Defining optimal dietary starch, oil, and amino acid inclusion levels for broilers experiencing a coccidiosis challenge.

Alternative methods to alleviate coccidiosis in broilers are of interest to producers, including dietary strategies to minimize disruptions in growth rate and efficiency when faced with health challenges. Our objective was to determine optimal combinations of dietary starch, amino acids (AA), and oil to benefit productivity of broilers experiencing Eimeria-induced immune activation. Two trials were conducted using 1,536 male Ross 308 broiler chicks in floor pens randomly assigned to 1 of 17 experimental treatments. All birds received common starter (d 0-10) and finisher (d 24-35) diets, and only differed based on their assigned experimental grower diet (d 10-24). Trial 1 experimental grower diets ranged from 2,700 to 3,300 kcal/kg AME. Trial 2 included 10 experimental grower diets following a simplex lattice design consisting of 3 basal lots formulated to have the highest starch (45.4%), oil (10.2%), or AA density (120, 1.33% digestible Lys) and mixed in 4 equally spaced levels for each component (0, 0.33, 0.67, 1). These mixtures enabled varying densities of AA (80-120% of recommendation), starch:oil (4:1-20:1), and AME (2,940-3,450 kcal/kg). Bird and feeder weights were collected on d 0, 10, 24, and 35, and birds were exposed to an Eimeria challenge on d 11 or 12. In trial 2, excreta samples were collected for AME determination and carcasses were processed on d 36. Data were analyzed using ANOVA, t test, or regression. In Trial 1, BW gain and feed conversion were improved (P < 0.05) by increasing dietary AME. In Trial 2, birds receiving diets containing AA at 93 to 107% of recommendations and higher oil exhibited improved (P < 0.05) performance, but increased starch at the expense of oil reduced performance (P < 0.05). Relative breast and fat pad weights were not influenced by diet in Trial 2. We determined that broilers mildly challenged with Eimeria would exhibit highest BW gain when receiving diets containing 35.8% starch, 8.9% oil, and 101.3% of AA recommendations, which can be utilized by producers to maintain productivity under health-challenged conditions.

Growth performance, carcass characteristics, fresh belly quality, and commercial bacon slicing yields of growing-finishing pigs from sire lines intended for different industry applications.

The objective was to control intrinsic and extrinsic factors associated with the production and slaughter of pigs to determine effects of sire line (Pietrain vs. Duroc ancestry) on growth performance, carcass and belly characteristics, and commercial bacon yields of growing-finishing pigs. There were no differences in growth performance (P ≥ 0.08) or belly processing characteristics (P ≥ 0.09). Pietrain sired pigs had a greater lean yield (P ≤ 0.01). Duroc sired pigs had darker, more highly marbled loins (P ≤ 0.04) and thicker bellies (P < 0.001). Bacon from Pietrain sired pigs had a greater (P = 0.04) lean to fat ratio with 1.58% increase (P = 0.04) in average bacon slice lean. Barrows had more highly marbled loins (P ≤ 0.01) and thicker bellies (P < 0.001) than gilts. Bacon from barrows had a greater slice area (P < 0.001) while bacon from gilts had a greater lean to fat ratio (P = 0.04).

Effect of packaging type during postmortem aging and degree of doneness on pork chop sensory traits of loins selected to vary in color and marbling.

