Genetic and phenotypic associations of mitochondrial DNA copy number, SNP, and haplogroups with growth and carcass traits in beef cattle

Mitochondrial DNA copy number (mtDNA CN) is heritable and easily obtained from low-pass sequencing (LPS). This study investigated the genetic correlation of mtDNA CN with growth and carcass traits in a multi-breed and crossbred beef cattle population. Blood, leucocyte, and semen samples were obtained from 2,371 animals and subjected to LPS that resulted in nuclear DNA (nuDNA) and mtDNA sequence reads. Mitochondrial DNA CN was estimated as the ratio of mtDNA to nuDNA coverages. Variant calling was performed from mtDNA, and 11 single nucleotide polymorphisms (SNP) were identified in the population. Samples were classified in taurine haplogroups. Haplogroup and mtDNA type were further classified based on the 11 segregating SNP. Growth and carcass traits were available for between 7,249 and 60,989 individuals. Associations of mtDNA CN, mtDNA haplogroups, mtDNA types, and mtDNA SNP with growth and carcass traits were estimated with univariate animal models, and genetic correlations were estimated with a bivariate animal model based on pedigree. Mitochondrial DNA CN tended (P-value ≤0.08) to be associated with birth weight and weaning weight. There was no association (P-value >0.10) between mtDNA SNP, haplogroups, or types with growth and carcass traits. Genetic correlation estimates of mtDNA CN were -0.30 ± 0.16 with birth weight, -0.31 ± 0.16 with weaning weight, -0.15 ± 0.14 with post-weaning gain, -0.11 ± 0.19 with average daily dry-matter intake, -0.04 ± 0.22 with average daily gain, -0.29 ± 0.13 with mature cow weight, -0.11 ± 0.13 with slaughter weight, -0.14 ± 0.13 with carcass weight, -0.07 ± 0.14 with carcass backfat, 0.14 ± 0.14 with carcass marbling, and -0.06 ± 0.14 with ribeye area. In conclusion, mtDNA CN was negatively correlated with most traits investigated, and the genetic correlation was stronger with growth traits than with carcass traits.

Evaluating the Shelf Life and Sensory Properties of Beef Steaks from Cattle Raised on Different Grass Feeding Systems in the Western United States

Consumer interest in grass-fed beef has been steadily rising due to consumer perception of its potential benefits. This interest has led to a growing demand for niche market beef, particularly in the western United States. Therefore, the objective of this study was to assess the impact of feeding systems on the change in microbial counts, color, and lipid oxidation of steaks during retail display, and on their sensory attributes. The systems included: conventional grain-fed (CON), 20 months-grass-fed (20GF), 25-months-grass-fed (25GF) and 20-months-grass-fed + 45-day-grain-fed (45GR). The results indicate that steaks in the 20GF group displayed a darker lean and fat color, and a lower oxidation state than those in the 25GF group. However, the feeding system did not have an impact on pH or objective tenderness of beef steaks. In addition, consumers and trained panelist did not detect a difference in taste or flavor between the 20GF or 25GF steaks but expressed a preference for the CON and 45GR steaks, indicating that an increased grazing period may improve the color and oxidative stability of beef, while a short supplementation with grain may improve eating quality.

Differences in carcass chilling rate underlie differences in sensory traits of pork chops from pigs with heavier carcass weights

Pork hot carcass weights (HCW) have been increasing 0.6 kg per year, and if they continue to increase at this rate, are projected to reach an average weight of 118 kg by the year 2050. This projection in weight is a concern for pork packers and processors given the challenges in product quality from heavier carcasses of broiler chickens. However, previous work demonstrated that pork chops from heavier carcasses were more tender than those from lighter carcasses. Therefore, the objective was to determine the effects of pork hot carcass weights, ranging from 90 to 145 kg with an average of 119 kg, on slice shear force and sensory traits of Longissimus dorsi chops when cooked to 63°C or 71°C, and to assess if differences in chilling rate can explain differences in sensory traits. Carcasses were categorized retrospectively into fast, medium, or slow chilling-rates based on their chilling rate during the first 17 h postmortem. Loin chops cut from 95 boneless loins were cooked to either 63°C or 71°C and evaluated for slice shear force and trained sensory panel traits (tenderness, juiciness, and flavor) using two different research laboratories. Slopes of regression lines and coefficients of determination between HCW and sensory traits were calculated using the REG procedure in SAS and considered different from 0 at P ≤ 0.05. As hot carcass weight increased, chops became more tender as evidenced by a decrease in SSF (63°C ß = -0.0412, P = 0.01; 71°C ß = -0.1005, P < 0.001). Further, HCW explained 25% (R 2 = 0.2536) of the variation in chilling rate during the first 5 h of chilling and 32% (R 2 = 0.3205) of the variation in chilling rate from 5 h to 13 h postmortem. Slow and medium-rate chilling carcasses were approximately 12 kg heavier (P < 0.05) than fast chilling carcasses. Slice shear force of chops cooked to 63° and 71°C was reduced in slow and medium chilling compared with fast chilling carcasses. Carcass temperature at 5 h postmortem explained the greatest portion of variation (R 2 = 0.071) in slice shear force of chops cooked to 63°C. These results suggest that carcasses tend to chill slower as weight increases, which resulted in slight improvements in sensory traits of boneless pork chops regardless of final degree of doneness cooking temperature.

Non-invasive metabolomics biomarkers of production efficiency and beef carcass quality traits

The inter-cattle growth variations stem from the interaction of many metabolic processes making animal selection difficult. We hypothesized that growth could be predicted using metabolomics. Urinary biomarkers of cattle feed efficiency were explored using mass spectrometry-based untargeted and targeted metabolomics. Feed intake and weight-gain was measured in steers (n = 75) on forage-based growing rations (stage-1, 84 days) followed by high-concentrate finishing rations (stage-2, 84 days). Urine from days 0, 21, 42, 63, and 83 in each stage were analyzed from steers with the greater (n = 14) and least (n = 14) average-daily-gain (ADG) and comparable dry-matter-intake (DMI; within 0.32 SD of the mean). Steers were slaughtered after stage-2. Adjusted fat-thickness and carcass-yield-grade increased in greater-ADG-cattle selected in stage-1, but carcass traits did not differ between ADG-selected in stage-2. Overall 85 untargeted metabolites segregated greater- and least-ADG animals, with overlap across diets (both stages) and breed type, despite sampling time effects. Total 18-bile acids (BAs) and 5-steroids were quantified and associated with performance and carcass quality across ADG-classification depending on the stage. Stepwise logistic regression of urinary BA and steroids had > 90% accuracy identifying efficient-ADG-steers. Urine metabolomics provides new insight into the physiological mechanisms and potential biomarkers for feed efficiency.

