Lower Marbling Research Articles

Relationships between European carcass evaluation and Meat Standards Australia grading scheme applied to young beef cattle

The European carcass grading scheme (EUROP) places large emphasis on meat yield and therefore on quantitative traits such as carcass conformation and superficial fat coverage. However, it falls short in considering sensory properties and consumer satisfaction. In contrast, the Meat Standards Australia (MSA) grading scheme considers, among others, animals' ossification, marbling, and ultimate pH as primary indicators of beef eating quality. This study aims to characterize MSA carcass grading scheme applied to the Italian beef production system, considering its significant role in European beef market. The study involved 3204 Charolais, Limousin, and crossbred young bulls and heifers slaughtered in a commercial Italian abattoir. Data collection spanned a broad range of variables, including animal characteristics, MSA traits, and EUROP carcass grading traits. Regardless of the sex of the animal, no significant relationship was observed between MSA traits and EUROP carcass grading scores. Factors such as sex, age, and arrival season at the fattening unit significantly affected most of MSA traits. Females had significantly higher marbling score, and lower ossification score and hump height than males. Animals imported in autumn and winter had significantly lower marbling score, but similar ossification score compared to those imported in spring and summer. Older females had the highest marbling scores. While further research is needed to assess whether the MSA grading scheme can be adapted to all different European rearing systems, results of this study are a prelude to the potential benefits that the MSA grading scheme can bring to the European beef industry.

Impact of rumen microbiome on cattle carcass traits

Rumen microbes are crucial in the anaerobic fermentation of plant polysaccharides to produce volatile fatty acids. However, limited information exists about the specific microbial species and strains in the rumen that affect carcass traits, and it is unclear whether there is a relationship between rumen metabolic functions and these traits. This study investigated the relationship between the rumen microbiome and carcass traits in beef cattle using 16S rRNA amplicon and shotgun sequencing. Metagenomic sequencing was used to compare the rumen microbiome between high-carcass weight (HW) and low-carcass weight (LW) cattle, and high-marbling (HM) and low-marbling (LM) cattle. Prokaryotic communities in the rumen of HW vs. LW and HM vs. LM were separated using 16S rRNA amplicon sequencing. Notably, shotgun metagenomic sequencing revealed that HW cattle had more methane-producing bacteria and ciliate protozoa, suggesting higher methane emissions. Additionally, variations were observed in the abundances of certain glycoside hydrolases and polysaccharide lyases involved in the ruminal degradation of plant polysaccharides between HW and LW. From our metagenome dataset, 807 non-redundant metagenome-assembled genomes (MAGs) of medium to high quality were obtained. Among these, 309 and 113 MAGs were associated with carcass weight and marbling, respectively.

PSVI-2 Economic Evaluation of Forage-Fed vs Concentrate-Fed Beef Finishing Systems

Abstract The objective of this study was to determine the price points at which it is more economical to finish beef animals on forage-based or concentrate-based diets. To accomplish this, Hereford steers (n = 21; BW = 444 ± 10 kg) were fed out on one of three diets: a long-stemmed grass hay (HAY, 10.8% CP, 2.11 Mcal ME/kg DM), an alfalfa hay diet (ALF, 20.5% CP, 2.85 Mcal ME/kg DM) or a mixed ration consisting of 30.0% corn silage, 28.0% DDGS, 30.0% rolled corn, 10.5% soybean meal, and 1.5% mineral supplement (CON, 22.0% CP, 2.90 Mcal ME/kg DM). The data were analyzed in SAS v9.4. Animals were evaluated on intake, growth, and performance measures during a 35-day feeding trial. Average daily gain (ADG) and hot carcass weight differed significantly (P < 0.05) between treatments with CON steers gaining 1.47 kg/d with a hot carcass weight of 394.8 kg, ALF steers gaining 0.77 kg/d with a hot carcass weight of 334.7 kg, and HAY steers gaining 0.1 kg/d with a hot carcass weight of 237.4 kg. Dressing percentage was significantly different between all treatments (P < 0.05). The dressing percentage was 58.2%, 54.3%, and 50.6% for CON, ALF, and HAY, respectively. The HAY diet rendered significantly lower marbling scores than ALF or CON (P < 0.05). It was concluded based on carcass quality data that there was no difference in the high-quality forage (ALF) and the concentrate diet (CON) other than diet cost and growth rate. Price per kilogram of gain was $1.42, $1.23, and $14.80 for CON, ALF, and HAY, respectively. Results of this trial are expected to indicate at what price point it becomes more economically effective to finish animals on a high-quality forage or a concentrate-based diet.

