Meta-analysis of genome-wide association from genomic prediction models.

Genome-wide association (GWA) studies based on GBLUP models are a common practice in animal breeding. However, effect sizes of GWA tests are small, requiring larger sample sizes to enhance power of detection of rare variants. Because of difficulties in increasing sample size in animal populations, one alternative is to implement a meta-analysis (MA), combining information and results from independent GWA studies. Although this methodology has been used widely in human genetics, implementation in animal breeding has been limited. Thus, we present methods to implement a MA of GWA, describing the proper approach to compute weights derived from multiple genomic evaluations based on animal-centric GBLUP models. Application to real datasets shows that MA increases power of detection of associations in comparison with population-level GWA, allowing for population structure and heterogeneity of variance components across populations to be accounted for. Another advantage of MA is that it does not require access to genotype data that is required for a joint analysis. Scripts related to the implementation of this approach, which consider the strength of association as well as the sign, are distributed and thus account for heterogeneity in association phase between QTL and SNPs. Thus, MA of GWA is an attractive alternative to summarizing results from multiple genomic studies, avoiding restrictions with genotype data sharing, definition of fixed effects and different scales of measurement of evaluated traits.

Polymorphisms in calpastatin and mu-calpain genes are associated with beef iron content.

The objective of this study was to assess the association of markers in the calpastatin and mu-calpain loci with iron in beef cattle muscle. The population consisted of 259 cross-bred steers from Beefmaster, Brangus, Bonsmara, Romosinuano, Hereford and Angus sires. Total iron and heme iron concentrations were measured. Markers in the calpastatin (referred to as CAST) and mu-calpain (referred to as CAPN4751) genes were used to assess their association with iron levels. The mean and standard error for iron and heme iron content in the population was 35.6 ± 1.3 µg and 27.1 ± 1.4 µg respectively. Significant associations (P < 0.01) of markers were observed for both iron and heme iron content. For CAST, animals with the CC genotype had higher levels of iron and heme iron in longissimus dorsi muscle. For CAPN4751, individuals with the TT genotype had higher concentrations of iron and heme iron than did animals with the CC and CT genotypes. Genotypes known to be associated with tougher meat were associated with higher levels of iron concentration.

Genetic markers on BTA14 predictive for residual feed intake in beef steers and their effects on carcass and meat quality traits.

With the high cost of feed for animal production, genetic selection for animals that metabolize feed more efficiently could result in substantial cost savings for cattle producers. The purpose of this study was to identify DNA markers predictive for differences among cattle for traits associated with feed efficiency. Crossbred steers were fed a high-corn diet for 140 days and average daily feed intake (ADFI), average daily gain (ADG), and residual feed intake (RFI) phenotypes were obtained. A region on chromosome 14 was previously associated with RFI in this population of animals. To develop markers with the highest utility for predicting an animal's genetic potential for RFI, we genotyped additional markers within this chromosomal region. These polymorphisms were genotyped on the same animals (n = 1066) and tested for association with ADFI, ADG and RFI. Six markers within this region were associated with RFI (P ≤ 0.05). After conservative correction for multiple testing, one marker at 25.09 Mb remained significant (P = 0.02) and is responsible for 3.6% of the RFI phenotypic variation in this population of animals. Several of these markers were also significant for ADG, although none were significant after correction. Marker alleles with positive effects on ADG corresponded to lower RFI, suggesting an effect increasing growth without increasing feed intake. All markers were also assessed for their effects on meat quality and carcass traits. All of the markers associated with RFI were associated with adjusted fat thickness (AFT, P ≤ 0.009) and three were also associated with hot carcass weight (HCW, P ≤ 0.003). Marker alleles associated with lower RFI were also associated with reduced AFT, and if they were associated for HCW, the effect was an increase in weight. These markers may be useful as prediction tools for animals that utilize feed more efficiently; however, validation with additional populations of cattle is required.

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.

Associations of polymorphisms in the promoter I of bovine acetyl-CoA carboxylase-alpha gene with beef fatty acid composition.

