The objective of this study was to determine the influence of beef LM nutrient components on beef palatability traits and evaluate the impact of USDA quality grade on beef palatability. Longissimus muscle samples from related Angus cattle (n = 1,737) were obtained and fabricated into steaks for trained sensory panel, Warner-Bratzler shear force (WBSF), lipid oxidation measured by thiobarbituric acid reactive substances (TBARS), fatty acid, and mineral composition analysis. Pearson phenotypic correlations were obtained by the correlation procedure of SAS. Beef palatability data were analyzed by the GLM procedure of SAS with USDA quality grade as the main effect. Specific mineral concentrations did not demonstrate strong correlations with WBSF or sensory traits (r = −0.14 to 0.16). However, minerals appeared to have a stronger relationship with flavor; all minerals evaluated except Ca and Mn were positively correlated (P < 0.05) with beef flavor. Stearic acid (C18:0), C18:2, C20:4, and PUFA were negatively correlated (P < 0.05) with all 3 panelist tenderness traits (r = −0.09 to −0.22) and were positively correlated (P < 0.05) with WBSF (r = 0.09 to 0.15). The MUFA were positively correlated (P < 0.05) with panelist tenderness ratings (r = 0.07 to 0.10) and negatively associated (P< 0.05) with WBSF (r = −0.11). The strongest correlations with juiciness were negative relationships (P < 0.05) with C18:2, C18:3, C20:4, and PUFA (r = −0.08 to −0.20). Correlations with beef flavor were weak, but the strongest was a positive relationship with MUFA (r = 0.13). Quality grade affected (P < 0.05) WBSF, TBARS, and all trained sensory panel traits, except livery/metallic flavor. As quality grade increased, steaks were more tender (P < 0.05), as evidenced by both WBSF and sensory panel tenderness ratings. Prime steaks were rated juiciest (P < 0.05) by panelists, whereas Select and Low Choice were similarly rated below Top Choice for sustained juiciness. Quality grade influenced (P < 0.05) beef flavor, but not in a linear fashion. Although there were significant correlations, these results indicate tenderness, juiciness, and flavor are not strongly influenced by individual nutrient components in beef LM. Furthermore, the positive linear relationships between USDA quality grade and beef palatability traits suggest quality grade is still one of the most valuable tools available to predict beef tenderness. ABSTRACT: The objective of this study was to determine the influence of beef LM nutrient components on beef palatability traits and evaluate the impact of USDA quality grade on beef palatability. Longissimus muscle samples from related Angus cattle (n = 1,737) were obtained and fabricated into steaks for trained sensory panel, Warner-Bratzler shear force (WBSF), lipid oxidation measured by thiobarbituric acid reactive substances (TBARS), fatty acid, and mineral composition analysis. Pearson phenotypic correlations were obtained by the correlation procedure of SAS. Beef palatability data were analyzed by the GLM procedure...

The objective of this study was to characterize variation and identify SNP and chromosomal regions associated with mineral concentrations in LM of Angus beef cattle. Samples of LM from 2,285 Angus cattle were obtained, and concentrations of 7 minerals, including iron, magnesium, manganese, phosphorus, potassium, sodium, and zinc, were quantified. Genomic DNA extracted from the ground beef sample used for mineral composition was genotyped with the Bovine SNP50 Infinium II BeadChip, and effects of SNP on each trait were estimated using the Bayes-Cπ module of GenSel software. Pedigree-based estimates of heritabilities and corresponding genetic variances indicate iron was the only mineral concentration that could be considered a good candidate for manipulation by genomic selection. The amount of variation that could be accounted for by SNP genotypes was concordant with pedigree-based heritabilities and varied from very low for potassium and sodium (<0.09) to medium high (0.37) for iron. Although significant chromosomal regions were identified for all minerals analyzed in this study, further study focused on iron. Seven regions on 6 chromosomes (1, 2, 7, 10, 15, and 28) were identified to have a major effect on the iron content of LM in Angus cattle. The accuracy of direct genomic values (DGV) for iron concentration was estimated using a 5-fold cross-validation strategy. The accuracy of DGV estimated as the genetic correlation between DGV and the phenotype (iron concentration) adjusted for contemporary groups was 0.59. A bivariate animal model was used to estimate genetic correlations between iron concentrations and a reduced set of economically important carcass traits: HCW, rib eye area, calculated USDA yield grade, percent KPH, and marbling score. The genetic correlations between iron concentration and HCW, percentage KPH, marbling score, and rib eye area were small (-0.19 to 0.15) and nonsignificant. Although still weak (0.22), a positive significant genetic correlation was identified between iron content and USDA calculated yield grade. Beef is a major contributor of iron and zinc in the human diet, and this study found that iron content might be effectively manipulated through marker-assisted selection programs, without compromising other carcass and palatability traits.

