Predicting aged pork quality using a portable Raman device.

The utility of Raman spectroscopic signatures of fresh pork loin (1 d & 15 d postmortem) in predicting fresh pork tenderness and slice shear force (SSF) was determined. Partial least square models showed that sensory tenderness and SSF are weakly correlated (R2 = 0.2). Raman spectral data were collected in 6 s using a portable Raman spectrometer (RS). A PLS regression model was developed to predict quantitatively the tenderness scores and SSF values from Raman spectral data, with very limited success. It was discovered that the prediction accuracies for day 15 post mortem samples are significantly greater than that for day 1 postmortem samples. Classification models were developed to predict tenderness at two ends of sensory quality as "poor" vs. "good". The accuracies of classification into different quality categories (1st to 4th percentile) are also greater for the day 15 postmortem samples for sensory tenderness (93.5% vs 76.3%) and SSF (92.8% vs 76.1%). RS has the potential to become a rapid on-line screening tool for the pork producers to quickly select meats with superior quality and/or cull poor quality to meet market demand/expectations.

Proteomic features linked to tenderness of aged pork loins.

There is considerable evidence that the protein component of fresh pork makes a major contribution to tenderness. In particular, the proteomic profile can be linked to postmortem events including pH decline, tissue oxidation, and protein degradation. The objectives for this study were to determine differences in sarcoplasmic proteomes that contribute to tenderness variation in aged pork longissimus dorsi muscles (LM). A defined set of pork loins selected to be similar in pH, color, and lipid yet different in tenderness were used. Pork loins were assigned to tenderness groups based on their star probe values; a high star probe group (HSP; n=12 mean star probe 7.75 kg) and low star probe group (LPS; n=12 star probe 4.95 kg) Samples were selected for proteomic experiments based on star probe values, and selected samples were within specified ranges for ultimate pH (5.54-5.86), marbling score (1.0-3.0), and percent total lipid (1.61-3.37%). Two-dimensional difference in gel electrophoresis (2D-DIGE) and mass spectrometry were used to examine sarcoplasmic protein abundance and potential modifications. Proteins spots that were significantly different across groups were selected for identification. Results from 2D-DIGE showed that HSP samples had significantly more abundant metabolic, stress response, and regulatory proteins in the sarcoplasmic fraction compared with LSP samples. The stress response protein peroxiredoxin-2 was more abundant in HSP samples as determined by 2D-DIGE ( ≤ 0.01; 2 spots) and western blot assay ( = 0.02). Low star probe samples showed significantly more degradation of the structural protein desmin in 2D-DIGE ( < 0.01) and western blot assay ( < 0.01). These results demonstrate that extreme proteolytic differences influenced measured tenderness of LSP and HSP samples and that soluble desmin and peroxiredoxin-2 may be used as biomarkers to differentiate between tough and tender aged pork products.

Postmortem protein degradation is a key contributor to fresh pork loin tenderness.

The objective of this study was to determine factors that influence tenderness independent of variation in pH, color, or marbling. To achieve the objective, 2 sample groups were chosen from a population of 159 pork loins aged 11 to 16 d. Predetermined ranges (ultimate pH, 5.54 to 5.86; marbling score, 1.0 to 3.0; percent total lipid, 1.61 to 3.37%) were defined for inclusion of individual loins in the study. The pork loins with the greatest ( = 12) and least ( = 12) Instron star probe values were assigned to 2 classification groups. The high star probe group had an average star probe that was 2.8 kg greater than the low star probe group (7.75 vs. 4.95 kg). Pork quality and sensory characteristics of pH, subjective and instrumental color values, cook loss, sensory tenderness, chewiness, juiciness, pork flavor, and off flavor were determined on fresh, never frozen pork chops. Lipid content, sarcomere length, myosin heavy-chain profile, and calpain autolysis were determined. Degradation of troponin-T, desmin, filamin, and titin were evaluated on the protein extracts from each sample. Pork loin pH, subjective color scores, Minolta L values, sarcomere length, and myosin heavy-chain composition were not different across groups. Chops from the low star probe group had a significantly greater marbling score (2.3 vs. 1.9) and lipid content (2.61 vs. 2.23%). Calpain-1 was completely autolyzed in both high and low star probe samples, demonstrating that calpain-1 potentially had been active in all samples. Low star probe whole-muscle protein extracts had more troponin-T ( < 0.01), desmin ( < 0.01), and filamin degradation ( < 0.01) than high star probe samples. Both classification groups showed degradation of titin. Remarkably, some high star probe samples still had observable intact bands of titin on SDS-PAGE gels. These results demonstrate that significant variation in instrumental tenderness is observed within a moderate pH range. Lipid content and proteolysis both appear to contribute to this variation.

