to chilling treatment (control) or left at room temperature (RT) for 120 min. P. major muscle from the RT treatment had lower ultimate pH, greater glycogen degradation and lactate accumulation. While these findings suggest that carcass chilling can contribute to the premature termination of postmortem metabolism, chilling did not fully explain the high ultimate pH of P. major muscle. Our results also revealed that glucose-6-phosphate (G6P) was very low at 24 h, and therefore we hypothesized that G6P was limiting. To test this hypothesis, muscle samples from P. major and porcine longissimus lumborum (LL) muscle were homogenized into a reaction buffer that mimics postmortem glycolysis with or without 0.5 mg/mL isolated mitochondria. While samples containing porcine LL muscle reached the normal level of ultimate pH, P. major muscle samples reached a value similar to that observed in vivo even in the presence of excess G6P, indicating that G6P was not limiting. Mitochondria enhanced the glycolytic flux and pH decline in systems containing muscle from both species. More importantly, however, was that in vitro system containing chicken with mitochondria reached pH value similar to that of samples containing LL muscle without mitochondria. To investigate further, phosphofructokinase (PFK) activity was compared in broiler P. major and porcine LL muscle at different pH values. PFK activity was lower in P. major muscle at pH 7, 6.5, and 6.2 than LL muscle. In conclusion, carcass chilling can partially contribute to the high ultimate pH of broiler P. major muscle, while low PFK activity and mitochondria content limit the flux through glycolysis.

Roughage levels impact on performance and carcass traits of finishing Nellore cattle fed whole corn grain diets.

This study was carried out to evaluate the effects of chopped hay levels in high-concentrate diets with whole corn grain (WCG) on performance and carcass traits of finishing Nellore cattle. One hundred and eight 24-month-old Nellore intact males (453 ± 75 kg) were fed one of three WCG-based diets that differed in roughage level: without roughage (WCG), with 5% chopped hay included (WCG5), or with 12% chopped hay included (WCG12) in a block design (based on initial body weight) for 86 days. Animals fed WCG5 or WCG12 had significantly improved on final body weight, dry matter intake, average daily gain, feed efficiency, hot carcass weight, and dressing percentage when compared to those fed WCG. The Longissimus muscle area (P = 0.1108), backfat thickness (BFT; P = 0.6089), and rump fat thickness (P = 0.1798) were not affected by roughage levels. Therefore, using WCG diets without roughage negatively affects the performance of feedlot Nellore cattle but does not affect carcass traits and does lead to the minimum BFT required by the industry.

Divergent temperaments are associated with beef tenderness and the inhibitory activity of calpastatin.

Ninety-six feedlot-finished Nellore steers were used to verify the relationship between temperament indicators and meat tenderization. Temperament index (TI), chute score (CS), and average of exit velocity (EV) with CS (AT) presented low positive correlations (P≤0.05) with shear force, either at 2 or 16days postmortem (WBSF-16). The rectal temperature was consistently correlated with temperament indicators (TI, CS, and AT) and WBSF-16. Two groups (n=12) representing the most tender (39.2±4.9N) and most tough meat (94.1±11.8N), based on WBSF-16, were compared for temperament, and calpastatin activity (CASTa) was determined 48h postmortem. The tender group presented lower EV, TI, and AT (P≤0.05). The tender group exhibited lower (P≤0.05) CASTa in the triceps brachii muscle, but there was no difference in CASTa in the longissimus lumborum muscle between WBSF groups. Meat tenderness and inhibitory activity of calpastatin may be associated with divergent temperament indices in zebu cattle.

Copy number variations and genome-wide associations reveal putative genes and metabolic pathways involved with the feed conversion ratio in beef cattle.

The use of genome-wide association results combined with other genomic approaches may uncover genes and metabolic pathways related to complex traits. In this study, the phenotypic and genotypic data of 1475 Nellore (Bos indicus) cattle and 941,033 single nucleotide polymorphisms (SNPs) were used for genome-wide association study (GWAS) and copy number variations (CNVs) analysis in order to identify candidate genes and putative pathways involved with the feed conversion ratio (FCR). The GWAS was based on the Bayes B approach analyzing genomic windows with multiple regression models to estimate the proportion of genetic variance explained by each window. The CNVs were detected with PennCNV software using the log R ratio and B allele frequency data. CNV regions (CNVRs) were identified with CNVRuler and a linear regression was used to associate CNVRs and the FCR. Functional annotation of associated genomic regions was performed with the Database for Annotation, Visualization and Integrated Discovery (DAVID) and the metabolic pathways were obtained from the Kyoto Encyclopedia of Genes and Genomes (KEGG). We showed five genomic windows distributed over chromosomes 4, 6, 7, 8, and 24 that explain 12 % of the total genetic variance for FCR, and detected 12 CNVRs (chromosomes 1, 5, 7, 10, and 12) significantly associated [false discovery rate (FDR) < 0.05] with the FCR. Significant genomic regions (GWAS and CNV) harbor candidate genes involved in pathways related to energetic, lipid, and protein metabolism. The metabolic pathways found in this study are related to processes directly connected to feed efficiency in beef cattle. It was observed that, even though different genomic regions and genes were found between the two approaches (GWAS and CNV), the metabolic processes covered were related to each other. Therefore, a combination of the approaches complement each other and lead to a better understanding of the FCR.

