Wagyu-Angus cross improves meat tenderness compared to Angus cattle but unaffected by mild protein restriction during late gestation.

For the spring-calving beef herds, late gestation coincides with winter and early spring, when cows are dependent on feed supplements with low quality hay, which is hard to meet their nutrient requirements. However, the effects of deficiencies of metabolizable protein intake during late gestation on offspring beef quality are unclear. Wagyu cattle have excellent marbling, and insemination with Wagyu vs Angus semen is a practical option for beef producers to improve beef quality. To test, Angus cows (621 ±â€¯73 kg) were selected and randomly separated into two groups. Each group was inseminated with either Angus or Wagyu semen. During the last 90 days of gestation, cows in each group were further separated and received either a low protein diet (85% of the NRC metabolizable protein requirement), which was a low quality hay-based diet common in northwestern region of the U.S., or an adequate protein diet (108% NRC requirement). All progeny was managed together and harvested at a final BW of 576.5 ±â€¯16.6 kg. Wagyu-sired offspring had higher marbling scores and quality grades than Angus (P < 0.01). Protein supplementation did not affect Slice Shear Force (SSF) in either breeds (P = 0.60). However, Wagyu-sired cattle had lower SSF than Angus-sired (P < 0.01). In addition, Wagyu-sired cattle had higher intramuscular fat (P < 0.05) and total collagen content (P < 0.05), but Angus-sired had greater mature collagen cross-links, as shown by higher contents of Pyridinoline (P < 0.01) and Ehrlich Chromogen (P < 0.01). Consistently, the mRNA expression of enzymes catalyzing collagen cross-linking was higher in Angus-sired offspring, including Plod 1 (P < 0.05), Plod 2 (P = 0.08), and P4Hα 2 (P < 0.01). In conclusion, Wagyu-sired cattle had greater tenderness and marbling score compared to Angus-sired, which was associated with lower collagen cross-links. Feeding mature grass hay-based diet with relatively low protein content during late gestation had no major effect on beef quality of subsequent cattle.

Effects of pregnancy and feeding level on carcass and meat quality traits of Nellore cows.

Carcass and meat quality traits of 16 pregnant and 5 non-pregnant cows fed at 1.2 times maintenance and 16 pregnant and 6 non-pregnant fed ad libitum were evaluated. Pregnancy did not affect final body weight (FBW; P=0.0923), cold carcass yield (CCY; P=0.0513), longissimus muscle area (LMA; P=0.8260), rib fat thickness (RFT; P=0.1873) and shear force (WBSF; P=0.9707). A lower FBW (P=0.0028), LMA (P=0.0048) and RFT (P=0.0001) were observed in feed restricted cows. However, no differences were found for CCY (P=0.7243) and WBSF (P=0.0759) among feeding level groups. These data suggests that carcass and meat quality traits are not affected by pregnancy status in Nellore cows. Moreover, although cows experiencing feed restriction did have reduced deposition of subcutaneous fat and lean tissue, there were no major impacts on meat quality traits.

Fatty acid composition of adipose tissue and muscle from Jersey steers was affected by finishing diet and tissue location.

To determine the impacts of finishing diet and tissue type and location on fatty acid composition and palatability of Jersey beef, twenty steers were assigned to a factorial treatment design with initial weight (Light vs. Heavy) and finishing diet (70 vs. 85% concentrate) as treatments. Ribeye steaks were collected for sensory evaluation. Muscle, seam and subcutaneous (s.c.) fat from steaks, kidney fat (KF) and omental fat (OMF) were collected for fatty acid analysis. Initial weight and finishing diet had little impact on beef palatability. The 85% concentrate decreased polyunsaturated fatty acids (PUFA) in muscle and increased trans fatty acids in all tissues (P<0.05). The monounsaturated:saturated fatty acid ratio (MUFA:SFA) was highest in s.c. fat, intermediate in muscle and seam fat, and lowest in KF and OMF. The PUFA:SFA was highest in muscle, intermediate in s.c. and seam fat, and lowest in KF and OMF. Fatty acid composition differed greatly among tissues and the lower concentrate diet increased omega-3 and PUFA percentages in muscle.