Transcriptomic analysis for pork color – the ham halo effect in biceps femoris

Pork color is a major indicator of product quality that guides consumerpurchasing decisions. Recently, industry has received an increase in consumercomplaints about the lightness and non-uniformity of ham color, primarilylighter color in the periphery termed “ham halo” that is not caused bymanufacturing procedures. This effect is seen in fresh and processed hams andthe outer, lighter muscle is associated with lower myoglobin concentration, pHand type I fibers. The objective of this study was to identify differences ingene expression profiles between light and normal colored portions of biceps femoris muscle from pork hams.RNA-sequencing was performed for paired light and normal colored muscle samplesfrom 10 animals showing the ham halo effect. Over 50 million paired-end reads(2x75bp) per library were obtained. An average of 99.74% of trimmed high-qualityreads were mapped to the Sscrofa 11.1 genome assembly. Differentially expressedgenes (DEGs) were identified using both the DESeq2 and GFOLD software packages.A total of 14,049 genes were expressed in bicepsfemoris; 13,907 were expressed in both light and normal muscle, while 56and 86 genes were only expressed in light and normal muscle, respectively. Analysiswith DESeq2 identified 392 DEGs with 359 genes being more highly expressed innormal colored muscle. A total of 61 DEGs were identified in the DESeq2analysis and also were identified in at least 7 of the 10 individual animalanalyses. All 61 of these DEGs were up-regulated in normal colored muscle. Geneontology (GO) enrichment analysis of DEGs identified the transition betweenfast and slow fibers, and skeletal muscle adaptation and contraction as themost significant biological process terms. The evaluation of gene expression byRNA-Seq identified DEGs between regions of the biceps femoris with the ham halo effect that are associated with thevariation in pork color.

Palatability of high-quality New Zealand grass-finished and American grain-finished beef strip steaks

The objective of this study was to evaluate palatability of strip loin steaks from grass- and grain-fed beef across five United States Department of Agriculture (USDA) quality grades and three wet aging periods. Beef strip loins (N = 200; 20 per USDA quality grade/fed cattle type) representing five USDA quality grades [USDA Prime, Top Choice (Average and High Choice), Low Choice, Select and Standard] and two fed cattle types [New Zealand grass-finished and United States (U.S.) grain-finished] were used in the study. Each strip loin was equally portioned into thirds and randomly assigned to one of three wet aging periods (7 d, 21 d or 42 d). Consumer panelists (N = 600; 120/location: Texas, California, Florida, Kansas, and Pennsylvania) evaluated eight grilled beef steak samples for palatability traits, acceptability, and eating quality. All palatability traits were impacted by the interaction of diet × quality grade (P &lt; 0.05). Although similar (P &gt; 0.05) to grass-fed Prime steaks for juiciness, tenderness and overall liking, grain-fed Prime steaks rated greater (P &lt; 0.05) than all other grass- and grain-finished treatments for all palatability attributes. Grass-finished Top Choice, Low Choice, and Standard steaks were rated greater (P &lt; 0.05) than the respective grain-finished quality grades for juiciness and tenderness. Grain-finished Standard steaks rated lower (P &lt; 0.05) than all other grass- and grain-finished treatments for juiciness, tenderness, and overall liking; but were similar (P &gt; 0.05) to grass-finished Standard steaks for flavor liking. Our results indicate beef strip loin steaks of similar quality grades from grass-finished New Zealand cattle produce similar eating experiences when compared to those from U.S. grain-finished beef, even following extended post-mortem aging. This indicates improved palatability for consumers based on marbling without respect to grass- or grain-finishing diets.&nbsp;

Extended Aging and Marbling Class Effects on Color Stability of Beef Longissimus lumborum, Gluteus medius, and Biceps femoris Steaks

Postmortem aging improves palatability of various muscles, especially those from lower quality grades. This study evaluated postmortem aging and marbling class effects on the color stability of longissimus lumborum, gluteus medius, and biceps femoris steaks. Carcasses were selected at grading to have Lower Small (Small00 to Small50; n = 50) or Upper Slight (Slight50 to Slight90; n = 50) marbling scores. Strip loin and top sirloin subprimals from each carcass side were assigned to aging treatments (14, 21, 28, or 35 d) in an incomplete block arrangement. After aging, subprimals were cut into longissimus lumborum, gluteus medius, and biceps femoris steaks, respectively. Steaks were placed in a simulated retail display for 11 d. Changes in redness (a* and hue angle) were much slower and less extensive (P &lt; 0.001) in longissimus lumborum steaks than in gluteus medius steaks, which had slightly slower and less extensive (P &lt; 0.01) redness changes than biceps femoris. Increasing aging time increased (P &lt; 0.001) the rate and extent of overall color change (ΔE) during simulated retail display. Steaks from Lower Small carcasses had higher (P &lt; 0.01) L* values than steaks from Upper Slight carcasses at 14, 28, and 35 d postmortem. In steaks from Upper Slight carcasses, L* values were lower (P &lt; 0.01) in steaks aged for 28 d compared to other aging times. In steaks from Lower Small carcasses, L* values were highest (P &lt; 0.001) when aged for 14 d. Increased aging time generally decreased (P &lt; 0.05) a*, b*, and chroma values. However, within each aging time, only b* values of steaks aged for 35 d differed (P = 0.01) with regard to marbling class. Results indicate that increasing aging time decreased color life of beef muscles, and that marbling class had minimal impact on lean color stability.