Immunological castration temporarily reduces testis size and function without long-term effects on libido and sperm quality in boars.

The objective was to determine the effects of immunization against gonadotropin-releasing hormone on reproductive characteristics in boars. A total of 72 boars were used in a randomized design with three treatments: single immunization (SI) (10 weeks of age) or double immunization (DI) (10 and 15 weeks of age) with Improvest® and intact controls (no Improvest®; CNT) (n=24/group). At 10, 15, 20, 25 and 40 weeks of age, blood was collected and serum harvested to evaluate testosterone concentrations. Testosterone concentrations were less for DI boars compared with CNT boars and SI boars at 20 and 25 weeks (P<0.001), but not at 40 weeks of age. At week 25, 18 pigs (n=6/group) were sacrificed and testes were removed, weighed and measured, and seminiferous tubules were examined and scored using histological slides of testes parenchyma. A sample of neck fat was assessed for boar taint aroma. All testicular measurements and weights and seminiferous tubule scores were less for DI boars compared with SI and CNT boars (P<0.001). More (P<0.05) SI and CNT boars had detectable boar taint aroma than DI boars. Libido was assessed at 32, 36, 47, 60 and 63 weeks of age and semen collected at 60 weeks of age was analyzed for indicators of quality. There were no effects of treatment (P=0.41) or treatment by week (P=0.71) on libido. Semen volume, gel weight and total number of sperm cells, determined in a subset of boars (n=3/treatment), were not different among treatments. Sperm concentration was greater for DI than SI (P=0.01), and tended to be greater for DI compared with CNT (P=0.10). Sperm motility tended to be greater for DI boars compared with CNT boars (P=0.066). In conclusion, our results show that there are no long-term effects of immunocastration on reproductive characteristics in boars.

Does heat stress alter the pig's response to dietary fat?

Heat stress (HS) results in major losses to the pork industry via reduced growth performance and, possibly, carcass fat quality. The experimental objective was to measure the effects of HS on the pig's response to dietary fat in terms of lipid digestion, metabolism, and deposition over a 35-d finishing period. A total of 96 PIC 337 × C22/C29 (PIC, Inc., Hendersonville, TN) barrows (initial BW of 100.4 ± 1.2 kg) were randomly allotted to 1 of 9 treatments arranged as a 3 × 3 factorial: thermoneutral (TN; constant 24°C; ad libitum access to feed), pair-fed thermoneutral (PFTN; constant 24°C; limit fed based on previous HS daily feed intake), or HS (cyclical 28°C nighttime, 33°C from d 0 to 7, 33.5°C from d 7 to 14, 34°C from d 14 to 21, 34.5°C from d 21 to 28, and 35°C from d 28 to 35 daytime; ab libitum access to feed) and diet (a corn-soybean meal-based diet with 0% added fat [CNTR], CNTR with 3% added tallow [TAL; iodine value {IV} = 41.8], or CNTR with 3% added corn oil [CO; IV = 123.0]). No interactions between environment and diet were evident for any major response criteria ( ≥ 0.063). Rectal temperature increased due to HS (39.0°C for HS, 38.1°C for TN, and 38.2°C for PFTN; < 0.001). Heat stress decreased ADFI (27.8%; < 0.001), ADG (0.72 kg/d for HS, 1.03 kg/d for TN, and 0.78 kg/d for PFTN; < 0.001), and G:F (0.290 for HS, 0.301 for TN, and 0.319 for PFTN; = 0.006). Heat stress barrows required 1.2 Mcal of ME intake more per kilogram of BW gain than PFTN ( < 0.001). Heat stress tended to result in the lowest apparent total tract digestibility of acid hydrolyzed ether extract (AEE; 59.0% for HS, 60.2% for TN, and 61.4% for PFTN; = 0.055). True total tract digestibility (TTTD) of AEE of CO-based diets (99.3%) was greater than that of CNTR (97.3%) and TAL-based diets (96.3%; = 0.012). Environment had no impact on TTTD of AEE ( = 0.118). Environment had no impact on jowl IV at market (69.2 g/100 g for HS, 69.3 g/100 g for TN, and 69.8 g/100 g for PFTN; = 0.624). Jowl IV at market increased with increasing degree of unsaturation of the dietary fat (68.5 g/100 g for CNTR, 68.2 g/100 g for TAL, and 71.5 g/100 g for CO; < 0.001). Heat stress decreased mRNA abundance of and ( ≤ 0.041). Heat stress and CO increased mRNA abundance of ( ≤ 0.047), and CO increased abundance of ( = 0.011). In conclusion, HS does not alter the pig's response to dietary fat. However, HS leads to reduced ADG, ADFI, G:F, and caloric efficiency and a suppression of mRNA abundance of genes involved in the lipolytic cascade, which resulted in a phenotype that was fatter than PFTN.

