Effects of high-oil corn on feedlot performance, carcass characteristics, fatty acid profiles, beef palatability, and retail case life traits of beef top loin steaks

Our objective was to compare the effects of feeding steam-flaked, high-oil corn with normal steam-flaked corn to which yellow grease was added to equalize dietary fat on performance and carcass characteristics of finishing beef steers, and palatability, retail case life, and fatty acid composition of strip loins. Angus steers (n = 120; initial BW = 288 kg) were allotted to dietary treatments consisting of 1) normal mill-run, steam-flaked corn plus added fat (NMR) or 2) high-oil, steam-flaked corn (HOC) and assigned randomly to pens (12 pens/treatment with 5 steers/pen). Performance (ADG, DMI, and G:F) was measured over time, and cattle were shipped to a commercial abattoir for collection of carcass data after 165 d on feed. Carcass data were collected at 48 h postmortem on all carcasses, and 2 carcasses from each pen were selected randomly for collection of strip loins (IMPS #180A). At 14 d postmortem, 4 steaks (2.54 cm thick) were removed for retail display, trained sensory panel analysis, Warner-Bratzler shear force determination, and fatty acid analysis. Daily BW gain was greater (P = 0.03) and G:F was increased 8.4% (P = 0.01) for steers fed NMR compared with HOC, but DMI was not affected (P > 0.10) by treatment. No treatment differences were observed (P > 0.10) for HCW, 12th-rib fat, KPH, and yield grade. Marbling scores were greater (P = 0.01) for NMR than for HOC, and LM area tended (P = 0.07) to be greater in NMR than in HOC carcasses. The proportion of carcasses grading USDA Choice did not differ (P = 0.77) between treatments, but a greater (P = 0.04) proportion of carcasses graded in the upper two-thirds of Choice for NMR vs. HOC. Trained sensory panel traits and Warner-Bratzler shear force values did not differ between treatments (P > 0.10), and no differences (P > 0.10) were detected for purge loss or fatty acid composition. Overall, ADG and G:F were less and marbling score was decreased, but there were no differences between treatments in beef palatability, retail case life, or concentrations of fatty acids in strip loins.     

Impact of beef cattle diets containing corn or sorghum distillers grains on beef color, fatty acid profiles, and sensory attributes

Strip loins from 236 carcasses from crossbred yearling steers were collected on each of 2 slaughter dates (slaughter 1 or 2) to determine the effects of feeding corn or sorghum distillers grains (DG) on beef color, fatty acid profiles, lipid oxidation, tenderness, and sensory attributes. Dietary treatments consisted of a steam-flaked corn (SFC) diet without (control) or with 15% (DM basis) corn dry or wet DG (CDDG and CWDG) or sorghum dry or wet DG (SDDG and SWDG) and alfalfa hay (R). Additional treatments included SDDG or SWDG with no alfalfa hay (NR). In slaughter 2, steaks from steers fed SFC had lesser L*, but greater a* (P < 0.05) values than those from steers fed DG. When comparing sorghum and corn DG steaks, the same color differences were detected. Steaks from steers fed sorghum DG had lower L*, but greater a* (P < 0.05) values than those from steers fed corn DG. Also, L* values in steaks from steers fed SWDG with R were greater (P < 0.05) than those from steers fed SWDG with NR. In slaughter 1, feeding DG increased (P < 0.05) steak n-6 fatty acid concentrations compared with SFC. In both slaughter groups, feeding dry DG increased (P < 0.05) steak linoleic acid concentrations compared with wet DG. In slaughter 2, feeding corn DG diets increased (P < 0.05) linoleic acid concentrations of steaks compared with sorghum DG diets. In addition, increased (P < 0.05) concentrations of alpha-linolenic acid in steaks resulted from feeding SDDG or SWDG with R compared with those sorghum treatments with NR. In each slaughter group, feeding DG increased (P < 0.05) the n-6:n-3 ratio of steaks compared with SFC, and feeding corn DG increased (P < 0.05) this ratio compared with sorghum DG. Furthermore, steaks from steers fed corn DG had greater (P < 0.05) concentrations of trans-vaccenic acid than those from steers fed sorghum DG. In slaughter 1, the CLA isomer 18:2, trans-10, cis-12 was greater (P < 0.05) in steaks from DG diets. On d 1 of retail display, steaks from steers fed SDDG with R in slaughter 2 had greater (P < 0.05) thiobarbituric acid reactive substances values than those from steers fed SDDG with NR. Feeding DG at 15% of the dietary DM did not affect sensory attributes or Warner-Bratzler shear force values of steaks. Feeding DG from either corn or sorghum as either a wet or dry by-product had no effect on beef sensory attributes.     