Omega-3 fatty acids affected human perception of ground beef negatively.

The objective was to determine the impact of increasing levels of Eicosapentaenoic acid (EPA; C20:5n3) and Docosahexaenoic acid (DHA; C22:6n3) on beef palatability. Two commercial supplements of EPA and DHA were added to 85% lean ground beef patties (176.2 ± 3.76 g) with different levels (0, 0.3, 0.4, 0.5, 0.6, 0.7, and 1% as-is). Olive oil was added so that all patties contained 1% added lipid. A control treatment was also prepared with no supplement or olive oil. Sensory evaluation and fatty acid analysis was conducted. Ground beef flavor decreased linearly (P<0.001) with increasing levels of EPA and DHA. Off-aroma and off-flavor increased linearly and then plateaued with increasing levels of EPA (P<0.0001). In conclusion, EPA had a greater negative impact on beef palatability than DHA. Also, the panelists were more sensitive to EPA in off-flavor perception than off-aroma.

The influence of forage diets and aging on beef palatability.

To investigate the influence of diet and aging on beef palatability, lipid oxidative stability, and fatty acid composition, crossbred steers were assigned to Feedlot S (alfalfa and grain), Forage TR (triticale and annual ryegrass), Forage TK (triticale and kale), or Forage+Feedlot (grazing ryegrass, fescue and orchardgrass, finished on alfalfa and grain) dietary treatments. Heifers were finished on Feedlot H (alfalfa and grain). Longissimus and tricep muscles were sampled from these animals for steaks and ground beef, respectively. Steaks were either dry- or wet-aged for 14 d. Ground beef was dry-aged, wet-aged for 14 d, or not aged. Trained sensory panelists evaluated palatability attributes of steaks and ground beef. Diet did not influence sensory attributes of steaks or ground beef. Aging impacted (P<0.05) sensory attributes of ground beef. Diet and aging had no impact on lipid oxidative stability but affected fatty acid composition of raw ground beef.

Effect of sampling fat location and cooking on fatty acid composition of beef steaks.

To investigate the impact of sampling fat location and cooking on fatty acid composition of beef steaks, 21 raw steaks from crossbred steers were dissected to obtain outer (OSC) and inner subcutaneous fat (ISC), seam fat, marbling, and lean muscle. Twenty-one cooked steaks were dissected to obtain OSC, ISC, seam fat, surface and inner muscle. Trans-vaccenic acid and c9, t11-CLA percentages were lower (P<0.05) in lean muscle than subcutaneous (s.c.) fat or marbling. Monounsaturated: saturated fatty acid ratios were lower (P<0.05) in seam fat and marbling than s.c. fat or lean muscle. Linoleic and linolenic acid levels were highest in lean muscle and longer chain n-6 and n-3 fatty acids were only detected in lean muscle. Cooking did not change fatty acid composition dramatically except that n-6: n-3 ratio in s.c. and seam fat decreased after cooking (P<0.05).

Effects of supplemental fat on growth performance and quality of beef from steers fed corn finishing diets.