Postmortem Aging Time and Marbling Class Effects on Flavor of Three Muscles From Beef Top Loin and Top Sirloin Subprimals

This study evaluated postmortem aging time and marbling class effects on flavor attributes of longissimus lumborum, gluteus medius, and biceps femoris steaks. Carcasses selected to have Lower Small (Small00 to Small49; n = 50) or Upper Slight (Slight50 to Slight99; n = 50) marbling were assigned to aging treatments (14, 21, 28, or 35 d) in an incomplete block arrangement. A trained sensory panel evaluated longissimus lumborum, gluteus medius, and biceps femoris steaks for tenderness, juiciness, and 31 flavor notes. Tenderness increases with aging time were linear (P &lt; 0.001) in longissimus lumborum and gluteus medius steaks and quadratic (P = 0.001) in biceps femoris steaks. Aging response of rancid flavor in longissimus lumborum steaks was cubic (P = 0.01), whereas the aging response of bloody/serumy flavor in biceps femoris steaks was quadratic (P = 0.03). Compared with Upper Slight marbling, carcasses with Lower Small marbling produced longissimus lumborum steaks with greater (P &lt; 0.01) beef flavor and lesser (P = 0.001) bitter flavor, gluteus medius steaks with greater (P = 0.05) brown/roasted flavor, and biceps femoris steaks with greater (P = 0.02) fat-like flavor, although differences were small. Principal component analysis indicated that bloody/serumy, sour, metallic, and bitter flavor attributes were the strongest contributors to a factor explaining 38% of longissimus lumborum flavor variation. Barnyard, bitter, sour, rancid, and bloody/serumy were the greatest contributors to a principal component explaining 41% of gluteus medius flavor. Barnyard, rancid, sour, bloody/serumy, and bitter were contributors to a component explaining 63% of biceps femoris sirloin cap flavor variance. Sample score plots indicated that neither aging time nor marbling class was associated with principal components and identified production lot as contributing to principal components explaining flavor variation in all 3 muscles. Results indicate that, in strip loin and top sirloin subprimals from carcasses with Upper Slight and Lower Small marbling scores, aging time and marbling class had little impact on beef flavor. Thus, increased aging times could be used to enhance tenderness with no adverse effects on other important palatability attributes.

Seasonal Prevalence of Shiga Toxin-Producing Escherichia coli on Pork Carcasses for Three Steps of the Harvest Process at Two Commercial Processing Plants in the United States

Shiga toxin-producing Escherichia coli (STEC) is a foodborne pathogen that has a significant impact on public health, with strains possessing the attachment factor intimin referred to as enterohemorrhagic E. coli (EHEC) and associated with life-threatening illnesses. Cattle and beef are considered typical sources of STEC, but their presence in pork products is a growing concern. Therefore, carcasses (n = 1,536) at two U.S. pork processors were sampled once per season at three stages of harvest (poststunning skins, postscald carcasses, and chilled carcasses) and then examined using PCR for Shiga toxin genes (stx), intimin genes (eae), aerobic plate count (APC), and Enterobacteriaceae counts (EBC). The prevalence of stx on skins, postscald, and chilled carcasses was 85.3, 17.5, and 5.4%, respectively, with 82.3, 7.8, and 1.7% of swabs, respectively, having stx and eae present. All stx-positive samples were subjected to culture isolation that resulted in 368 STEC and 46 EHEC isolates. The most frequently identified STEC were serogroups O121, O8, and O91 (63, 6.7, and 6.0% of total STEC, respectively). The most frequently isolated EHEC was serotype O157:H7 (63% of total EHEC). Results showed that scalding significantly reduced (P < 0.05) carcass APC and EBC by 3.00- and 2.50-log10 CFU/100 cm2, respectively. A seasonal effect was observed, with STEC prevalence lower (P < 0.05) in winter. The data from this study show significant (P < 0.05) reduction in the incidence of STEC (stx) from 85.3% to 5.4% and of EHEC (stx plus eae) from 82.3% to 1.7% within the slaughter-to-chilling continuum, respectively, and that potential EHEC can be confirmed present throughout using culture isolation.IMPORTANCE Seven serogroups of STEC are responsible for most (>75%) cases of severe illnesses caused by STEC and are considered adulterants of beef. However, some STEC outbreaks have been attributed to pork products, although the same E. coli are not considered adulterants in pork because little is known of their prevalence along the pork chain. The significance of the work presented here is that it identifies disease-causing STEC, EHEC, demonstrating that these same organisms are a food safety hazard in pork as well as beef. The results show that most STEC isolated from pork are not likely to cause severe disease in humans and that processes used in pork harvest, such as scalding, offer a significant control point to reduce contamination. The results will assist the pork processing industry and regulatory agencies to optimize interventions to improve the safety of pork products.

Sire Variation in the Severity of the Ham Halo Condition

A study was conducted to examine genetic variation in the ham halo condition. The distal portion of the biceps femoris was sampled by taking cores (2.54-cm diameter) from progeny (n = 1,016) from a Duroc meat quality–focused line. Commission Internationale de l ́Éclairage (CIE; “International Commission on Illumination”) color-space values (L*, a*, and b*) and myoglobin concentration were measured on the halo (“Halo”) and inside (“Inside”) portion of each core. The Halo portion of the biceps femoris had greater L* and b* and lesser a* and myoglobin content (all P &lt; 0.001) than the Inside portion. Sires with 11 or more progeny were compared. The sire × muscle-location interaction affected (P &lt; 0.001), L*, a*, and myoglobin concentration. Sire progeny groups differed for each trait in both portions of the muscle, but differences in the Halo portion of the muscle were not mirrored in the Inside portion of the muscle. Similarly, sire group affected the magnitude of the difference in L* (P = 1.4 × 10−4) and a* (P = 9.0 × 10−6) between the Halo and Inside portions of the muscle and tended (P = 0.08) to affect myoglobin content. However, the largest sire-group differences were not necessarily seen in the sires with the highest means for these attributes. Thus, selecting for myoglobin concentration, L*, or a* content in the Halo portion of the biceps femoris muscle would be an effective strategy for reducing the severity of the ham halo condition.