全株玉米青贮与湿玉米芯饲喂肉牛效果对比

[目的]试验旨在研究全株玉米青贮与湿玉米芯饲喂肉牛效果对比,[方法]选择体重450 kg左右的西门塔尔杂交牛30头,随机分为2组,保证精饲料不变,分别饲喂全株玉米青贮与湿玉米芯,试验期70 d。[结果]结果表明,(1)全株玉米青贮组的日增重显著高于玉米芯组(P<0.01),比玉米芯组高出20.92%,全株玉米青贮组的料重比较玉米芯组低21.16%;(2)每头牛全株玉米青贮组的养殖效益为15.38元/d,比玉米芯组高出52.37%。[结论]综上所述,全株玉米青贮组的饲喂效果优于湿玉米芯组。     

Effects of feeding high-oil corn to beef steers on carcass characteristics and meat quality

To assess the effects of feeding high-oil corn on carcass characteristics and meat quality, 60 yearling steers were fed high concentrate diets containing either control corn (82% of diet), high-oil corn (82% of diet), or high-oil corn at a concentration that was isocaloric with the control diet (74% of diet). After being fed for 84 d, steers were slaughtered. At 72 h postmortem, carcass data were collected and rib sections from five steers grading U.S. Choice and five steers grading U.S. Select from each treatment were collected, vacuum packaged, and aged for 14 d. Three steaks (2.54 cm thick) were removed from each rib for Warner-Bratzler shear force measurement, sensory appraisal, and fatty acid composition analyses. Data were analyzed with treatment as the main effect for the carcass data and treatment, quality grade, and two-way interaction in the model for the longissimus data. The two-way interaction was nonsignificant (P > 0.05) for all variables tested. No differences were detected (P > 0.05) in carcass measurements except for marbling scores and quality grades, both of which were greater (P < 0.05) for carcasses from steers fed the high-oil corn. Overall, 78% of steers fed the high-oil corn graded U.S. Choice compared with 47% for the control and 67% for isocaloric group. Shear force and sensory properties of the longissimus were not different (P > 0.05) among treatments. Steaks from U.S. Choice carcasses rated higher (P < 0.05) for tenderness and tended to rate higher (P < 0.10) for juiciness. Feeding the isocaloric and high-oil diets increased (P < 0.05) linoleic acid, arachidonic acid, and the total PUFA content of lipid extracted from the longissimus. Saturated fatty acid percentage was lowest (P < 0.05) for high-oil corn and highest (P < 0.05) for control, with isocaloric being intermediate. Feeding high-oil corn increased (P < 0.05) pentadecyclic acid, margaric acid, and total odd-chain fatty acid content. Feeding high-oil corn in finishing beef cattle diets enhanced intramuscular lipid deposition and increased unsaturation of fatty acids of the longissimus.     

Improving beef hamburger quality and fatty acid profiles through dietary manipulation and exploitation of fat depot heterogeneity

Background:Hamburger is the most consumed beef product in North America,but lacks in nutritional appeal due to its high fat content and high proportion of saturated fatty acids(SFA).Objectives of the present study were to improve the FA profiles of hamburgers made with perirenal fat(PRF) and subcutaneous fat(SCF) when feeding steers different diets along with examining differences in sensory attributes and oxidative stability.Diets included a control diet containing 70:30 red clover silage:barley based concentrate,a diet containing sunflower-seed(SS)substituted for barley,and diets containing SS with 15%wheat dried distillers' grain with solubles(DDGS-15) or30%DDGS(DDGS-30).Hamburgers were made from triceps brachii and either PRF or SCF(80:20 w/w).Results:Perirenal fat versus SCF hamburgers FA had 14.3%more(P 0.05) 18:0,11.8%less cis(c)9-18:1(P 0.05),and 1.82%more total trans(f)-18:1 mainly in the form of t11-18:1.During sensory evaluation,PRF versus SCF hamburgers had greater(P 0.05) mouth coating,but the difference was less than one panel unit.Examining effects of steer diet within PRF hamburgers,feeding the SS compared to the control diet increased(P 0.05) t-18:1by 2.89%mainly in the form of t11-18:1,feeding DGGS-15 diet led to no further changes(P 0.05),but feeding DDGS-30 diet reduced the proportions of(P 0.05) of f-18:l chiefly t11-18:1.Feeding SS and DDGS diets had small but significant(P 0.05) effects on hamburger sensory attributes and oxidative stability.Conclusions:Feeding high-forage diets including SS and 15%DDGS,and taking advantage of the FA heterogeneity between fat depots offers an opportunity to differentially enhance beef hamburgers with 18:2n-6 biohydrogenation products(i.e.,t11-18:1) with potential human health benefits without compromising their sensory attributes and oxidative stability during retail display.     