To measure the effects of dietary fat on feedlot performance and carcass characteristics, and on beef appearance, moisture binding, shelf life, palatability, and fatty acid content, 126 crossbred beef steers (321.1 +/- 0.57 kg of BW) were allotted to a randomized complete block (3) design with a 3 x 2 + 1 factorial arrangement of dietary treatments. The main effects were level of yellow grease (0, 3, or 6%) and alfalfa hay (3.5 or 7%) in corn-based diets containing 15% potato by-product (PB). The added treatment was 6% tallow and 7% alfalfa in a barley-based diet containing 15% PB. Dry matter intake and ADG were not affected by diet; however, G:F and diet NE content increased linearly (P < 0.10) with yellow grease. Kidney, pelvic, and heart fat (2.0 to 2.3 +/- 0.07) and yield grade (2.8 to 3.1 +/- 0.09) increased linearly (P < or = 0.05) with yellow grease. Steers fed corn plus 6% yellow grease had lower (P < 0.05) beef firmness and beef texture scores but greater (P < 0.01) fat color score than those fed barley plus 6% tallow. Moisture retention of beef was not affected by dietary treatment, except purge score during retail storage, which was decreased linearly (P < 0.01) from 2.1 to 1.6 +/- 0.06 by level of yellow grease. Steaks from steers fed barley plus 6% tallow had greater (P < 0.05) shear force than those from steers fed corn plus 6% yellow grease, and beef flavor increased linearly (P < 0.05) from 6.2 to 6.7 +/- 0.11 as the level of yellow grease increased. Level of yellow grease linearly increased (P < 0.01) transvaccenic acid (TVA) by 61% and CLA content of beef by 48%. Beef from steers fed corn plus yellow grease had lower (P < 0.05) palmitoleic and oleic acids and greater (P < 0.05) linoleic, TVA, and CLA than beef from steers fed the barley-tallow diet. Feeding yellow grease increased diet energy content, which increased carcass fatness, and altered beef fatty acid content, which increased beef flavor without affecting moisture retention, shelf life, or cooking properties of the beef. Additionally, beef from steers fed corn plus 6% yellow grease was more tender and had more polyunsaturated fatty acid content and CLA than beef from steers fed barley plus 6% tallow.

A direct method for fatty acid methyl ester synthesis: application to wet meat tissues, oils, and feedstuffs.

A simplified protocol to obtain fatty acid methyl esters (FAME) directly from fresh tissue, oils, or feedstuffs, without prior organic solvent extraction, is presented. With this protocol, FAME synthesis is conducted in the presence of up to 33% water. Wet tissues, or other samples, are permeabilized and hydrolyzed for 1.5 h at 55 degrees C in 1 N KOH in MeOH containing C13:0 as the internal standard. The KOH is neutralized, and the FFA are methylated by H(2)SO(4) catalysis for 1.5 h at 55 degrees C. Hexane is then added to the reaction tube, which is vortex-mixed and centrifuged. The hexane is pipetted into a gas chromatography vial for subsequent gas chromatography. All reactions are conducted in a single screw-cap Pyrex tube for convenience. The method meets many criteria for fatty acid analysis, including not isomerizing CLA or introducing fatty acid artifacts. It is applicable to fresh, frozen, or lyophilized tissue samples, in addition to oils, waxes, and feedstuffs. The method saves time and effort and is economical when compared with other methods. Its unique performance, including easy sample preparation, is achieved because water is included rather than eliminated in the FAME reaction mixtures.

Changes in the forms of iron and in concentrations of taurine, carnosine, coenzyme Q(10), and creatine in beef longissimus muscle with cooking and simulated stomach and duodenal digestion.

Longissimus muscle samples from 31 Angus-cross heifers finished on either a high-concentrate feedlot diet or pasture were used to evaluate the effects of cooking (71°C) on the concentration and forms of iron in the meat, and also on concentrations of the bioactive compounds taurine, carnosine, coenzyme Q(10), creatine and creatinine. For a sub-sample of 15 the effects of pepsin and pancreatin digestion were assessed. For iron, cooking resulted in some overall loss together with a major change from soluble haem and non-haem iron to the insoluble forms, but solubility was regained to a significant extent following digestion. Total haem iron percentage, however, decreased at each step from an initial 88% to a final 61% of total iron. For the bioactive compounds, cooking led to a reduction in taurine, carnosine, coenzyme Q(10), and creatine. The effects of digestion on the bioactive compounds varied. No clear differences were shown in the way in which beef from pasture-finished and feedlot-finished cattle responded to cooking and digestion.

The effect of production system and age on levels of iron, taurine, carnosine, coenzyme Q(10), and creatine in beef muscles and liver.