Effects of space allowance and marketing strategy on growth performance of pigs raised to 165 kg

A total of 976 pigs (PIC 327 × Camborough; PIC, Hendersonville, TN; initially 22.0 ± 1.53 kg body weight [BW]) were used in a 160-d growth study to evaluate the effects of increasing space allowance and varying marketing strategies on growth performance of pigs raised to market weights of ~165 kg. Pens of pigs were blocked by location within the barn and allotted to one of six treatments. Pen served as the experimental unit, and there were eight replicate pens per treatment. The first four treatments consisted of increased initial stocking density and did not utilize topping strategies: (1) 14 pigs/pen (1.17 m²/pig), (2) 17 pigs/pen (0.97 m²/pig), (3) 20 pigs/pen (0.82 m²/pig), and (4) 23 pigs/pen (0.71 m²/pig). The fifth treatment began with 25 pigs/pen (0.66 m²/pig) and had four marketing events with the heaviest 3 pigs/pen removed on day 93, and additional pigs removed to a common inventory of 20 pigs/pen on day 122 and 17 pigs/pen on day 147 with final marketing on day 160. The final treatment began the experiment with 23 pigs/pen (0.71 m²/pig) with three marketing events to achieve a common inventory of 20 pigs/pen on day 108 and 17 pigs/pen on day 147. Pens of pigs were weighed and feed disappearance measured on days 0, 55, 93, 108, 122, 135, 147, and 160. As space allowance decreased from 1.17 to 0.71 m²/pig via increased initial pen inventory (treatments 1 to 4), overall average daily gain (ADG) and average daily feed intake (ADFI) decreased (linear, P < 0.001), while gain:feed ratio (G:F) did not differ (P > 0.05). The treatments with multiple marketing events were compared with each other and with the treatment that began with 0.71 m²/pig and only marketed once at the end of the study. Overall ADG and ADFI were not different (P > 0.05) among these three treatments. Marketing pigs three or four times improved (P < 0.05) G:F compared with the treatment that began the study with 0.71 m²/pig and marketed only once. Reducing floor space allowance for heavy weight pigs decreased intake, which resulted in lower growth rate and final BW, with these reductions occurring before the critical k-value was reached. Total weight gain per pen was maximized with the lowest space allowance and the multiple marketing treatments. Thus, strategic use of pig removals prior to final marketing may allow producers to maximize both number of pigs and total weight marketed through a barn when feeding to heavy weights.

118 Awardee Talk - Genomic control of fatty acid profile in beef

Steers (n = 868) were raised, feedlot-finished with ad libitum access to a high-energy diet and harvested to determine if there is genomic control of fatty acid profile traits in beef breeds common to the United States. Cattle included purebred and crossbred progeny of Angus, Red Angus, Hereford, Shorthorn, Simmental, Charolais, Limousin, Gelbvieh, Maine Anjou, Chiangus, Braunvieh, Salers, Brahman, Brangus, Santa Gertrudis, and Beefmaster as well as three composite lines. Either directly or through imputation, genotypes were determined for &gt; 133,000 functional single nucleotide polymorphisms (SNP). At approximately 38 h postmortem, a 2.54-cm-thick longissimus steak was obtained from the 13th rib region of the left side of each carcass. At 14 d postmortem, steaks were cooked and subsequently longissimus was pulverized in liquid nitrogen. Fatty acid profile was determined by gas chromatography and mass spectrometry. A genome-wide association study was conducted for fatty acid profile traits expressed as a deviation from the contemporary group mean using the Mixed Linear Model Analysis of SNP & Variation Suite 8.8.3 (Golden Helix) and Pre-computed Kinship Matrix using the GBLUP Genomic Relationship Matrix. A SNP in coiled coil domain containing 57 (CCDC57; Chromosome 19 at 51,349,695) affected the percentage of C14:0 (P &lt; 10–46), short-chain fatty acids (P &lt; 10–36), and saturated fatty acids (P &lt; 10–17). Also, a SNP in thyroid hormone responsive (THRSP; Chromosome 29 at 18,090,403) affected the percentage of C14:0 (P &lt; 10–16) and short-chain fatty acids (P &lt; 10-10). The percentage of polyunsaturated fatty acids was affected by SNP in myostatin (Chromosome 2 at 6,213,980; P &lt; 10–15). These results show that fatty acid profile of beef can be changed through genetic selection but, it is not clear if the level of change will be great enough to impact human health.

Effects of Increased Pork Hot Carcass Weights. II: Loin Quality Characteristics and Palatability Ratings

The objective of this study was to evaluate the effects of increased pork hot carcass weight on loin quality and palatability of top loin chops. Pork loins (N = 200) were collected from 4 different hot carcass weight groups: A light weight (LT; less than 111.8 kg), medium-light weight (MLT; 111.8 to 119.1 kg), medium-heavy weight (MHVY; 119.1 to 124.4), and a heavyweight group (HVY; 124.4 and greater). Following fabrication, chops were assigned to fat and moisture analysis, Warner-Bratzler shear force (WBSF), consumer sensory panels, or trained sensory panels. Chops from the HVY group were rated as more (P < 0.05) tender compared to chops from the LT carcasses. Additionally, chops from the HVY weight group had greater (P < 0.05) consumer overall like ratings compared to chops from both the LT and MLT groups. Carcass weight did not affect (P > 0.05) consumer flavor liking ratings. Hot carcass weight treatment did not contribute (P > 0.05) to the percentage of chops rated acceptable for flavor and overall liking. The greatest (P < 0.05) percentage of samples were rated acceptable for juiciness for chops from the HVY weight group, and the lowest (P < 0.05) percentage of acceptable ratings for tenderness were for chops from the LT weight group. Both initial and sustained juiciness from MHVY carcasses were rated as more (P < 0.05) juicy compared to chops from both MLT and LT carcasses by trained sensory panelists. Additionally, chops from the LT carcasses had the lowest (P < 0.05) myofibrillar tenderness ratings. Chops from MHVY and HVY carcasses were similar (P > 0.05), with greater (P < 0.05) overall tenderness ratings compared to chops from LT carcasses. These results indicate chops from heavier weight carcasses may have improved tenderness and juiciness compared to chops from lighter carcasses.