Improving beef hamburger quality and fatty acid profiles through dietary manipulation and exploitation of fat depot heterogeneity

Background

Hamburger is the most consumed beef product in North America, but lacks in nutritional appeal due to its high fat content and high proportion of saturated fatty acids (SFA). Objectives of the present study were to improve the FA profiles of hamburgers made with perirenal fat (PRF) and subcutaneous fat (SCF) when feeding steers different diets along with examining differences in sensory attributes and oxidative stability. Diets included a control diet containing 70:30 red clover silage: barley based concentrate, a diet containing sunflower-seed (SS) substituted for barley, and diets containing SS with 15% wheat dried distillers’ grain with solubles (DDGS-15) or 30% DDGS (DDGS-30). Hamburgers were made from triceps brachii and either PRF or SCF (80:20 w/w).

Results

Perirenal fat versus SCF hamburgers FA had 14.3% more (P <0.05) 18:0, 11.8% less cis (c)9-18:1 (P <0.05), and 1.82% more total trans (t)-18:1 mainly in the form of t11-18:1. During sensory evaluation, PRF versus SCF hamburgers had greater (P <0.05) mouth coating, but the difference was less than one panel unit. Examining effects of steer diet within PRF hamburgers, feeding the SS compared to the control diet increased (P <0.05) t-18:1 by 2.89% mainly in the form of t11-18:1, feeding DGGS-15 diet led to no further changes (P >0.05), but feeding DDGS-30 diet reduced the proportions of (P <0.05) of t-18:1 chiefly t11-18:1. Feeding SS and DDGS diets had small but significant (P <0.05) effects on hamburger sensory attributes and oxidative stability.

Conclusions

Feeding high-forage diets including SS and 15% DDGS, and taking advantage of the FA heterogeneity between fat depots offers an opportunity to differentially enhance beef hamburgers with 18:2n-6 biohydrogenation products (i.e., t11-18:1) with potential human health benefits without compromising their sensory attributes and oxidative stability during retail display.     

Effects of marbling and shear force on consumers' willingness to pay for beef strip loin steaks

Experimental economic procedures were used to measure the effects of changes in marbling score and Warner-Bratzler shear force (WBSF) value on consumer purchasing behavior and willingness to pay for beef strip loin steaks (n = 541). Consumers were more likely to bid on a steak during the experimental auction if the steak had a high marbling score or low WBSF value. Averaging across all consumers in the study (n = 489), the predicted odds that consumers would submit a nonzero bid were favorable for steaks with a marbling score greater than Modest(50) or a WBSF value less than 3.9 kg. Bid prices for steaks were analyzed with respect to changes in steak marbling score, WBSF value, quality grade marketing category classification (Select, Low Choice, Premium Choice, and Prime), and WBSF marketing category classification (very tender, 5.40 kg). The percentage of bids that were zero was highest (P < 0.05) for Select steaks, intermediate (P < 0.05) for Low Choice steaks, and lower (P <0.05) for Premium Choice or Prime steaks. Steaks in the very tender category had the lowest (P < 0.05) percentage of zero bids, and steaks in the slightly tough and very tough categories had the highest (P < 0.05) percentage of zero bids submitted from "buyers" in the auction. Premium Choice and Prime steaks were valued higher (P < 0.05) than Select steaks by consumers. On average, Premium Choice steaks received a 0.89 dollars/kg premium, and Prime steaks received a 2.47 dollars/kg premium over the mean bid price for Select steaks. Predicted mean bid prices for steaks decreased by 1.02 dollars/kg for each 1 kg increase in WBSF value. On average, steaks in the very tender marketing category received a higher (P < 0.05) bid price than the bid price for steaks in the slightly tender, slightly tough, and very tough categories (+0.83 dollars/kg, +2.09 dollars/kg, and +2.55 dollars/kg, respectively). Mean bid prices for steaks from the slightly tough and very tough categories did not differ (P = 0.184). Compared with the mean bid price for steaks in the slightly tender category, steaks from the slightly tough and very tough categories were discounted (P < 0.05) by 1.26 dollars/kg and 1.72 dollars/kg, respectively. Results suggest that marbling score and WBSF influence both the probability that consumers will purchase and the price they are willing to pay for strip loin steaks.     

Dietary supplementation with pioglitazone hydrochloride and l-carnosine improves the growth performance,muscle fatty acid profiles and shelf life of yellow-feathered broiler chickens