Effects of the F94L myostatin gene mutation in beef × dairy crossed cattle on muscle fiber type, live performance, carcass characteristics, and boxed beef and retail cut yields.

Producer live performance data and carcasses from steers (n = 116) resulting from the mating of four Limousin/Angus sires heterozygous for the F94L myostatin mutation to Jersey/Holstein dams were utilized to evaluate the effects of one copy of the F94L allele on live performance, carcass traits and USDA grades, and boxed beef and retail yields. Slaughter data were collected at time of harvest and carcass data were collected 48 hours postmortem. One side from each of the 58 carcasses was fabricated into boxed beef and retail cuts by experienced lab personnel 5-8 d postmortem. One copy of the F94L allele did not affect gestation length, birth weight, percentage of unassisted births, feedlot average daily gain, live weight at harvest, hot carcass weight, or dressing percentage (P > 0.05). Muscle fiber analysis indicated that the increase in muscularity by the F94L allele in the semitendinosus and longissimus was likely due to hyperplasia as there was a 19% increase in the quantity of myosin heavy chain type IIA and IIX fibers in the semitendinosus (P < 0.05) with no effect on muscle fiber size (P > 0.05). Carcasses from steers with one F94L allele had larger ribeye areas (99.2 vs. 92.3 sq.cm.), greater ribeye width:length ratios (0.498 vs. 0.479), lower USDA yield grades (2.21 vs. 2.66), and lower marbling scores (438 vs. 480) (P < 0.05). Additionally, for boxed beef yields, one F94L allele, vs. zero F94L alleles, increased (P < 0.05) 85/15 trimmings (+0.59%), top round (+0.28%), strip loin (+0.12%), eye round (+0.11%), tenderloin (+0.07%), boneless foreshank (+0.07%), cap/wedge (+0.06%), and tri-tip (+0.04%). Overall, carcasses from steers with one F94L allele had a greater boxed beef yield (+1.06%), boxed beef plus 85/15 trimmings yield (+1.65%), and total retail cuts plus ground beef 85/15 yield (+1.78%) than carcasses from steers with zero F94L alleles (P < 0.05). One copy of the F94L allele utilized in beef-on-dairy breeding system had no significant impact on live performance traits but resulted in lower marbling scores and increased muscularity as evidenced through larger, more beef-shaped ribeyes, lower USDA yield grades, and greater carcass cutout yields (both boxed beef and retail yields).

Towards improving classification of Canadian dark-cutting beef carcasses: Consumer sensory evaluation

This study evaluated whether different colour intensities of ribeye steaks from dark-cutting (B4 grade) beef carcasses (Dark–B4DK/Moderate–B4MD) were similar in appearance and eating quality to steaks from normal (N) carcasses of lower marbling grades (AA or A) as assessed by consumers. The B4MDAAA and B4DK/MDAA had similar raw appearance and eating quality to N carcasses with a one quality downgrade for marbling (P > 0.1), potentially supporting a B4MDAAA and B4DK/MDAA re-class to NAA and NA grades, respectively. Cooked B4DKAAA steaks had greater juiciness and tenderness acceptability (P < 0.01) and similar appearance, flavour and overall acceptability and purchase intent compared to NAA steaks (P > 0.1). However, consumers perceived greater marbling and lower colour acceptability (P < 0.01) in raw B4DKAAA compared to NAA steaks, lowering the purchase intent scores of B4DKAAA steaks (P < 0.01). These results suggest merit for continuing a B4DKAAA segregated grade, unless the superior eating quality of B4DKAAA could offset its poorer raw appearance through consumer education or modified atmosphere packaging.

Association between rumen microbiota and marbling grade in Hu sheep.