Effects of Increased Pork Hot Carcass Weights. I: Chop Thickness Impact on Consumer Visual Ratings

The objective of this study was to evaluate the effect of increased pork hot carcass weights on consumer visual acceptability and purchase intent ratings of top loin chops cut to various thicknesses in a price labeled versus unlabeled retail display scenario. Pork loins (N = 200) were collected from 4 different hot carcass weight groups: light weight (LT; less than 111.8 kg), medium-light weight (MLT; 111.8 to 119. kg), medium-heavy weight (MHVY; 119.1 to 124.4 kg), and a heavy weight group (HVY; 124.4 kg and greater). Loins were fabricated into 4 pairs of chops of specified thicknesses (1.27, 1.91, 2.54, and 3.18 cm). One chop from each pair was assigned to be packaged with or without a label. Consumers assessed chops for appearance, desirability, and purchase intent. For both appearance and purchase intent ratings, chops from HVY carcasses were given more desirable (P < 0.05) ratings compared to LT chops. Consumers gave greater (P < 0.05) appearance ratings to thicker cut chops. There was a hot carcass weight × chop thickness interaction (P < 0.05) for the percentage of consumers that indicated the chop was desirable overall. Regardless of hot carcass weight group, chops with a thickness of 1.27 cm had the lowest (P < 0.05) percentage of consumers indicate they were desirable overall. A greater (P < 0.05) percentage of consumers indicated “yes” they would purchase chops cut to a thickness of 2.54 cm compared to all other thicknesses. Additionally, there was a greater (P < 0.05) percentage of consumers who indicated they would purchase unlabeled chops compared to labeled chops. These results, within the population sampled, indicate that carcass weight and chop thickness can affect consumer preference and thus should be considered by retailers when marketing fresh pork loin chops.

Characterizing Ham and Loin Quality as Hot Carcass Weight Increases to an Average of 119 Kilograms

The objective was to characterize ham and loin quality of carcasses ranging from 78 to 145 kg (average ∼119 kg). Hot carcass weight (HCW), back fat depth, and loin depth was measured on 666 carcasses. Loin pH, instrumental and visual color and iodine value of clear plate fat (all 3 layers) was measured on approximately 90% of the population. Quality measurements of the ham, 14 d aged loin and chop, and loin chop shear force (SSF) were evaluated on approximately 30% of the population. Myosin heavy chain fiber type determination was completed on 49 carcasses. Slopes of regression lines and coefficients of determination between HCW and quality traits were calculated using the REG procedure in SAS and considered significantly different from 0 at P ≤ 0.05. As HCW increased, loin depth (b1 = 0.2496, P < 0.0001), back fat depth (b1 = 0.1374, P < 0.0001), loin weight (b1 = 0.0345, P < 0.0001), and ham weight (b1 = 0.1044, P < 0.0001) increased. Estimated lean (b1 = –0.0751, P < 0.0001) and iodine value (b1 = –0.0922, P < 0.0001) decreased as HCW increased, where HCW accounted for 24% (R2 = 0.24) of the variation in estimated lean and 7% (R2 = 0.07) of the variation in iodine value. However, HCW did not explain variation in ham quality traits (P > 0.15) and did not explain more than 1% (R2 ≤ 0.01) of the variation in 1 d loin color or pH. Loins from heavier carcasses were more tender (decreased SSF; b1 = –0.0674, P < 0.0001), although HCW only explained 9% of the variation in SSF. Hot carcass weight did not alter (P > 0.22) muscle fiber type percentage or area. These results suggest that increasing HCW to an average of 119 kg did not compromise pork quality.

PSV-3 Effects of space allowance and marketing strategy on growth performance of pigs raised to heavy market weights

A total of 976 pigs (PIC 327×L42, initially 22 ± 1.5 kg BW) were used in a 160-d study to determine the influence of space allowance and marketing strategy on performance of pigs raised to heavy market weights (165 kg). Pens were blocked by location and allotted to 1 of 6 treatments with 8 pens/treatment. The first four treatments reduced space allowance/pig via initial pen stocking density: 14 pigs/pen (1.20 m2/pig), 17 pigs/pen (0.98 m2/pig), 20 pigs/pen (0.84 m2/pig), or 23 pigs/pen (0.73 m2/pig). The fifth treatment began with 25 pigs/pen (0.67 m2/pig) and the heaviest 3 pigs/pen were removed on d 93, then on d 122 pens were marketed to a common inventory of 20 pigs/pen, and on d 147 marketed to a common pen inventory of 17 pigs/pen. The sixth treatment began with 23 pigs/pen (0.73 m2/pig) and were marketed to a common inventory of 20 pigs/pen on d 108 and marketed to a common inventory of 17 pigs/pen on d 147. Data were analyzed using PROC GLIMMIX with pen as the experimental unit. Overall (d 0 to 160) ADG, ADFI, and final BW decreased (linear, P < 0.001) and G:F increased (quadratic, P = 0.042) as space allowance decreased. When comparing treatments with multiple marketing events (treatments 5 and 6) to treatment 4, there was no evidence for differences (P > 0.05) for overall ADG or ADFI; however, overall G:F was improved (P < 0.05) for pigs initially stocked at 0.67 m2/pig and marketed four times compared to both treatments that initially allowed 0.73 m2/pig, regardless of marketing structure. These results indicate that decreasing space allowance of heavy weight pigs reduces growth, feed intake and final BW, although use of multiple marketing events prior to final marketing may allow for increased number of pigs marketed/pen while balancing reduced growth performance often associated with increased stocking density. http://www.conferenceharvester.com/

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Effect of hot carcass weight on the rate of temperature decline of pork hams and loins in a blast-chilled commercial abattoir123