The present study aimed to investigate the effects of dietary pioglitazone hydrochloride (PGZ) and l-carnosine (LC) supplementation on the growth performance, meat quality, antioxidant status, and meat shelf life of yellow-feathered broiler chickens. Five hundred broiler chickens were randomly assigned into 4 experimental diets using a 2 × 2 factorial arrangement with 2 PGZ supplemental levels (0 and 15 mg/kg) and 2 LC supplemental levels (0 and 400 mg/kg) in basal diets for 28 d. The feed-to-gain ratio decreased whereas the average daily gain increased with PGZ supplementation. Greater dressing percentages, contents of intramuscular fat (IMF) in breast and thigh muscles, C18:3n-6, C18:1n-9 and monounsaturated fatty acid (MUFA) percentages of thigh muscle were observed with PGZ addition. Additionally, significant synergistic effects between PGZ and LC on the C18:1n-9 and MUFA contents were found. Supplementation with LC decreased drip loss, cooking loss and total volatile basic nitrogen, and increased the redness (a∗) value, the superoxide dismutase and glutathione peroxidase activities in thigh muscles. Moreover, the malondialdehyde content decreased when diets were supplemented with LC, and there was a synergistic effect between PGZ and LC. Additionally, the mRNA abundance of lipogenesis-related genes, such as peroxisome proliferator-activated receptor γ (PPARγ), PPARγ co-activator 1α and fatty acid-binding protein 3, increased with PGZ supplementation, and relevant antioxidation genes, such as nuclear factor erythroid-2-related factor 2 and superoxide dismutase 1, were enhanced with LC supplementation. In conclusion, the results indicated that the supplementation of PGZ and LC could improve the growth performance, antioxidant ability, IMF content, and meat shelf life of yellow-feathered broiler chickens.     

Effect of endophyte type on carcass traits, meat quality, and fatty acid composition of beef cattle grazing tall fescue

Fourteen Hereford steers were used to compare carcass traits, meat quality, and fatty acid composition of beef from cattle grazing tall fescue infected with either wild-type (E+; n = 6) or novel, nil ergot alkaloid (AR542; n = 8) endophyte for 209 d. Average daily gain, live weight, and HCW were greater (P < 0.05) for AR542 cattle than for E+. No differences in LM color or pH were observed between AR542 and E+. Steaks from E+ cattle tended (P = 0.10) to have higher L* and b* than those from AR542 cattle at 0 d of display. Ground beef from E+ cattle also had higher (P < 0.05) L* than AR542 cattle, with no differences in a* or b* at 0 d of display. Color changes during display did not differ for both steaks and ground beef from E+ and AR542. Lipid oxidation levels increased (P < 0.05) during simulated retail display, but they did not differ between endophyte treatments. Adipose tissues from E+ cattle had a higher (P < 0.05) percentage of SFA, and a lower (P < 0.05) percentage of MUFA than adipose from AR542 cattle. Ground beef and i.m. fat had higher (P < 0.05) concentrations of SFA, MUFA, and cis-9, trans-11 isomer of conjugated linoleic acid, and lower (P < 0.05) concentrations of PUFA and PUFA:SFA ratio than s.c. fat. The n-6:n-3 fatty acid ratio did not differ among fat depots. Ergot-alkaloids were detected in s.c. adipose tissues, and alkaloid concentration was greater (P < 0.05) for E+ than AR542. Warner-Bratzler shear force values did not differ between endophyte types, but it decreased (P < 0.01) across the postmortem aging period. Conversely, sensory panel evaluation detected greater (P < 0.01) chewiness and lower (P < 0.05) juiciness for AR542 than for E+ steaks aged for 14 d. Although grazing cattle on tall fescue pastures infected with nil ergot alkaloid endophyte improved cattle performance, these results suggest that endophyte type has minor effects on carcass traits and meat quality of pasture-fed beef. Moreover, finishing cattle on tall fescue pastures showed the potential to enhance the fatty acid profile of beef from a human health perspective. Alkaloid concentration was greater (P < 0.05) in s.c. fat from E+ than AR542 (2.81 vs. 0.92 ppb; fresh-tissue basis). This is the first published report demonstrating the presence of alkaloids in beef tissues.     

三种不同方法处理的玉米青贮饲喂肉牛效果对比

摘要：本试验旨在研究不同方法处理的玉米青贮饲喂肉牛效果对比,选择体重340kg左右的西门塔尔杂交牛30头,随机分为3组,保证精饲料不变,粗饲料分别饲喂3种不同方法处理的玉米青贮,其中试验Ⅰ组为全株玉米青贮、试验Ⅱ组添加剂全株玉米青贮、试验Ⅲ组玉米秸秆黄贮,试验期70d。结果表明：1）试验Ⅱ组的平均日增重极显著高于试验Ⅰ组、试验Ⅲ组（P＜0.01）,分别比Ⅰ组、Ⅲ组高出17.57%、65.71%;Ⅲ组干物质采食量显著高于Ⅰ组、Ⅱ组（P＜0.05）;Ⅰ组和Ⅱ组料重比极显著低于Ⅲ组（P＜0.01）。试验Ⅱ组养殖效益最高为14.14元?天-1?头-1,比试验Ⅰ组高5.05元,比试验Ⅲ组高15.74元。综上,添加剂全株玉米青贮饲喂肉牛效果和养殖效益最佳,全株玉米青贮、玉米秸秆黄贮次之。     

Effects of rearing system on meat quality,fatty acid and amino acid profiles of Hu lambs