The objective was to determine the interactions between packaging type and degree of doneness on sensory traits of pork loins classified based on the newly proposed USDA quality grades. A total of 144 loins were selected from 2 groups of pigs (lean growth or meat quality production focus) to represent as much variation in visual color and marbling as possible. Selection was achieved with a VQG grading camera. The ventral surface of the loins was evaluated for loin quality traits at 1 d postmortem. At 2 d postmortem loins were sliced into 28-mm-thick chops. Chop within each loin was randomly assigned to either individual vacuum packages or to individual Styrofoam trays and overwrapped in polyvinyl chloride (PVC) oxygen permeable film. Overwrapped PVC packages were then placed in bulk packages and flushed with a gas mixture that contained approximately 0.4% carbon monoxide, 30% carbon dioxide, and 80% nitrogen. Vacuum-packaged chops were aged until 14 d postmortem. Chops packaged in PVC overwrap were aged until 9 d postmortem in the bulk packages, then placed on simulated retail display until 14 d postmortem. Chops from each packaging type were cooked to an internal temperature of either 63 °C or 71 °C for the evaluation of slice shear force (SSF) or for evaluation of tenderness, juiciness, and flavor by a trained panel. Data were analyzed as split-split plot design with production focus of the pigs, proposed USDA quality grade, packaging type, and degree of doneness as fixed effects. While there were main effect differences between production focuses, there were no interactions with production focus. There were also no 3-way (P ≥ 0.19) interactions and only one 2-way interaction among quality grade, packaging type, or degree of doneness. There were no differences in sensory tenderness (P = 0.30), juiciness (P = 0.49), flavor (P = 0.89), SSF (P = 0.13), or cook loss (P = 0.06) among USDA quality grades. There were no differences in sensory tenderness (P = 0.06), juiciness (P = 0.32), flavor (P = 0.74), SSF (P = 0.99), or cook loss (P = 0.12) between chops aged in vacuum packages or PVC packages. Chops cooked to 63 °C were 4.6% more tender (P < 0.0001), 10.1% juicier (P < 0.0001), and 2.9% less flavorful (P = 0.01) than chops cooked to 71 °C. These data suggest that cooking chops to 63 °C rather than 71 °C was a more effective way to improve tenderness and juiciness than selecting chops of a certain quality grade or altering packaging postmortem.

Growth performance, carcass quality, fresh belly characteristics, and commercial bacon slicing yields of growing-finishing pigs fed a subtherapeutic dose of an antibiotic, a natural antimicrobial, or not fed an antibiotic or antimicrobial.

The objective was to compare growth performance, belly characteristics, and bacon slicing yields of growing-finishing pigs fed a subtherapeutic dose of an antibiotic, a natural antimicrobial, or a diet containing no antibiotics or antimicrobials. Barrows and gilts (96 each, initial BW: 27.52±3.98kg) were housed in 48 pens (8 replications per treatment) in a 2×3 factorial randomized complete block design. Pens were assigned 1 of 3 diets: antibiotic free, oregano or tylosin phosphate. Pigs were slaughtered at an average BW of 127.31±10.18kg. There were no differences among dietary treatments for growth performance (P≥0.06), carcass cutability (P≥0.42), loin quality (P≥0.28), fresh belly dimensional characteristics (P≥0.11), IV (P≥0.87) or bacon processing characteristics (P≥0.07). Given the lack of differences in meat quality from pigs fed diets without antibiotics, the implementation of VFD in the United States should not result in changes in pork quality.

The effects of instrumental color and extractable lipid content on sensory characteristics of pork loin chops cooked to a medium-rare degree of doneness.

Boneless loins ( = 286) were selected from a population of pigs of a common genetic line and management strategy to be used in an experiment to determine the effects of instrumental color and extractable lipid content on sensory traits of boneless pork chops cooked to an end point internal temperature of 63°C. Loins were cut into 2.54-cm-thick chops and aged until 14 d postmortem. Chop L* values ranged from 57.60 (light) to 43.11 (dark) and extractable lipid ranged from 0.80 to 5.52%. Using these values, chops were assigned to 5 color and 6 marbling categories using National Pork Producers Council (NPPC) standards, resulting in a 5 × 6 factorial arrangement of treatments. Chops were also assigned a quality grade using a proposed grading system. Low-quality loins ( = 56) had marbling scores < 1.5, regardless of color, or had color scores ≤ 2.5 and marbling scores ≤ 2.0. Medium-quality loins ( = 180) had color scores of 2.0 to 3.5 and marbling scores ≥ 2.5 or loins with color scores of 3.0 through 3.5 and marbling scores ≥ 2.0. High-quality loins ( = 50) had color scores > 4.0 and marbling scores ≥ 2.0. Chops were cooked to a medium-rare degree of doneness (63°C) and evaluated for tenderness, juiciness, and pork flavor by trained panelists. Slice shear force (SSF) and cooking loss were also evaluated. Data were analyzed using the MIXED procedure of SAS as a 1-way ANOVA with the fixed effect of quality grade and using the REG procedure of SAS. Individually, extractable lipid content and instrumental color accounted for no more than 2% ( ≤ 0.02) of the variation in tenderness, juiciness, or pork flavor. High-quality chops had 6.5 and 11.2% less SSF ( ≤ 0.04) than medium- and low-quality chops, respectively, and medium-quality chops had 5.6% less SSF ( < 0.04) than low-quality chops. Trained sensory panelists did not detect differences in tenderness ( = 0.09) or juiciness ( = 0.48) among quality grades, but low- and medium-quality chops were more flavorful ( < 0.01) than high-quality chops. Cooking loss tended ( = 0.06) to decrease from 16.57% to 15.32% as quality grade increased. Neither color nor marbling alone was predictive of sensory quality. But when these were used together, as they were in the proposed grading system, pork sensory flavor ratings were greater for low-quality chops than for high- and medium-quality chops. Also, the proposed grading system was able to discern differences in SSF but not sensory tenderness among the quality grades.

