B. R. Wiegand

Impact of dietary energy level and ractopamine on growth performance, carcass characteristics, and meat quality of finishing pigs

A total of 54 finishing barrows (initial BW = 99.8 ± 5.1 kg; PIC C22 × 337) reared in individual pens were allotted to 1 of 6 dietary treatments in a 2 × 3 factorial arrangement of treatments with 2 levels of ractopamine (0 and 7.4 mg/kg) and 3 levels of dietary energy (high, 3,537; medium, 3,369; and low, 3,317 kcal of ME/kg) to determine the effects of dietary ractopamine and various energy levels on growth performance, carcass characteristics, and meat quality of finishing pigs. High-energy diets were corn-soybean-meal-based with 4% added fat; medium-energy diets were corn-soybean meal based with 0.5% added fat; and low-energy diets were corn-soybean meal based with 0.5% added fat and 15% wheat middlings. Diets within each ractopamine level were formulated to contain the same standardized ileal digestible Lys:ME (0 mg/kg, 1.82; and 7.4 mg/kg, 2.65 g/Mcal of ME). Individual pig BW and feed disappearance were recorded at the beginning and conclusion (d 21) of the study. On d 21, pigs were slaughtered for determination of carcass characteristics and meat quality. No ractopamine × energy level interactions (P > 0.10) were observed for any response criteria. Final BW (125.2 vs. 121.1 kg), ADG (1.2 vs. 1.0 kg/d), and G:F (0.31 vs. 0.40) were improved (P < 0.001) with feeding of ractopamine diets. Feeding of the low-energy diet reduced (P = 0.001) final BW and ADG compared with the high- and medium-energy diets. Gain:feed was reduced (P = 0.005) when the medium-energy diets were fed compared with the high-energy diets. Additionally, G:F was reduced (P = 0.002) when the low-energy diets were compared with the high- and medium-energy diets. Feeding ractopamine diets increased (P < 0.05) HCW (93.6 vs. 89.9 kg) and LM area (51.2 vs. 44.2 cm(2)). The LM pH decline was reduced (P ≤ 0.05) by feeding ractopamine diets. The feeding of low-energy diets reduced (P = 0.001) HCW when compared with the high- and medium-energy diets and reduced (P = 0.024) 10th-rib backfat when compared with the high- and medium-energy diet. These data indicate that feeding ractopamine diets improved growth performance and carcass characteristics, while having little or no detrimental effect on meat quality. Reductions in energy content of the diet by adding 15% wheat middlings resulted in impaired ADG, G:F, and 10th-rib backfat. There were no ractopamine × energy level interactions in this trial, which indicates that the improvements resulting from feeding ractopamine were present regardless of the dietary energy levels.

Dietary conjugated linoleic acid changes belly and bacon quality from pigs fed varied lipid sources

