Effects of grain processing and dietary lipid source on performance, carcass characteristics, plasma fatty acids, and sensory properties of steaks from finishing cattle

An experiment was conducted to evaluate the effects of grain processing and lipid addition to finishing diets on cattle performance, carcass characteristics, and meat quality. Eighty Hereford x Angus steers (384 kg +/- 17 kg of BW) were fed diets containing steam-flaked corn (SFC) or dry-rolled corn (DRC) with and without the addition of tallow (SFC/Fat and DRC/Fat) or steam-flaked corn with ground flaxseed (SFC/Flax). Ribeye steaks from steers fed SFC, SFC/Fat, or SFC/ Flax were used to evaluate the effects of fat source on meat quality. Cattle fed SFC and SFC/Fat tended to have greater ADG, G:F, HCW, and USDA yield grade, compared with those fed DRC and DRC/Fat (P < 0.10). Steaks from steers fed SFC/Flax developed a detectable off-flavor (P < 0.05) compared with steaks from steers fed SFC and SFC/Fat, and steaks from steers fed SFC retained desirable color longer than those from steers fed SFC/Flax (P < 0.05). Feeding SFC/Flax increased deposition of alpha-linolenic acid in muscle tissue compared with feeding SFC or SFC/Fat (P < 0.01). Dietary treatment did not cause differences in tenderness, juiciness, or flavor intensity. Ground flaxseed can replace tallow in finishing diets without loss in performance, but flax may affect flavor and color stability of beef. Feeding flaxseed can effectively alter composition of carcass tissues to yield beef that is high in n-3 fatty acids.     

Effects of dry, wet, and rehydrated corn bran and corn processing method in beef finishing diets

Two finishing trials were conducted to determine the effects of adding different types of corn bran, a component of corn gluten feed, on cattle performance. In Trial 1, 60 English crossbred yearling steers (283 +/- 6.7 kg) were used in a completely randomized design with four dietary treatments. Treatments were diets with no corn bran, dry corn bran (86% DM), wet corn bran (37% DM), and rehydrated dry bran (37% DM). Bran was fed at 40% of dietary DM. All finishing diets had (DM basis) 9% corn steep liquor with distillers solubles, 7.5% alfalfa hay, 3% tallow, and 5% supplement. Gain efficiency and ADG were greater (P < 0.01) for cattle fed no corn bran compared with all treatments containing corn bran; however, no differences were detected across corn bran types. In Trial 2, 340 English crossbred yearling steers (354 +/- 0.6 kg) were used in a randomized block design with treatments assigned based on a 2 x 4 + 2 factorial arrangement (four pens per treatment). One factor was the corn processing method used (dry-rolled corn, DRC; or steam-flaked corn, SFC). The other factor was corn bran type: dry (90% DM), wet (40% DM), or dry bran rehydrated to 40 or 60% DM. Bran was fed at 30% of dietary DM, replacing either DRC or SFC. Two control diets (DRC and SFC) were fed with no added bran. All finishing diets contained (DM basis) 10% corn steep liquor with distiller's solubles, 3.5% alfalfa hay, 3.5% sorghum silage, and 5% supplement. Corn bran type did not affect DMI (P = 0.61), ADG (P = 0.53), or G:F (P = 0.10). Dry matter intake was greater (P < 0.01) by steers fed bran compared with those fed no bran, and was greater by steers fed DRC than by steers fed SFC (P < 0.01). Interactions occurred (P < 0.01) between grain source and bran inclusion for ADG and G:F. The ADG by steers fed the SFC diet without bran was greater (P < 0.01) than by steers fed SFC diets with bran, whereas the ADG by steers fed DRC diets with or without bran was similar. Daily gain was 15.2% greater (P < 0.01) by steers fed SFC without bran than by steers fed DRC without bran. Gain efficiency was 16.9% greater (P < 0.01) for steers fed SFC without bran compared with steers fed DRC without bran. In DRC and SFC diets, feeding bran decreased (P < 0.01) G:F by 5.2 and 13.8%, respectively. The moisture content of corn bran had no effect on finishing steer performance, and drying corn bran did not affect its energy value in finishing cattle diets.     