A comparison of intact and degraded desmin in cooked and uncooked pork longissimus thoracis and their relationship to pork quality.

The objective was to compare desmin abundance (intact, degraded, and the ratio of intact desmin to degraded desmin) in samples from cooked and uncooked pork and establish its relationship to pork quality traits. Pork chops (2.54-cm thick) from twenty-four pork loins were randomly assigned to treatment (cooked or uncooked). Intact and degraded desmin in cooked and uncooked chops aged 1d were weakly correlated (r<|0.35|) with Warner-Bratzler shear force at 1 and 14d postmortem aging. Intact and degraded desmin in cooked and uncooked chops aged 14d were moderately correlated (|0.35|

A summary review of carcass cutability data comparing primal value of immunologically and physically castrated barrows.

The objectives were to 1) assess cutability, quality, and value of carcasses from immunologically castrated (IC) barrows compared with carcasses from physically castrated (PC) barrows and 2) evaluate the effect of hot carcass weight (HCW) on cutability and value of IC barrows summarizing U.S. data. Lean cutting yield (LCY) was defined as: LCY = [(whole ham + trimmed loin + Boston butt + picnic + spareribs)/chilled side wt] x 100. Carcass cutting yield (CCY) was determined using the following equation: CCY = [(lean cutting yield components + natural fall belly)/chilled side wt] x 100. To evaluate the effects of HCW of IC barrows on carcass cutting yields, IC barrows were grouped by HCW: light ( < 90.9 kg), average (90.9-97.7 kg), or heavy ( > 97.7 kg). Differences in the value of the carcass components for IC and PC barrow carcasses were calculated using a 5 yr average of meat prices from the USDA Agriculture Marketing Service and the carcass cutting yield estimates generated from this summary. Data were analyzed using the MIXED procedure of SAS with fixed effects of Improvest treatment or HCW group. Study was included as a random effect. This review allowed for a summarization of the treatment averages of 851 IC and PC barrow carcasses. Lean cutting yield of IC barrows was 1.41 units greater (P < 0.0001) than PC barrows (70.97 vs. 69.56%). Similarly, CCY of IC barrows was 1.29 units greater (P < 0.001) compared with PC barrows (87.27 vs. 85.98%). As HCW of IC barrows increased, both CCY and LCY declined (P < 0.01), with light IC barrow carcasses having a 1.43 unit advantage in CCY compared with heavy IC barrow carcasses (P < 0.01). Natural fall bellies of PC barrows comprised a greater (P < 0.05) percentage of side weight than those from IC barrows (15.81 vs. 15.50%). A reduction in belly primal value was confirmed by a 3.43 unit reduction in the commercial bacon slicing yields of IC barrows. However, belly yield and slicing yield differences were minimized when IC barrows were marketed at a heavier weight. Using carcass cutout estimates determined in the summary as the foundation for value calculations, lean cuts of IC barrow carcasses were worth $2.66 to $3.80 more than PC barrow carcasses. Therefore, after adjustment for the reduction in belly primal value, the primal value of an IC barrow carcass was $2.08 to $3.13 greater than a PC barrow carcass.

Relationships among early postmortem loin quality and aged loin and pork chop quality characteristics between barrows and gilts.

