Effects of beef carcass size, and subsequent aging time, on yield and color characteristics of top round steaks

Variation in cut size and weight of fabricated subprimals is a challengeof increased beef carcass weights. Subsequently, variation in carcass size hasresulted in consistency challenges during retail display. Theobjective of this study was to assess the retail shelf-life of commerciallyavailable top rounds from varying carcass weights. In the current study, 21industry average weight (AW, 340-409 kg; no industry discount) beef carcassesand 21 oversized (OS, exceeding 454 kg; receive a discount) beef carcasses wereevaluated. Carcasses were selected at a commercial beef packing plant, wherethe left and right (paired) top round subprimals of each carcass were procured.Paired top rounds were assigned to a short (8d), average (23d), or extended(42d) postmortem aging period. After wet-aging, subprimals were fabricated intosteaks for additional analysis. Steaks were evaluated as whole top round steaksor further fabricated into “superficial” and “deep” portions at 5.08 cm fromthe superficial edge of the Semimembranosus and the Adductor muscle.Top rounds and steaks from OS carcasses were larger (P < 0.01) thanthose from AW carcasses. Quantitative color of the anatomically deep locationsof the OS steaks had the greatest mean L* (lightness; P < 0.01), a*(redness; P < 0.01) and b* (yellowness; P < 0.01) values. Extendingthe aging timeline increased L* (lightness; P < 0.01), decreased a*(redness; P < 0.01), and decreased b* (yellowness; P <0.01). Alternative top round steak fabrication which separates the deep andsuperficial anatomical locations could be an effective means of providing moreuniform steaks. 

Predicting Beef Carcass Fatness Using an Image Analysis System

The amount and distribution of subcutaneous fat is an important factor affecting beef carcass quality. The degree of fatness is determined by visual assessments scored on a scale of five fatness levels (the SEUROP system). New technologies such as the image analysis method have been developed and applied in an effort to enhance the accuracy and objectivity of this classification system. In this study, 50 young bulls were slaughtered (570 ± 52.5 kg) and after slaughter the carcasses were weighed (360 ± 33.1 kg) and a SEUROP system fatness score assigned. A digital picture of the outer surface of the left side of the carcass was taken and the area of fat cover (fat area) was measured using an image analysis system. Commercial cutting of the carcasses was performed 24 h post-mortem. The fat trimmed away on cutting (cutting fat) was weighed. A regression analysis was carried out for the carcass cutting fat (y-axis) on the carcass fat area (x-axis) to establish the accuracy of the image analysis system. A greater accuracy was obtained by the image analysis (R2 = 0.72; p < 0.001) than from the visual fatness scores (R2 = 0.66; p < 0.001). These results show the image analysis to be more accurate than the visual assessment system for predicting beef carcass fatness.

Occurrence of Virulence Genes and Antimicrobial Resistance of E. coli O157:H7 Isolated from the Beef Carcass of Bahir Dar City, Ethiopia

E. coli O157:H7 is one of the most virulent foodborne pathogens. The aim of this study was to isolate E. coli O157:H7, determine virulence genes carried by the organism, and assess the antimicrobial susceptibility pattern of the isolates from beef carcass samples at Bahir Dar city. Swab samples (n = 280) were collected from the carcass of cattle slaughtered at the abattoir and processed using sorbitol MacConkey agar supplemented with cefixime telluride and confirmed with latex agglutination test. A polymerase chain reaction was performed on isolates for the detection of virulence genes stx1, stx2, hlyA, and eae. Antimicrobial susceptibility testing was performed using the disk diffusion method. Of 280 samples processed, 25 (8.9%) isolates were positive. Out of 25 isolates subjected for molecular detection, 8 (32%) and 14 (56%) isolates possessed stx1 and stx2 genes, respectively; from those, 5 (20%) isolates had both genes for the production of Shiga toxins. Compared from other virulent genes relatively higher proportion of 18 (72%) isolates carried the hlyA gene. Only 5 (2%) isolates were positive for eae. Resistance was detected in all 25 (100%) isolates and 3 (12%) against clindamycin and trimethoprim, respectively. This study result highlights the potential threat to public health. The abattoir workers need to be aware about the pathogen and should follow appropriate practices to prevent contamination of meat intended for human consumption.

An investigation into the anaerobic spoilage microbiota of beef carcass and rump steak cuts using high- throughput sequencing

The presence of anaerobic microflora on fresh beef carcass and rump steaks, which may contribute to meat spoilage, was explored in this study. A total of 120 carcass and 120 rump steak swabs were collected immediately after slaughtering and boning, respectively from five meat plants, anaerobically incubated and enriched d at 4°C for 3 weeks. This was followed by DNA extraction and 16S rRNA amplicon sequencing using the Illumina MiSeqTM, with subsequent bioinformatics analysis. The enriched microbiota of the samples was classified and grouped into 149 operational taxonomic units (OTUs). The microbiota recovered from both sample types consisted mainly of Carnobacterium, with an average relative abundance of 28.4% and 32.8% in beef carcasses and beef rump steaks, respectively. This was followed by Streptococcus, Serratia, Lactococcus, Enterococcus, Escherichia-Shigella, Raoultella and Aeromonas ranging from 1.5–20% and 0.1–29.8% in enriched carcasses and rump steak swabs, respectively. Trichococcus, Bacteroides, Dysgomonas, Providencia, Paraclostridium and Proteus were also present ranging from 0–0.8% on carcass and 0–1.8% on rump steak swabs, respectively. Alpha and Beta diversity measurements showed limited diversity between the two sample types, but some differences between samples from the beef plants investigated were evident. This study highlights the presence of potential spoilage bacteria, mainly anaerobic genera on and between carcass and rump steaks, as an indication of contamination on and between these samples.

