Ryan B. Cox

Carcass, sensory, fat color, and consumer acceptance characteristics of Angus-cross steers finished on ryegrass (Lolium multiflorum) forage or on a high-concentrate diet

Fall-born Angus-cross steers (n=30) from 1 of 2 sires, were randomly assigned to either an 85% corn, 7.5% cotton-seed hulls, and 7.5% vitamin/mineral/urea supplement diet (GRAIN), 100% ryegrass grazing (RG), or ryegrass grazing then the GRAIN diet for 94d (RG/GRAIN). USDA Yield Grade of steers finished on either the GRAIN or RG/GRAIN regimens were higher (P<0.02) compared to those finished on RG. Marbling score and USDA Quality Grade did not differ (P=0.21 and 0.12, respectively) among the three finishing regimens. Yellowness (b(∗)) values of the subcutaneous fat from both strip loins (SL) and ribeye (RE) rolls was lowest (P<0.05) in cuts taken from steers finished on GRAIN. Subcutaneous fat of both SL and RE had lower L(∗) and hue angle values, and higher a(∗) and b(∗) values before trimming than after the fat was trimmed to 0.3cm. Initial and sustained tenderness scores of SL from steers finished on GRAIN were higher when compared to RG/GRAIN or RG regimens (P<0.05). Flavor intensity and beef flavor scores were higher (P<0.05) for SL from GRAIN- or RG/GRAIN-finished steers compared to RG-finished steers. GRAIN SL had lower (P<0.05) WBSF values than RG, but similar (P>0.05) to RG/GRAIN. Trained sensory tenderness and flavor scores and WBSF values for RE were not affected by finishing regimen (P>0.05). GRAIN steaks had a higher consumer overall acceptability score, average price/kg, and rank (P<0.05). While carcass, fat, and sensory disadvantages were present in RG cattle, the overall magnitude of the differences compared to GRAIN cattle was fairly small.

Influence of genetic type and level of concentrate in the finishing diet on carcass and meat quality traits in beef heifers

Carcass and meat quality traits of thirty-six feedlot beef heifers from different genetic groups (GG) fed at two concentrate levels (CL) were evaluated using 12 - Nellore (NE), 12 - ½Angus x ½Nellore (AN) and 12 - ½Simmental x ½Nellore (SN) animals. Six heifers of each GG were randomly assigned into one of two treatments: concentrate at 0.8% or 1.2% of body weight (BW). Heifers fed concentrate at 0.8% of BW had greater (P<0.05) dressing percentage. None of the proximate analysis components of the beef were affected (P>0.05) by either CL or GG. Heifers from the AN group had higher (P<0.05) carcass weights, 12th rib fat thickness and lower dressing percentage (P<0.05) compared to the other groups. NE heifers had greater WBSF values (P<0.05) than the other genetic groups. Data suggest that the concentrate level can be reduced without compromising meat quality traits.

Influence of dental carcass maturity on carcass traits and meat quality of Nellore bulls.

Carcasses of sixty-three Nellore bulls slaughtered at a commercial beef plant were randomly selected by dental classification (2, 4, 6 or 8 permanent incisors) in order to evaluate the influence of dental maturity on carcass traits and meat quality. Carcasses with 8 permanent incisors (p.i.) had greatest values (P<0.05) of carcass weight and longissimus area. Carcasses with 4 and 6 p.i. presented similar values of rib fat thickness being greater (P<0.05) than the other groups. Carcasses with 6 and 8 p.i. presented greater (P<0.05) values of shear force than the other groups. Conversely, carcasses with 2 and 4 p.i. displayed greater (P<0.05) myofibrillar fragmentation index and collagen solubility. Greatest values of thawing loss were observed in carcasses with 2 p.i. (P<0.05) while carcasses with 8 p.i. presented greatest values (P<0.05) of drip loss. Regarding longissimus color, carcasses with 8 p.i presented greatest value (P<0.05) of b*. Data suggests that dental maturity influences carcass traits and meat quality of Nellore bulls.