Samples of longissimus (LL) and triceps brachii (TB) muscles from Angus-cross heifers finished either on a high-concentrate ration in Washington, USA, (US cattle, n=15) or on pasture in New Zealand (NZ cattle, n=16) were assessed for composition characteristics. Half of the NZ cattle were of a similar age to the US cattle (NZAge) and half were of a similar weight (NZWt). Iron concentration was higher in TB (20.9 vs. 17.5µgg(-1); P<0.001) and was higher for the NZWt group than the NZAge group or the US cattle. The proportion of iron as haem iron was highest for the NZWt group (87.3%; P<0.01), but the proportion as soluble haem iron was highest for the US cattle. For a sub-group of 10 pasture-finished cattle, iron levels in cheek muscle were higher than for LL or TB, and liver levels were 66% higher than cheek muscle. The proportion of haem iron, however, was lowest in liver (55.3%) and was lower in cheek muscle (78.4%) than LL or TB. Relative to LL, TB had higher levels of taurine and coenzyme Q(10), but lower levels of carnosine, creatine and creatinine, as expected for a muscle with a more aerobic metabolism. These differences were magnified for the even more aerobic cheek muscle. Differences between the two NZ groups were small, but muscles from the US cattle contained less taurine, carnosine, coenzyme Q(10), and creatinine. Reasons for these differences in various meat components for similar cattle from different production systems are not clear.

The effect of production system and age on concentrations of fatty acids in intramuscular fat of the longissimus and triceps brachii muscles of Angus-cross heifers.

The concentrations of fatty acids were measured in intramuscular fat from the longissimus lumborum (LL) and triceps brachii (TB) muscles of Angus-cross heifers finished either on a high-concentrate ration in Washington, USA, (US cattle, n=15) or on pasture in New Zealand (NZ cattle, n=16). Half of the NZ cattle were of a similar age to the US cattle (NZAge) and half were of a similar weight (NZWt). Intramuscular fat levels were higher for the LL muscle and for the US cattle but only within the LL muscle (P<0.05). Aspects of the fatty-acid patterns that are of relevance to human nutrition tended to favour the pasture-finished NZ cattle with lower n-6/n-3 fatty acid ratios (P<0.001), higher concentrations of an anticarcinogenic conjugated linoleic acid (C18:2 c9,t11) (P<0.05) and its precursor (trans-vaccenic acid, TVA) (P<0.01), and lower levels of the 18-carbon trans monounsaturated fatty acids other than TVA (P<0.01). Concentrations of 20 of the 22 fatty acids analysed differed significantly between the two muscles. When values were adjusted to a common intramuscular fat level by covariance, most of the group differences remained, but a number of the muscle differences became non-significant. For almost half the fatty acids considered, there was a significant interaction between treatment group and muscle, which indicates that the results for one muscle do not necessarily apply to other muscles, although the ranking of the groups was usually the same for both muscles.

Effects of supplemental fat on growth performance and quality of beef from steers fed barley-potato product finishing diets: I. Feedlot performance, carcass traits, appearance, water binding, retail storage, and palatability attributes.

To measure the effects of dietary fat on feedlot performance, carcass characteristics, and beef appearance, moisture binding, shelf life, and palatability, 168 crossbred beef steers (317 +/- 1.0 kg) were allotted randomly, within weight blocks, to a randomized complete block design with a 3 x2 + 1 factorial arrangement of dietary treatments. Main effects were level of yellow restaurant grease (RG; 0, 3, or 6%) and level of alfalfa hay (AH; 3.5 or 7%), with the added treatment of 6% tallow and 7% AH in barley-based diets containing 15% potato by-product and 7% supplement fed for 165 d (all dietary levels on a DM basis). Dietary treatment did not (P >0.10) affect DMI, LM area, beef brightness, or beef texture. Level of RG linearly increased (P <0.05) ADG from 1.48 to 1.60 kg/d, diet NE(m) from 2.4 to 2.6 Mcal/kg, diet NE(g) from 1.7 to 1.9 Mcal/kg, and internal fat from 2.1 to 2.4%. Level of RG linearly increased (P <0.05) G:F from 0.184 to 0.202, but decreased (P <0.05) beef firmness score from 3.0 to 2.8 and fat luster score from 3.1 to 2.8. Level of AH did not (P >0.10) affect any of the measurements; however, AH interacted with level of RG on fat thickness and yield grade (linear; P <0.05), as well as marbling score and percentage of carcasses grading USDA Choice (quadratic; P <0.05). Fat thickness and yield grade increased with increasing RG level in 3.5%, but not in 7%, AH diets. In steers fed 3.5% RG, marbling scores and percentage of carcasses grading Choice were greatest when fed with 3.5% AH, and least when fed 7% AH. Steers fed tallow had lower marbling scores (P = 0.01) and percentage of carcasses grading Choice (P = 0.066) than those fed RG. Retail storage attributes, including visual and instrumental color, decreased during storage (P <0.01), but were not (P >0.10) affected by diet. Trained sensory panel scores for initial tenderness increased quadratically (P = 0.07) as dietary RG increased, but diet did not (P >0.10) affect drip loss, cooking loss, or trained sensory panel scores for sustained tenderness, initial and sustained juiciness, and beef flavor. Therefore, RG increased diet energy, improved performance, and increased carcass fatness; however, dietary fat and AH did not affect most measurements of water retention, color stability, or palatability of beef.