To determine the effects of early rearing system on meat quality traits, fatty acid and amino acid profiles of meat, 48 Hu lambs were selected and randomly divided into four treatments: control lambs were ewe‐reared from birth to 60 days of age (ER), while treatment lambs were segregated from their dams at 10, 20 and 30 days of age, then artificially reared with milk replacer until 60 days of age (EW10, EW20 and EW30, respectively). All lambs had no access to the milk replacer or their dams from 61 to 90 days. Creep feed was supplied ad libitum to all lambs from 15 to 90 days of age. Artificially reared lambs (EW10, EW20 and EW30) had higher (p < .05) creep feed intake, average daily gain, slaughter weight, hot carcass weight, meat ether extract content, bright meat color (lightness and yellowness) than ewe‐reared lambs. The content of unsaturated fatty acids and monounsaturated fatty acids in EW10 and EW20 were greater (p < .05) than that in ER, whereas the proportions of saturated fatty acids in EW10 and EW20 were lower than that in ER (p < .05). The percentages of C18:0, C18:2, C18:3 and the ratio of polyunsaturated fatty acids and saturated fatty acids of artificially reared lambs were greater than ewe‐reared lambs (p < .05). The meat proportions of leucine, alanine and proline were higher (p < .05) in artificially reared lambs than ewe‐reared ones. Finally, the artificially reared system increased meat production and changed the fatty acid and amino acid profiles of meat, and it would be appropriate to rear Hu lambs artificially from 10 days with milk replacer.     

Comparison of muscle fatty acid profiles and cholesterol concentrations of bison,beef cattle,elk, and chicken

The objective of this study was to compare fatty acid weight percentages and cholesterol concentrations of longissimus dorsi (LD), semitendinosus (ST), and supraspinatus (SS) muscles (n = 10 for each) of range bison (31 mo of age), feedlot-finished bison (18 mo of age), range beef cows (4 to 7 yr of age), feedlot steers (18 mo of age), free-ranging cow elk (3 to 5 yr of age), and chicken breast. Lipids were analyzed by capillary GLC. Total saturated fatty acids (SFA) were greater (P < 0.01) in range bison than in feedlot bison and were greater (P < 0.01) in SS of range beef cattle than in feedlot steers. Muscles of elk and range bison were similar (P > 0.05) in SAT. In LD, polyunsaturated fatty acids (PUFA) were highest (P < 0.01) for elk and range bison and lowest (P < 0.01) for feedlot steers within each muscle. Range bison and range beef cows had greater (P < 0.01) PUFA in LD and ST than feedlot bison or steers, respectively. Range-fed animals had higher (P < 0.01) n-3 fatty acids than feedlot-fed animals or chicken breast. Chicken breast n-6 fatty acids were greater (P < 0.01) than for muscles from bison, beef, or elk. Elk had higher (P < 0.01) n-6 fatty acids than bison or beef cattle; however, range-fed animals had higher (P < 0.01) n-6 fatty acids than feedlot-fed animals in ST. Conjugated linoleic acid (CLA, 18:2cis-9, trans-11) in LD was greatest (P < 0.01) for range beef cows (0.4%), and lowest for chicken breast and elk (mean = 0.1%). In ST, CLA was greatest (P < 0.01) for range and feedlot bison and range beef cows (mean = 0.4%) and lowest for elk and chicken breast (mean = 0.1%). Also, SS CLA was greatest (P < 0.01) for range beef cows (0.5%) and lowest for chicken breast (0.1%). Mean total fatty acid concentration (g/100 g tissue) for all muscles was highest (P < 0.01) for feedlot bison and feedlot cattle and lowest (P < 0.01) for range bison, range beef cows, elk, and chicken. Chicken breast cholesterol (mg/100 g tissue) was higher (P < 0.01) than LD and ST cholesterol, which were lowest (P < 0.01; 43.8) for range bison and intermediate for the other species. Cholesterol in SS was highest (P < 0.01) for feedlot bison and steers, which were similar to chicken breast (mean = 61.2 vs 52.8 for the mean of the other species). We conclude that lipid composition of bison muscle varies with feeding regimen, and range-fed bison had muscle lipid composition similar to that of forage-fed beef cows and wild elk.     

Bruises in beef cattle at slaughter in Mexico: implications on quality,safety and shelf life of the meat

In emergent economies and developing countries of Africa, Asia and Latin America, the major cause for carcass rejection from the international market is bruising; nevertheless, many of these carcases are destined to local markets and meat processing industries for human consumption. Therefore, the aim of the present study was to assess the effect of bruised meat on pH, microbiologic count and biogenic amine (BA) profiles along 21 days of ageing (sampling 1st, 7th, 14th and 21st day) with two packaging method (plastic bag vs vacuum) at 4 °C. A total of 50 bruised carcasses were sampled from 1000 young bulls (Brown Swiss X Zebu) of 18–24 months old and an average live weight of 450?±?66 kg. The results showed significant differences between packaging systems and bruised vs non-bruised meat. The bruised meat caused higher biogenic amine concentrations than did non-bruised meat. We conclude that bruised meat favoured increments of biogenic amine concentrations, even more than did non-bruised meat. The plastic bag?+?vacuum system limited the increments of BA concentration during storage time therefore it improved shelf life of meat. These results emphasized the importance of implementing best management practices during pre-slaughter operations of cattle in order to reduce a possible risk factor for bruised meat.     