Utilization of distillers grains from the fermentation of sorghum or corn in diets for finishing beef and lactating dairy cattle

Beef finishing and dairy lactation experiments were conducted to evaluate the nutritional value of distillers grains (DG) from sorghum or corn fermentation, in both wet (35.4% DM) and dry (92.2% DM) form (dairy trial only). In the finishing experiment, 60 yearling steers were used in a completely randomized design with three diets that were fed for 127 d: 1) control diet with 86% (DM basis) dry-rolled corn and no DG; 2) 30% of ration DM as wet corn DG in place of dry-rolled corn; and 3) 30% of ration DM as wet sorghum DG in place of dry-rolled corn. All diets contained a minimum of 6.8% degradable intake protein and 13.0% CP. Steers fed DG had 10% greater ADG (< 0.01) and 8% greater efficiency of gain (P < 0.01) than steers fed the control diet. Wet corn and sorghum DG resulted in similar ADG and efficiency of gain. Hot carcass weights, fat thickness, and yield grades were greater for steers fed DG than for controls (P < 0.07). Improvements in ADG and feed efficiency observed when DG replaced dry-rolled corn indicated that the NEg content of wet DG is approximately 29% greater than that of dry-rolled corn. In the dairy lactation experiment, 16 lactating Holstein cows (eight multiparous, including four fistulated) were used in a replicated 4 x 4 Latin square design with 4-wk periods. Corn and sorghum DG were fed at 15% of the ration DM in either wet or dry form. Diets were fed as total mixed rations that contained 50% of a 1:1 mixture of alfalfa and corn silages, 24.3% ground corn, and 9.1% soybean meal (DM basis). There was no effect of source or form of DG on DMI, ruminal pH and VFA, or in situ digestion kinetics of NDF from DG. Efficiency of milk production was unaffected by diet. Corn and sorghum DG resulted in relatively similar performance when fed to beef or dairy cattle in this study.     

Effect of long-term corn by-product feeding on beef quality, strip loin fatty acid profiles, and shelf life

The objective of this study was to evaluate the meat quality and shelf life of steaks from steers fed dried distillers grains with solubles (DDGS) or dried corn gluten feed (CGF) compared with soybean meal with corn (SBM) as a protein supplement from weaning to slaughter. Angus cross steers (n = 81; BW = 306 ± 26.1 kg) were randomly assigned to pens (n = 9) and fed a stocker diet of corn silage (75% of DM) with DDGS, CGF, or SBM and ground ear corn. After 84 d of stockering, 12 steers (BW = 397 ± 15.3 kg) were randomly selected from each treatment and finished using the same protein supplement at 25% of DM for 100 d. Carcass data were collected (24 h) and the longissimus lumborum was fabricated into steaks at 48 h postmortem. Steaks were assigned to proximate analysis, Warner-Bratzler shear force (7-, 14-, or 21-d aging), and retail display (1, 3, 6, or 9 d). Protein source did not affect carcass yield, quality, or longissimus lumborum composition (P > 0.05). After 7 d of aging, DDGS and CGF steaks were more tender (P < 0.01) than SBM, but were similar (P = 0.30) after 14 and 21 d of aging. Feeding corn by-products did not influence subjective overall color acceptance (P = 0.17) in this study, but acceptance declined over time (P < 0.01). Subjective redness was similar (P > 0.05) among diets except SBM steaks were more red (P < 0.01) than DDGS after 9 d. On d 3 and 6 of retail display, CGF steaks exhibited more discoloration (P < 0.04) than SBM or DDGS steaks. However, after 9 d DDGS steaks were more discolored (P < 0.01) than CGF or SBM. Objective L* was lighter for CGF (P < 0.04) over 9 d of display, and all treatments became darker (P < 0.01) as time increased. Redness (a*) declined (P < 0.01) over time with SBM steaks maintaining more color in the red spectrum than CGF and DDGS after 6 d of display. Protein source did not affect (P > 0.05) the rate of lipid oxidation. Total SFA concentrations were similar (P > 0.05) among treatments; however, total MUFA were less (P < 0.05) and total PUFA concentrations were greater (P < 0.05) in DDGS steaks compared with SBM or CGF steaks. These data show that DDGS or CGF can be fed as a protein supplement at 25% DM from weaning until slaughter while maintaining meat quality when compared with steers fed soybean meal as a protein supplement.     

Impact of feeding various amounts of wet and dry distillers grains to yearling steers on palatability, fatty acid profile, and retail case life of longissimus muscle

Due to increased production of ethanol, abundance of distillers grains (DG) is increasing. Steers (n = 176) were assigned to 1 of 5 treatment groups: steam-flaked corn (SFC), 10% dry DG (DDG), 10% wet DG (WDG), 20% WDG, or 30% WDG. The objectives were to determine the effects of feeding greater amounts of WDG, or DDG on meat quality. Steaks, 2.54 cm, were cut from strip loins and identified for simulated retail display, Warner-Bratzler shear force analysis, palatability, and fatty acid composition. Steaks from cattle fed 10% WDG and 30% WDG had smaller (P < 0.05) Warner-Bratzler shear force values than steaks from cattle fed 20% WDG. Trained sensory panelists found no differences (P > 0.05) in overall tenderness and off-flavors. No differences were found in total SFA and MUFA composition among treatments; however, 20% and 30% WDG had a greater proportion of PUFA and n-6 fatty acids than 10% WDG. No differences were found during simulated retail display between various amounts of WDG. Further research needs to be conducted to evaluate methods that aid in increasing shelf life of steaks from cattle fed greater rates of WDG.     