The marbling fat regulates the flavor of mutton and measures the fat density in the loin eye and is the most important parameter of carcass grading. The objective of this study was to explore the relationship of rumen microbiota and mutton marbling grade. One hundred and eighty-seven feedlot-finished Hu male lambs (Age: 180 day; Final BW: 46.32 ± 6.03 kg) were slaughtered, and ruminal contents and marbling grade were collected. Ruminal microbial DNA extraction and 16S rRNA gene sequencing was performed to investigate microbial composition and to predict microbial metabolic pathways. The animal cohort was then grouped based on marbling grades [low marbling (LM), marbling grade ≤ 1; Medium marbling (MM), 1 < marbling grade ≤ 3; High Marbling (HM), 3 < marbling grade ≤ 5] and intramuscular fat-associated microorganisms were pinpointed using LEfSe and random forest classification model. Intramuscular fat content had significantly differences among the three groups (P < 0.05), and was significantly correlated with VFAs profiling. HM sheep showed a higher abundance of one bacterial taxon (Kandleria), and two taxa were overrepresented in the MM sheep (Pseudobutyrivibrio and Monoglobus), respectively. In addition, the main intramuscular fat deposition pathway was found to involve peroxisome proliferator-activated receptor (PPAR) fatty acid synthesis. By studying the effect of the ruminal microbiome on the marbling of sheep, the present study provides insights into the production of high-quality mutton.

Characterization of novel lncRNA muscle expression profiles associated with meat quality in beef cattle.

The aim of this study was to identify novel lncRNA differentially expressed (DE) between divergent animals for beef tenderness and marbling traits in Nellore cattle. Longissimus thoracis muscle samples from the 20 most extreme bulls (of 80 bulls set) for tenderness, tender (n = 10) and tough (n = 10) groups, and marbling trait, high (n = 10) and low (n = 10) groups were used to perform transcriptomic analysis using RNA‐Sequencing. For tenderness, 29 lncRNA were DE (p‐value ≤ 0.01) in tough beef animals in relation to tender beef animals. We observed that genic lncRNAs, for example, lncRNA_595.1, were overlapping exonic part of the PICK gene, while lncRNA_3097.2 and lncRNA_3129.5 overlapped intronic part of the genes GADL1 and PSMD6. The lncRNA associated with PICK1, GADL1, and PMD6 genes were enriched in the pathways associated with the ionotropic glutamate receptor, gamma‐aminobutyric acid synthesis, and the ubiquitin–proteasome pathway. For marbling, 50 lncRNA were DE (p‐value ≤ 0.01) in high marbling group compared with low marbling animals. The genic lncRNAs, such as lncRNA_3191.1, were overlapped exonic part of the ITGAL gene, and the lncRNA_512.1, lncRNA_3721.1, and lncRNA_41.4 overlapped intronic parts of the KRAS and MASP1 genes. The KRAS and ITGAL genes were enriched in pathways associated with integrin signaling, which is involved in intracellular signals in response to the extracellular matrix, including cell form, mobility, and mediates progression through the cell cycle. In addition, the lincRNAs identified to marbling trait were associated with several genes related to calcium binding, muscle hypertrophy, skeletal muscle, lipase, and oxidative stress response pathways that seem to play a role important in the physiological processes related to meat quality. These findings bring new insights to better understand the biology mechanisms involved in the gene regulation of these traits, which will be valuable for a further investigation of the interactions between lncRNA and mRNAs, and of how these interactions may affect meat quality traits.

Analysis of the Impact of Beef Grading System Reform on the Price of Premium Hanwoo Beef

Korea has been implementing a beef grading system consisting of quality and quantity grades since 1992. The quality grade consists of 1++ (highest), 1+, 1, 2, 3 (lowest) grades and is determined by marbling score (% fat content), meat color, fat color, texture, and maturity. The quantity grade consists of A, B, and C grades and is determined by back-fat thickness, eye muscle area, and carcass weight. The quality grade, mostly determined by the marbling score, is the key factor in determining the price of beef. This pricing mechanism has increased the production costs by breeding beef cattle for a long time to receive a quality grade 1 or higher. In addition, the recent trend of meat consumption in Korea is moving toward avoiding fat in the diet. Accordingly, the Korean government changed the beef grading system from December 1, 2019. In the new grading system, beef with a lower marbling score receives a higher quality grade than before. Therefore, the new system is expected to affect the price of beef, especially premium beef (a quality grade 1 or higher). This study analyzed the effect of changing the beef grading system on premium beef price. To do this, we applied DID (Differences in Differences) model to the wholesale price of beef. As a result, it was found that the real price of premium beef increased by 709~779 won per kg due to the change in the beef grading system.