The objective of this study was to estimate genetic parameters for concentrations of minerals in LM and to evaluate their associations with beef palatability traits. Samples of LM from 2,285 Angus cattle were obtained and fabricated into steaks for analysis of mineral concentrations and for trained sensory panel assessments. Nine minerals, including calcium, copper, iron, magnesium, manganese, phosphorus, potassium, sodium, and zinc, were quantified. Restricted maximum likelihood procedures were used to obtain estimates of variance and covariance components under a multiple-trait animal model. Estimates of heritability for mineral concentrations in LM varied from 0.01 to 0.54. Iron and sodium were highly and moderately heritable, respectively, whereas the other minerals were lowly heritable except for calcium, copper, and manganese, which exhibited no genetic variation. Strong positive genetic correlations existed between iron and zinc (0. ABSTRACT: The objective of this study was to estimate genetic parameters for concentrations of minerals in LM and to evaluate their associations with beef palatability traits. Samples of LM from 2,285 Angus cattle were obtained and fabricated into steaks for analysis of mineral concentrations and for trained sensory panel assessments. Nine minerals, including calcium, copper, iron, magnesium, manganese, phosphorus, potassium, sodium, and zinc, were quantifi ed. Restricted maximum likelihood procedures were used to obtain estimates of variance and covariance components under a multiple-trait animal model. Estimates of heritability for mineral concentrations in LM varied from 0.01 to 0.54. Iron and sodium were highly and moderately heritable, respectively, whereas the other minerals were lowly heritable except for calcium, copper, and manganese, which exhibited no genetic variation. Strong positive genetic correlations existed between iron and zinc (0.49, P < 0.05), between magnesium and phosphorus (0.88, P < 0.05), between magnesium and sodium (0.68, P < 0.05), and between phosphorus and potassium (0.69, P < 0.05). Overall tenderness assessed by trained sensory panelists was positively associated with manganese, potassium, and sodium and negatively associated with phosphorus and zinc concentrations (P < 0.05). Juiciness assessed by trained sensory panelists was negatively associated with magnesium and positively associated with manganese and sodium concentrations (P < 0.05). Livery or metallic fl avor was not associated with any of the minerals (P > 0.05). Beefy fl avor was positively associated with calcium, iron, and zinc and negatively associated with sodium concentration, whereas a painty or fi shy fl avor was positively associated with sodium and negatively associated with calcium and potassium concentrations (P < 0.05). Beef is a major contributor of iron and zinc in the human diet, and these results demonstrate suffi cient genetic variation for these traits to be improved through marker-assisted selection programs without compromising beef palatability. 05). Li...

SummaryBeef is considered to be an excellent source of dietary iron. However, little is known about the genetic control of beef iron content. We hypothesized that genetic polymorphisms in transferrin receptor 2 (TFR2) and solute carrier family 40 (iron‐regulated transporter), member 1 (SLC40A1) could influence skeletal muscle iron content. The objective of this study was to use Angus cattle to identify single‐nucleotide polymorphisms (SNPs) in the exons and flanking regions of the bovine TFR2 and SLC40A1 genes and to evaluate the extent to which genetic variation in them was associated with bovine longissimus dorsi muscle iron content. Ten novel SNPs were identified in TFR2, of which one SNP tended to be associated (P < 0.013) with skeletal muscle iron content. Nine novel SNPs in SLC40A1, NC007300: rs133108154, rs137140497, rs135205621, rs136600836, rs134388440, rs136347850, rs134186279, rs134621419 and rs137555693, were identified, of which SNPs rs134388440, rs136347850 and rs137555693 were significantly associated (P < 0.007) with skeletal muscle iron content. High linkage disequilibrium was observed among SLC40A1 SNPs rs134388440, rs136347850 and rs137555693 (R2 > 0.99), from which two haplotypes, TGC and CAT, were defined. Beef from individuals that were homozygous for the TGC haplotype had significantly (P < 0.001) higher iron content than did beef from CAT homozygous or heterozygous individuals. The estimated size of effect of the identified haplotypes was 0.3% of the phenotypic variance. In conclusion, our study provides evidence for genetic control of beef iron concentration. Moreover, SNPs identified in SLC40A1, rs134388440, rs136347850 and rs137555693 might be useful markers for the selection of Angus cattle for altered iron content.

Cucurbit bacterial wilt, caused by Erwinia tracheiphila, is a damaging disease of cucurbit crops in the Midwest and Northeast U.S. Current management of bacterial wilt relies primarily on insecticide applications to control striped and spotted cucumber beetles (Acalymma vittatum and Diabrotica undecimpunctata howardi, respectively), which vector E. tracheiphila. Development of alternative management strategies is constrained by a lack of understanding of bacterial wilt etiology. The impact of host age on rate on symptom development and extent of bacterial movement in the xylem of muskmelon (Cucumis melo cv. Athena) was evaluated following wound inoculation of 2-to 8-week-old plants in growth chamber experiments. Wilting occurred more rapidly in plants after inoculating E. tracheiphila into 2-or 4-week-old plants than 6-or 8-week-old plants. Recovery of viable cells from stem segments revealed that vascular spread of E. tracheiphila was more extensive below than above the inoculation point. These findings provide experimental evidence that host age impacts the rate of symptom development in cucurbit bacterial wilt and that movement of the xyleminhabiting pathogen E. tracheiphila within muskmelon plants occurs primarily in the downward direction.