Infrared thermography as a tool to evaluate body surface temperature and its relationship with feed efficiency in Bos indicus cattle in tropical conditions.

The aims of this study were to evaluate the use of infrared thermography (IRT) images as a tool for monitoring body surface temperature and to study its relationship with residual feed intake (RFI) in Nellore cattle. We also evaluated IRT as an indicator of feed efficiency in Bos indicus cattle. In this study, 144 Nellore steers were fed high-concentrate diets for 70 days to evaluate feedlot performance. We examined nine animals classified as high RFI and nine animals classified as low RFI by measuring rectal temperature (RT), respiratory frequency (RF), and IRT in the front, eye, ocular area, cheek, flank, ribs, rump, and front feet. The measurements were taken at 0700, 1200, and 1600 hours. The IRT temperatures measured at the eye, cheek, flank, ribs, rump, and front feet were positively associated with RF and RT. These results indicate that increases in the temperatures are associated with increased RF and RT. There was an effect in the RFI group in the front region where IRT correlates with RT. The front IRT for high-RFI cattle was lower (P < 0.01) than that for low-RFI cattle. The higher skin temperature measured by IRT for animals in the RFI group may be related to improved efficiency of thermoregulatory mechanisms because the RT remained lower in the low-RFI group. IRT can be used in the head for studies related to RFI in beef cattle.

Predicting pork quality using Vis/NIR spectroscopy.

Visible and near-infrared reflectance spectroscopy (Vis/NIRS) was used to predict the ultimate pH (pHu), color, intramuscular fat (IMF) and shear force (WBSF) of pork samples and to build classifiers capable of categorizing the samples by tenderness (tender or tough) and juiciness (juicy and dry). Spectra were collected from 400 to 1495nm, and 200 data points were generated for every sample (n=134). Sixty-seven percent of the sample set was used for calibration, and 33% was used for validation. Partial least squares (PLS) calibration models were developed for each characteristic measured. A coefficient of determination (R(2)) and residual prediction deviation (RPD) were used to evaluate the accuracy of the calibration models. The pHu and color prediction models developed in this study fit this classification, indicating that these predictive models can be used to predict quality traits of intact pork samples. The Vis/NIRS offered great potential for correctly classifying pork Longissimus into two tenderness and two juiciness classes.

Effects of processing corn on the carcass traits and meat quality of feedlot lambs.

The objectives of this study were to evaluate and compare the effect of the corn grain processing (whole grain, dry beans ground, and wet grain) on carcass characteristics and meat quality in lambs. Twenty-two Dorper vs. Santa Inês uncastrated lambs (27 ± 4 kg BW; ±3 months old) were distributed in a randomized complete block (initial BW). The diets were composed of 20 % protein-mineral pellet, 5 % hay, and 75 % corn in the form of whole grain, ground grain, or wet grain. The harvest weight of animals fed whole corn (50.2 kg) and ground (49.03 kg) were equal and higher than the moisture corn fed lambs (44.89 kg); therefore, the same differences were expected to be seen in the cold vs hot carcass comparison. However, there was no difference between treatments comparing hot or cold carcass performance, averaging 47 and 46 %, respectively. Also unaffected by the treatments were subcutaneous fat thickness values, loin muscle area, pH, temperature, drip loss, water loss by cooking, color, and tenderness. It can be concluded that the shape and size of corn grain in diets of high concentrate resulted in no measurable influence on carcass traits, but whole grain is more easily managed by the producer.

Effects of supplementation with two sources and two levels of copper on meat lipid oxidation, meat colour and superoxide dismutase and glutathione peroxidase enzyme activities in Nellore beef cattle.

In the present study, thirty-five Nellore bulls were used to determine the effects of two levels and two sources (organic and inorganic) of Cu supplementation on the oxidative stability of lipids, measured by the thiobarbituric acid-reactive substance (TBARS) test, meat colour and superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) enzyme activities. The following treatments were used: (1) control (C) - basal diet without supplementation of Cu (7 mg Cu/kg DM); (2) I10 - basal diet supplemented with 10 mg Cu/kg DM in the form of copper sulphate (inorganic form); (3) I40 - basal diet supplemented with 40 mg Cu/kg DM in the form of copper sulphate; (4) O10 - basal diet supplemented with 10 mg Cu/kg DM in the form of copper proteinate (organic form); (5) O40 - basal diet supplemented with 40 mg Cu/kg DM in the form of copper proteinate. Lipid oxidation was determined in meat samples exposed to display, modified atmosphere (MA) and vacuum packaging (VC) conditions and in liver samples using the TBARS test. These samples were also evaluated for meat discolouration after exposure to air. The activities of SOD and GSH-Px enzymes were determined in liver samples. In display, MA and VC conditions, the TBARS values of samples from animals supplemented with 40 mg Cu/kg DM were lower than those of samples from control animals. There was no effect of treatment on the colour variables (L*, a*, b*). There was also no significant effect of treatment on hepatic TBARS concentrations and GSH-Px activity. Supplementation with Cu at 40 mg/kg, regardless of the source, induced higher hepatic SOD activity compared with the control treatment. In conclusion, Cu supplementation improved the oxidative stability of lipids in samples exposed to display, MA and VC conditions, demonstrating the antioxidant effect of this mineral.