Color stability and sensory characteristics of fresh and enhanced pork loins from immunologically castrated barrows.

Our objective was to evaluate color changes during storage of fresh pork chops and enhanced and nonenhanced loin quality from anti-gonadotropin-releasing factor (Improvest) immunologically castrated (IC) barrows. In study 1, treatments evaluated were IC barrows, IC barrows fed ractopamine (IC+RAC), physically castrated (PC) barrows, intact males (IM), and gilts. Fresh loins were evaluated for sensory characteristics and instrumental tenderness including both Warner-Bratzler Shear force (WBSF) and star probe force. In study 2, treatments evaluated were IC barrows fed 0.55% and 0.65% standard ileal digestible (SID) lysine and PC barrows fed 0.55% SID lysine. Loin chops were displayed for 7 d, and color was evaluated. The remaining loin was halved, and one half was enhanced with a 3.5% salt and phosphate solution. Enhanced loins were evaluated for sensory characteristics and instrumental tenderness. In both studies, pen served as the experimental unit for all traits measured. Data from individual animals were averaged by pen and analyzed, per study, as a 1-way ANOVA using the MIXED procedure of SAS. In study 1, there were no differences ( 0.05) between treatments for juiciness, tenderness, chewiness, or off-flavor. Intact males had the most intense ( 0.05) boar aroma. Gilts had the most intense ( < 0.05) pork flavor, whereas IM had the least intense pork flavor; all other treatments were intermediate. Tenderness (WBSF) was similar between treatments at 1 d of aging; however, at 7, 14, and 21 d of aging, loins from IC barrows were more tender ( 0.05) than those from gilts, IM, and IC+RAC but were similar ( 0.05) to those from PC. In study 2, discoloration of fresh loin chops during storage was similar ( 0.42) between PC and IC barrows. Chops from enhanced loins were more tender and juicy but had more off-flavor than nonenhanced loins ( 0.01). Star probe and WBSF were also reduced ( 0.01) in enhanced loins compared with nonenhanced loins. Sensory characteristics and tenderness were not different between treatments of IC and PC barrows ( > 0.05), and there were no interactions of enhancement with castration treatments. These data suggest that immunological castration does not negatively impact the color stability, sensory characteristics, or tenderness of enhanced or nonenhanced pork loins.

The impact of dietary fat withdrawal on carcass iodine value, belly characteristics, and changes in body fat over time.

The inclusion of unsaturated fats in pig diets has raised issues related to pork carcass fat quality. The objective of this experiment was to understand how withdrawal from the diet of unsaturated dietary fat before slaughter impacts the composition of jowl fat during the growth cycle and at market. Fifty individually housed pigs (PIC 337 × C22/29; initial BW = 59.3 ± 0.55 kg) were allotted based on sex and initial BW to 10 treatments for an 82-d experiment as follows: 3 dietary fat withdrawal times before slaughter (21, 42, or 63 d) by 3 dietary fat unsaturation loads (DFUL), which includea high intake of unsaturated fatty acids supplied through an inclusion of 5% corn oil (HIGH), a high intake of a mixture of saturated and unsaturated fatty acids supplied through an inclusion of 5% animal-vegetable blend (MED), and a moderate intake of unsaturated fatty acids supplied through an inclusion of 2.5% corn oil (LOW). Pigs were weighed and jowl adipose samples were collected on d 0, 21, 42, and 63 and at harvest on d 82. Data were analyzed using PROC MIXED with treatment and sex as fixed effects. At market (d 82), increasing the withdrawal of dietary fat further away from market increased 18:1 (P = 0.045) and tended to increase 14:0 concentrations (P = 0.054). It also significantly decreased 18:2 (P < 0.001) and tended to decrease 18:3 concentrations (P = 0.081). A HIGH DFUL resulted in the greatest 18:2 concentrations in jowl fat followed by LOW; MED resulted in the lowest 18:2 levels (P < 0.001). Dietary fat withdrawal before market significantly reduced carcass iodine value (IV) measured at d 82 (P = 0.006). In conclusion, elevated 18:2 intake makes lowering carcass IV in the depot fat very difficult and may take as long as 61 d. The withdrawal of unsaturated dietary fat apparently altered the fat depot to be more reflective of fat synthesized de novo, resulting in a more saturated depot fat. Importantly, this alteration of deposited fat composition did not translate into improved belly firmness, depth, weight, or fat color.

Impact of dietary fat source and concentration and daily fatty acid intake on the composition of carcass fat and iodine value sampled in three regions of the pork carcass.