The objective of this experiment was to determine the effects of dietary lipid source with or without the addition of CLA on bacon composition and quality. Forty-eight barrows at a beginning BW of 55 kg +/- 2.2 were fed 1 of 6 diets for 56 d. These diets consisted of: 1) normal corn (NC), 2) NC + 1.25% CLA-60 oil (NC + CLA), 3) high-oil corn (HOC), 4) HOC + 1.25% CLA-60 oil (HOC-CLA), 5) NC + choice white grease (CWG; NC + CWG), and 6) NC + CWG + 1.25% CLA-60 oil (NC + CWG + CLA). The CLA-60 contains 60% CLA isomers in the oil, and therefore, 1.25% oil was needed to achieve 0.75% CLA in the diet. Soy oil replaced CLA in control diets. Choice white grease and high-oil corn were selected as fat sources for this study because of their utility in energy density for growing-finishing pigs, especially in hot weather. Pigs were slaughtered at an average BW of 113 kg +/- 4.1, and carcasses were fabricated at 24 h postmortem. Statistical analysis was performed using the mixed model procedure of SAS, and the main effects tested were dietary lipid source, CLA, and 2-way interaction. The addition of CLA to each basal diet improved (P < 0.05) belly firmness measured either lean side down or fat side down from the belly bar firmness test [4.39 cm vs. 7.01 cm (lean down) and 5.75 cm vs. 10.54 cm (fat down)] for 0 and 0.75% dietary CLA, respectively. The compression test used on bacon slabs showed that bacon from CLA-supplemented pigs was approximately 20% firmer than that from controls. Pigs fed the HOC diets had softer bellies compared (P < 0.05) with pigs fed the NC diet as measured by the belly bar test [6.94 cm vs. 9.26 cm (fat down)], respectively. Conjugated linoleic acid did not, however, improve bacon sliceability. No differences were observed for moisture, protein, or lipid percentages between any treatments. Overall, there was a CLA effect (P < 0.04) for lipid oxidation, in which the addition of CLA decreased bacon oxidation (0.1498 CLA vs. 0.1638 no CLA). Dietary CLA increased the percentage of SFA in tissues from pigs supplemented with CLA. Dietary inclusion of CLA increased the concentration of all measured isomers of CLA in bacon. Sensory scores of bacon showed no differences for any of the sensory attributes measured between any of the treatments. Our results indicate that inclusion of dietary CLA will improve belly firmness, extend the shelf life stability of bacon, and increase the degree of fat saturation.

Prediction of fat percentage within marbling score on beef longissimus muscle using 3 different fat determination methods.

Consumers are concerned with fat consumption from meat products, and the ability to determine fat has changed with recent technological advances. The objective of this study was to predict fat percentage within marbling scores and compare 3 fat analysis procedures. Steaks (n = 119) were selected by USDA grading system using an E + V Vision Grading camera at a commercial beef plant during 1 d. Two samples per carcass were cut from the 13th rib, both sides, and transported to the University of Missouri meat laboratory. The sample from the right side of the carcass was allotted to Warner-Bratzler shear force, and the sample from the left side, which was graded by the camera, was allotted to fat extraction. Warner-Bratzler shear force samples were cut into 2.54-cm steaks and aged for 14 d. Steaks allotted to fat extraction were trimmed of all external fat and twice ground using 8- and 4-mm grinding plates. The finely ground beef was then split into its allotted fat-extraction methods. The 3 methods used in fat extraction were 2:1 chloroform/methanol (Folch), ether-extractable fat (ether), and microwave drying and nuclear magnetic resonance (CEM). Warner-Bratzler shear force values were not different between marbling scores (P > 0.05). Regardless of fat extraction method, fat percentage increased as marbling score increased (P < 0.05). All regression equations for fat percentage, regardless of extraction method, were linear. Prediction equation for fat percentage using CEM was -3.46 + 0.016 (marbling score), R(2) of 0.824 (P < 0.0001). Prediction equation for fat percentage using ether was -3.08 + 0.017 (marbling score), R(2) of 0.859 (P < 0.0001). Prediction equation for fat percentage using Folch was -3.42 + 0.019 (marbling score), R(2) of 0.816 (P < 0.0001). When the CEM, Folch, and ether methods were compared, CEM and Folch regression lines had different slopes (P < 0.05). The slope of the regression line for ether was not different (P > 0.05) from CEM or Folch. Overall, ether is the most accurate method based on the R(2) value, but CEM is environmentally safe and the fastest method for determining total crude fat percentage.

Short-term feeding of vitamin D3 improves color but does not change tenderness of pork-loin chops.