Effects of supplemental fat on growth performance and quality of beef from steers fed barley-potato product finishing diets: II. Fatty acid composition of muscle and subcutaneous fat.

One hundred sixty-eight crossbred steers (317.1 +/- 1.0 kg) were used to evaluate the effects of supplemental fat in finishing diets on the fatty acid composition, including the 9,11 isomer of conjugated linoleic acid, of beef. Steers were allotted within three weight blocks to a randomized complete block design with a 3 x 2 + 1 factorial arrangement of dietary treatments. Main effects were level of yellow restaurant grease (RG; 0, 3, and 6%), and level of alfalfa hay (AH; 3.5 and 7%) with an added treatment containing 6% tallow (T) and 7% AH in barley-based diets containing 15% potato by-product and 7% supplement (all dietary levels are on a DM basis) fed for an average of 165 d. Fatty acids of the LM and s.c. fat from four randomly selected steers per pen were quantified using GC after methylation with sodium methoxide. Dietary treatment did not (P > 0.10) affect total fatty acid (FA) content of the LM (143 +/- 5.2 mg/g) or fat (958 +/- 7.9 mg/g). Myristic acid increased linearly (P < 0.01) with increasing RG from 3.1 to 3.7 +/- 0.1 g/100 g of FA in muscle. Stearic acid increased linearly (P < 0.05) as RG increased in the diet, from 11.4 to 12.9 +/- 0.4 g/100 g of FA in LM and from 9.9 to 12.2 +/- 0.3 g/100 g of FA in fat. Compared with T, steers fed 6% RG had more (P < 0.05) oleic acid in LM (42.7 vs. 40.3 +/- 0.5 g/100g FA) and in fat (43.0 vs. 40.9 +/- 0.5 g/100g FA). The cis-9, trans-11 conjugated linoleic acid (CLA) increased quadratically (P < 0.01) with increasing dietary RG in LM from 0.45 to 0.64 to 0.62 +/- 0.03 g/100 g of FA and increased in fat from 0.61 to 0.84 to 0.83 +/- 0.04 g/100 g of FA. Moreover, cis-9, trans-11 CLA was higher (P < 0.05) in fat from steers fed RG compared with T (0.81 vs. 0.69 +/- 0.04 g/100 g of FA), and tended to be higher (P = 0.07) in muscle (0.62 vs. 0.54 +/- 0.03 g/100 g of FA. Feeding yellow restaurant grease increased content of cis-9, trans-11 CLA in beef without an increase total FA content.

Effects of biological type and dietary fat treatment on factors associated with tenderness: I. Measurements on beef longissimus muscle.