The increased inclusion of unsaturated fats in pig diets has raised issues related to pork carcass fat quality. The objective of this experiment was to more precisely measure how differing levels of daily fatty acid intake alters the fatty acid composition in 3 different fat depots. A total of 42 gilts and 21 barrows (PIC 337×C22/29) with an average initial weight of 77.80±0.38 kg were allotted randomly based on sex and BW to 7 treatments: 3 and 6% of each of tallow (TAL; iodine value [IV]=41.9), choice white grease (CWG; IV=66.5), or corn oil (CO; IV=123.1) and a control (CNTR) corn-soybean meal-based diet with no added fat. Pigs were individually housed to allow accurate measurement of individual feed intake, in particular, daily dietary fatty acid and energy intake. Fat samples were collected from the jowl, belly, and loin at slaughter. Diet and carcass fat samples were analyzed for IV. Belly weights were recorded at slaughter along with a subjective belly firmness score (1=firmest to 3=least firm). Carcass lipid IV was increased (P<0.001) by increasing the degree of unsaturation of the dietary fat source (66.8, 70.3, and 76.3 for TAL, CWG, and CO, respectively). Carcass lipid IV for TAL and CWG was not affected (P>0.05) by inclusion levels; however, carcass lipid IV was greater (P<0.001) in pigs fed 6 than 3% CO (80.0 vs. 72.6), and carcasses of gilts had greater IV (P<0.001) than carcasses of barrows (71.5 vs. 69.1). Increasing the level of TAL and CO but not CWG from 3 to 6% decreased the apparent total tract digestibility of GE, resulting in a source×level interaction (P<0.05). Dietary fat source had no effect (P≥0.66) on apparent total tract digestibility of either DM or GE, but feeding 6% dietary fat increased G:F (P=0.006) over pigs fed 3% fat (0.358 vs. 0.337). Of all the fatty acids measured, only linoleic acid intake presented a reasonable coefficient of determination (R2=0.61). Overall, IV product (IVP) was approximately equal to linoleic acid intake as a predictor of carcass IV (R2=0.93 vs. R2=0.94). When inclusion of dietary fat and PUFA intake increased, IVP placed more emphasis on the dietary fat inclusion level rather than the dietary fat composition. Linoleic acid intake corrected the overemphasis placed on dietary fat inclusion by IVP. To conclude, linoleic acid intake showed a strong relationship with carcass IV and can be used as a predictor.

A comparison of slice characteristics and sensory characteristics of bacon from immunologically castrated barrows with bacon from physically castrated barrows, boars, and gilts.

The objectives were to compare slice characteristics and sensory attributes of bacon from immunologically castrated (IC) barrows with bacon from other sexes using a trained sensory panel. Bacon was obtained for sensory evaluation from 3 experiments. In Exp. 1, trimmed and squared bellies (n=180) of IC barrows, IC barrows fed ractopamine hydrochloride (IC+RAC), physically castrated (PC) barrows, intact males (IM), and gilts were used. Data were analyzed as a general linear mixed model and pen (n=48) served as the experimental unit. Treatment (sex or diet) was a fixed effect in all 3 experiments. In Exp. 2, untrimmed, natural fall bellies (n=96) from IC and PC barrows fed 0 or 30% or a withdrawal distillers dried grains with solubles (DDGS) program when slaughtered at 5 wk after the second dose (25 wk of age) were used. In Exp. 3, untrimmed, natural fall bellies (n=96) from IC and PC barrows fed the same experimental diets as in experiment 2 but slaughtered at 7 wk after the second dose (27 wk of age) were used. Data from Exp. 2 and 3 were analyzed as a 2×3 factorial arrangement in a randomized complete block design and pen was the experimental unit. Bellies from all 3 experiments were processed using the same protocols. In Exp. 1, IM had the greatest (P<0.0001) boar aroma and flavor scores among all treatments. No differences were detected among the other treatment groups for boar aroma or flavor. Intact males had the least (P<0.0001) desirable cured bacon aroma and flavor among all treatments. No differences were detected among the other treatment groups for bacon aroma or flavor. There were no differences in bacon aroma or off-flavor between IC and PC barrows slaughtered at 5 wk after the second dose regardless of DDGS feeding program. Bacon from PC barrows was saltier (P<0.01) than bacon from IC barrows when slaughtered at 5 wk after the second dose. There were no differences in bacon aroma, off-aroma, bacon flavor, or saltiness between IC and PC barrows slaughtered at 7 wk after the second dose regardless of DDGS feeding program. Total slice area of bacon slices from IC barrows slaughtered at 5 wk after the second dose were less (P<0.01) than PC barrows, but the differences diminished (P=0.16) when slaughtered at 7 wk after the second dose. Overall, panelists successfully detected boar odor and flavor in Exp. 1. Immunological castration was as effective as physical castration at eliminating boar aroma and boar flavor in bacon even when feeding differing DDGS feeding programs or when slaughtered at 5 or 7 wk after the second dose.