The objective of this study was to determine the effect of short-term feeding of vitamin D3 (D3) on blood plasma calcium concentrations and meat quality of pork-loin chops. Three experiments were carried out to meet this objective. Experiment 1 used 250,000 IU and 500,000 IU/d to determine the effective dose of dietary D3 to raise blood plasma calcium concentration. Experiment 2 used 500,000 IU D3/d to determine the appropriate length of feeding time to elevate blood plasma calcium prior to harvest. Experiment 3 used 500,000 IU D3/d to determine the effectiveness of increased blood plasma calcium in improving postmortem quality and tenderness of pork-loin chops. Pigs fed 500,000 IU D3/d in Exp. 1 exhibited higher (P < 0.05) and more stable plasma calcium concentration over a 14-d feeding trial compared with pigs fed 250,000 IU D3/d and control pigs. Therefore, 500,000 IU D3/d was the dose chosen for Exp. 2, in which pigs fed 500,000 IU D3/d for 3 d prior to harvest exhibited elevated and stable plasma calcium concentrations; this length of time was deemed sufficient in which to observe differences in postmortem meat tenderness in Exp. 3. Vitamin D3 supplementation resulted in lower (P < 0.02) L* values and higher (P < 0.03) a* values of loin chops at 7 and 14 d of shelf storage. Vitamin D3 supplementation did not affect quality characteristics (measured by use of subjective scores) or tenderness (quantified via Warner-Bratzler shear force or Star probe values). On the basis of these findings, feeding 500,000 IU D3/d to finishing pigs improved most Hunter color values at 14 d of storage but did not improve pork-loin chop tenderness at 1 to 21 d of retail shelf storage.

The effect of corn distiller's dried grains with solubles, ractopamine, and conjugated linoleic acid on the carcass performance, meat quality, and shelf-life characteristics of fresh pork following three different storage methods.

The objective of this study was to evaluate dietary corn distillers dried grains with solubles (DDGS), ractopamine hydrochloride (RAC), and conjugated linoleic acid (CLA) on growth performance, carcass and fat quality, and shelf-life of fresh pork from finishing pigs. Barrows (n=72) were fed one of eight treatments consisting of two diet sources (corn-soy and corn-soy+20% DDGS), two levels of RAC (0 and 7.4ppm), and two levels of CLA (0 and 0.6%) for 28days. Loins were portioned (n=3) into one of three storage conditions (fresh, cold, frozen); each followed with seven days of retail display. Feeding RAC improved ADG and G:F (P<0.05), whereas DDGS decreased belly fat firmness (P<0.05). Dietary DDGS increased total polyunsaturated fatty acids in jowl and belly samples and increased Iodine Value (IV) (P<0.05), but addition of CLA decreased IV. Dietary DDGS, RAC, or CLA had minimal impact on pork quality following varied storage methods.

Fatty acid profiles and iodine value correlations between 4 carcass fat depots from pigs fed varied combinations of ractopamine and energy.

A total of 54 finishing barrows (initial BW = 99.8 ± 5.1 kg; PIC C22 × 337) reared in individual pens were allotted to 1 of 6 dietary treatments in a 2 × 3 factorial arrangement of treatments with 2 levels of ractopamine (0 and 7.4 mg/kg) and 3 levels of dietary energy (high: 3,537, medium: 3,369, and low: 3,317 kcal/kg of ME) to determine the effects of feeding ractopamine and various dietary energy levels on the fatty acid profile of 4 carcass fat depots (jowl, belly, subcutaneous loin, and intramuscular) and the predictive relationships of calculated iodine value (IV) between these 4 fat depots. Carcasses were sampled for fat tissues at the anterior tip of the jowl, posterior to the sternum on the belly edge, three-quarters the distance around the LM (subcutaneous fat; SC), and within the LM (intramuscular fat; IMF). Feeding ractopamine diets reduced (P < 0.05) total SFA in SC and IMF and increased (P = 0.04) total MUFA in SC. Also, feeding ractopamine diets increased (P < 0.01) the IV of IMF. Total MUFA of belly fat was reduced (P < 0.05) when the low-energy diet was fed compared with the high-energy diet. Jowl fat total MUFA was reduced (P < 0.05) and total PUFA was increased (P < 0.05) when the medium-energy diet was fed compared with the high- and low-energy diets. Iodine values, independent of treatment, were 60.97, 64.51, 55.59, and 58.26 for belly, jowl, IMF, and SC fat depots, respectively. The IV correlations within fat depots were not consistent across dietary treatments because of the effect of treatments on carcass fatty acid characteristics. Feeding ractopamine diets shifted the fatty acid profile from SFA to MUFA in the SC depot. Feeding ractopamine diets did not change belly fat profiles, thus avoiding the potential negative effect of softening belly fat, which is detrimental to processing value. The IV of one fat depot may not be a good indication of IV of other fat depots because of weak correlation coefficients and the apparent influence of dietary treatment.