Adequate carcass chilling is required to optimize pork quality and food safety. The rate at which carcasses chill is dependent on their mass. Hot carcass weight has increased steadily over the years, certainly affecting the chilling rate of the average carcass in contemporary abattoirs. Therefore, the objective was to model the effect of HCW on temperature decline of a contemporary population of pork carcasses slaughtered at a commercial abattoir that used a blast-chilling method. In addition, carcasses were sorted into HCW classes, and the effect of HCW group was tested on the rate of temperature decline of the longissimus dorsi and semimembranosus. Hot carcass weight, internal temperature of the loin muscle (at the 10th rib) and ham, as well as ambient temperature, were recorded from 40 to 1,320 min postmortem (45 time points) on 754 pork carcasses. An exponential decay model based on Newton's law of cooling,  T(t)=Ta+(T0-Ta)e-kt, was fit to temperature decline of the ham and loin of the whole population using PROC MODEL of SAS. The initial models for the decline of both ham and loin temperature displayed significant autocorrelation of errors based on evaluation of the autocorrelation function plots and Durbin-Watson test (P < 0.0001). Therefore, second- and third-order autocorrelation parameters were tested. Based on Durbin-Watson test, the use of second-order autocorrelation model with lags of 1 and 2 was deemed adequate and was therefore included in all subsequent models. This base model and its respective parameter estimates were all significant (P < 0.01) for the whole population. Carcasses approximating 85, 90, 95, 100, and 105 kg (± 1 kg) were selected and binned into their respective weight classes. Dummy variables were used to compare the effect of HCW class on parameter estimate of ham and loin models. The developed model significantly fit all weight classes (P < 0.01) for both ham and loin temperature decline. For both loin and ham models, estimates of the rate constant (k) generally decreased as HCW increased. For loin temperature, k estimate for 105-kg carcasses was 0.00124 less (P = 0.02) than 85-kg carcasses, with the intermediate HCW classes not differing from the 85-kg class. For ham temperature, estimates of k for 90, 95, 100, and 105 kg HCW were all significantly and successively less than the k estimate for 85 kg class. For perspective, loins of 95-kg carcasses were estimated to reach 2 °C in 17 h, whereas loins from 105-kg carcasses would not reach 2 °C until 27 h. For hams, 95-kg carcasses were projected to reach 2 °C in 21 h, whereas those from 105-kg carcasses would take 28 h. Overall, HCW significantly affects the rate of temperature decline of pork hams, but not loins from pork carcasses weighing between 85 and 100 kg.

Enhanced estimates of carcass and meat quality effects for polymorphisms in myostatin and µ-calpain genes

The objective of this study was to enhance estimates of additive, dominance, and epistatic effects of marker polymorphisms on beef carcass and quality traits. Myostatin (MSTN) F94L SNP and the µ-calpain (CAPN1) 316 and 4751 SNP haplotype have previously been associated with fat and muscle traits in beef cattle. Multiyear selection in a composite population segregating these polymorphisms increased minor allele (F94L L) and chosen haplotype (CAPN1 CC and GT) frequencies to intermediate levels resulting in more precise estimates of additive and nonadditive genetic effects. During the 3 yr after selection, 176 steers were evaluated for growth, carcass, meat quality, tenderness (n = 103), and meat color traits. The statistical model included year, age of dam, age of the steer, and genotype in a random animal model. The 9 genotypes (3 CAPN1 diplotypes × 3 F94L genotypes) affected marbling score, ribeye area, adjusted fat thickness, vision yield grade (all P < 0.001), slice shear force (P = 0.03), and CIE L* reflectance (P = 0.01). Linear contrasts of the 9 genotypes estimated additive, recessive, and epistatic genetic effects. Significant additive effects of the F94L L allele decreased marbling score, adjusted fat thickness, vision yield grade, and slice shear force; and increased ribeye area and CIE L* reflectance. The homozygous F94L FF and LL genotypes differed by 1.3 to 1.9 phenotypic SD for most carcass traits and by 0.8 to 0.9 SD for slice shear force and CIE L* reflectance but carcass weight differed by only 3 kg (0.1 SD). The L allele was partially recessive to F for ribeye area (P = 0.02) and the heterozygous FL means tended to be closer to the FF genotype than the LL genotype for other carcass traits but differences from additive were not significant. The CAPN1 additive × F94L additive effect on slice shear force was the only significant epistatic estimate. The F94L L allele is prevalent in Limousin but nearly absent in other U.S. purebreds. This allele had about half of the effects on birth weight, muscle, and fat traits reported for severe MSTN mutations in Belgian Blue and Piedmontese breeds. The interaction between MSTN and CAPN1 genotypes may reflect the strong additive effects of MSTN F94L L allele on fat and muscle traits interfering with the phenotypic effect of CAPN1 genotype on meat tenderness.

Comparison of Machine Learning Algorithms for Predictive Modeling of Beef Attributes Using Rapid Evaporative Ionization Mass Spectrometry (REIMS) Data

Ambient mass spectrometry is an analytical approach that enables ionization of molecules under open-air conditions with no sample preparation and very fast sampling times. Rapid evaporative ionization mass spectrometry (REIMS) is a relatively new type of ambient mass spectrometry that has demonstrated applications in both human health and food science. Here, we present an evaluation of REIMS as a tool to generate molecular scale information as an objective measure for the assessment of beef quality attributes. Eight different machine learning algorithms were compared to generate predictive models using REIMS data to classify beef quality attributes based on the United States Department of Agriculture (USDA) quality grade, production background, breed type and muscle tenderness. The results revealed that the optimal machine learning algorithm, as assessed by predictive accuracy, was different depending on the classification problem, suggesting that a “one size fits all” approach to developing predictive models from REIMS data is not appropriate. The highest performing models for each classification achieved prediction accuracies between 81.5–99%, indicating the potential of the approach to complement current methods for classifying quality attributes in beef.

Metabolomic Investigation of Tenderness and Aging Response in Beef Longissimus Steaks