Effects of Oregano Oil Brine Enhancement on Quality Attributes of Beef Longissimus dorsi and Semimembranosus Muscles from Various Age Animals

UNLABELLED The study reports whether or not oregano oil can reduce lipid oxidation and evaluate palatability variations in beef longissimus dorsi and semimembranosus muscles from various age animals (approximately 18 mo; 18 M, 30 to 60 mo; 30 M, and >60 mo; 60 M). Six muscles of each age group were halved and enhanced with a control brine containing no antioxidants (CN) or a brine containing oregano oil (OR), cut into steaks, and stored in modified atmosphere packaging for 0, 4, 7, and 11 d. Each sampling day, surface color (Minolta L, a, b), lipid oxidation (TBARS), cook yield, sensory analysis, and Warner-Bratzler shear force (WBSF) were measured. OR enhancement decreased TBARS values and slowed the rate of decline in a values (P < 0.05), but had no effect on WBSF, or sensory tenderness and juiciness scores (P > 0.05) compared to CN steaks. OR steaks had less rancidity detection, more off-flavor, lower overall acceptability in sensory analysis (P < 0.05). This indicated oregano oil can effectively reduce lipid oxidation and extend shelf-life of meat products, but further investigation would be needed to avoid off-flavor and acceptability of product quality. PRACTICAL APPLICATION Decreases in meat consumption have led the meat industry to become more innovative in product development. Reducing lipid oxidation is a viable method to reduce rancidity, and improving product acceptability. Our research indicated that although oregano oil did reduce lipid oxidation, the adverse effects of flavor were too great, and thus would not be tolerable in fresh meat products at this concentration. However, there is potential to use oregano oil at lower concentrations and in a variety of processed products which could be beneficial to further the use of natural antioxidants.

Evaluation of trace mineral source and preharvest deletion of trace minerals from finishing diets for pigs on growth performance, carcass characteristics, and pork quality

Weanling crossbred pigs (Sus scrofa; 72 barrows and 72 gilts; BW = 7.4 ± 1.1 kg) were used to evaluate dietary supplemental trace mineral (Cu, Fe, Mn, and Zn) source (inorganic vs. organic) and deletion (0, 2, 4, and 6 wk preharvest) on growth performance, carcass characteristics, and pork quality. Pigs were blocked by BW, ancestry, and sex, and randomly allotted to 24 pens, and fed a diet containing either inorganic or organic trace minerals supplemented at the 1998 NRC requirement estimates for each of 5 BW phases from 7 to 120 kg (equivalent to 14, 14, 42, 28, and 42-d periods, respectively). Two pigs were removed from each pen at the end of Phase IV (BW = 82.6 ± 6.0 kg), and 2 other pigs were removed at the end of Phase V (BW = 128.0 ± 8.3 kg) for collection of various tissues and for determination of carcass characteristics and pork quality. On d 1, 15, and 29 of Phase V, 3 pens within each source of minerals were switched to a common diet without supplemental trace minerals, whereas the remaining 3 pens within each source of minerals were fed diets containing trace minerals throughout the Phase V period. This resulted in 4 groups within each mineral treatment, in which trace mineral supplementation was deleted for 6, 4, 2, or 0 wk of Phase V. Trace mineral source (inorganic vs. organic) did not affect ADG, ADFI, and G:F (773 vs. 778 g/d, 1,680 vs. 1,708 g/d, and 461 vs. 456 g/kg, respectively) during the first 4 phases. During the mineral deletion period, ADG and G:F were not affected by the duration of trace mineral deletion, but ADFI increased when trace minerals were removed from the diet for 6 wk (6 vs. 0 wk, 3,393 vs. 3,163 g/d; P = 0.05). Hot carcass weight, cold carcass weight, carcass shrink, dressing percentage, LM area, 10th rib and midline average backfat, and carcass fat-free lean weight and percentage were not affected (P > 0.10) by the source of mineral or length of mineral deletion, but carcass length tended to decrease (P = 0.09) when time of trace mineral deletion increased. Increasing mineral deletion from 0 to 6 wk tended to reduce linearly (P = 0.08) Hunter a* scores on the day of carcass processing (24 h after slaughter), as well as 2 d after processing, and Hunter b* scores on d 2 and d 6 after processing. Results of this experiment indicate that use of organic trace minerals, rather than inorganic trace minerals, did not influence pig growth performance or carcass characteristics and quality; however, deletion of minerals during the last 6 wk before harvest increased ADFI and affected drip loss, some color scores of the LM, and carcass length.