The influence of creatine and a high glycemic carbohydrate on the growth performance and meat quality of market hogs fed ractopamine hydrochloride

Crossbred barrows (n=128; 85±0.91kg) were randomly allotted to one of four dietary treatments. A pelleted corn-soybean diet containing 5ppm Paylean(®) (PAY) was tested against a negative control (NCON) diet formulated to meet or exceed the National Research Councils requirements for the growing pig, a pelleted corn-soybean diet containing 0.92% creatine and 2.75% dextrose (COMBO), and a pelleted corn-soybean diet containing a combination of 5ppm Paylean(®), 0.92% creatine, and 2.75% dextrose (PAYPLUS). No treatment differences were noted when comparing ADG (P=0.66) and hot carcass weight (P=0.75). Over the 27d test, barrows fed PAY and PAYPLUS produced loins with a larger (P<0.01) loin muscle area (LMA) than those fed NCON or COMBO diets. Barrows fed the NCON diet were fatter at the 10th-rib (P<0.01) than those animals fed the remaining dietary treatments. Dietary treatment did not affect the ultimate pH (P=0.87), Japanese color score (P=0.25) or Minolta L(∗) (P=0.61) and b(∗) (P=0.56) values of the loin. Loin chops from NCON, COMBO and PAYPLUS tended (P=0.07) to contain a higher intramuscular fat content than those from barrows fed PAY. Additionally, loin chops from the NCON and COMBO fed animals were more red (higher a(∗)-value) than those chops coming from animals fed the PAY diet (P<0.01).

Effect of corn dried distillers grains with solubles, conjugated linoleic acid, and ractopamine (paylean) on growth performance and fat characteristics of late finishing pigs.

An experiment was performed to evaluate effects of dietary ractopamine, CLA, and corn distillers dried grains with solubles (DDGS) on growth and carcass and fat quality of finishing pigs. This study was conducted as a split-split plot arrangement in a generalized randomized block design. In total 1,102 crossbred barrows and gilts (initial BW = 100.4 kg, SD = 3.7 kg; pic 337 × c22) were randomly assigned to 1 of 8 dietary treatments that consisted of 2 diet sources [corn-soybean meal (corn-soy) and corn-soy + 20% DDGS], 2 levels of ractopamine (0 and 7.4 mg/kg), and 2 levels of CLA (0% and 0.6%). The pen was the experimental unit, with 6 replications per treatment for a total of 48 pens with 23 pigs per pen. Pigs had ad libitum access to water and feed during the 27-d experimental period. Ractopamine addition improved (p < 0.05) ADG and G:F over the control group. Furthermore, carcass weight, carcass yield, loin depth, and lean percentage were increased and back fat depth was decreased (p < 0.05) by feeding ractopamine. Feeding CLA resulted in improved (p < 0.05) ADG and G:F and increased lean percentage but reduced carcass yield (p < 0.05). The inclusion of DDGS did not affect ADG, adfi, or g:f but reduced (p < 0.05) carcass dressing percent. An increase (p < 0.05) in the concentration of pufa was observed with inclusion of DDGS, ractopamine, and CLA. Iodine value (iv) increased (p < 0.001) in both belly and jowl samples by feeding DDGS and ractopamine, whereas a decrease (p < 0.01) was observed when CLA was included in the diets. The fatty acid profiles of belly and jowl fat samples were affected (p < 0.05) by diet source × ractopamine, indicating that effects of dietary ractopamine depend on the fatty acid profile of the diet. These results indicate that feeding ractopamine and CLA could improve growth and carcass measures and that CLA was effective in diminishing some of the negative effects, especially on IV, caused by DDGS.