The objective was to evaluate chemical, mechanical, and sensory attributes associated with tenderness in divergent cattle breeds--Wagyu (W; n = 12), Limousin (L; n = 12) and F1-cross (WxL; n = 12)--fed two dietary treatments (0 or 6% sunflower oil (DM basis)). A randomized complete block repeated measures design in a 3 x 2 factorial arrangement of treatments was used, and effects of breed, diet, block, and associated interactions were tested. Cattle were fed barley-based diets for an average of 259 d. Twenty-four hours postmortem (PM), steaks from the longissimus muscle (LM) were sliced, vacuum-packaged, aged (1, 3, 7, 14, 28, and 56 d PM) at 2 degrees C, and frozen (-40 degrees C) until analyzed. Wagyu steaks had lower (P < 0.05) Warner-Bratzler shear force (WBSF) values than L steaks across all aging times. At 1 d PM, W steaks required slightly more (P > 0.05) force to shear than WxL or L (0.30 and 0.11 kg, respectively); however, by d 14 PM, W steaks required 0.77 kg less (P < 0.05) force to shear than L. Wagyu steaks received higher (P < 0.05) sensory panel sustained tenderness scores at d 14 PM than L. The pH decline was slower (P < 0.05), and temperature decline more (P < 0.05) rapid, in W carcasses than L or WxL carcasses. Breed and diet did not affect (P > 0.10) free calcium levels (FCL) over time (0, 1, 3, 7, and 14 d PM), 0-h calpastatin activity (CA), d-1 percent collagen (OH-PRO), or d-1 collagen cross-linking (HP). Western blot analysis for the presence of the troponin-T (TNT) 30-kDa fragment, conducted only on samples from steers fed the 0% sunflower oil diet, demonstrated more proteolysis by d 3 PM in L than W or WxL. Overall, breed differences in mechanical and sensory measures of tenderness were not explained by FCL, CA, OH-Pro, and HP. Even though the initial appearance of the TNT 30-kDa fragment was greater in L, linear slopes for appearance of TNT degradation product across aging time were greater for W and WxL (P < 0.01 and P = 0.056, respectively) than for L, suggesting that tenderness differences due to breed may have been facilitated by more-rapid proteolytic degradation over time.

Effects of biological type and dietary fat treatment on factors associated with tenderness: II. Measurements on beef semitendinosus muscle.

The objective of this study was to evaluate attributes in semitendinosus muscle (ST) associated with tenderness in divergent breeds--Wagyu (W; n = 12), Limousin (L; n = 12), and Wagyu x Limousin cross cattle (WxL; n = 12)--fed two dietary treatments (0 or 6% sunflower oil, DM basis). A randomized complete block repeated measures design with a 3 x 2 factorial arrangement of treatments was used to measure effects of breed, diet, block, and associated interactions. Cattle were fed barley-based diets for an average of 259 d. Temperature and pH were measured at 0, 1, 3, 6, 12, and 24 h postmortem (PM). Steaks from the ST were removed 24 h postmortem, vacuum-packaged, aged (1, 3, 7, 14, 28, and 56 d postmortem) at 2 degrees C, and frozen (-40 degrees C) until analyzed. Dietary treatment did not (P > 0.10) affect Warner-Bratzler shear force (WBSF), collagen amount (OH-PRO) or cross-linking (HP), temperature, or pH. Steaks from WxL aged 14 d postmortem had lower (P < 0.05) WBSF values than L (W were intermediate). Cooking time was longer (P < 0.01) in W and WxL than in L; however, breed did not affect (P > 0.10) cooking loss. Cooking time was not influenced by diet, but steaks from cattle fed 6% sunflower oil had lower (P < 0.05) cooking losses. Temperature decreased more (P < 0.05) rapidly, and pH more slowly (P < 0.05), in W and WxL than L in the first 24 h postmortem. Limousin steaks were lighter (higher L*) and more yellow (higher b*) in color than steaks from W and WxL (P < 0.05). The control diet (no oil added) resulted in steaks that were lighter (P < 0.05) than the treatment diet (6% added sunflower oil). Neither breed nor diet affected (P > 0.10) OH-PRO or HP concentration. The results of this study indicate that biological type differences may not be as great in the ST as in longissimus muscle; thus, to increase tenderness in ST, emphasis may need to be placed on processing and cooking techniques rather than genetic selection.

Measuring the effects of phenotype and mechanical restraint on proteolytic degradation and rigor shortening in callipyge lamb longissimus dorsi muscle during extended aging.