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.     

Fatty acid indices of stearoyl-CoA desaturase do not reflect actual stearoyl-CoA desaturase enzyme activities in adipose tissues of beef steers finished with corn-, flaxseed-, or sorghum-based diets

We hypothesized that stearoyl-CoA desaturase (SCD) enzyme activity would not correlate with fatty acid indices of SCD activity in steers fed different grains. Forty-five Angus steers (358 +/- 26 kg BW) were individually fed for 107 d diets differing in whole cottonseed (WCS) supplementation (0, 5, or 15% of DM) and grain source (rolled corn, flaxseed plus rolled corn, or ground sorghum grain) in a 3 x 3 factorial arrangement. Flaxseed- and corn-fed steers had greater (P < 0.01) G:F (0.119 and 0.108, respectively) than sorghum-fed steers (0.093). Marbling score was decreased by WCS (P = 0.04), and LM area was decreased (P < 0.01) by sorghum. Plasma 14:0, 16:0, 16:1n-7, and 18:2n-6 were greatest in corn-fed steers, whereas plasma 18:3n-3 and 20:5n-3 were greatest in the flax-seed-fed steers (P < 0.01). Plasma 18:1trans-11 was least in sorghum-fed steers, and plasma cis-9,trans-11 CLA was barely detectable, in spite of high intestinal mucosal SCD enzyme activity (118 to 141 nmol*g tissue(-1).7 min(-1)). Interfascicular (i.f.) and s.c. cis-9,trans-11 CLA remained unchanged (P > or = 0.25) by treatment, although 18:1trans-11 was increased (P < or = 0.02) in steers fed corn or flaxseed. Steers fed flaxseed also had greater (P < 0.01) i.f. and s.c. concentrations of 18:3n-3 than steers fed the other grain sources. Oleic acid (18:1n-9) was least and total SFA were greatest (P < 0.01) in i.f. adipose tissue of steers fed 15% WCS. Lipogenesis from acetate in s.c. adipose tissue was greater (P < 0.01) in flaxseed-fed steers than in the corn- or sorghum-fed steers. Steers fed flaxseed or corn had larger i.f. mean adipocyte volumes (P < 0.01) than those fed sorghum and tended (P = 0.07) to have larger s.c. adipocyte volumes. Several fatty acid indices of SCD enzyme activity were decreased (P < or = 0.03) by WCS in i.f. adipose tissue, including the 18:2cis-9,trans-11/ 18:1trans-11 ratio. The 18:2cis-9,trans-11/18:1trans-11 ratio also tended to be decreased (P = 0.09) in s.c. adipose tissue by flaxseed; however, SCD enzyme activities in i.f. and s.c. adipose tissue were not affected by dietary WCS (P > or = 0.47) or grain source (P > or = 0.37). Differences in SFA seemed to be independent of SCD enzyme activity in both adipose tissues, suggesting that duodenal concentrations of fatty acids were more important in determining tissue fatty acid concentrations than endogenous desaturation by SCD.     

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.     

Effects of supplemental vitamin D3 on feed intake, carcass characteristics, tenderness, and muscle properties of beef steers.