The objectives of this study were to identify single nucleotide polymorphisms (SNPs) in the promoter I (PI) region of the bovine acetyl-CoA carboxylase-alpha (ACACA) gene and to evaluate the extent to which they were associated with lipid-related traits. Eight novel SNPs were identified, which were AJ276223:g.2064T>A (SNP1), g.2155C>T (SNP2), g.2203G>T (SNP3), g.2268T>C (SNP4), g.2274G>A (SNP5), g.2340A>G (SNP6), g.2350T>C (SNP7) and g.2370A>G (SNP8). Complete linkage disequilibrium was observed among SNP1, 2, 4, 5, 6 and 8. Phenotypic data were collected from 573 cross-bred steers with six sire breeds, including Hereford, Angus, Brangus, Beefmaster, Bonsmara and Romosinuano. The genotypes of SNP1/2/4/5/6/8 were significantly associated with adjusted backfat thickness. The genotypes of SNP3 were significantly associated with triacylglycerol (TAG) content and fatty acid composition of longissimus dorsi muscle (LM) in Brangus-, Romosinuano- and Bonsmara-sired cattle. Cattle with g.2203GG genotype had greater concentrations of TAG, total lipid, total saturated fatty acid and total monounsaturated fatty acid than did cattle with g.2203GT genotype. The genotypes of SNP7 were significantly associated with fatty acid composition of LM. Cattle with genotype g.2350TC had greater amounts of several fatty acids in LM than did cattle with genotype g.2350CC. Our results suggested that the SNPs in the PI region of ACACA gene are associated with variations in the fatty acid contents in LM.

Markers on bovine chromosome 20 associated with carcass quality and composition traits and incidence of contracting infectious bovine keratoconjunctivitis.

The objective of this study was to use single nucleotide polymorphisms (SNP) located on bovine chromosome 20 to fine map a previously identified QTL associated with the incidence of infectious bovine keratoconjunctivitis (IBK). Crossbred steers (GPE 7; n = 539) derived from sires of 7 Bos taurus breeds and having veterinary records related to IBK were used to test the association of a total of 105 SNP located under the most relevant region of the QTL. Five SNP were significantly associated with IBK (P < 0.05), as animals inheriting differing genotypes from individual SNP exhibited significantly different incidence rates of IBK. The population also had numerous other phenotypes, supporting evaluation of association of the 105 markers with carcass traits to identify potential antagonistic effects of implementing a marker-assisted selection program for IBK susceptibility. An association of 2 SNP for marbling and tenderness was identified, along with 3 SNP associated with the percentage of carcasses classified as choice. Four SNP were significantly associated with fat yield, 2 SNP with longissimus muscle area, and 2 additional SNP with dressing percentage. The association of these markers indicates that the evaluated QTL region may, in fact, harbor the causative mutations responsible for the variation observed in IBK susceptibility and carcass quality and composition traits. Thus, further evaluation of SNP in this region is necessary in order to identify mutations accounting for the largest degree of variation for IBK and carcass traits.

Relationships among calpastatin single nucleotide polymorphisms, calpastatin expression and tenderness in pork longissimus.

Genome scans in the pig have identified a region on chromosome 2 (SSC2) associated with tenderness. Calpastatin is a likely positional candidate gene in this region because of its inhibitory role in the calpain system that is involved in postmortem tenderization. Novel single nucleotide polymorphisms (SNP) in calpastatin were identified and used to genotype a population (n = 1042) of Duroc-Landrace-Yorkshire swine for association with longissimus lumborum slice shear force (SSF) measured at days 7 and 14 postmortem. Three genetic markers residing in the calpastatin gene were significantly associated with SSF (P < 0.0005). Haplotypes constructed from markers in the calpastatin gene were significantly associated with SSF (F-ratio = 3.93; P-value = 0.002). The levels of normalized mRNA expression of calpastatin in the longissimus lumborum of 162 animals also were evaluated by real-time RT-PCR and were associated with the genotype of the most significant marker for SSF (P < 0.02). This evidence suggests that the causative variation alters expression of calpastatin, thus affecting tenderness. In summary, these data provide evidence of several significant, publicly available SNP markers associated with SSF that may be useful to the swine industry for marker assisted selection of animals that have more tender meat.

Prevalence of Mycobacterium avium subsp. paratuberculosis in ileocecal lymph nodes and on hides and carcasses from cull cows and fed cattle at commercial beef processing plants in the United States.