The purpose of this study was to determine if tenderness of callipyge (CLPG) longissimus dorsi muscle (LM) could be improved by: (1) extending the aging period to 48 days postmortem or (2) preventing rigor shortening by clamping. In CLPG and normal (NML) chops respectively, initial Warner-Bratzler shear values (WBS) were lower (P<0.05) in clamped (CL) (5.5 and 3.6 kg) compared to unclamped (UCL) (7.4 and 4.9 kg) LM. In CLPG, an acceptable WBS (3.6 kg) was reached at 48 days PM, whereas, NML lambs reached an acceptable level (3.8 kg) by 3 days PM. Sarcomere lengths (SL) of CL (1.68 µm) were longer (P <0.05) than for UCL (1.44 µm) and were negatively correlated with WBS (r=-0.55; P<0.1). The appearance of Troponin-T (TNT) degradation product coincided with tender WBS values; 3 days postmortem in NML UCL and 48 days postmortem in CLPG. In conclusion, clamping reduced WBS possibly by reducing rigor shortening. Extended aging resulted in CLPG LM with acceptable WBS values, concurrent with the appearance of TNT degradation products.

Growth, carcass characteristics, muscle conjugated linoleic acid (CLA) content, and response to intravenous glucose challenge in high percentage Wagyu, Wagyu x Limousin, and Limousin steers fed sunflower oil-containing diet.

The effect of breed and diet on insulin response to glucose challenge and its relation to intramuscular fat deposition was determined in 36 steers with 12 each of greater than 87% Wagyu (referred to as Wagyu), Wagyu x Limousin, and Limousin breeds. Weaned steers were blocked by weight into heavy, medium, and light calves and placed in six pens with two pens per weight type and with two steers of each breed per pen. Three pens with steers from each weightclass were fed backgrounding and finishing diets for 259 d, while the other three pens were fed the same diets where 6% of the barley grain was replaced with sunflower oil. Prior to initiation of the finishing phase of the study the intravenous glucose tolerance test (VGTIT) was conducted in all steers. Once steers were judged as carrying adequate 12th-rib fat, based on weight and days on feed, they were harvested and graded and samples of the longissimus muscle were procured for determination of fat content and fatty acid composition. Dietary oil improved (P = 0.011; 0.06) ADG and feed conversion efficiency of steers during the latter part of backgrounding and only ADG during early part ofthe finishing period. Generally percent kidney, pelvic, and heart fat was the only adiposity assessment increased (P = 0.003) by dietary oil. The IVGTT results indicated that insulin response to intravenous glucose was lower in Limousin steers than in Wagyu steers. Dietary oil decreased (P = 0.052) fasting plasma insulin concentration in Wagyu steers compared with Limousin steers. The correlation coefficients among the IVGTT measures and intramuscular fat content or marbling score were less than 0.4, and only a negative trend existed between fasting insulin and USDA marbling scores. However, the carcasses of the Wagyu steers graded US Choice, and 66% of the Wagyu carcasses graded US Prime, which were substantially better than the quality grades obtained for the carcasses from the other breed types. Dietary oil did not affect muscle fat content but increased (P = 0.01) conjugated linoleic acid (CLA) concentrations by 339%. Results indicated that IVGTT measures were not appropriate indices of marbling potential in cattle and that dietary oil can enhance CLA content of beef.

Differences among Wagyu sires for USDA carcass traits and palatability attributes of cooked ribeye steaks.

The objective of this experiment was to evaluate the effects of various Wagyu sires on carcass quality traits and palatability attributes of cooked ribeye steaks. Wagyu sires were used and grouped as Old (n = 6) or New (n = 2) sires, based on the chronological order in which they were imported into the United States. One hundred thirteen F1 heifer and steer calves sired by Wagyu bulls out of three different sources of cows were fed a backgrounding diet for 112 d consisting of an 80:20 ratio of roughage:concentrate then grazed on a mixture of orchardgrass and bluegrass pasture for 84 d and finished on a 10:90 ratio of roughage:concentrate diet for 231 d in a feedlot. Progeny from New sires had larger (P < .05) ribeye areas, higher (P < .05) marbling scores, and lower (P < .05) maturity scores than progeny from Old sires. Marbling was positively correlated (P < .05) to brightness (r = .56), texture (r = .60), and fat luster (r = .38). Progeny of New sires had lower shear force values (P < .05) than progeny of Old sires. These results indicate the superiority of New Wagyu sires to produce progeny with more marbling, lower shear force values, and larger ribeye areas than Old Wagyu sires. Furthermore, there are substantial differences between Wagyu sires for carcass quality traits and palatability attributes.