Research was conducted to determine the effects of supplemental dietary vitamin D3 on DMI, carcass traits, Warner Bratzler shear (WBS) force, calpastatin activity, plasma minerals, pH (0, 3, 12, and 24 h after slaughter), water-holding capacity (WHC), and sensory characteristics of three muscles. Pre-slaughter vitamin D3 treatments included no supplemental vitamin D3, 6 x 106 IU (MIU) of vitamin D3 for 4 d, or 6 MIU of vitamin D3 for 6 d. Cattle were slaughtered and carcasses were chilled for 48 h before removal of steaks from the longissimus, gluteus medius, and biceps femoris muscles. Steaks were aged at 2 degrees C for 7, 14, or 21 d before cooking to a final internal temperature of 70 degrees C for WBS and sensory panel analysis. Dry matter intake was lower for steers supplemented with vitamin D3 for 4 or 6 d. Live and carcass weights were lower (P < 0.05) in steers supplemented with vitamin D3. Supplementing 6 MIU/6 d of vitamin D3 decreased (P < 0.05) WBS values of gluteus steaks (pooled over aging times). Longissimus steaks from steers supplemented with vitamin D3 for 6 d had lower (P < 0.05) WBS force values than these steaks from control steers or steers fed vitamin D3 for 4 d at 7 d postmortem. Biceps femoris steaks from steers receiving vitamin D3 for 4 d had higher WBS values than steaks from control steers at 14 and 21 d postmortem. Feeding vitamin D3 at 6 MIU for 6 d decreased (P < 0.05) the percentage of steaks that had WBS values > or = 3.86 kg for all steaks. Feeding vitamin D3 had no effect on palatability traits evaluated by trained panelists. Blood Ca concentrations were greater (P < 0.05) when vitamin D3 was fed and with increased vitamin D3 feeding time. Feeding vitamin D3 for 6 d (vs 4 d) delayed pH decline for all muscle types after 0, 3, and 12 h postmortem. Water-holding capacity was increased (P > 0.02) after 0 h, 24 h, and 21 d postmortem when vitamin D3 was fed and was greater at 0 and 24 h if vitamin D3 was fed for 6 d rather than 4 d. These data suggest that supplementing 6 MIU of vitamin D3 will decrease DMI and improve beef tenderness through increased blood plasma Ca concentrations and WHC.     

Effects of roughage source and distillers grain concentration on beef cattle finishing performance, carcass characteristics, and in vitro fermentation

Two experiments were conducted to evaluate the effects of wet distillers grains plus solubles (DG) and roughage source on finishing cattle performance, carcass characteristics, and in vitro fermentation. In Exp. 1, crossbred beef steers (n=224, initial BW=349 kg) were used in a randomized complete block design with a 2 × 3 + 1 factorial arrangement of treatments. Experimental diets were a standard steam-flaked corn (SFC)-based control (no DG and 10% alfalfa hay), and either 15 or 30% DG (DM basis) with roughage sources of alfalfa hay (15-AH and 30-AH), Coastal bermudagrass hay (15-BG and 30-BG), or sorghum silage (15-SS and 30-SS). Within each DG concentration, roughages provided an equivalent percentage of NDF to 7.5% AH. Steers consuming 15% DG had greater (P < 0.04) final BW, ADG, and G:F than those fed 30% DG. Feeding AH as the roughage source with DG resulted in decreased final shrunk BW and ADG (P < 0.02) compared with BG and SS. Feeding SS as the roughage source decreased (P=0.01) G:F relative to BG. Hot carcass weight was greater (P < 0.01) for steers consuming 15 vs. 30% DG, tended to be least for diets with AH as the roughage source (P=0.06), and did not differ for the control vs. the other diets (P=0.86). Control cattle had an increased (P=0.05) proportion of USDA Choice or greater carcasses compared with the average of the other treatments. In Exp. 2, the same 2 × 3 +1 factorial arrangement as in Exp. 1 was used to examine the effects of roughage source and DG on IVDMD, culture fluid osmolality, and gas production kinetics. In vitro DMD tended (P < 0.09) to be greater for BG compared with SS at 6 and 36 h of incubation and was greater for AH vs. the mean of BG and SS at 18 h (P=0.01). Culture fluid osmolality, asymptotic maximal gas production, fractional rate of gas production, and lag time of gas production did not differ among treatments (P > 0.14). Overall, feeding 15% DG in SFC-based diets increased ADG, BW, and HCW relative to 30% DG. In addition, feeding AH tended to decrease ADG, final BW, and HCW relative to the other 2 roughage sources, whereas BG improved G:F over SS. These data suggest that including the smaller amount of DG and BG as the roughage source resulted in improved performance relative to other combinations, and that substituting roughages on the basis of equivalent NDF concentration might not be ideal for optimizing performance when feeding SFC-based finishing diets that contain DG.     