Effect of high-oil corn or added corn oil on ruminal biohydrogenation of fatty acids and conjugated linoleic acid formation in beef steers fed finishing diets

Three Angus steers (410 kg) cannulated in the proximal duodenum were used in a replicated 3 x 3 Latin square to evaluate the effects of dietary lipid level and oil source on ruminal biohydrogenation and conjugated linoleic acid (CLA) outflow. Dietary treatments included: 1) typical corn (TC; 79.2% typical corn), 2) high-oil corn (HOC; 79.2% high-oil corn), and 3) the TC diet with corn oil added to supply an amount of lipid equal to the HOC diet (OIL; 76.9% TC + 2.4% corn oil). Duodenal samples were collected for 4 d following 10-d diet adaptation periods. Data were analyzed with animal, square, period, and treatment in the model and planned, nonorthogonal contrasts were used to test the effects of dietary lipid content (TC vs HOC and OIL) and oil source (HOC vs OIL) on ruminal biohydrogenation. Intake and duodenal flow of total long-chain fatty acids were increased (P < 0.05) by over 63% for diets containing more lipid regardless of oil source. Apparent ruminal dry matter and long chain fatty acid digestibilities were not altered (P > 0.05) by dietary lipid level or oil source. Ruminal biohydrogenation of total and individual 18-carbon unsaturated fatty acids was greater (P < 0.05) for diets with higher lipid content. Biohydrogenation of oleic acid was greater (P < 0.05) for HOC than OIL, but biohydrogenation of linoleic acid was lower (P < 0.05) for HOC than OIL. Duodenal flows of palmitic, stearic, oleic, linoleic, and arachidic acids were more than 30% greater (P < 0.05) for diets containing more lipid. Flow of all trans-octadecenoic acids was greater (P < 0.05) for diets containing more lipid. Corn oil addition increased (P < 0.05) the flow of trans-10 octadecenoic acid and the trans-10, cis-12 isomer of CLA by threefold compared to feeding high-oil corn. Feeding high-oil corn or adding corn oil to typical corn rations increased intake, biohydrogenation, and duodenal flow of unsaturated long-chain fatty acids. Compared with high-oil corn diets, addition of corn oil increased duodenal flow of trans-10, trans-12 and cis-12 isomers of octadecenoic acid and the trans-10, cis-12 isomer of CLA. The amount of cis-9, trans-11 isomer of conjugated linoleic acid flowing to the duodenum was less than 260 mg/d, a value over 20 times lower than flow of trans-11 vaccenic acid indicating the importance of tissue desaturation for enhanced conjugated linoleic acid content of beef.     

Relationships of consumer sensory ratings, marbling score, and shear force value to consumer acceptance of beef strip loin steaks

Logistic regression was used to quantify and characterize the effects of changes in marbling score, Warner-Bratzler shear force (WBSF), and consumer panel sensory ratings for tenderness, juiciness, or flavor on the probability of overall consumer acceptance of strip loin steaks from beef carcasses (n = 550). Consumers (n = 489) evaluated steaks for tenderness, juiciness, and flavor using nine-point hedonic scales (1 = like extremely and 9 = dislike extremely) and for overall steak acceptance (satisfied or not satisfied). Predicted acceptance of steaks by consumers was high (> 85%) when the mean consumer sensory rating for tenderness,juiciness, or flavor for a steak was 3 or lower on the hedonic scale. Conversely, predicted consumer acceptance of steaks was low (< or = 10%) when the mean consumer rating for tenderness, juiciness, or flavor for a steak was 5 or higher on the hedonic scale. As mean consumer sensory ratings for tenderness, juiciness, or flavor decreased from 3 to 5, the probability of acceptance of steaks by consumers diminished rapidly in a linear fashion. These results suggest that small changes in consumer sensory ratings for these sensory traits have dramatic effects on the probability of acceptance of steaks by consumers. Marbling score displayed a weak (adjusted R2 = 0.053), yet significant (P < 0.01), relationship to acceptance of steaks by consumers, and the shape of the predicted probability curve for steak acceptance was approximately linear over the entire range of marbling scores (Traces67 to Slightly Abundant97), suggesting that the likelihood of consumer acceptance of steaks increases approximately 10% for each full marbling score increase between Slight to Slightly Abundant. The predicted probability curve for consumer acceptance of steaks was sigmoidal for the WBSF model, with a steep decline in predicted probability of acceptance as WBSF values increased from 3.0 to 5.5 kg. Changes in WBSF within the high (> 5.5 kg) or low (< 3.0 kg) portions of the range of WBSF values had little effect on the probability of consumer acceptance of steaks.     

