Kenneth J. Prusa

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 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.

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.

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.

Control of Campylobacter jejuni in chicken breast meat by irradiation combined with modified atmosphere packaging including carbon monoxide.

Campylobacter is one of the leading causes of human foodborne illnesses originating from meat and poultry products. Cross-contamination of this organism occurs in many poultry processing plants, and can occur in the kitchens and refrigerators of consumers. Therefore, new intervention strategies are needed for meat and poultry products to better protect consumers from this pathogen. Vacuum or modified atmosphere packaging is a common packaging technique used by the meat and poultry industry to extend the shelf life of meat products. In addition, irradiation has been well established as an antibacterial treatment to reduce pathogens on meat and poultry products. Irradiation in combination with high-CO(2) + CO modified atmosphere packaging (MAP) was investigated in this study for the control of Campylobacter jejuni in chicken breast meat. The radiation sensitivity (D(10)-value) of this foodborne pathogen in chicken breast meat was similar in vacuum or high-O(2) MAP (0.31 ± 0.01 kGy in vacuum packaging and 0.29 ± 0.03 kGy in MAP). C. jejuni survived in both vacuum and high-CO(2) MAP through 6 weeks of refrigerated storage. Irradiation was effective for eliminating C. jejuni from meat or poultry packaged in vacuum or MAP, and should reduce the chance of cross-contamination in retail stores or home kitchens. However, irradiated off-odor and sour aroma were observed for raw, irradiated chicken breast packaged with either vacuum or MAP. Therefore, additional means to mitigate quality changes appear necessary for these products.

Prevalence and relationships of sensory taint, 5α-androstenone and skatole in fat and lean tissue from the loin (Longissimus dorsi) of barrows, gilts, sows, and boars from selected abattoirs in the United States

This study assessed prevalence of boar taint in backfat and lean of barrows, gilts, sows, and boars, collected from abattoirs, without knowledge of the farms of origin, in different regions in the United States. Concentrations of 5α-androstenone (liquid chromatography/mass spectroscopy) and skatole (liquid chromatography with fluorescent detection) in backfat were measured. A trained panel evaluated boar taint aroma in heated samples. Mean 5α-androstenone and skatole levels were low among barrows, gilts, and sows, whereas 55.8% of boars scored above a 1.0 μg/g threshold for 5α-androstenone concentrations and 34.2% were above a 0.2 μg/g threshold for skatole concentrations. Mean aroma scores for backfat and lean from barrows, gilts, and sows were low. In comparison, 59.2% of boars had elevated mean aroma scores from fat samples and 31.7% from lean. Importantly, boar taint aroma was detectable by the trained panel in at least some animals in each of the sex classes.

Composition and quality characteristics of carcasses from pigs divergently selected for residual feed intake on high or low energy diets

The objective was to determine the extent to which feeding low-energy, high-fiber (LEHF) and high-energy, low-fiber (HELF) diets impacts meat quality and carcass composition of pigs divergently selected for residual feed intake (RFI). Two experiments were conducted in the divergently selected Iowa State University RFI lines: Exp. 1 evaluated carcasses of generation (G) 8 pigs fed on commercial feeders; Exp. 2 evaluated composition, pork quality, sensory, and postmortem proteolysis of pigs fed on electronic single-space feeders in G 8 and 9. Pigs (N = 177) in Exp. 1 were randomly assigned a pen (mixed sex and line; N = 8). Groups (n = 3) of pigs were slaughtered at a mean BW of 121.5 kg. Pigs in Exp. 2 (G8: n = 158; G9: n = 157) were randomly assigned to 1 of 6 pens of each diet per G. Pigs from G8 were slaughtered at a mean BW of 122.5 kg and G9 at a mean of 128.4 kg. Data were analyzed using the mixed procedure of SAS. Fixed effects were line, diet, sex, and all appropriate interactions. Random effects were group, pen, litter, and sire and covariate of off-test BW. For Exp. 2, G was added as a fixed effect and sensory day was added as a random effect when applicable. In Exp. 1, carcasses from low RFI (LRFI) pigs were leaner and had less fat depth (P < 0.01). Carcasses from pigs fed the LEHF diet had a lighter HCW and greater estimated percent lean than pigs fed HELF diet (P < 0.01). In Exp. 2, LRFI pigs on the HELF diet had the greatest loin depth (P < 0.01). Chops from HRFI pigs had greater drip loss, color scores, lean tissue a*, and percent lipid and lesser percent moisture than LRFI ( P< 0.05). Chops from pigs on the LEHF diet had lesser muscle L* values and greater percent moisture than chops from pigs fed the HELF diet (P < 0.05). Chops from LRFI pigs were juicer than those from HRFI pigs (P < 0.05). Protein extracted at d 2 postmortem from LRFI pigs on the LEHF diet had a greater 38 kDa desmin degradation product than protein from LRFI pigs fed the HELF diet (P < 0.05). Day 5 postmortem extracted protein from HRFI pigs had greater 38 kDa desmin degradation product than LRFI (P = 0.05). Pigs fed LEHF (P < 0.01) had adipose with a greater iodine value than adipose from HELF fed pigs. Pork sensory quality from pigs differentially selected for residual feed intake was not influenced by energy content of the diet the pigs were fed.

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.

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.

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 pigs 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 pigs 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.