Effects of preslaughter feed withdrawal time on finishing pig carcass, body weight gain, and food safety characteristics in a commercial environment.

The effects of feed withdrawal time before slaughter on finishing pig carcass composition were evaluated in 2 studies. In Exp. 1, 728 pigs (BW = 128.9 ± 1.2 kg) were allotted to 1 of 4 treatments in a randomized design with number of pigs per pen and location within barn balanced across treatment. The 4 treatments were feed withdrawal times of 8, 24, 36, or 48 h and there were 12 replicate pens per treatment. Before feed withdrawal, pigs were fed a standard corn-soybean meal diet containing dried distillers grains with solubles (DDGS), bakery coproducts, and 5.0 mg/kg ractopamine HCl. Feed withdrawal time decreased (linear; P < 0.02) live weight, HCW, and backfat while increasing percentage yield (quadratic; P < 0.01) and fat-free lean index (FFLI; linear; P < 0.001). In Exp. 2, 843 pigs (BW = 125.4 ± 1.6 kg) were used to determine the impact of feed withdrawal on growth, carcass, blood lactate, and meat quality. There were 4 treatments: withholding feed for 8, 12, 24, or 36 h, with 10 replicates per treatment. Pigs were fed a common corn-soybean meal-based diet containing 20% DDGS and 5.0 mg/kg ractopamine HCl. Withholding feed decreased (linear; P < 0.001) live weight, ultimately resulting in decreased (P < 0.01) HCW. There were no differences in FFLI or backfat, but percentage yield (linear; P < 0.001) increased with longer withdrawal times. Carcass contaminations by stomach contents escaping from the oral cavity after shackling (leaking ingesta) or visible fecal contamination of the exterior of the carcass (runny bung) were also measured. Although withholding feed did not affect runny bung, it increased (linear; P < 0.001) the incidence of leaking ingesta, whereas blood lactate, visual color score, and purge loss were unaffected. Withholding feed increased 45-min pH (quadratic; P > 0.02) and ultimate pH (linear; P < 0.01) and increased (quadratic; P < 0.03) visual marbling score. Withholding feed decreased (linear; P < 0.001) feed intake, resulting in feed savings of up to 3 kg/pig. Although several heavyweight pigs were removed before trial commencement and the variable number of remaining pigs per pen may have influenced the response to feed withdrawal, the present data indicates that finishing pigs can experience between 24 and 36 h of feed withdrawal without negatively affecting carcass composition. However, the increased incidence of leaking ingesta beyond 12 h of feed withdrawal is concerning.

Profile of biochemical traits influencing tenderness of muscles from the beef round.

The objective of this study was to define the biochemical differences that govern tenderness and palatability of economically important muscles from the beef round using cuts with known tenderness differences. At 24h postmortem, the longissimus dorsi (LD), gracillus (GR), adductor (AD), semimembranosus (SM), sartorius (SAR), vastus lateralis (VL), and vastus intermedius (VI) muscles were removed from ten market weight beef cattle. Sensory and biochemical characteristics were determined in each cut and compared with the LD. The GR, SAR and VI had sensory traits similar to the LD while the SM, AD and VL differed. The GR, SAR, AD, and SM all had multiple biochemical characteristics similar to the LD, while the VI and AD had numerous biochemical differences. While no one biochemical characteristic can be used to predict tenderness across all muscles, analysis of the biochemical characteristics revealed that in most beef round cuts postmortem proteolysis provided a good indication of the tenderization occurring during aging.

Control of Salmonella enterica Typhimurium in chicken breast meat by irradiation combined with modified atmosphere packaging.

Salmonella is one of the leading causes of human foodborne illnesses originating from meat and poultry products. Cross-contamination of Salmonella from raw to cooked products continues to be problematic in the food industry. Therefore, new intervention strategies are needed for meat and poultry products. Vacuum or modified atmosphere packaging (MAP) are common packaging techniques used to extend the shelf life of meat products. Irradiation has been well established as an antibacterial treatment to reduce pathogens on meat and poultry. Combining irradiation with high-CO(2)+CO MAP was investigated in this study for improving the control of Salmonella enterica Typhimurium on chicken breast meat. The radiation sensitivities (D10-values) of this pathogen in chicken breast meat were found to be similar in vacuum and in high-CO(2)+CO MAP (0.55 ± 0.03 kGy and 0.54 ± 0.03 kGy, respectively). Irradiation at 1.5 kGy reduced the Salmonella population by an average of 3 log. Some Salmonella cells survived in both vacuum and high-CO(2) + CO MAP through 6 weeks of refrigerated storage following irradiation. This pathogen also grew in both vacuum and MAP when the product was held at 25°C. This study demonstrated that irradiation is an effective means of reducing Salmonella on meat or poultry, but packaging in either vacuum or MAP had little impact during subsequent refrigerated storage.