Use of dried distillers grains throughout a beef production system: effects on stocker and finishing performance, carcass characteristics, and fatty acid composition of beef

A 2-yr study was conducted using a 3 × 2 factorial arrangement of treatments to evaluate the effects of feeding dried distillers grains throughout a beef production system on performance, carcass characteristics, and fatty acid profile of beef. Factors were wheat pasture supplement [no supplement (CON), dry-rolled corn (DRC), and dried distillers grains (DDG)] fed at 0.5% BW daily and finishing diet [steam-flaked corn based diet containing 0 (SFC) or 35% (35DDG) DDG]. Each year, 60 preconditioned Hereford steers (initial BW = 198 kg ± 3) grazed winter wheat pasture with or without supplement. Body weight gain was 8% greater for steers consuming DDG supplement compared with CON and DRC steers (P < 0.01). After the grazing period, pastures within supplement treatment were randomly assigned to SFC or 35DDG. There was no supplement by finishing diet interaction for any performance or carcass variable of interest (P ≥ 0.41). Previous supplementation on winter wheat affected BW at feedlot entry and adjusted G:F (P ≤ 0.05) but had no effect on finishing ADG or carcass traits (P ≥ 0.12). On a carcass-adjusted basis, steers consuming 35DDG had reduced final BW, ADG, G:F, and total BW gain throughout the system (P ≤ 0.04) compared with SFC. Additionally, steers consuming 35DDG had reduced HCW, dressing percent, and fat thickness (P ≤ 0.03) compared with SFC. There was a supplement by finishing diet interaction (P = 0.02) for 18:0, in which cattle supplemented with DRC and fed the SFC finishing diet had the lowest concentration of 18:0 but DRC supplemented steers fed the 35DDG diet had the greatest concentration. The interaction was not significant (P ≥ 0.18) for other fatty acids. Main effects of supplement and finishing diet affected (P ≤ 0.05) several other fatty acids of interest, particularly 18:2, which is associated with reduced flavor-stability of beef. The use of DDG as a supplement to wheat pasture resulted in greater ADG during wheat grazing and heavier BW at feedlot entry, but final BW was not different from CON or DRC groups. Feeding DDG at 35% DM in steam-flaked corn-based finishing diets reduced ADG, G:F, and HCW, and affected the fatty acid composition of beef.     

Influence of steam-flaked, steamed-whole or whole shelled corn on performance and digestion in beef steers

Three trials were conducted to evaluate finishing diets containing 67% steam-flaked corn (SFC), steamed-whole corn (SWC) or whole corn (WC). In a feeding trial, steers fed SWC consumed more (P less than .05) dry matter per day (7.6 kg) than those fed WC (7.0 kg) or SFC (6.7 kg). Average daily gain was greater (P less than .05) for steers fed SFC (1.33 kg) and SWC (1.31 kg) than for those fed WC (1.25 kg), and feed efficiency was better (P less than .05) for steers fed SFC (5.06 kg dry matter/kg gain) than for those fed WC (5.62) and SWC (5.79). Carcass characteristics were not different among the three groups. In a digestion trial, method of corn processing did not affect digestibility of dry matter and crude protein. Starch digestibility was greater (P less than .05) for SFC (99.1%) than for SWC (93.8%) and WC (93.0%). There were no differences in nitrogen (N) intake or fecal N among the three diets; however, urinary N was less (P less than .05) for SWC (19 g/d) than for SFC (27 g/d) and WC (32 g/d), and N retention was higher (P less than .05) for the SWC diet. In vitro dry matter digestibility of the SFC diet was higher (P less than .05) than for WC at 4 and 8 h of incubation and higher (P less than .05) than the SWC diet at 8, 12 and 24 h of incubation. In vitro gas production after 6 h was greater (P less than .05) for SFC than for SWC grain, which was greater (P less than .05) than WC.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of early postmortem protein oxidation on beef quality

The objective of this study was to examine the effect of early postmortem protein oxidation on the color and tenderness of beef steaks. To obtain a range of oxidation levels, the longissimus lumborum muscles (LM) from both strip loins of 20 steers fed either a finishing diet with vitamin E (1,000 IU per steer daily, minimum of 126 d [VITE]; n = 10 steers) or fed the same finishing diet without vitamin E (CON; n = 10 steers) were used. Within 24 h after slaughter, the LM muscle from each carcass was cut into 2.54-cm-thick steaks and individually vacuum packaged. Steaks from each steer were assigned to a nonirradiated group or an irradiated group. Steaks were irradiated within 26 h postmortem, and were aged at 4 degrees C for 0, 1, 3, 7, and 14 d after irradiation. Steaks from each diet/irradiation/aging time treatment were used to determine color, shear force, and degree of protein oxidation (carbonyl content). Steaks from steers fed the VITE diet had higher (P < 0.01) alpha-tocopherol contents than steaks from steers fed the CON diet. Immediately following irradiation, steaks that had been irradiated had lower (P < 0.05) L* values regardless of diet. Irradiated steaks, regardless of diet, had lower a* (P < 0.05) and b* (P < 0.01) values than nonirradiated steaks at all aging times. Carbonyl concentration was higher (P < 0.05) in proteins from irradiated steaks compared to nonirradiated steaks at 0, 1, 3, and 7 d postirradiation. Immunoblot analysis showed that vitamin E supplementation decreased the number and extent of oxidized sarcoplasmic proteins. Protein carbonyl content was positively correlated with Warner-Bratzler shear force values. These results indicate that increased oxidation of muscle proteins early postmortem could have negative effects on fresh meat color and tenderness.     