Genetic variation inLUMAN/CREB3and association with stress and meat quality traits in Yorkshire pigs

LUMAN/CREB3 is a stress regulatory gene that affects the activity of the hypothalamic–pituitary–adrenal axis in mice and presents a promising avenue for exploring variable stress-responsiveness in pigs. Pigs with similar characteristics to LUMAN-deficient mice, including greater resilience to stress and receptivity to human handling, would be valuable in the pork industry from animal welfare and production efficiency perspectives. We previously identified eight genetic variations and five haplotypes throughout the LUMAN locus in Yorkshire pigs. In this study, we analysed associations between LUMAN variations with behavioural stress response during three tests (open field test, novel object test, and human approach test), physiological stress responsiveness (cortisol), and carcass/meat quality measurements from purebred Yorkshire pigs. Haplotypes A1 and A2 were associated with decreased activity levels in novel environments and greater plasma cortisol concentrations at slaughter. Haplotype A1 was associated with lower carcass scratch scores and meat with lower cooking losses and greater tenderness. Haplotypes B1 and B2 were associated with the opposite traits including increased activity levels in novel environments and characteristics for lower meat quality including greater cooking losses, lower marbling, and paler coloured meat. We conclude that DNA variations in the LUMAN locus could potentially be used as genetic markers for stress resistance and meat quality in pig breeding.

Meat quality of cattle subjected to period of aging process: a cross-heifer study

The aim of this study was to evaluate the effects of aging on meat quality of crossbred heifers. Qualitative and quantitative evaluations of carcasses and meat of 148 crossbred heifers with an average age of 13 months and 407.5 ± 29.22 kg body weight at slaughter were performed. After cooling for 24 h, the carcasses were evaluated for hot carcass weight, pH, conformation, physiological maturity, finishing, fat distribution, and length. Characteristics, such as pH, color, marbling, exudation, as well as cooking losses, percentage of ether extract, and shear force were evaluated in meat at time zero and after seven days of aging. The carcasses displayed satisfactory results for parameters such as pH at 24 h of cooling (pH24), finishing, distribution of fat, and subcutaneous fat thickness (5.58, 3.27, 2.40, and 6.62 mm, respectively). The meat had a low marbling score (5.08) and percentage of ether extract (1.71), indicating that the meat was relatively lean. Exudation and cooking losses showed similar results at zero and seven days of aging. The meat subjected to seven days of aging showed higher lightness and hue (40.98 and 0.77, respectively) and tenderness of 5.25 kg. These results indicated that aging affected meat color and shear force parameters; the meat of cross-heifers was softer but less red after maturation.

Evaluation of coated steroidal combination implants on feedlot performance and carcass characteristics of beef heifers fed for constant or varying days on feed

Two experiments evaluated the effects of delayed, long-lasting implant strategies for finishing heifers fed for constant or varying days on feed. In Exp. 1, heifers (n = 500; initial BW = 280 ± 21 kg) were allotted randomly to 1 of 5 treatments, including no implant (CON), Revalor-XH on d 1 (XH), Revalor-200 on d 1 (E200), Revalor-XR on d 1 (XR), or Revalor-200 on d 70 (D200). All implants contained 200 mg of trenbolone acetate and 20 mg of estradiol. In Exp. 2, 720 heifers (initial BW = 281 ± 10 kg) were assigned randomly to treatments in a 3 × 4 factorial arrangement, with 3 implant treatments [no implant (NCON), Revalor-200 on d 1 and 100 (PCON), or Revalor-XH on d 1 (XH)] and 4 serial slaughter dates following 151, 165, 179, or 193 d on feed. In Exp. 1, implanted heifers were heavier, gained more, and were more efficient (P ≤ 0.03) compared with CON heifers, but no differences were observed among implant treatments (P ≥ 0.21) over the 198-d finishing trial. Implanted heifers had greater hot carcass weight but lower marbling scores compared with CON heifers (P ≤ 0.04). In Exp. 2, there were no serial slaughter × implant treatment interactions for growth performance (P ≥ 0.23) or carcass characteristics (P ≥ 0.31). Final BW, fat thickness, and numerical YG increased linearly (P < 0.01), whereas ADG (P = 0.01) and G:F (P = 0.02) decreased linearly, with increasing days on feed. Hot carcass weight was increased by implanting strategy and increasing days on feed, but aggressive initial implants did not improve performance.