Clinical associations between Crohn's disease in humans and Mycobacterium avium subsp. paratuberculosis (MAP) have been suggested but not confirmed. Cattle could be sources for MAP, but little information on MAP prevalence with beef has been reported. Samples of ileocecal lymph nodes and swabs of hides and carcasses from 343 animals at cull cattle slaughtering facilities and 243 animals at fed cattle slaughtering facilities across the United States were analyzed for the presence of MAP. Amplification of genetic sequences detected MAP DNA predominantly on hides and in lymph nodes of samples taken at both types of processing facilities. More than 34% of the cattle at cull cow slaughtering facilities had ileocecal lymph nodes that tested positive for MAP DNA. From these same cattle, hide prevalence was more than twofold greater than the prevalence in ileocecal lymph nodes, suggesting that cross-contamination could be occurring during transport and lairage. The prevalence of MAP DNA decreased during processing, and less than 11% of the carcasses tested positive after interventions in the cull cow processing facilities. Using standard double-decontamination and culture techniques, less than 1% of the postintervention carcasses tested positive for viable MAP at cull cow facilities. In samples from the facilities processing only fed cattle, MAP prevalence of 1% or less was detected for ileocecal lymph node, hide, and carcass samples, and viable MAP was not detected. Based on this study, fed cattle carcasses are unlikely sources of MAP, and carcasses at cull cow plants have only a slight risk for transmitting viable MAP, due to current interventions.

Prevalence and level of Escherichia coli O157:H7 in feces and on hides of feedlot steers fed diets with or without wet distillers grains with solubles.

The objective of this study was to determine if wet distillers grains with solubles (WDGS) from corn in diets affected Escherichia coli O157:H7 in growing and finishing cattle; steers (n = 603) were randomly assigned to diets with or without WDGS. Hide and fecal samples were collected monthly (October through June) from each animal for enumeration and enrichment of E. coli O157:H7. In the growing phase (0 or 13.9% WDGS diets), fecal prevalence for E. coli O157:H7 in steers fed a diet with WDGS was twice that of the prevalence in control steers (P < 0.001). In the finishing phase (0 or 40% WDGS diets), the average prevalence in feces (P < 0.001) and on hides (P < 0.001) was higher for cattle fed WDGS. The average percentage of fecal E. coli O157:H7 enumerable samples during the finishing phase for cattle fed WDGS was 2.7% compared with 0.1% for control steers (P < 0.001). The average percentage of E. coli O157:H7 enumerable hide samples was not different between diets, but the cattle fed WDGS had higher levels (P < 0.05) of the pathogen. Animals fed WDGS had higher levels of E. coli (P < 0.001), higher pH values (P < 0.001), and lower concentrations of L-lactate (P < 0.001) in feces than those values of the control steers. These results indicate that feeding 40% WDGS could increase the level and prevalence of E. coli O157:H7 in and on feedlot cattle when E. coli O157:H7 is seasonally low.

Consumer acceptance and steak cutting yields of beef top sirloin and knuckle subprimals.

Beef knuckles (n=150) and center-cut top sirloin butts (n=150) were used to determine portion-controlled steak cutting yields, palatability characteristics, and consumer acceptance of rectus femoris (RF), vastus lateralis (VL), and gluteus medius (GM) steaks. Steak yields were higher (P<0.05) for top sirloins than knuckles. Trained sensory panel ratings for overall tenderness, juiciness, and flavor were similar between RF and GM. Consumer panel ratings for tenderness and juiciness were higher (P<0.05) for GM than RF; however, consumer perceptions of overall like and flavor were similar for GM and RF. Vastus lateralis received lower (P<0.05) trained panel and consumer ratings for all traits than either RF or GM. Palatability of VL will need improvement to be a viable foodservice offering. Yet, these data suggest that RF would amply substitute for GM in foodservice settings, and that knuckle steak yields would be adequate for foodservice applications.

Predicting aged pork quality using a portable Raman device.

The utility of Raman spectroscopic signatures of fresh pork loin (1 d & 15 d postmortem) in predicting fresh pork tenderness and slice shear force (SSF) was determined. Partial least square models showed that sensory tenderness and SSF are weakly correlated (R2 = 0.2). Raman spectral data were collected in 6 s using a portable Raman spectrometer (RS). A PLS regression model was developed to predict quantitatively the tenderness scores and SSF values from Raman spectral data, with very limited success. It was discovered that the prediction accuracies for day 15 post mortem samples are significantly greater than that for day 1 postmortem samples. Classification models were developed to predict tenderness at two ends of sensory quality as "poor" vs. "good". The accuracies of classification into different quality categories (1st to 4th percentile) are also greater for the day 15 postmortem samples for sensory tenderness (93.5% vs 76.3%) and SSF (92.8% vs 76.1%). RS has the potential to become a rapid on-line screening tool for the pork producers to quickly select meats with superior quality and/or cull poor quality to meet market demand/expectations.