Effects of graded levels of potato by-products in barley- and corn-based beef feedlot diets: I. Feedlot performance, carcass traits, meat composition, and appearance.

To measure effects of diet on feedlot performance, carcass characteristics, and beef appearance, 144 crossbred beef steers (333+/-.44 kg) were allotted within weight block (3) to a randomized complete block design with a 2 x 3 factorial arrangement of dietary treatments. Main effects were grain (barley or corn) and level of potato by-product (PB) (0, 10, or 20% of diet DM). Steers were fed diets containing 83% concentrate (grain plus PB), 10% supplement, and 7% alfalfa on a DM basis for an average of 130 d. Level of PB quadratically affected (P < .10) DM intake and gain such that steers fed 10% PB ate more and gained faster. Corn-fed steers were more (P < .05) efficient (5.8 vs 6.3 kg DM/kg gain) and had more (P < .05) kidney, pelvic, and heart fat (2.2 vs 2.0%) than barley-fed steers. A grain x PB interaction was detected (P < .10) for marbling score, which was minimized in steers fed barley diets (small 0) but maximized in those fed corn diets (small 30) at 10% PB. Diet did not affect beef firmness or beef color score. Barley-fed beef had whiter fat (P < .05) than corn-fed beef (2.6 vs 2.9 on a 1 to 7 scale); however, fat luster score was not affected by diet. Small differences were noted in fatty acid profile, purge, drip loss, and muscle pH. No differences were noted in color measurements due to dietary treatment over 7 d of retail shelf life. Overall, differences were small and probably not biologically important. These results indicate that these diets had minimal effects on beef appearance and carcass characteristics, meat composition, and water retention properties.

Effects of graded levels of potato by-products in barley- and corn-based beef feedlot diets: II. Palatability.

The objective of this study was to evaluate the effects of barley- or corn-based diets containing 0, 10, or 20% potato by-product (DM basis) on Warner-Bratzler shear force and palatability of beef. One hundred forty-four crossbred beef steers (333+/-.44 kg) were allotted within weight block (3) to a randomized complete block design with a 2 x 3 factorial arrangement of dietary treatments. Main effects were grain (barley or corn) and level of potato by-product (0, 10, or 20% of diet DM). There were a total of 18 pens with eight steers per pen and three pens per treatment. Steers were fed diets containing 83% concentrate (grain plus potato by-product), 10% supplement, and 7% alfalfa (DM basis) for an average of 130 d. Longissimus muscle cuts were used for Warner-Bratzler shear force determination (four steers per pen) and evaluation (two steers per pen) by a 10-member trained laboratory panel, a professional flavor/texture profile panel, and by consumer panels. Diet did not affect (P > .10) Warner-Bratzler shear force or trained laboratory panel tenderness, juiciness, and flavor intensity scores. Flavor/texture profile panel scores indicated feeding a corn-based diet as opposed to barley-based diet produced a more appropriate well-balanced and well-blended beef flavor and texture. However, the magnitudes of the differences were relatively small, and flavor and texture amplitude ratings for both barley- and corn-fed beef were well above average. Beef from steers fed 10 or 20% potato by-product had lower (P < .05) incidences of inappropriate aromatics and aftertastes, which may have a slightly beneficial effect on beef flavor, but flavor amplitude was not affected (P > .05) by level of potato. Moreover, consumer panel overall acceptability scores were not affected by diet. Thus, feedlot diets containing corn or barley with or without potato by-product should result in palatable beef products.