Effects of reduced-fat modified wet distillers grains with solubles on beef steer performance and carcass composition

Two experiments were conducted to examine feedlot performance and carcass characteristics of beef steers fed reduced-fat, modified wet distillers grains with solubles (RMDGS). Angus cross steers were stratified by BW in each experiment and assigned to 20 pens containing either 6 or 7 steers per pen. In Exp. 1, pens were randomly assigned to 1 of 4 diets containing 15% corn silage and 1) 25.0% RMDGS and 57.04% whole shelled corn (25 RMDGS); 2) 40.0% RMDGS and 42.69% whole shelled corn (40 RMDGS); 3) 70.0% RMDGS and 12.49% whole shelled corn, fed 84 d, then switched to 40 RMDGS (70/40 RMDGS); 4) 70.0% RMDGS and 12.49% whole shelled corn (70 RMDGS). In Exp. 2, the same diets were fed except 70/40 RMDGS was replaced with a diet containing 73.16% whole shelled corn and 9.60% soybean meal (0 RMDGS). In Exp. 1, no significant differences in DMI, ADG, G:F, or carcass characteristics were found. In Exp. 2, DMI increased (P = 0.003) with increasing RMDGS. In Exp. 2, LM samples from 2 steers in each pen at each slaughter date were analyzed. There were no differences (P > 0.05) in percentage of moisture, fat, or cooking loss in shear force of rib steaks among treatments. Steers fed the 70 RMDGS diet produced rib steaks with lower a* (P < 0.05) following 7 d of chilled storage. Fatty acid analysis showed an increase (P < 0.05) in SFA at the expense of MUFA because of RMDGS supplementation. Increases were observed in PUFA, PUFA/SFA, conjugated linoleic acid, and omega-6 fats, with increasing RMDGS. Steers fed 70 RMDGS had inconsistent feedlot performance with a trend for lighter HCW, lower QG, and reduced meat quality.

RAPID COMMUNICATION: Impact of contemporary light sources on oxidation of fresh ground beef

Meat color is considered one of the driving factors in consumer purchasing decisions. The objective of this study was to determine the impact of 2 different lighting sources on color and lipid oxidation of ground beef patties in a controlled environment. USDA Select top rounds ( = 20) were processed to produce ground beef at 2 different fat levels (5 and 25%) and made into patties (113.4 g). Patties were packaged with oxygen permeable polyvinyl chloride, assigned to one of three lighting treatments (low UV fluorescent [FLO], light emitting diode [LED], and no light [DRK, negative control]), and placed within deli cases at 5°C. Patty removal for evaluation occurred on retail display d 1, 3, 5, and 7. Objective color measurements were obtained using a HunterLab MiniScan 45/0 LAV. These values were utilized to determine myoglobin redox forms as a measure of myoglobin oxidation. Additionally, thiobarbituric acid reactive substances (TBARS) were measured to indicate lipid oxidation. Objective color measurement for a* (redness), decreased for all light treatments by retail display day ( < 0.0001). Oxymyoglobin values for all light treatments decreased daily but showed no differences between treatments until d 5 ( < 0.0001) where DRK > LED > FLO. Conversely, metmyoglobin values increased daily ( < 0.0001), but showed no differences between treatments until d 5 where FLO > LED > DRK. TBARS values increased by day for each fat percentage ( < 0.0001) with 5% fat patties having higher TBARS values indicating great oxidation occurring in the phospholipids than adipose tissues. Results indicate that light treatment affected discoloration and metmyoglobin formation in ground beef patties LED lighting may lead to increased meat quality shelf life in a retail setting.