Interventions to reduce/eliminate Escherichia coli O157:H7 in ground beef.

The Escherichia coli O157:H7 (E. coli O157:H7) outbreak in the Northwestern United States ushered in an era that has dramatically changed the way beef processors in the United States convert live cattle into meat. Unprecedented cooperation among the beef processors and massive investment in research by the US government and the beef industry have resulted in an acceptable level of control of E. coli O157:H7 in ground beef. The evidence to support the progress in control of E. coli O157:H7 is the CDC data for reduction in human illness as well as the dramatic reduction in the number of E. coli O157:H7-positive samples in USDA-FSIS ground beef monitoring. This manuscript highlights some of the recent findings from our laboratory on the control of E. coli O157:H7 in ground beef. We have also summarized the key events/decisions/milestones that have contributed to the control of E. coli O157:H7 in ground beef in the United States. While there is much to be done to bring E. coli O157:H7 under complete control in the beef sector of the food industry, E. coli O157:H7 also is becoming a major issue in the fresh vegetable sector, as evidenced by the 2006 outbreaks in the United States. We have discussed how the fresh vegetable industry can benefit from the beef industry's experience to expedite the control of E. coli O157:H7 in their products.

Endocannabinoid concentrations in plasma during the finishing period are associated with feed efficiency and carcass composition of beef cattle.

We previously have shown that plasma concentrations of endocannabinoids (EC) are positively correlated with feed efficiency and leaner carcasses in finishing steers. However, whether the animal growth during the finishing period affects the concentration of EC is unknown. The objective of this study was to quantify anandamide (AEA) and 2-arachidonyl glycerol (2-AG) in plasma during different stages of the finishing period and identify possible associations with production traits and carcass composition in beef calves. Individual DMI and BW gain were measured on 236 calves ( = 127 steers and = 109 heifers) for 84 d on a finishing ration. Blood samples were collected on d 0 (early), 42 (mid), and 83 (late) of days on study (DOS). Cattle were slaughtered 44 d after the feeding study. Plasma concentration of AEA at 0 DOS was indirectly associated with the G:F ( < 0.01) and directly associated with residual feed intake (RFI; < 0.05) in steers. In contrast, plasma concentration of AEA at 83 DOS was directly associated with the G:F and indirectly associated RFI in heifers and steers ( < 0.01). In addition, AEA concentration at 42 and 83 DOS was positively associated with ADG and DMI ( < 0.01) in heifers and steers. Furthermore, 2-AG concentration at 42 DOS was positively associated with ADG in steers ( < 0.01) and heifers ( < 0.10). Plasma concentration of AEA was positively associated ( < 0.05) with HCW, USDA-calculated yield grade, and 12th-rib fat thickness in heifers, whereas no associations were found in steers. In contrast, 2-AG concentration was not associated with any carcass traits. These results provide evidence that circulating EC change during animal growth and that AEA concentration may be a useful predictor of growth and feed efficiency and, in females, of carcass attributes.

Effect of hot carcass weight on loin, ham, and belly quality from pigs sourced from a commercial processing facility,.