Amino acid digestibility and energy content of deoiled (solvent-extracted) corn distillers dried grains with solubles for swine and effects on growth performance and carcass characteristics.

A study with 3 experiments was conducted to determine the AA digestibility and energy concentration of deoiled (solvent-extracted) corn distillers dried grains with solubles (dDGS) and to evaluate its effect on nursery pig growth performance, finishing pig growth performance, and carcass traits. In Exp. 1, a total of 5 growing barrows (initial BW = 30.8 kg) were fitted with a T-cannula in the distal ileum and allotted to 1 of 2 treatments: 1) a diet with dDGS as the sole protein source, or 2) a N-free diet for determining basal endogenous AA losses in a crossover design at 68.0 kg of BW. Apparent and standardized (SID) ileal digestibility of AA and energy concentration of dDGS were determined. In Exp. 2, a total of 210 pigs (initial BW = 9.9 kg) were used in a 28-d experiment to evaluate the effect of dDGS on nursery pig performance. Pigs were allotted to 5 dietary treatments (0, 5, 10, 20, or 30% dDGS) formulated to contain equal ME (increased added fat with increasing dDGS) and SID Lys concentrations based on the values obtained from Exp. 1. In Exp. 3, a total of 1,215 pigs (initial BW = 29.6 kg) were used in a 99-d experiment to determine the effect of dDGS on growth and carcass characteristics of finishing pigs. Pigs were allotted to dietary treatments similar to those used in Exp. 2 and were fed in 4 phases. The analyzed chemical composition of dDGS in Exp. 1 was 35.6% CP, 5.29% ash, 4.6% fat, 18.4% ADF, and 39.5% NDF on a DM basis. Apparent ileal digestibility values of Lys, Met, and Thr in dDGS were 47.2, 79.4, and 64.1%, respectively, and SID values were 50.4, 80.4, and 68.9%, respectively. The determined GE and DE and the calculated ME and NE values of dDGS were 5,098, 3,100, 2,858, and 2,045 kcal/kg of DM, respectively. In Exp. 2, nursery pig ADG, ADFI, and G:F were similar among treatments. In Exp. 3, increasing dDGS reduced (linear; P < 0.01) ADG and ADFI but tended to improve (linear; P = 0.07) G:F. Carcass weight and yield were reduced (linear; P < 0.01), loin depth tended to decrease (linear; P = 0.09), and carcass fat iodine values increased (linear; P < 0.01) as dDGS increased. No difference was observed in backfat, percentage of lean, or fat-free lean index among treatments. In conclusion, dDGS had greater CP and AA but less energy content than traditional distillers dried grains with solubles. In addition, when dietary fat was added to diets to offset the reduced ME content, feeding up to 30% dDGS did not affect the growth performance of nursery pigs but did negatively affect the ADG, ADFI, and carcass fat quality of finishing pigs.

Effects of dried distillers grains with solubles on carcass fat quality of finishing pigs.

A total of 1,112 pigs (initial BW of 49.8 kg) were used in a 78-d study to evaluate the effects of 0, 5, 10, 15, or 20% dried distillers grains with solubles (DDGS) and sex on carcass fat quality of finishing pigs. All diets contained 6% choice white grease and were fed in 4 finishing phases (50 to 59, 59 to 82, 82 to 105, and 105 to 123 kg, respectively). The experiment was conducted in a commercial research finishing barn in southwestern Minnesota. There were 9 replicates of each dietary treatment, with 25 to 28 pigs per pen, and barrows and gilts were distributed equally in each pen. On d 57, the 3 heaviest barrows from each pen were visually selected, removed, and marketed, and a total of 6 pigs per treatment were selected randomly for fatty acid analysis. On d 78, the remaining pigs from each pen were individually tattooed and shipped to a pork processing plant. Jowl fat, backfat, and belly fat samples were collected from 1 barrow and 1 gilt chosen randomly from each pen and analyzed for fatty acid composition. Iodine value (IV) was calculated for diets and fat samples. Fat quality data were analyzed as a split plot with DDGS treatment as the whole plot and sex as the subplot. Concentrations of C18:2n-6, PUFA, and IV increased (linear, P = 0.02) with increasing DDGS in backfat, jowl fat, and belly fat in pigs marketed on d 57 and 78. In contrast, C18:1 cis-9 and MUFA concentrations decreased linearly (P = 0.05) in all 3 fat depots with increasing DDGS. For every 10% DDGS included in the diet, IV of backfat, jowl fat, and belly fat increased by 2.3, 1.6, and 2.2 g/100 g, respectively. In pigs slaughtered on d 78, there were no (P ≥ 0.10) sex × dietary DDGS interactions observed. Compared with barrows, gilts had greater (P < 0.05) C18:2n-6, PUFA, and PUFA:SFA ratio and lesser (P < 0.03) C14:0 concentrations in backfat and belly fat but not jowl fat. Gilts had greater (P = 0.03) belly fat IV than barrows, but there were no (P > 0.25) differences between gilts and barrows in backfat and jowl fat IV. In summary, feeding increasing amounts of DDGS linearly increased the IV of backfat, jowl fat, and belly fat in pigs. Although jowl fat was less responsive to increased DDGS than backfat and belly fat, pigs fed diets with 20% DDGS and 6% choice white grease exceeded the maximum jowl IV of 73 g/100 g set by some packing plants.