Effects of wet corn gluten feed and roughage levels on performance, carcass characteristics, and feeding behavior of feedlot cattle

Two experiments were conducted to evaluate the effects of feeding different levels of wet corn gluten feed (WCGF) and dietary roughage on performance, carcass characteristics, and feeding behavior of feedlot cattle fed diets based on steam-flaked corn (SFC). In Exp. 1, crossbred steers (n = 200; BW = 314 kg) were fed 4 dietary treatments (DM basis): a standard SFC-based diet containing 9% roughage (CON) and 3 SFC-based diets containing 40% WCGF, with either 9, 4.5, or 0% roughage. A linear (P = 0.04) increase in final BW and DMI (P < 0.01) was observed in diets containing WCGF as dietary roughage increased. Steers fed WCGF and higher levels of roughage had greater (P = 0.01) ADG than steers fed lower levels of roughage. Steers fed the CON diet had lower (P = 0.04) daily DMI and greater (P = 0.03) G:F than those fed WCGF. Most carcass characteristics of steers fed CON did not differ (P > 0.10) from those of steers fed WCGF. Based on feed disappearance and visual scan data, consumption rate did not differ (P > 0.10) among treatments; however, feeding intensity (animals present at the bunk after feeding) was greater for steers fed CON (P < 0.01) than for steers fed WCGF. In Exp. 2, yearling crossbred steers (n = 1,983; BW = 339 kg) were fed 4 dietary treatments (DM basis): a standard SFC-based control diet that contained 9% roughage (CON) and 3 SFC-based diets containing either 20% WCGF and 9% roughage or 40% WCGF with 9 or 4.5% roughage. Steers fed the CON diet tended to have lower final BW (P = 0.14), ADG (P = 0.01), and DMI (P < 0.01) than steers fed diets containing WCGF. Steers fed the 20% WCGF diet had greater (P = 0.08) G:F than steers fed the 40% WCGF diets. With 40% WCGF, increasing roughage from 4.5 to 9% decreased (P < 0.01) G:F and increased (P = 0.06) DMI. Gain efficiency was improved (P < 0.01) for steers fed CON vs. those fed diets containing WCGF, whereas HCW (P = 0.02) and dressing percentage (P < 0.01) were greater for steers fed WCGF. Percentage of cattle grading USDA Choice was greater (P = 0.02) for cattle fed WCGF. Results suggest that replacing SFC with up to 40% WCGF increased ADG and decreased G:F when 4.5 to 9.0% roughage was supplied. More CON steers were present at the feed bunk during the first hour after feeding than WCGF steers, suggesting that including WCGF at 40% of the diet affected feeding behavior.     

The effects of grazing, liquid supplements, and implants on feedlot performance and carcass traits of Holstein steers

In each of 2 yr, 20 Holstein steers (185+/-7 kg initial BW) were allocated to each of three treatments: pastured for 4.5 mo on grass/legume pastures and then fed 80% corn diets (DM basis) until slaughter; pastured for 4.5 mo on grass/legume pastures with ad libitum access to molasses-based protein supplements and fed 80% corn diets until slaughter; and placed in a feedlot and fed only 80% corn diets until slaughter (FEEDLOT). Half of the steers in each treatment were initially implanted with Revalor-S and not reimplanted. Supplemented steers on pasture had greater (P < 0.05) ADG than unsupplemented steers, and FEEDLOT steers gained faster and were fatter (P < 0.05) after 4.5 mo. Implanted steers had greater (P < 0.05) ADG with no significant treatment x implant status effect. Supplement intake was variable and related to ambient temperature. During the feedlot phase, steers previously on pasture had greater DMI and ADG (P < 0.05) but were not more efficient than FEEDLOT steers. Percentage of USDA Choice carcasses, fat thickness, dressing percentage, yield grade, and final weight were greater (P < 0.05) for FEEDLOT steers than for steers on other treatments. Implanting increased ADG of all steers but did not affect carcass traits, carcass composition, or feedlot performance during the finishing phase. Holstein steers consuming supplemented and unsupplemented pasture before slaughter will be leaner, have lower carcass weights, and have generally lower quality grades than those fed exclusively in a feedlot when slaughtered at similar ages.     