The objective was to determine the predictive abilities of HCW for loin, ham, and belly quality of 7,684 pigs with carcass weights ranging from 53.2 to 129.6 kg. Carcass composition, subjective loin quality, and ham face color were targeted on all carcasses, whereas in-plant instrumental loin color and belly quality were assessed on 52.0 and 47.5% of carcasses, respectively. Loin chop slice shear force (SSF), cured ham quality, and adipose iodine value (IV) were evaluated on at least 10% of the population. The slope of regression lines and coefficients of determination between HCW and quality traits were computed using PROC REG of SAS and considered significant at ≤ 0.05. As HCW increased, boneless loins became darker and redder, evidenced by lower L* (ß = -0.0243, < 0.001) and greater a* values (ß = 0.0106, < 0.001); however, HCW accounted for only ≤0.80% of the variability in loin L* and a* values. Similarly, subjective loin color score (ß = 0.0024, < 0.001) increased with increasing carcass weight, but subjective marbling score was not affected by HCW (ß = -0.0022, = 0.06). After 20 d of aging, HCW explained only 0.98% of the variability in loin L* values (ß = -0.0287, < 0.01). Heavier carcasses had lower SSF values (ß = -0.1269, < 0.001) of LM chops, although HCW explained only 4.46% of the variability in SSF. Although heavier carcasses produced loins that exhibited lower ultimate pH values (ß = -0.0018, < 0.001), HCW explained only 1.23% of the variability in ultimate loin pH. Interestingly, cook loss decreased (ß = -0.0521, < 0.001) as HCW increased, with HCW accounting for 5.60% of the variability in cook loss. Heavier carcasses resulted in darker, redder ham face color ( < 0.001), but HCW accounted for only ≤2.87% of the variability in ham face L* values and 0.47% of the variability in a* values. Heavier carcasses produced thicker and firmer bellies, with HCW accounting for 37.81% of the variability in belly thickness (ß = 0.0272, < 0.001), 20.35% of the variability in subjective flop score (ß = 0.0406, < 0.001), and 10.35% of the variability in IV (ß = -0.1263, < 0.001). Overall, the proportion of variability in loin and ham quality explained by HCW was poor (≤5.60%), suggesting that HCW is a poor predictor of the primal quality of pigs within this weight range. Nonetheless, HCW was a moderate predictor of belly quality traits. The findings of this study suggest that increasing HCW did not compromise loin, ham, or belly quality attributes.

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.

Effects of dietary protein concentration and ractopamine hydrochloride on performance and carcass characteristics of finishing beef steers.

Ractopamine hydrochloride (RAC) is used in the feedlot industry to increase daily gain, improve feed efficiency, and increase HCW. However, little work has been done to determine whether additional protein is needed in the diet to maximize the benefit of RAC in beef cattle. Objectives of our experiment were to determine if feeding additional CP in conjunction with RAC would improve animal performance and carcass characteristics. Therefore, an experiment was conducted using finishing diets containing 13.5 or 17.5% CP with 0 or 300 mg of RAC for 30 to 33 d at the end of the finishing period. Beef steers ( = 438; 387.8 ± 1.9 kg initial BW) were randomly assigned to 1 of 4 treatments in a 2 × 2 factorial arrangement (16 pens total, 4 pens/treatment). No interactions between feeding RAC and CP level were detected ( > 0.19) for animal performance or carcass traits. Final BW did not differ among treatment ( = 0.37); however, final BW had a tendency to be 2% greater ( = 0.07) when the 13.5% CP diet was fed. Dry matter intake was not different between steers fed 0 or 300 mg/d of RAC ( = 0.20), yet DMI was 12% greater for cattle fed the 13.5% CP compared with steers fed the 17.5% CP diet ( < 0.01). Daily gain did not differ for cattle fed different levels of RAC or CP ( > 0.16). The G:F was 3.6% greater for cattle fed 300 vs. 0 mg/d of RAC ( = 0.04). The G:F was 8.7% greater for cattle fed the 17.5% diet vs. the 13.5% CP diet ( < 0.01), which can be attributed to the decreased DMI for cattle fed the 17.5% CP diet. Hot carcass weight was not different for steers fed 0 or 300 mg/d of RAC ( = 0.36) or for steers fed the 13.5% diet vs. 17.5% CP diet ( = 0.93). Dressing percentage was 1.5% greater for cattle fed 300 vs. 0 mg/d of RAC ( = 0.05) but was not different between cattle fed the different CP levels in the diet ( = 0.16). Longissimus area, adjusted 12th-rib fat, and marbling score did not differ across RAC or CP treatments ( > 0.26). Additionally, no differences in USDA yield grade or percentage of cattle grading USDA Choice were detected for RAC or CP treatments ( > 0.26), which also supports the idea that quality grade of cattle fed RAC at the same level of fatness is not impacted. Our data indicate excess protein did not enhance the response to RAC, and furthermore, the improved performance from RAC reported by others was not observed other than a small increase in G:F.

The effects of degree of dark cutting on tenderness and sensory attributes of beef.