24 Structural variants affecting mRNAs isoforms splice sites associated with marbling in Nellore cattle

Abstract The mRNA identification and associated splice variants affecting meat marbling in Nellore cattle could contribute to a better understanding of the genetic architecture of this complex trait. Longissimus thoracis samples from the 20 most extreme bulls (out of 80 bulls set) for marbling [high (n=10) and low (n=10) groups] trait were used to perform transcriptomic analysis using RNA-Sequencing. The CLC Genomics Workbench software was used to align the fragments of each sample to the bovine reference genome (ARS-UCD1.2) and to perform differential expressed transcript analysis (DE). An average of 37,000 transcripts and 14 mRNA DE (P ≤ 0.001; FC &amp;gt; 2) were detected in the muscle transcriptome. Among them, three transcripts were up-regulated (COL4A2-202, GHRH-201 and ENSBTAT00000070459.1) and 11 down-regulated (HBB-201, HBA-201, RPL14-202, CATHL1-201, CATHL4-201, MAPKAPK2-204, PCBD1-201, RPL30-203, NEURL1-202, PGLYRP1-201 and ENSBTAT00000038384.2) in high marbling group in relation to low group. Structural variants, including Single Nucleotide Variant (SNV), insertion or deletion were also found in the mRNA DE (4 in high and 6 in low marbling groups), causing possible splice site disruption. For high marbling group, in the COL4A2-202 transcript, three SNVs [one guanine (G) located on chromosome 12 at 85,104,867 bp, two cytosine (C), at the positions: 85,119,139 and 85,145,937 bp] were found. From these, one is a non-synonyms mutation [SNV (G) 85,145,937bp], causing an amino acid change (ENSBTAP00000005916.5: p.Glu1088Asp) in Collagen alpha-2(IV) chain protein (COL4A2). Interestingly, animals with low marbling presented also deletions (85,100,930 pb) in this same gene, causing an amino acid change (ENSBTAP00000005916.5:p.Pro113fs)in the COL4A2 protein. Functional enrichment analysis, using the DE mRNAs list, identified significant metabolic pathways (FDR &amp;lt; 0.05), such as O2/CO2 exchange in erythrocytes, tyrosine biosynthesis and phenylalanine degradation. The results suggest potential key regulatory genes associated with marbling, an economically important trait for the beef industry and for the consumer. Funding FAPESP (#2009/16118-5, #11/21241-0, #2017/02470-3, #2017/10630–2, #2018/ 20026–8, #2018/11154-2) and CAPES (#001).

28 Genomic prediction for marbling score in Hanwoo cattle using sequence data

Abstract As sequence information becomes available for some livestock species, there is a question on the amount of non-redundant information that may be embedded in the extra millions of SNPs or in causative variants within sequence. The objective of this study was to assess the gain in accuracy by using imputed whole-genome and selected SNP from sequence data in a beef cattle population. The dataset consisted of marbling score phenotypes for 545K Hanwoo cattle and pedigree information for 1.3M, of which 1,160 were genotyped for 50K SNPs. Imputation was done first to 777K and then to whole-genome sequence (WGS), which comprised 11,146,536 SNPs. Additionally, differentially expressed genes (DEG) and their 321,614 harboring SNPs were identified based on RNA-seq analysis of animals with high and low marbling score. An extra scenario combined 50K with DEG SNPs. Genomic predictions were obtained using GBLUP and single-step GBLUP (ssGBLUP) with and without weights, and BayesR. The last method could not be used for the WGS data because of the large number of SNPs. Predictive ability was calculated as the correlation between phenotypes adjusted for fixed effects and GEBV for 169 young animals. For all the methods, WGS and DEG had a slightly negative impact on predictive ability. Both GBLUP and BayesR had similar performances when using 50K, DEG, and 50K+ DEG, with predictive abilities equal to 0.19, 0.16, and 0.18, respectively. Predictive ability for ssGBLUP was 0.27, 0.26, and 0.27, in the aforementioned order. Using WGS, predictive ability for GBLUP was 0.17 and for ssGBLUP was 0.26. Weighting SNP differently did not improve predictions. As ssGBLUP uses all data available, not only genotyped animals with phenotypes as the other methods, it is more robust for genomic predictions. No gain in accuracy was observed, possibly because the selected sequence variants were not causative.