A study was conducted to identify molecular changes reflective of beef tenderness variation and tenderization during postmortem aging. Carcasses (U.S. Select) were selected to represent extremes in tenderness (n = 20; 10 per class). Two pairs of adjacent longissimus lumborum steaks from each strip loin were blocked by location and assigned to each aging time (2, 7, 14, or 28 d postmortem). One steak from each pair was designated for slice shear force determination and the other was used for sarcomere length, western blotting for desmin, and non-targeted LC- and GC–MS metabolite profiling. Tough steaks had higher (P &lt; 0.001) slice shear force values than tender steaks, and increasing aging time decreased (P &lt; 0.001) slice shear force values. Tender steaks had a greater (P &lt; 10–4) proportion of desmin degraded than tough steaks, and increasing aging time increased (P &lt; 10–22) desmin degradation in steaks from both classes. From 2,562 profiled metabolites, 102 metabolites were included in the final analysis after statistical screening. Twenty-eight metabolites could be annotated and loosely categorized into amino acids/peptides (n = 16), metabolism intermediates (n = 7), glycosides (n = 4), and fatty acids and phospholipids (n = 3). Amino acids were primarily associated with desmin degradation. Increased glucose levels were strongly associated to the tender classification and moderately associated to increased proteolysis, while increased glucose-6-phosphate was strongly related to the tender class but was related to decreased proteolysis. Increased malic acid was strongly associated to the tough classification, increased slice shear force, and decreased proteolysis. Increased levels of 3-phosphoglyceric acid and glycerol-3-phosphate was moderately associated with increased slice shear force and decreased proteolysis. These data indicate that accumulation of amino acids during aging is strongly related to postmortem proteolysis and may provide evidence of the fate of proteins degraded postmortem. Measures of glucose, glucose-6-phosphate, and malic acid concentrations may provide a metabolic fingerprint indicative of tenderness differences in beef longissimus.

Determining the relationship between early postmortem loin quality attributes and aged loin quality attributes using meta-analyses techniques

Meta-analyses techniques using 11 independent datasets were used to determine correlations between pork loin quality evaluated at 1-d postmortem and quality evaluated at 12- to 28-d postmortem. Datasets encompassed approximately 3,957 loins. The effects of aging on ventral loin surface quality were determined using a paired-T test. Ventral loin surfaces become 8% lighter (P < 0.0001), 44.5% redder (P < 0.0001), and 46% more yellow (P < 0.0001) during the aging period. Therefore, it is apparent that loin quality changes during postmortem aging. Because of this, it becomes necessary to determine the correlation between early and aged pork quality parameters. Pearson correlation coefficients within original datasets were calculated, and then sample-weighted mean correlations r¯ and variances [Var(r)] were calculated across datasets. Early postmortem ventral instrumental lightness (L*) was moderately correlated with aged ventral L* r¯ = 0.50), aged ventral visual color r¯ = -0.38), aged chop face (freshly cut) L* r¯ = 0.44), and aged chop face visual color r¯ = -0.38). Early postmortem ventral instrumental redness (a*) was moderately correlated with aged ventral a* r¯ = 0.49) and aged chop face a* r¯ = 0.46). Early postmortem ventral visual color was moderately correlated with aged ventral L* r¯ = -0.51), aged ventral color (r¯ = 0.50), aged chop face L* r¯ = -0.43), and aged chop face visual color r¯ = 0.43). However, no instrumental or visual color parameters were moderately or strongly correlated with instrumental tenderness or sensory panel ratings of tenderness and juiciness (|r¯| ≤ 0.36). Early postmortem ventral visual marbling was moderately correlated with aged ventral marbling r¯ = 0.63) and aged chop face visual marbling r¯ = 0.56). Visual marbling was not (|r¯| ≤ 0.12) correlated with instrumental tenderness or sensory panel ratings of tenderness and juiciness. Stepwise regression, using a holo-analysis approach, was used to determine the predictive ability of early postmortem ventral color, marbling, firmness, and pH on sensory panels ratings of tenderness (R2 = 0.13), juiciness (R2 = 0.09), and flavor (R2 = 0.28). Early postmortem color and marbling are important pork quality traits in consumers purchasing decisions, but are poorly related to traits associated with eating experience. Still, they may be predicative of traits associated with purchasing intent.

Characterizing the Ham Halo Condition: A Color Defect in Fresh Pork Biceps Femoris Muscle

This experiment characterized a color defect called halo, involving pale tissue in the superficial portion of ham muscles, causing a two-toned appearance. Biceps femoris muscles (n = 200) were obtained from the ham-boning line of a large processor. Instrumental color attributes were determined on the medial (inside) and lateral (halo) surfaces of the muscle. Muscles were sliced (2.54-cm-thick) perpendicular to the long axis of the muscle. Slices were numbered from the proximal end of the muscle so that slice numbers represented anatomical location. Severity of the defect was greatest on the distal end of the muscle corresponding to slices 6 and 7 (9 locations). The halo and inside portions of slices 6 and 7 were separated for myoglobin concentration and muscle pH determination. The inside portion of muscle had lower (P < 0.001) L* (53.1 versus 63.4) and greater (P < 0.001) a* (23.2 versus 15.3) and b* (18.5 versus 15.4) values than the halo portion. Compared to the halo portion, the inside portion of the muscle had greater (P < 0.001) muscle pH (5.7 versus 5.5) and myoglobin concentration (1.97 versus 0.85 mg/g). Four minimally and 5 severely affected muscles were sampled in the halo and inside portions for muscle fiber typing. Fiber type distribution did not differ (P > 0.05) between locations within minimally affected muscles. In severely affected muscles, the inside portion had increased (P < 0.001) proportion of type I fibers, and concomitant decrease (P < 0.001) in type IIB fibers relative to the halo portion. These data indicate that the halo portion of the muscle is much lighter and less red in color, resulting from reduced myoglobin concentration in this portion of the muscle associated with a shift in muscle fiber type. These results should contribute to solutions to mitigate the ham halo color defect.

Surface pH of Fresh Beef as a Parameter To Validate Effectiveness of Lactic Acid Treatment against Escherichia coli O157:H7 and Salmonella

The U.S. beef industry must provide documentation to the U.S. Department of Agriculture, Food Safety and Inspection Service (USDA-FSIS) that the antimicrobial interventions implemented or any subsequent changes in the process are effective under the actual conditions that apply in its operation. The main objective of this study was to determine whether surface pH after application of diluted lactic acid solution on surfaces of fresh meat can be used as a control measure indicator for the reduction of E. coli O157:H7 and Salmonella. Samples (240 each) of lean and adipose beef tissues were inoculated with cocktail mixtures of Escherichia coli O157:H7 and Salmonella. Application parameters were varied such that lean and adipose tissues were spray treated with either 2 or 4.5% lactic acid solution at either 38 or 60°C for 1 to 10 s. Lean and adipose tissues were collected before and after spray treatments for enumeration of the pathogens. Based on the conditions of this study, there was no difference between spray treatments at 38 or 60°C, but 4.5% lactic acid solution reduced pathogens more effectively ( P ≤ 0.05) than did 2% lactic acid solution. Spray treatment with lactic acid solution for 1 to 10 s reduced surface pH values of lean tissues (3 to 3.8) and adipose tissues (2.75 to 3.65). At surface pH values of 3.0 and 2.75, lactic acid reduced E. coli O157:H7 on surfaces of lean and adipose tissues by approximately 1.60 and 1.54 log CFU/cm², respectively. At surface pH values of 3.8 and 3.65, lactic acid reduced E. coli O157:H7 on lean and adipose tissues by approximately 0.3 and 0.42 log CFU/cm², respectively. The surface pH values after lactic acid treatment and the reductions of both pathogens showed a strong linear relationship; this indicates that a surface pH of 3.1 would provide at least 1-log reduction of E. coli O157:H7 and Salmonella, regardless of lactic acid application parameters. Therefore, surface pH after spray treatment with lactic acid could be used to validate pathogen reduction.