Corn processing method in finishing diets containing wet corn gluten feed

Two trials were conducted to determine the effect of corn processing method on performance and carcass traits in steers fed finishing diets containing wet corn gluten feed (WCGF). In Trial 1, 480 steer calves (303 kg initial BW) were fed eight finishing diets: 1) dry-rolled corn (DRC) without; and 2) with 32% (DM basis) WCGF; 3) steam-flaked corn (SFC) without; and 4) with WCGF; 5) a combination of DRC and SFC without WCGF; 6) finely-ground corn (FGC) with WCGF; 7) high-moisture corn (HMC) with WCGF; and 8) whole corn (WC) with WCGF. Feeding WC + WCGF increased (P < 0.10) DMI and decreased gain:feed compared with all other treatments. Feeding DRC + WCGF increased (P < 0.10) DMI and decreased (P < 0.10) gain:feed compared with treatments other than WC + WCGF. Steers on treatments that included WCGF gained similarly, regardless of corn processing method, and at a rate 6% faster (P < 0.10) than steers fed diets that did not include WCGF. Gain:feed did not differ among steers fed SFC, SFC + WCGF, SFC + DRC, and HMC + WCGF. Steers fed SFC or SFC + WCGF were more efficient (P < 0.10) than steers fed DRC or FGC + WCGF. In Trial 2, 288 steer calves (382 kg initial BW) were fed six finishing diets: 1) DRC without; and 2) with 22% (DM basis) WCGF; 3) SFC without; and 4) with WCGF; 5) finely rolled corn (FRC) with WCGF; and 6) HMC corn with WCGF. Steers fed DRC + WCGF or FRC + WCGF consumed more DM (P < 0.10) than steers fed DRC, SFC, or SFC + WCGF. Feed intake did not differ between steers fed SFC + WCGF and HMC + WCGF. All treatment groups receiving WCGF consumed more DM (P < 0.10) feed than steers fed DRC or SFC without WCGF. Steers fed SFC + WCGF gained 8% faster (P < 0.10), and steers fed DRC 9.5% slower (P < 0.10) than steers receiving all other treatments. Daily gains did not differ among other treatment groups. Steers fed SFC or SFC + WCGF gained 10% more (P < 0.10) efficiently than all other treatment groups. Feed efficiency did not differ among steers fed DRC, DRC + WCGF, FRC + WCGF, and HMC + WCGF. Estimates for the NEg of WCGF calculated from animal performance indicated that WCGF contained approximately 25.3% more energy when fed with SFC than when fed with DRC. In general, more intensively processing corn improved gain:feed in finishing diets containing WCGF.     

Effects of distillers grains with high sulfur concentration on ruminal fermentation and digestibility of finishing diets

Twelve ruminally cannulated crossbred Angus steers were used to evaluate ruminal fermentation characteristics and diet digestibility when 30% (DM) corn dried distillers grains with solubles (DDGS) containing 0.42 or 0.65% (DM) of dietary S was incorporated into finishing diets based on steam-flaked corn (SFC) or dry-rolled corn (DRC). The study was a replicated, balanced randomized incomplete block design with a 2 × 2 factorial arrangement of treatments. Factors consisted of dietary S concentration (0.42 and 0.65% of DM; 0.42S and 0.65S, respectively) and grain processing method (SFC or DRC). The 0.65S concentration was achieved by adding H(2)SO(4) to DDGS before mixing rations. Steers were assigned randomly to diets and individual, slatted-floor pens, and fed once daily for ad libitum intake. Two 15-d experimental periods were used, each consisting of a 12-d diet adaptation phase and a 3-d sample collection phase. Samples were collected at 2-h intervals postfeeding during the collection phase. Ruminal pH was measured immediately after sampling, and concentrations of ruminal ammonia and VFA were determined. Fecal samples were composited by steer within period and used to determine apparent total tract digestibilities of DM, OM, NDF, CP, starch, and ether extract. Feeding 0.65S tended (P = 0.08) to decrease DMI but resulted in greater apparent total tract digestibilities of DM (P = 0.04) and ether extract (P = 0.03). Ruminal pH increased (P < 0.05) in steers fed 0.65S diets, which may be attributable, in part, to decreased (P = 0.05) VFA concentrations and greater (P < 0.01) ruminal ammonia concentrations when 0.65S was fed, compared with feeding 0.42S. These effects were more exaggerated in steers fed DRC (interaction, P < 0.01), compared with steers fed SFC. Steers fed DRC-0.65S had greater (P < 0.01) acetate concentration than steers fed DRC-0.42S, but acetate concentration was not affected by S concentration when SFC was fed. Propionate concentration was decreased (P < 0.01) in steers fed SFC-0.65S compared with steers fed SFC-0.42S, but dietary S concentration had no effect on propionate concentration when DRC was fed. Butyrate concentration was less (P < 0.01) in steers fed 0.65S diets than in steers fed 0.42S. Lactate concentrations tended (P = 0.06) to decrease in steers fed 0.65S diets. Feeding DDGS with increased S concentration may decrease feed intake and ruminal VFA concentration but increase ruminal ammonia concentration.     