Rapid assessment of pork quality by packers necessitates using early postmortem (∼1 d) traits as an indication of aged pork quality (∼14 d). Efforts have been made to develop a grading system based on color and marbling of the ventral side of boneless loins. In order for this system to be successful, there must be a correlation between early postmortem quality traits observed by packers and the same traits observed by consumers after aging. However, the strength and direction of those correlations are unclear. It is also unknown if the correlations between early and aged postmortem quality differ between barrows (B) and gilts (G). Therefore, the objectives were to determine correlations between early postmortem loin quality characteristics and aged loin quality characteristics, and determine if those correlations differed between barrows and gilts. Early postmortem (∼1 d) quality traits included: instrumental and subjective color, marbling and firmness, and loin pH on the ventral surface of the loin. Loins were aged until 14 d postmortem in vacuum packages. Aged quality traits included traits evaluated early as well as shear force and cook loss. Correlations were compared between barrows and gilts using a Fisher's z test. Overall, early subjective firmness scores of barrows were greater (P < 0.001) than those of gilts. No other early quality traits differed between sexes. Early pH was correlated with aged pH (r = 0.80 B; 0.75 G), ventral lightness (r = -0.57 B; -0.54 G), ventral yellowness (r = -0.55 B; -0.55 G), subjective ventral color (r = 0.55, B; 0.41 G), and subjective chop color (r = 0.42 B; 0.44 G). Correlations of early pH and aged quality did not differ between sexes. Early lightness was correlated with aged ventral pH (r = -0.56) and subjective color (r = -0.39) in barrows but not gilts (P ≤ 0.04). Early lightness was correlated with aged lightness (r = 0.60 B; 0.51 G) and yellowness (r = 0.49 B; 0.55 G), but was not correlated with to any aged chop quality traits. Early marbling was correlated with ventral color (r = 0.42) in barrows and ventral marbling (r = 0.67 B; 0.66 G) and chop marbling (r = 0.57 B; 0.59 G) in barrows and gilts. In summary, early pH and lightness were correlated with aged quality characteristics and correlations rarely differed between barrows and gilts. Sex does not need to be accounted for when relating early and aged quality characteristics.

Characterization of variability in pork carcass composition and primal quality,.

The objective was to characterize the factors and production practices that contribute to variation in pork composition and quality. It is possible the variation in pork quality traits, such as color, marbling, and tenderness, contributes to reduced customer confidence in the predictability of finished product quality and, therefore, pork products becoming less competitive for consumer dollars. Pigs raised in 8 different barns representing 2 seasons (hot and cold) and 2 production focuses (lean and quality) were used in this study. Pigs were marketed in 3 groups from each barn and marketing procedures followed commercial marketing procedures. Data were collected on a total of 7,684 pigs. The mivque0 option of the VARCOMP procedure in SAS was used to evaluate the proportion of variation each independent variable (season, production focus, marketing group, sex, and random variation) contributed to total variance. Random variation including inherent biological differences, as well as factors not controlled in this study, contributed the greatest proportion to total variation for each carcass composition and quality trait. Pig and other factors contributed to 93.5% of the variation in HCW, and marketing group, sex, season, and production focus accounted for 4.1, 1.4, 0.8, and 0.3%, respectively. Variation in percent carcass lean was attributed to production focus (36.4%), sex (15.8%), and season (10.2%). Pig and other factors contributed the greatest percentage of total variation (39.4%). Loin weight variation was attributed to production focus (21.4%), sex (5.4%), season (2.7%), marketing group (1.8%), and pig (68.7%). Belly weight variation was attributed to pig (88.9%), sex (4.1%), marketing group (3.8%), production focus (3.0%), and season (0.1%). Variation in ham weight was attributed to pig and other factors (93.9%), marketing group (2.8%), production focus (2.2%), and season (1.1%). Ultimate pH variation was attributed to pig (88.5%), season (6.2%), production focus (2.4%), marketing group (2.2%), and sex (0.7%). Aside from pig (71.9%), production focus (14.0%) was the next largest contributor to variation in iodine value followed by sex (13.2%) and marketing group (0.9%). Variation in carcass quality and composition could be accounted for, but the greatest percentage of variation was due to factors not accounted for in normal marketing practices.

Effect of hot carcass weight on loin, ham, and belly quality from pigs sourced from a commercial processing facility,.