The objective of this study was to determine the effect of degree of dark cutting (DC) on the tenderness, juiciness, and flavor attributes of beef. During carcass grading at a large U.S. commercial beef harvesting facility, DC carcasses ( = 160) and matching normal control (NC) carcasses ( = 160) were selected. Longissimus lumborum (LL) pH was determined and DC carcasses were classified as severe (severe dark cutter [SEDC]; mean pH = 6.9; = 40), moderate (moderate dark cutter [MODC]; mean pH = 6.6; n = 40), mild (mild dark cutter [MIDC]; mean pH = 6.4; = 40), or shady (shady dark cutter [SHDC]; mean pH = 6.1; = 40). Strip loins were obtained from the left carcass sides, vacuum-packaged, and aged at 1°C. Slice shear force (SSF) was measured (14 d postmortem) fresh (never frozen), and trained descriptive sensory analysis of tenderness, juiciness, and flavor was measured (13 d postmortem) on frozen/thawed LL steaks. Cooked SSF pieces were frozen and used for western blotting of desmin to determine extent of postmortem proteolysis. Thaw and cook loss decreased as intensity of DC increased, with SEDC having the lowest loss (1.83 and 10.1%, respectively) compared with NC (3.37 and 14.9%, respectively). Slice shear force was higher (P < 0.05) for SHDC (25.6 kg) and MIDC (22.9 kg) compared with SEDC (16.8 kg), MODC (19.4 kg), and NC (17.8 kg). Sarcomere length was shorter ( < 0.05) between DC class (1.66, 1.67, 1.71, and 1.73 µm for SEDC, MODC, MIDC, and SHDC, respectively) and NC (1.86 µm). Postmortem proteolysis of desmin was greater ( < 0.05) for NC compared with all DC classes (59.83% vs. 49.20, 40.31, 42.07, and 43.30% for SEDC, MODC, MIDC, and SHDC, respectively). Trained sensory panel ratings for tenderness differed ( < 0.05) among DC class with SEDC (6.51) the most tender followed by MODC (6.04) and then MIDC (5.19), whereas SHDC (4.66) and NC (4.93) were the toughest. Juiciness ratings differed ( < 0.05) among each DC class (5.9, 5.7, 5.4, and 5.2 for SEDC, MODC, MIDC, and SHDC, respectively), with no difference between MIDC or SHDC compared with NC (5.23). Fat-like, rancid, heated oil, chemical, and musty/earthy/hummus flavors increased ( < 0.05) whereas metallic, sour, and salty flavors decreased as severity of DC increased. This study showed DC and NC differed in LL tenderness, juiciness, and flavor. The direction and/or magnitude of those differences were greatly dependent on severity of DC. Steaks with intermediate pH (SHDC and MIDC) are most likely to be tough and are regularly included in U.S. Select and U.S. Choice product lines.

Endocannabinoids concentrations in plasma associated with feed efficiency and carcass composition of beef steers.

Endocannabinoids, including anandamide (AEA) and 2-arachidonoylglycerol (2-AG), are a class of endogenous lipid mediators that activate cannabinoids receptors and may be involved in the control of feed intake and energy metabolism. The objective of this study was to quantify AEA and 2-AG in plasma and identify possible associations with production traits and carcass composition in finishing beef steers. Individual DMI and BW gain were measured on 140 Angus-sired steers for 105 d on a finishing ration. Blood samples were collected on d 84 of the experiment, which was 40 d before slaughter. Variables were analyzed using Pearson CORR procedure of SAS. Mean endocannabinoid concentrations in plasma were 4.48 ± 1.82 ng/mL and 0.44 ± 0.24 ng/mL for AEA and 2-AG, respectively. The AEA concentration was positively correlated with G:F ratio ( = 0.20; = 0.02), indicating that more efficient animals had greater AEA plasma concentrations. In addition, AEA concentration tended to be negatively correlated with the 12th rib fat thickness ( = -0.17; = 0.07); but no correlation was found with USDA-calculated yield grade ( = -0.14; = 0.11), or marbling score ( = 0.05; = 0.54). The concentration of 2-AG was positively correlated with AEA ( = 0.21; = 0.01); however, 2-AG concentration was not correlated with parameters of feed efficiency or carcass composition. To our knowledge, this study is the first to report plasma concentration of endocannabinoids in steers. These results provide evidence that plasma concentration of a key endocannabinoid, AEA, was favorably correlated with feed efficiency and fat thickness in finishing steers.

Effects of marketing group and production focus on quality and variability of adipose tissue and bellies sourced from a commercial processing facility.