68 Assessing the Performance of Multiple Grass-fed Beef Production Systems in California

Abstract With demand for grass-fed beef continuing to increase, there is an immediate need to determine animal performance and product quality from varying grass-fed systems. Therefore, using a whole systems approach, we investigated the performance and carcass quality of multiple grass-fed beef systems in California. The treatments included: 1) steers stocked on pasture, then feedyard finished for 140 days (CON); 2) steers grass-fed for 20 months (20GF); 3) steers grass-fed for 20 months with a 45-day grain finish (GR45); and 4) steers grass-fed for 25 months (25GF). The data were analyzed using a mixed model procedure in R. Final body weight (FBW) varied significantly between treatments (P &amp;lt; 0.05) with the CON cattle finishing at 626 kg and GF20 finishing with the lowest FBW of 478 kg. There were no significant differences in FBW between GF45 and GF25 treatments (P &amp;gt; 0.05), with FBW equaling 551 kg and 570 kg, respectively. Dressing percentage (DP) differed significantly between all treatments (P &amp;lt; 0.05), with CON DP at 61.8%, followed by GR45 at 57.5%, GF25 at 53.4%, and GF20 at 50.3%. Marbling scores and quality grades were significantly higher for CON compared to all other treatments (P &amp;lt; 0.05), with a marbling score of 421; 14% of CON animals graded select and 85% graded choice or upper choice. Cattle in the GR20 had the lowest marbling score of 285 (P &amp;lt; 0.05); 59% of the GR20 cattle graded select and 41% graded standard. There was no difference in marbling when comparing the GF25 and GR45 (P &amp;gt; 0.5). In addition, carcasses graded similarly between the two treatments with GF25 grading 13% standard 82% select, and 6% choice, GR45 graded 85% select and 15% choice. The findings from this study indicate that varying CA grass-fed beef production systems results in significant differences in both animal performance and meat quality.

250 Evaluation of Green Grass as a feed ingredient in beef finishing rations and impact on cattle performance, carcass characteristics, and fatty acid profiles in meat

Abstract A finishing study used 240 crossbred steers (initial BW=340 ±24 kg) to evaluate performance, carcass characteristics, and fatty acid profiles of beef from finishing steers. Four inclusions (0, 10, 20, 30 % DM basis) of Green Grass displaced dry rolled corn in the finishing diet. Green Grass is a blend of herbs and plants imported from Korea that are high in omega-3 fatty acids with 13.9 % fat,32.0 % CP, and 27.0 % Acid detergent fiber. The remaining diet consisted of 15 % WDGS, 20 % corn silage, and 6 % liquid supplement (DM basis). There were no differences in final BW, gain or carcass traits (P³0.14). Cattle were harvested over three slaughter days and were fed for 190, 199, or 203 days. Dry matter intake linearly increased (P = 0.04)as Green Grass inclusion increased in the diet. A linear response (P£0.01) to feeding Green Grass was observed for G:F, with steers fed Green Grass having lower feed efficiency than control cattle. The G:F of cattle fed Green Grass was 5.4, 3.4, and 6.8 % lower in G:F as inclusion increased suggesting Green Grass has 68.6 % the energy of corn it replaced. Steers fed 30 % Green Grass had a lower marbling score. Linear increases in alpha linolenic acid, trans-unsaturated fatty acids, and omega-3 fatty acids (P£0.01) were observed in steak samples from steers fed increasing inclusion of Green Grass. Including up to 30 % inclusion of Green Grass on a DM basis in finishing diets decreased G:F; however, it appeared to have no other effects on performance or carcass characteristics. Feeding Green Grass linearly improved omega-3 fatty acid concentration in beef.

Differential Gene Expression in Longissimus Dorsi Muscle of Hanwoo Steers-New Insight in Genes Involved in Marbling Development at Younger Ages.

The Korean Hanwoo breed possesses a high capacity to accumulate intramuscular fat, which is measured as a marbling score in the beef industry. Unfortunately, the development of marbling is not completely understood and the identification of differentially expressed genes at an early age is required to better understand this trait. In this study, we took muscle samples from 12 Hanwoo steers at the age of 18 and 30 months. From the contrast between age and marbling score, we identified in total 1883 differentially expressed genes (FDR < 0.05 and logarithm fold change ≥ 1.5) with 782 genes up-regulated and 1101 down-regulated. Differences in gene expression were higher between the ages x marbling groups rather than between high and low marbling groups. At 18 months of age, the genes SLC38A4, ABCA10, APOL6, and two novel genes (ENSBTAG00000015330 and ENSBTAG00000046041) were up-regulated in the high marbling group. From the protein–protein interaction network analysis, we identified unique networks when comparing marbling scores between different ages. Nineteen genes (AGT, SERPINE1, ADORA1, FOS, LEP, FOXO1, FOXO3, ADIPOQ, ITGA1, SDC1, SDC4, ITGB3, ITGB4, CXCL10, ACTG2, MX1, EDN1, ACTA2, and ESPL1) were identified to have an important role in marbling development. Further analyses are needed to better understand the role of these genes.