The objective was to determine the predictive abilities of HCW for loin, ham, and belly quality of 7,684 pigs with carcass weights ranging from 53.2 to 129.6 kg. Carcass composition, subjective loin quality, and ham face color were targeted on all carcasses, whereas in-plant instrumental loin color and belly quality were assessed on 52.0 and 47.5% of carcasses, respectively. Loin chop slice shear force (SSF), cured ham quality, and adipose iodine value (IV) were evaluated on at least 10% of the population. The slope of regression lines and coefficients of determination between HCW and quality traits were computed using PROC REG of SAS and considered significant at ≤ 0.05. As HCW increased, boneless loins became darker and redder, evidenced by lower L* (ß = -0.0243, < 0.001) and greater a* values (ß = 0.0106, < 0.001); however, HCW accounted for only ≤0.80% of the variability in loin L* and a* values. Similarly, subjective loin color score (ß = 0.0024, < 0.001) increased with increasing carcass weight, but subjective marbling score was not affected by HCW (ß = -0.0022, = 0.06). After 20 d of aging, HCW explained only 0.98% of the variability in loin L* values (ß = -0.0287, < 0.01). Heavier carcasses had lower SSF values (ß = -0.1269, < 0.001) of LM chops, although HCW explained only 4.46% of the variability in SSF. Although heavier carcasses produced loins that exhibited lower ultimate pH values (ß = -0.0018, < 0.001), HCW explained only 1.23% of the variability in ultimate loin pH. Interestingly, cook loss decreased (ß = -0.0521, < 0.001) as HCW increased, with HCW accounting for 5.60% of the variability in cook loss. Heavier carcasses resulted in darker, redder ham face color ( < 0.001), but HCW accounted for only ≤2.87% of the variability in ham face L* values and 0.47% of the variability in a* values. Heavier carcasses produced thicker and firmer bellies, with HCW accounting for 37.81% of the variability in belly thickness (ß = 0.0272, < 0.001), 20.35% of the variability in subjective flop score (ß = 0.0406, < 0.001), and 10.35% of the variability in IV (ß = -0.1263, < 0.001). Overall, the proportion of variability in loin and ham quality explained by HCW was poor (≤5.60%), suggesting that HCW is a poor predictor of the primal quality of pigs within this weight range. Nonetheless, HCW was a moderate predictor of belly quality traits. The findings of this study suggest that increasing HCW did not compromise loin, ham, or belly quality attributes.

Comparison of variability in pork carcass composition and quality between barrows and gilts.

Pigs ( = 8,042) raised in 8 different barns representing 2 seasons (cold and hot) and 2 production focuses (lean growth and meat quality) were used to characterize variability of carcass composition and quality traits between barrows and gilts. Data were collected on 7,684 pigs at the abattoir. Carcass characteristics, subjective loin quality, and fresh ham face color (muscles) were measured on a targeted 100% of carcasses. Fresh belly characteristics, boneless loin weight, instrumental loin color, and ultimate loin pH measurements were collected from 50% of the carcasses each slaughter day. Adipose tissue iodine value (IV), 30-min loin pH, LM slice shear force, and fresh ham muscle characteristic measurements were recorded on 10% of carcasses each slaughter day. Data were analyzed using the MIXED procedure of SAS as a 1-way ANOVA in a randomized complete block design with 2 levels (barrows and gilts). Barn (block), marketing group, production focus, and season were random variables. A 2-variance model was fit using the REPEATED statement of the MIXED procedure, grouped by sex for analysis of least squares means. Homogeneity of variance was tested on raw data using Levene's test of the GLM procedure. Hot carcass weight of pigs (94.6 kg) in this study was similar to U.S. industry average HCW (93.1 kg). Therefore, these data are representative of typical U.S. pork carcasses. There was no difference ( ≥ 0.09) in variability of HCW or loin depth between barrow and gilt carcasses. Back fat depth and estimated carcass lean were more variable ( ≤ 0.0001) and IV was less variable ( = 0.05) in carcasses from barrows than in carcasses from gilts. Fresh belly weight and thickness were more variable ( ≤ 0.01) for bellies of barrows than bellies of gilts, but there was no difference in variability for belly length, width, or flop distance ( ≥ 0.06). Fresh loin subjective color was less variable ( < 0.01) and subjective marbling was more variable ( < 0.0001) in loins from barrows than in those from gilts, but there were no differences ( ≥ 0.08) in variability for any other loin traits or fresh ham traits. Overall, traits associated with carcass fatness, including back fat depth, belly thickness, and marbling, but not IV, were more variable in carcasses from barrows than in carcasses from gilts, whereas minimal differences in variability existed between carcasses of barrows and carcasses of gilts for traits associated with carcass muscling and lean quality.