Effects of abrupt introduction and removal of high and low digestibility corn distillers dried grains with solubles from the diet on growth performance and carcass characteristics of growing-finishing pigs

Two experiments were conducted to evaluate the effects of feeding continuously a diet containing 40% dried distillers grains with solubles (DDGS) or intermittently diets containing 20 or 40% DDGS on growth performance and carcass quality of pigs. Responses of the pigs to abrupt introduction and removal of dietary DDGS with differing concentrations of standardized ileal digestible (SID) AA were also evaluated. In Exp. 1, crossbred pigs (n=216; initial BW=51.3±3.1 kg) were assigned randomly to 1 of 4 treatments, which included a corn-soybean meal control (CON), a 20% DDGS diet (D20), a switch between D20 and CON (D20-CON), and a switch between a 40% DDGS diet and CON (D40-CON) with 6 pens per treatment. Pigs abruptly introduced and removed from a 20% DDGS diet (D20-CON) exhibited no differences in growth performance or carcass quality compared with CON pigs. However, intermittently feeding a 40% DDGS diet (D40-CON) resulted in lighter HCW (P<0.05) compared with all other treatments. In Exp. 2, crossbred pigs (n=324; initial BW=33.2±3.0 kg) were assigned randomly to 1 of 6 treatments, including a corn-soybean meal control (CON), a 40% low SID AA DDGS diet (LD), a 40% high SID AA DDGS diet (HD), LD and CON diets alternated (LD-CON), HD and CON diets alternated (HD-CON), or HD and LD diets alternated (HD-LD) with 6 pens per treatment. Final BW and ADG were less (P<0.05) for LD and HD-LD pigs compared with CON pigs, but HD pigs tended to have reduced (P<0.10) final BW and ADG. Loin muscle area was smaller for LD and HD-LD pigs compared with CON pigs (P<0.05). Percentage carcass lean was not affected by dietary treatment. Backfat of DDGS-fed pigs was more unsaturated than CON pigs, but AA digestibility of DDGS did not affect this response. Digestibility of AA in DDGS can influence pig performance and carcass quality when fed at high concentrations (40% or more). The use of a high SID AA DDGS source may diminish some of the negative responses observed for growth performance and carcass characteristics when feeding high concentrations of DDGS if accurate values of SID AA are used in diet formulation. Periodic inclusion and removal of 40% DDGS from diets did not adversely affect growth performance or carcass quality regardless of the SID AA digestibility of the DDGS used. These results indicate that it is possible to abruptly incorporate and remove DDGS from grower-finisher swine diets without meaningful detrimental effects on growth performance or carcass quality.

Effect of temperature on the survival of porcine circovirus type 2b in fresh pork.

Porcine circovirus type 2b (PCV2b) causes PCV-associated disease in pigs. This study was conducted to investigate the effect of temperature on the survival of PCV2b in fresh pork. Several pieces of longissimus dorsi muscle were injected with 100 μL of a suspension containing 10(5.2) TCID50 (50% tissue culture infective doses) of the virus. Virus-inoculated pieces of pork were stored at 25 °C, 4 °C and -20 °C and tested for the presence of infectious virus after different times of storage. PCV2b was found to survive in fresh pork for up to 2 days post inoculation (dpi) at room temperature, for 6 dpi at 4 °C and for up to 30 dpi at -20 °C indicating that the survival of PCV2b in fresh pork depends on temperature of storage.

Effect of time interval between the second Improvest® dose and slaughter and corn dried distillers grains with solubles feeding strategies on carcass composition, primal cutout, and pork quality of immunologically castrated pigs.

Effects of dried distillers grains with solubles (DDGS) feeding strategies on carcass composition, primal cutout, and lean quality of immunologically castrated (IC; n=863) pigs were evaluated, and consisted of: 1) corn-soybean meal (CS) diet (PCon); 2) CS+40% DDGS (NCon); 3) CS+40, 30, 20, or 10% DDGS fed in phases 1 to 4, respectively (SD); or 4) CS+40% DDGS fed in phase 1 to 3 and CS in phase 4 (WD). All pigs received the first dose of Improvest® at 11weeks. of age, and the second dose was administered at either 9, 7, or 5weeks. before slaughter at 24weeks. of age. The SD and WD improved carcass dressing percentage and resulted in intermediate primal cut yields and pork loin quality compared with pigs fed PCon and NCon. Increasing the time interval between second dose of Improvest® and slaughter increased adipose tissue accretion but did not affect lean quality of pork.