Effect of low vitamin A diets with high-moisture or dry corn on marbling and adipose tissue fatty acid composition of beef steers

Angus-cross steers (n = 165; 295 +/- 16 kg of BW) were used evaluate the effect of low vitamin A diets with high-moisture corn (HMC) or dry corn (DC) on marbling and fatty acid composition. Steers were allotted to 24 pens (7 steers/pen), such that each pen had the same average initial BW. Treatments were randomly allotted to the pens. The experiment had a completely randomized design, with a 2 x 2 factorial arrangement of treatments: low vitamin A (Lo, no supplemental vitamin A) and HMC (LoHMC); LoDC; high vitamin A (Hi, supplemented with 2,200 IU of vitamin A/kg of DM) and HMC (HiHMC); and HiDC. Diets contained 76% corn, 10% corn silage, 11% protein supplement, and 3% soybean oil (DM basis). Samples of feed ingredients were collected for carotenoid analysis. Blood samples were collected for serum retinol determination. Steers were slaughtered after 145 d on feed. Carcass characteristics and LM composition were determined. Samples from the s.c. fat depot were analyzed for fatty acid composition. High-moisture corn had a greater vitamin A content, based on its carotenoid content, than DC (614 vs. 366 IU/kg of DM, P < 0.01). No vitamin A x corn type interactions were detected for feedlot performance, carcass characteristics, or serum, s.c. fat, or liver retinol concentration. Average daily gain, DMI, and G:F were not affected by vitamin A (P > 0.05). Marbling score and USDA quality grade were greater (P < 0.05) in Lo vs. Hi steers. Hot carcass weight, backfat, and yield grade were not affected by the treatments (P > 0.05). Vitamin A and corn type did not affect LM composition (DM, ash, CP, or ether-extractable fat, P > 0.05). Vitamin A supplementation increased (P < 0.06) serum retinol on d 112 and 145 and increased (P < 0.01) liver retinol at slaughter (Lo = 38.7 vs. Hi = 102.9 mug/g). The s.c. fat retinol concentrations were less (P < 0.01) for Lo (0.8 mug/g) than for Hi (1.4 mug/g) at slaughter. Cell diameter of adipocytes in the i.m. depot was not affected by dietary vitamin A (P > 0.05). A vitamin A x corn type interaction was observed (P < 0.05) for the s.c. fat cellularity. Feeding HMC increased the number of cells per square millimeter when Lo diets were fed (LoHMC = 128 vs. LoDC = 100 cells/mm(2), P < 0.05), but not when Hi diets were fed (HiHMC = 109 vs. HiDC = 111 cells/mm(2), P > 0.05). The CLA content of adipose tissue was not affected by the treatments. Regardless of the corn type used, feeding low vitamin A diets for 145 d to Angus-cross steers increased marbling and quality grade without affecting yield grade, animal health, or performance.     

The effect of flaxseed supplementation on growth, carcass characteristics, fatty acid profile, retail shelf life, and sensory characteristics of beef from steers finished on grasslands of the northern Great Plains

The objective of this trial was to determine if daily supplementation of flaxseed for 85 d to steers finished on grasslands of the northern Great Plains would influence growth and carcass characteristics or the fatty acid profile, tenderness, and sensory characteristics of beef steaks. Eighteen Angus yearling steers (initial BW 399 ± 21 kg) were randomly divided into 3 groups. Steers in treatment 1 (FLX; n = 6) received a daily supplement of ground flaxseed (0.20% of BW), whereas steers in treatment 2 (CSBM; n = 6) received a daily supplement of ground corn and soybean meal (0.28% of BW), with contents of CP and TDN being similar to the supplement for FLX. Control steers (CONT; n = 6) were not supplemented. Treatments were given to each individual steer in side-by-side stalls and were fed from mid-August to November 7, 2007, the day before slaughter. All steers grazed growing forage from early May through the first week of November. Growth rate of steers fed FLX was 25% greater (P < 0.01) than that of steers fed CONT, but was similar (P = 0.45) to that of steers fed CSBM. No differences were observed for carcass characteristics (P ≥ 0.14), tenderness (Warner-Bratzler shear force; P ≥ 0.24), or sensory attributes (P ≥ 0.40) except for a slight off-flavor detected in steaks from steers fed FLX compared with CONT (7.4 vs. 7.8, respectively, with 8 indicating no off-flavor and 1 indicating extreme off-flavor; P = 0.07) and CSBM (7.9; P = 0.01). The n-3 fatty acids α-linolenic acid and eicosapentaenoic acid were 62 and 22% greater, respectively, in beef from steers fed FLX compared with those fed CONT (P < 0.001). The ratio of n-6 to n-3 fatty acids was smaller (P < 0.001) in beef from steers fed FLX compared with the ratios in beef from steers fed CONT and CSBM. Daily supplementation of flaxseed to steers grazing growing vegetation on the northern Great Plains may improve growth rate and enhance the n-3 fatty acid profile of the steaks.     