Objectives were to determine the effects of marketing group on quality and variability of belly and adipose tissue quality traits of pigs sourced from differing production focuses (lean vs. quality). Pigs ( = 8,042) raised in 8 barns representing 2 seasons (cold and hot) were used. Three groups were marketed from each barn with 2 barns per production focus marketed per season. Data were collected on 7,684 carcasses at a commercial abattoir. Fresh belly characteristics, American Oil Chemists' Society iodine value (AOCS-IV), and near-infrared iodine value were measured on a targeted 50, 10, and 100% of carcasses, respectively. Data were analyzed as a split-plot design in the MIXED procedure of SAS 9.4 with production focus as the whole-plot factor and marketing group as the split-plot factor. Barn (block), season, and sex were random variables. A multivariance model was fit using the REPEATED statement with the marketing group × production focus interaction as the grouping variable. Variances for production focus and marketing groups were calculated using the MEANS procedure. Homogeneity of variance was tested on raw data using the Levene's test of the GLM procedure. Among quality focus carcasses, marketing group 3 bellies weighed less ( ≤ 0.03) than those from either marketing group 1 or 2, but there was no difference ( ≥ 0.99) among marketing groups of the lean focus carcasses. There was no effect ( ≥ 0.11) of production focus on fresh belly measures, SFA, or iodine value (IV), but lean focus carcasses had decreased ( = 0.04) total MUFA and increased ( < 0.01) total PUFA compared with quality focus carcasses. Marketing group did not affect ( ≥ 0.10) fresh belly dimensions, total SFA, total MUFA, total PUFA, or IV. Belly weight, flop score, width, and all depth measurements were less variable ( ≤ 0.01); whereas, belly length, total SFA, and total MUFA were more variable ( < 0.0001) in lean focus carcasses than in quality focus carcasses. There was no difference ( ≥ 0.17) in total PUFA or AOCS-IV variability between production focuses. Variance of flop score, total MUFA, and total PUFA were not equal ( ≤ 0.01) among marketing groups. Belly weight, length, width, and depth measurements; SFA; or IV variance did not differ ( ≥ 0.06) among marketing groups. Although a multiple-marketing strategy was effective at minimizing differences in belly characteristics, differences in the variability of these traits exist among marketing groups and are likely dependent on the production system used.

Comparison of variability in pork carcass composition and quality between barrows and gilts.

Pigs ( = 8,042) raised in 8 different barns representing 2 seasons (cold and hot) and 2 production focuses (lean growth and meat quality) were used to characterize variability of carcass composition and quality traits between barrows and gilts. Data were collected on 7,684 pigs at the abattoir. Carcass characteristics, subjective loin quality, and fresh ham face color (muscles) were measured on a targeted 100% of carcasses. Fresh belly characteristics, boneless loin weight, instrumental loin color, and ultimate loin pH measurements were collected from 50% of the carcasses each slaughter day. Adipose tissue iodine value (IV), 30-min loin pH, LM slice shear force, and fresh ham muscle characteristic measurements were recorded on 10% of carcasses each slaughter day. Data were analyzed using the MIXED procedure of SAS as a 1-way ANOVA in a randomized complete block design with 2 levels (barrows and gilts). Barn (block), marketing group, production focus, and season were random variables. A 2-variance model was fit using the REPEATED statement of the MIXED procedure, grouped by sex for analysis of least squares means. Homogeneity of variance was tested on raw data using Levene's test of the GLM procedure. Hot carcass weight of pigs (94.6 kg) in this study was similar to U.S. industry average HCW (93.1 kg). Therefore, these data are representative of typical U.S. pork carcasses. There was no difference ( ≥ 0.09) in variability of HCW or loin depth between barrow and gilt carcasses. Back fat depth and estimated carcass lean were more variable ( ≤ 0.0001) and IV was less variable ( = 0.05) in carcasses from barrows than in carcasses from gilts. Fresh belly weight and thickness were more variable ( ≤ 0.01) for bellies of barrows than bellies of gilts, but there was no difference in variability for belly length, width, or flop distance ( ≥ 0.06). Fresh loin subjective color was less variable ( < 0.01) and subjective marbling was more variable ( < 0.0001) in loins from barrows than in those from gilts, but there were no differences ( ≥ 0.08) in variability for any other loin traits or fresh ham traits. Overall, traits associated with carcass fatness, including back fat depth, belly thickness, and marbling, but not IV, were more variable in carcasses from barrows than in carcasses from gilts, whereas minimal differences in variability existed between carcasses of barrows and carcasses of gilts for traits associated with carcass muscling and lean quality.