Growth performance, carcass characteristics, meat quality, and tissue histology of growing pigs fed crude glycerin-supplemented diets.

The effects of dietary crude glycerin on growth performance, carcass characteristics, meat quality indices, and tissue histology in growing pigs were determined in a 138-d feeding trial. Crude glycerin utilized in the trial contained 84.51% glycerin, 11.95% water, 2.91% sodium chloride, and 0.32% methanol. Eight days postweaning, 96 pigs (48 barrows and 48 gilts, average BW of 7.9 +/- 0.4 kg) were allotted to 24 pens (4 pigs/pen), with sex and BW balanced at the start of the experiment. Dietary treatments were 0, 5, and 10% crude glycerin inclusion in corn-soybean meal-based diets and were randomly assigned to pens. Diets were offered ad libitum in meal form and formulated to be equal in ME, sodium, chloride, and Lys, with other AA balanced on an ideal AA basis. Pigs and feeders were weighed every other week to determine ADG, ADFI, and G:F. At the end of the trial, all pigs were scanned using real-time ultrasound and subsequently slaughtered at a commercial abattoir. Blood samples were collected pretransport and at the time of slaughter for plasma metabolite analysis. In addition, kidney, liver, and eye tissues were collected for subsequent examination for lesions characteristic of methanol toxicity. After an overnight chilling of the carcass, loins were removed for meat quality, sensory evaluation, and fatty acid profile analysis. Pig growth, feed intake, and G:F were not affected by dietary treatment. Dietary treatment did not affect 10th-rib backfat, LM area, percent fat free lean, meat quality, or sensory evaluation. Loin ultimate pH was increased (P = 0.06) in pigs fed the 5 and 10% crude glycerin compared with pigs fed no crude glycerin (5.65 and 5.65 versus 5.57, respectively). Fatty acid profile of the LM was slightly changed by diet with the LM from pigs fed 10% crude glycerin having less linoleic acid (P < 0.01) and more eicosapentaenoic acid (P = 0.02) than pigs fed the 0 or 5% crude glycerin diets. Dietary treatment did not affect blood metabolites or frequency of lesions in the examined tissues. This experiment demonstrated that pigs can be fed up to 10% crude glycerin with no effect on pig performance, carcass composition, meat quality, or lesion scores.

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.

Influence of lipid content on pork sensory quality within pH classification.

The objective of this project was to determine the contribution of lipid content to textural and sensory properties of fresh pork within defined pH classifications. Pigs (n = 1,535; from 248 sires and 836 dams) from the 1991, 1992, and 1994 National Barrow Show Sire Progeny Test were used in this study. The test included purebred Berkshire (107), Chester White (113), Duroc (249), Hampshire (220), Landrace (165), Poland China (101), Spotted (181), and Yorkshire (399) barrows (901) and gilts (634). Diets were uniform across breeds within test. The halothane (Hal 1843) genotype (1346 NN and 189 Nn) was determined. Pigs were slaughtered at 105 kg of BW, and samples of the LM were obtained from each carcass at the 10th rib. Star probe, sensory traits, and lipid content were determined on the LM from each pig. A pH classification of LM was assigned as follows: class A, > 5.95, n = 186; class B, > or = 5.80 to 5.95, n = 236; class C, > or = 5.65 to 5.80, n = 467; class D, > or = 5.50 to 5.65, n = 441; class E, < 5.50, n = 205. Data were analyzed using a mixed linear model including pH classification, test, sex, halothane genotype, breed, and breed x sex interaction as fixed effects, with sire and dam within breed included as random effects. Correlations were determined within pH class. Lipid content was a significant source of variation for models predicting star probe values in class C and D and for chewiness in class B, C, and D. Increasing lipid content tended to increase sensory tenderness in pH class D. Sensory tenderness was not affected by lipid content in pH class A, B, or E. Lipid content was not a significant source of variation for juiciness scores within any pH class. Intramuscular lipid is correlated with sensory texture traits primarily in classes C and D. Within class C and D, correlations indicate that increasing lipid content is associated with high sensory tenderness, low sensory chewiness, and low star probe values. It is concluded that lipid content is a small source of variation in texture and tenderness of pork loin with pH between 5.80 and 5.50, but not at a greater or lesser pH.