Effects of supplemental rumen-protected conjugated linoleic acid or corn oil on fatty acid composition of adipose tissues in beef cattle

Thirty-six Angus x Hereford heifers (365 +/- 60 kg) were used to determine the effects of supplemental dietary lipid sources on fatty acid composition of i.m., perianal (p.a.), and s.c. lipid depots. Lipid was supplied to diets as either corn oil or a rumen-protected conjugated linoleic acid (CLA) salt for two specific treatment periods of either the final 32 or 60 d on feed. Following an initial 56-d feeding period, heifers were fed one of three dietary treatments (DM basis): 1) basal diet containing 88% concentrate and 12% grass hay (CON), 2) basal diet plus 4% corn oil (OIL), or 3) basal diet plus 2% rumen-protected CLA salt (RPCLA) containing 31% CLA. The trans-10, cis-12 CLA concentration was greatest (P < 0.05) for heifers fed RPCLA and OIL diets and least (P < 0.05) for CON, regardless of time on dietary treatment. Heifers fed supplemental RPCLA had greater (P < 0.05) total CLA content than either CON- or OIL-fed heifers. Adipose tissue concentration of trans-11 vaccenic acid (TVA) was less (P < 0.05) for CON than OIL or RPCLA, which did not differ (P > 0.05). Percentages of C18:1 trans-10 were least (P < 0.05) in i.m. lipid compared with p.a. and s.c., which did not differ (P > 0.05). Following 60 d of lipid supplementation, heifers fed OIL and RPCLA had lower (P < 0.05) concentrations of oleic acid and total monounsaturated fatty acids (MUFA) compared with CON. The ratio of cis-9, trans-11 CLA:TVA was higher (P < 0.05) for heifers fed 60 vs. 32 d, but did not differ (P > 0.05) between adipose depots. Feeding OIL increased (P < 0.05) adipose concentration of C18:2 fatty acid, whereas feeding RPCLA increased (P < 0.05) total CLA isomers by 22%. Intramuscular lipid contained the lowest (P < 0.05) percentage of cis-9, trans-11 CLA, total CLA, C18:1 cis-9, C18:1 trans-10, and TVA. Total CLA and cis-9, trans-11 CLA isomers were increased (P < 0.05) in p.a. and s.c. adipose depots, whereas i.m. adipose tissue contained increased (P < 0.05) amounts of total PUFA. Results from this study indicate that short-term lipid supplementation to feedlot cattle can increase adipose tissue CLA concentrations, but only marginally (8.3 to 17.5%). Moreover, observed decreases in oleic acid and total MUFA concentrations of adipose tissues from heifers fed rumen-protected CLA or corn oil suggest that lipid supplementation may decrease delta9 desaturase activity in adipose tissues, which in turn would lower the conversion of TVA to cis-9, trans-11 CLA isomer.     

Effects of dietary conjugated linoleic acid on fatty acid composition, lipid oxidation, color, and water-holding capacity of pork loin

The effects of dietary conjugated linoleic acid (CLA) on fatty acid composition, lipid oxidation, and pork quality were investigated. Pigs (n = 20) were fed a diet containing 0, 1, 2.5, or 5% CLA for 4 wk and slaughtered at 105 kg. The longissimus thoracis et lumborum muscle was collected at 24 h postmortem. Pork loin chops (3 cm thick) were packaged aerobically and stored at 4 degrees C for 7 d. Samples were analyzed for ultimate pH, intramuscular fat content, fatty acid composition, thiobarbituric acid-reactive substances, color (L*, a*, b*), and water-holding capacity. Dietary CLA reduced the concentration of linoleic acid and increased CLA concentration in intramuscular fat of pork loin (P < 0.05). The concentration of CLA in muscle was increased with dietary CLA level and did not change during storage. Thiobarbituric acid-reactive substance value of control was higher than that of the CLA-fed groups (P < 0.05). Intramuscular fat content was increased by dietary CLA, and less purge loss was observed with samples from CLA-fed pigs (P < 0.05). Dietary CLA improved the color stability of pork loin during cold storage. After 7 d, lightness (L*) and yellowness (b*) of the 5% CLA-fed group were significantly lower than those of control (P < 0.05). The results indicated that the water-holding capacity of pork loin was increased with increased intramuscular fat content apparently caused by dietary CLA. Also, the data indicated that color stability of pork was improved with inhibition of lipid oxidation and changing of fatty acid composition by dietary CLA.