Evaluation of the changes in composition of pork chops during cooking.

The objective was to determine the change in extractable lipid concentration during cooking of boneless pork chops to different endpoint temperatures. Pork loins (152 total) were used and three consecutive chops were cut from each loin. Chop 1 was evaluated raw (not cooked) for intramuscular fat (IMF) percentage. Raw IMF percentages were used to categorize the remaining two chops, from each loin, into low, average, and high marbling bins. The low bin included ≤3% IMF, the average bin included 3–4% IMF, and the high bin included ≥4% IMF. Chop 2 was cooked to 63 °C and chop 3 was cooked to 71 °C to evaluate cook loss, Warner–Bratzler shear force (WBSF), and IMF percentage. When cooked to either 63 or 71 °C, high IMF chops maintained greater (P < 0.001) IMF percentage than average and low IMF chops. Additionally, average IMF chops maintained greater (P < 0.001) IMF percentage than low chops, regardless of endpoint cooking temperature. The three marbling categories did not differ in cook loss (P = 0.28) or WBSF (P = 0.23) when chops were cooked to either 63 or 71 °C. However, both WBSF (2.76 kg) and cook loss (18.72%) were decreased (P < 0.001) in chops cooked to 63 °C compared with chops cooked to 71 °C (3.08 kg, 23.45%). Overall, differences in IMF percentages persisted even after cooking. Furthermore, IMF percentage of pork chops did not affect tenderness.

342 Economic evaluation of Jersey steers using an aggressive implant strategy

Abstract Our objective was to evaluate the profitability of Jersey steers fed in a Non-Hormone Treated Cattle (NHTC) program compared to those receiving an aggressive implant strategy. Jersey steers (n = 30; initial BW 183.3 ± 43.4kg) were allocated to one of two treatments: IMP (Revalor-200 administered at d0-d70-d140-d210-d280-d350) or CON (negative control) and fed for 420 days to assess economic viability for beef production. Live cattle, carcass, and subprimal prices were collected and consolidated from USDA Mandatory Price Reports for the 2018 calendar year. Data were analyzed via independent t-test. Initial cost was $357.02 per animal. Daily feed and yardage costs totaled $2.58 and $2.13 for IMP and CON, respectively. Live cattle value was greater for IMP cattle (P = 0.02; $1,281.20 vs $1,180.70 hd-1) than CON, which resulted from greater live weight. Base grid value was greater for IMP than CON (P = 0.01; $1,209.80 vs $1,076.00) however quality grade discounts were hefty for IMP (-$73.55) due to low marbling and dark-firm-dry outcomes, whereas all CON (+$37.50) carcasses graded Choice and Prime. Premiums for NHTC averaged $121.60 for CON cattle. Although not different (P = 0.19) CON steers netted greater numerical carcass value when marketed on a value-based grid than IMP steers ($1,178.92 vs $1,063.93). Boxed beef values for six steers randomly fabricated per treatment but did not differ (P = 0.87) between IMP and CON ($1,227.19 vs $1,207.92 hd-1). When marketed live, CON returned greater net production value (P = 0.04; -$69.23 vs -$160.60) than IMP, as well as on the grid (P &amp;lt; 0.01; -$71.05 vs -$377.83). However, net production value did not differ when marketed as boxed beef (P = 0.18; -$42.05 vs -$214.56). Marketing Jersey steer beef as NHTC appears to be more economically viable than an aggressive implant strategy, yet neither treatment yielded profit.