Effects of steam-flaked sorghum grain or corn and supplemental fat on feedlot performance, carcass traits, longissimus composition, and sensory properties of steers.

One hundred forty British x Exotic crossbred, yearling steers (370 kg) were used in a 2 x 2 factorial experiment to evaluate main effects and the interaction of grain type (steam-flaked sorghum grain [SFSG] or steam-flaked corn [SFC]) and level of supplemental far (0 or 4% yellow grease [YG]) on feedlot performance, diet NE concentration, carcass traits, and chemical composition and sensory properties of longissimus muscle. Steer performance and estimated dietary NEm and NEg values were not different between SFSG and SFC. Supplemental YG improved (P less than or equal to .05) gain/feed and estimated NEm and NEg of both SFSG and SFC diets. Compared with steers fed SFSG, steers fed SFC had a more yellow (P less than .05) subcutaneous fat color. Supplemental YG had an additive effect (P less than .025) on yellow color of subcutaneous fat but improved (P less than .08) the lean color of longissimus muscle. Grain type or supplemental YG had no effect on sensory properties or mechanical shear of longissimus muscle. Longissimus muscle cholesterol content was elevated (P less than .05) by supplemental YG (.49 vs .52 mg/g of wet tissue for 0 vs 4% YG, respectively); however, the biological significance of this result is questionable. Similarly, effects of YG on increased (P less than .05) stearic acid concentration and a higher concentration (P less than .05) of linoleic acid measured in longissimus muscle of steers fed SFSG vs SFC were small in magnitude. These data indicate that under the conditions of this experiment, NE contents of SFSG and SFC were similar.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of ractopamine supplementation and postmortem aging on longissimus muscle palatability of beef steers differing in biological type

Effects of ractopamine hydrochloride (RAC) supplementation and postmortem aging on palatability of beef from steers differing in biological type were evaluated using LM samples from British, Continental crossbred, and Brahman crossbred calf-fed steers (n = 98/type). Equal numbers of steers within each type were assigned to treatments of 0 or 200 mg.steer(-1).d(-1) of RAC fed during the final 28 d of the finishing period. Warner-Bratzler shear force (WBSF) was measured at 3, 7, 14, and 21 d postmortem, and trained sensory panel (TP) evaluation was conducted using LM samples aged for 14 d postmortem. A RAC x type interaction (P = 0.006) was detected for WBSF. Within each type, steers fed RAC produced steaks with greater (P < 0.05) WBSF values than steaks from control steers; however, the magnitude of the effect of RAC on WBSF was more pronounced among Brahman cross-breds (5.53 vs. 4.96 +/- 0.10 kg) than among Continental crossbred (4.16 vs. 3.96 +/- 0.10 kg) and British steers (4.10 vs. 3.75 +/- 0.10 kg). The effect of RAC on WBSF, though diminished slightly by aging (mean WBSF difference: 3 d = 0.49 kg; 21 d = 0.24 kg), was not completely mitigated by 21 d of postmortem storage (P(RAC x AGE) = 0.16). Steers fed RAC produced steaks that received lower (P < 0.05) TP ratings for tenderness (8.09 vs. 8.95 +/- 0.18) and juiciness (7.41 vs. 8.07 +/- 0.16 kg), along with slightly lower (P = 0.06) ratings for beef flavor (6.67 vs. 6.93 +/- 0.10 kg), compared with steaks from unsupplemented steers, regardless of biological type. Among the 3 biological types, Brahman crossbred cattle produced steaks with the greatest (P < 0.05) WBSF values at each aging period; WBSF values for steaks from British and Continental type steers did not differ (P > 0.05) at any aging time. Sensory panel ratings of tenderness, juiciness, and beef flavor were greatest (P < 0.05) for steaks from British steers, and least (P < 0.05) for steaks produced by Brahman-type steers. Results from this study suggest that RAC supplementation slightly decreases LM tenderness (WBSF and TP) of British, Continental crossbred, and Brahman cross-bred steers, and that the effect of RAC on WBSF may be more pronounced in steaks from Brahman crossbred cattle than among stenks from Continental type or British steers.     

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.