Comparison of a Miniaturized Cassette PCR System with a Commercially Available Platform for Detecting Escherichia coli in Beef Carcass Swabs

Detection sensitivity of cassette PCR was compared with a commercial BAX® PCR system for detection of eae and stx genes in Escherichia coli from 806 beef carcass swabs. Cassette PCR detects multiple genetic markers on multiple samples using PCR and melt curve analysis. Conventional PCR served as a gold standard. Overall, for positive and negative concordance, cassette PCR was 98.6% concordant with conventional PCR, and BAX PCR was 65.4% concordant. Of 806 beef carcass swabs, 339 by cassette PCR and 84 by BAX PCR harbored eae + stx+E. coli. For BAX PCR reactions, 84% of eae+ swabs, 79% of stx+ swabs, and 86% of eae + stx+ swabs were also detected by cassette PCR. For cassette PCR reactions, 457 swabs were eae+ with only 117 scored as eae+ using BAX PCR for 26% positive concordance. For stx primers, cassette PCR scored 480 samples as stx+ but only 215 samples were stx+ by BAX PCR, giving 45% positive concordance. Importantly, cassette PCR scored 339 swabs as harboring eae + stx+ E. coli, but BAX PCR detected only 71 positives giving only 21% positive concordance, with many false negatives. Cassette PCR is a highly sensitive method for detection of STEC genes in E. coli found in carcass swabs.

Assessment of beef carcass contamination with Salmonella and E. coli O 157 in slaughterhouses in Bishoftu, Ethiopia

Background Salmonella and E. coli O157 are common causes of foodborne diseases. Evisceration and de-hiding steps can lead to carcass contamination during slaughter operation. In Ethiopia, information on the association between the presence of these pathogens in the rectal content and/or on the hide of cattle and their presence on the carcass is lacking. Methods The aim of this study was to assess the sources of beef carcass contamination with Salmonella and E. coli O157 during slaughter. Rectal contents and hide- and carcass-swabs (from three sites: foreleg, brisket and hind leg) were collected from 70 beef cattle at two small scale slaughterhouses. Isolates were genotyped by the Pulsed Field Gel Electrophoresis method and tested for resistance against 14 microbial drugs. Results Salmonella was detected at equal proportions (7.1%) in rectal content samples and hide swabs. E. coli O157 was detected in 8.6% of the rectal contents and 4.3% of the hide swabs. The proportion of contaminated carcasses was 8.6% for Salmonella and 7.1% for E. coli O157. Genetic linkage between the Salmonella and E. coli O157 isolates from the rectal contents and/or hides and carcasses were observed only in a few cases (2 and 1 carcasses, respectively) indicating the limited direct transfer of the pathogens from the feces and/or hide to the carcass during slaughter. Most carcasses became positive by cross contamination. All the S. Typhimurium isolates (n = 8) were multidrug resistant being resistant to ampicillin, chloramphenicol, sulfamethoxazole and tetracycline. The two S. Dublin isolates were resistant to colistin. All E. coli O157 isolates were susceptible to the antimicrobials tested. Conclusion The results indicated that cross contamination may be an important source for carcass contamination.

GpNet: Genomic Prediction Network Using Locally Connected Layers in Korean Native Cattle

Background: The use of DNA marker information for the prediction of genetic merit in animal and plant breeding, and susceptibility to disease in human medicine has become widespread. Therefore, an increasing number of methods have been proposed for more accurate and efficient genomic prediction. However, most of the commonly used models for genomic prediction only account for additive effects since most of them are designed based on the linear model. Results: Here, we proposed a GpNet, a deep learning network for genomic prediction in Korean beef cattle. With a locally connected layer, GpNet can estimate LD-block effects of single nucleotide polymorphisms (SNP) with adjacent two or more SNPs closer to 3’-end. This operation is quite similar to how the DNA sequence is used in the translation process in which the RNA polymerase interprets DNA sequence by units of codons to downstream (3’ to 5’). GpNet archived a superior performance than previous state-of-arts methods for beef carcass weight with a predictive ability of 0.721%. GpNet also found two significant quantitative trait locus (QTL) on the regions (bta 6:38464203–39816133, bta 14:25307116–29987025) for carcass weight. However, GpNet showed less performance than linear methods in backfat thickness and eye-muscle area.Conclusions: GpNet outperformed the previous state-of-arts methods for beef carcass weight. However, GpNet cannot achieve superior performance in backfat thickness and eye-muscle area. We noticed that the lack of ability to estimate distant epistasis and dominance was the weakness of GpNet. Therefore, it remains a future research issue to expand GpNet to resolve these flaws and this further study will accelerate the new phase of the genomic prediction.