Effects of preslaughter management on the quality of carcasses from porcine stress syndrome heterozygous market hogs.

The objectives of this study were to determine whether two preslaughter management treatments, rest and mixing, influence the muscle quality of porcine stress syndrome (PSS) heterozygous (Nn) market hogs and to verify the expected quality characteristics of carcasses produced from PSS-normal (NN) and PSS-susceptible (nn) animals. Twenty-nine Nn, 14 NN, and 9 nn market hogs were randomly assigned to preslaughter handling treatments. One-half of the animals in each genotype group received 16 h of rest before slaughter, and the remaining pigs were slaughtered immediately upon arrival at the Iowa State University Meat Laboratory. Within each group, half of the Nn animals were mixed with unfamiliar pigs during transport and lairage. Length, backfat, and loin muscle area (LMA) were not affected by mixing and rest treatment. The carcasses from nn pigs had less fat (P < .05) measured at the 10th rib (off midline) and last lumbar vertebra (midline) and possessed larger LMA than carcasses from NN pigs. Heterozygous pigs were intermediate for most carcass traits. Carcass pH values among heterozygous groups were not significantly different, except that the rested animals had higher ultimate pH values (P < .01) and higher 45-min pH values. Resting had no effect on pH of NN or nn pigs. The 45-min pH values of nn carcasses were lower (P < .01) than those of NN carcasses, but ultimate pH values were similar. Values of unrested Nn animals were between those of NN and nn genotypes but with rest approached values of NN pigs. Loin muscle Minolta-Y and Hunter-L values from unrested Nn animals were higher ( P < .05) than those of rested Nn animals. Mixing did not influence these traits. The longissimus muscle lipid content was not influenced by treatment but differed among genotypes (P < .01). Glycogen levels of rested Nn animals tended to be lower than those of NN animals and approached those of nn pigs. Mixing of Nn animals resulted in higher (P < .05) chewiness scores of cooked loin chops. No significant cooking loss or InstronTM tenderness differences were observed between the PSS-Nn treatment groups. Even though 16 h of rest before slaughter improved the color and water-holding capacity of Nn pigs, effects were small and were much less than those that were due to the PSS gene.

Effects of porcine somatotropin (PST) administration on the fat/lean content and processing properties of pork bellies.

Porcine somatotropin (PST)-supplemented pigs were slaughtered at 109 or 131·8 kg; bellies were analyzed for compositional and bacon processing characteristics and compared with bellies from controls (slaughtered at 109 kg). Bellies from control and 109 kg, PST-treated pigs were significantly lighter (P < 0·01) in weight whereas the PST-treated bellies were significantly (P < 0·01) leaner than controls regardless of slaughter weight. The leaner bellies resulted in greater (P < 0·01) brine pickup, reduced smokehouse yields and bacon with less fat regardless of slaughter weight. Frying yield for the bacon from PST-treated pigs was significantly (P < 0·01) higher than that of the controls probably because of the fat/lean difference. The changes observed in bacon from PST-supplemented pigs appear to be due to the compositional change induced by PST administration.

Nutrient composition and sensory attributes of cooked ground beef: effects of fat content, cooking method, and water rinsing.

Ground beef with 10%, 20%, and 30% fat was shaped into patties or crumbled and cooked by panfrying, panbroiling, or microwaving. After cooking, half of the crumbles were water rinsed. Samples were analyzed for yield, energy, moisture, protein, total lipid, cholesterol, iron, and zinc. In other experiments, cooked crumbled samples were analyzed for vitamin B-12 content and sensory qualities. Effects of cooking method on total lipid and cholesterol levels were generally small. Initial fat level significantly affected total lipid content in cooked ground beef; cooked samples with 10% initial fat contained slightly less total lipid than those with 20% or 30% initial fat. Rinsing with warm water significantly reduced fat and increased the moisture content of cooked ground beef crumbles. Protein, iron, zinc, and vitamin B-12 were well retained during rinsing. We conclude that consumers can achieve a significant reduction in fat content, without substantial losses in protein, iron, zinc, or vitamin B-12, if they water rinse cooked ground beef crumbles. The flavor and texture of the cooked ground beef crumbles are altered somewhat by rinsing. Acceptance in mixed recipes was not determined.