42 Carcass quality of cattle raised in tropical/subtropical environments

Abstract Cattle raised in tropical/subtropical environments typically are Bos indicus full blood or crossbred cattle. While they are ideally suited for reproductive performance in hot and humid climates, they frequently produce carcasses with lesser marbling scores than Bos taurus cattle. Early research from our laboratory compared subcutaneous (s.c.) and intramuscular (i.m.) adiposity and lipogenic capacity in Angus and Santa Gertrudis and Angus and Braford steers.; cattle with predominantly Bos indicus has lower marbling scores and smaller i.m. adipocytes. These and other studies suggested that genetic differences in adipose tissue metabolism between B. taurus and B. indicus breed types were expressed only when there were visible differences in marbling score and adjusted fat thickness (AFT). A subsequent study suggested that fatty acid Δ9 desaturase enzyme activity [stearoyl-CoA desaturase (SCD)] was greater in adipose tissue from Bos indicus cattle than in Bos taurus cattle, thereby resulting in a greater proportion of oleic acid (18:1n-9). We recently reported a comprehensive study comparing three-fourths Brahman progeny to three-fourths Angus progeny, in which progeny were raised to a constant age and constant AFT. Subcutaneous adipocyte cell was similar between Brahman and Angus progeny (276 vs 288 pL) but i.m. adipocytes were smaller in Brahman progeny than in Angus progeny (170 vs 207 pL). This was consistent with the lower marbling scores of the Brahman progeny. There was no difference between the proportions of stearic acid (18:0) and oleic acid between Brahman and Angus progeny; nor was there a difference in s.c. or i.m. adipose tissue SCD activity. We conclude that time on feed and/or animal age has a greater impact on fatty acid than genetics (Brahman vs Angus). However, research has demonstrated consistently that i.m adipose tissue in Bos indicus cattle does not develop to the same extent as in Bos taurus cattle.

Potential Mechanisms for Marbling Content Differences in M. Longissimus Dorsi From Wagyu And Brahman Cattle

ObjectivesIntramuscular fat (marbling) affects consumer perceptions of meat quality. Recent studies indicated that intramuscular adipocytes are derived from fibroadipogenic progenitors (FAPs), a type of bipotent mesenchymal progenitor cells in extracellular matrix of muscle fiber. Platelet-derived growth factor receptor α (PDGFRa) is a marker in identifying FAPs. The amount of PDGFRa positive cells refers to the abundance of FAPs, a key factor determining the intramuscular adipogenic efficiency of the animal. In addition, it has been shown that both satellite cells and skeletal muscle fibers regulate the activity of FAPs. In this study, we aimed to identify some underlying mechanisms for the differences in intramuscular fat accumulation between Wagyu, a high marbling breed, and Brahman, a low marbling breed, through a comparison study.Materials and MethodsFive cattle of each breed approaching mature body composition (Wagyu born January to May 2017; Brahman two 2-yr-old and three 3-yr-old, born April 2017 and 2015) were selected for this study. Biopsy samples of M. Longissimus muscle (LM) were taken after local anesthesia between the 12th and 13th ribs. Fresh samples were frozen in isopentane chilled by liquid nitrogen immediately after trimming fat and connective tissue. Other samples were fixed for 4 h in ice-cold 4% paraformaldehyde, soaked overnight in 30% sucrose solution, and then processed in Optimal Cutting Temperature embedding medium. Frozen samples were stored at –80°C before cryosectioning (5 mm) at –25°C for immunochemical staining. Unfixed muscle tissue sections were only used for muscle fiber determinations by rinsing with 1X Tris Buffer Saline (TBS) 3 times, 5 min each, before blocking in 10% goat serum and 1% bovine serum albumin, followed by overnight incubation with primary antibodies at 4°C. Subsequent secondary antibody staining at room temperature for 1 h. TBS/T (0.3% Triton) was used for membrane permeabilization to identify satellite cells, FAPs, and basement membrane. Mounting media containing 4,6-diamidino-2-phenylindole (DAPI) was used for nucleus staining. Primary antibodies against PDGFRα, paired box 7 (PAX7), laminin, and different isoforms of skeletal muscle myosins were used to identify FAPs, satellite cells, basement membrane, and different types of muscle fiber, respectively. All the sections were visualized under a Nikon inflorescence microscope, and images were analyzed by Image J software to identify different muscle fiber types and positive signals of PDGFRα and PAX7. Minimum diameter of each muscle fiber type was the average of 30 randomly selected fibers per section. Data were analyzed with R-studio using ‘t.test ()’ function with the critical value being equal to 0.05.ResultsWagyu muscle demonstrated a greater (P = 0.01) number of FAPs compared with Brahman muscle. A trend toward a higher (P = 0.06) abundance of satellite cells in Wagyu muscle than in Brahman muscles was also identified. No differences were found in muscle fiber diameter or muscle fiber type composition between these two breeds of cattle.ConclusionThe greater number of FAP cells observed in the LM of Wagyu cattle than in Brahman cattle suggests that the higher marbling content of Wagyu meat is at least partially attributed to the more abundant adipogenic progenitor cells, which increases the capacity and efficiency of intramuscular adipogenesis in Wagyu cattle.