Characterization of variability in pork carcass composition and primal quality,

The objective was to characterize the factors and production practices that contribute to variation in pork composition and quality. It is possible the variation in pork quality traits, such as color, marbling, and tenderness, contributes to reduced customer confidence in the predictability of finished product quality and, therefore, pork products becoming less competitive for consumer dollars. Pigs raised in 8 different barns representing 2 seasons (hot and cold) and 2 production focuses (lean and quality) were used in this study. Pigs were marketed in 3 groups from each barn and marketing procedures followed commercial marketing procedures. Data were collected on a total of 7,684 pigs. The mivque0 option of the VARCOMP procedure in SAS was used to evaluate the proportion of variation each independent variable (season, production focus, marketing group, sex, and random variation) contributed to total variance. Random variation including inherent biological differences, as well as factors not controlled in this study, contributed the greatest proportion to total variation for each carcass composition and quality trait. Pig and other factors contributed to 93.5% of the variation in HCW, and marketing group, sex, season, and production focus accounted for 4.1, 1.4, 0.8, and 0.3%, respectively. Variation in percent carcass lean was attributed to production focus (36.4%), sex (15.8%), and season (10.2%). Pig and other factors contributed the greatest percentage of total variation (39.4%). Loin weight variation was attributed to production focus (21.4%), sex (5.4%), season (2.7%), marketing group (1.8%), and pig (68.7%). Belly weight variation was attributed to pig (88.9%), sex (4.1%), marketing group (3.8%), production focus (3.0%), and season (0.1%). Variation in ham weight was attributed to pig and other factors (93.9%), marketing group (2.8%), production focus (2.2%), and season (1.1%). Ultimate pH variation was attributed to pig (88.5%), season (6.2%), production focus (2.4%), marketing group (2.2%), and sex (0.7%). Aside from pig (71.9%), production focus (14.0%) was the next largest contributor to variation in iodine value followed by sex (13.2%) and marketing group (0.9%). Variation in carcass quality and composition could be accounted for, but the greatest percentage of variation was due to factors not accounted for in normal marketing practices.

The effects of backgrounding system on growing and finishing performance and carcass characteristics of beef steers

The objective of this 2-yr study was to evaluate growing and finishing performance as well as carcass characteristics of spring-born steers backgrounded on 3 different systems, using feedstuffs readily available in the Midwest: 1) grazing corn residue and being supplemented with dried distillers plus solubles at 2.68 kg DM/steer 6 d/wk (RESIDUE), 2) grazing a late summer-planted oat-brassica forage mix (CCROP), or 3) being fed a corn silage-based diet in a drylot (DRYLOT). Steers ( = 715) were stratified by BW (278 kg ± 23 in yr 1 and 291 kg ± 91 in yr 2) and assigned to treatment and replicate (4 replications per treatment per yr). Steers assigned to DRYLOT were fed a corn silage-based diet for 54 d in yr 1 and 52 d in yr 2 before being transitioned to the finishing diet. Steers assigned to RESIDUE and those assigned to CCROP grazed 65 d in yr 1 and 66 d in yr 2 and then were fed a corn silage-based diet for 21 d in yr 1 and 33 d in yr 2 before being transitioned to the finishing diet. During backgrounding, the ADG (SEM 0.022) of steers assigned to DRYLOT (1.48 kg/d) was greater ( < 0.01) than that of steers assigned to both CCROP (1.05 kg/d) and RESIDUE (0.87 kg/d) and ADG of steers assigned to CCROP was greater ( < 0.01) than that of steers assigned to RESIDUE. At the start of the finishing period, BW of steers assigned to CCROP (381 kg) was greater ( < 0.01, SEM 2.5) than that of steers assigned to DRYLOT (361 kg) and RESIDUE (366 kg). The finishing period lasted 160 d for all treatments. Both 12th-rib fat ( = 0.89) and calculated yield grade ( = 0.39) did not differ among treatments. Finishing G:F of steers assigned to DRYLOT (0.162 kg/kg) was greater ( < 0.01, SEM 0.0015) than that of steers assigned to RESIDUE (0.153 kg/kg) and CCROP (0.153 kg/kg), which did not differ ( = 0.79). In yr 1, HCW of steers assigned to CCROP (402 kg) was greater ( < 0.01, SEM 2.1) than that of steers assigned to both RESIDUE (389 kg) and DRYLOT (391 kg), which did not differ ( = 0.40). This difference in HCW is most likely a result of differences in BW at the start of the finishing phase in yr 1. However in yr 2, HCW of steers assigned to CCROP (400 kg) and RESIDUE (397 kg) did not differ ( = 0.26, SEM 2.1) but were greater ( < 0.01) than that of steers assigned to DRYLOT (367 kg), despite the fact that steers assigned to RESIDUE entered the finishing phase at a lighter BW than steers assigned to CCROP. Marbling was greater ( = 0.01, SEM 3.9) for steers assigned to DRYLOT (429) than for steers assigned to RESIDUE (414), although steers assigned to CCROP (424) were not different ( ≥ 0.10) from steers assigned to DRYLOT or RESIDUE. When cost and price scenarios from the last 5 yr were conducted, no treatment appeared to be consistently superior in terms of cost of gain or net return. Therefore, all 3 systems appear to be viable options for producers.