Effects of adding minimally refined cottonseed oil or crude glycerol to diets containing 40% corn distiller’s dried grains with solubles on growth performance, carcass characteristics, and pork fat firmness of growing–finishing pigs

Diets containing more than 20% distillers dried grains with solubles (DDGS) reduce fat firmness in pork, but supplementation of cottonseed oil or crude glycerol may improve fat firmness. The objective of this study was to assess the effect of feeding minimally refined cottonseed oil or crude glycerol on growth performance, carcass composition, and fat quality of growing-finishing pigs. Mixed sex pigs ( = 216; 24 ± 4 kg initial BW) were blocked by BW and allotted to 1 of 3 dietary treatments: 1) a basal corn-soybean meal diet with 40% DDGS (CON), 2) CON diet plus 5% minimally refined cottonseed oil added throughout the experiment (COT), or 3) CON fed during the first 8 wk and CON + 8% crude glycerol fed during the last 6 wk of the experiment (GLY). Although diets were not isocaloric, total AA-to-ME ratios were calculated to be equal among diets. Carcass composition was estimated using real-time ultrasound 2 d before harvest. Gilts (16/treatment) closest to the mean BW of each pen were harvested (115 ± 8 kg BW), and bellies were retrieved for in-depth analysis of fat quality. Belly fat was sampled and analyzed for fatty acid composition. Overall, ADFI of pigs fed COT (2.30 kg/d) was less ( < 0.01) than that of pigs fed CON or GLY (2.47 and 2.49 kg/d, respectively). Pigs fed COT (0.93 kg/d) had greater ( < 0.01) ADG compared with pigs fed CON or GLY (0.88 and 0.87 kg/d, respectively). Greater ( < 0.01) G:F was observed for pigs fed COT (0.41) than for pigs fed CON or GLY diets (0.36 and 0.35, respectively). Final BW of pigs fed COT (124.3 kg) was greater ( < 0.01) than that of pigs fed CON or GLY (118.9 and 118.6 kg, respectively). Pigs fed COT had greater ( < 0.01) HCW (94.9 kg) compared with pigs fed CON or GLY (89.9 and 89.2 kg, respectively). No differences were observed for dressing percentage (75.7, 76.3, and 75.3%), fat-free carcass lean percentage (50.5, 49.7, and 50.0%), and belly flop angle (6.21, 8.57, and 6.06°) for CON, COT, and GLY, respectively. Pigs assigned to COT had higher ( < 0.01) melting point of belly fat compared with pigs assigned to CON or GLY (30.4 vs. 26.3 and 25.3°C, respectively). Pigs fed COT had increased ( < 0.05) SFA, PUFA, and iodine value (IV) compared with CON-fed pigs. Glycerol supplementation had no influence on SFA, MUFA, and PUFA concentrations or IV of belly, jowl, and back fat compared with CON. In conclusion, COT diets improved growth performance due to greater energy density, but carcass composition was not affected by treatments. In this experiment, feeding neither COT nor GLY improved fat firmness of pigs fed diets containing 40% DDGS.

Application of plant extracts to improve the shelf-life, nutritional and health-related properties of ready-to-eat meat products

Plant extracts are increasingly becoming important additives in food industry due to their antimicrobial and antioxidant abilities that delay the development of off-flavors and improve the color stability in ready-to-eat (RTE) meat products. Due to their natural origin, they are excellent candidates to replace synthetic molecules, which are generally considered to have toxicological and carcinogenic effects. The efficient extraction of these antioxidant molecules from their natural sources, along with the determination of their activity in the commercialized products, have been a great challenge for researchers and food chain contributors. The objective of this review is to highlight the application of plant extracts to improve the shelf-life, nutritional and health-related properties of RTE meat products. The sensory effects of these extracts on RTE meat products as well as the possible synergistic effects of a combination of extracts are discussed.