Predicting pork loin chop yield using carcass and loin characteristics.

The objective was to determine the predictive ability of carcass length for the number of equal-thickness chops obtained from a boneless pork loin. Longer pork carcasses are assumed to yield longer loins and, therefore, an increased number of chops. Loins were collected from pigs (1,238 total) raised under commercial conditions and marketed when the mean pig weight in a pen reached 138 kg. Pigs were slaughtered over 7 wk in a commercial facility. Carcass length was measured at 1 d postmortem on the left side of each carcass from the anterior edge of the symphysis pubis bone to the anterior edge of the first rib. Carcasses were fabricated, and boneless loins (North American Meat Processors number 414) were vacuum packaged and transported to the University of Illinois Meat Science Laboratory. Loins were stored at 4°C for 14 d. At the end of the aging period, loins were weighed, measured for stretched length (stretched to maximum length without distortion) and compressed length (compressed to minimum length without distortion), and sliced into 2.54-cm-thick chops. Boneless chops were counted and weighed. Carcass length ranged from a minimum of 78.2 cm to a maximum of 96.5 cm and the number of boneless chops ranged from a minimum of 13 to a maximum of 20 chops. Data were analyzed using the regression procedure of SAS. The dependent variable was the number of boneless chops. Coefficient of determination () was calculated for carcass length, boneless loin weight, compressed loin length, and stretched loin length. Carcass length explained 15% ( < 0.0001) of the variation in the number of loin chops. Loin weight explained 33% ( < 0.0001) of the variation in the number of loin chops. Compressed loin length and stretched loin length explained 28 and 8% ( < 0.0001), respectively, of the variation in the number of loin chops. Multiple linear regression was used to determine a predictive equation for the number of loin chops using the stepwise selection option of all independent variables. The combination of boneless loin weight, compressed loin length, 10th-rib carcass fat depth, and carcass length explained 45% of the variation ( < 0.0001; C(p) = 16.76) in the number of loin chops using a required statistic at the SLENTRY and SLSTAY level = 0.15. Overall, carcass length is a poor predictor of the number of equal-thickness loin chops that can be derived from a boneless pork loin.

Effect of immunological castration management strategy on lipid oxidation and sensory characteristics of bacon stored under simulated food service conditions.

The objectives of this study were to determine the effect of 1) immunological castration (Improvest, a gonadotropin releasing factor analog-diphtheria toxoid conjugate) management strategy (age at slaughter and time of slaughter after second dose) and 2) sex on lipid oxidation and sensory characteristics of bacon stored under simulated food service conditions. For Objective 1, immunological castration management strategies included 24-wk-old immunologically castrated (IC) barrows 4, 6, 8, or 10 wk after the second Improvest dose (ASD); 26-wk-old IC barrows 6 wk ASD; and 28-wk-old IC barrows 8 wk ASD ( = 63). Objective 2 ( = 97) included IC barrows, physically castrated (PC) barrows, and gilts slaughtered at 24, 26, and 28 wks of age. Bellies from 2 slaughter dates were manufactured into bacon under commercial conditions. Bacon slices were laid out on parchment paper, packaged in oxygen-permeable poly-vinyl-lined boxes, and frozen (-33°C) for 1, 4, 8, or 12 wk to simulate food service conditions. At the end of each storage period, bacon was evaluated for lipid oxidation, moisture and lipid content, and sensory characteristics. Data from both objectives were analyzed using the MIXED procedure in SAS with belly as the experimental unit. For both objectives, as storage time increased, lipid oxidation of bacon increased ( < 0.01), regardless of management strategy or sex. Also, there was no sex or management strategy × week of frozen storage interaction for any traits evaluated ( ≥ 0.25). For Objective 1, lipid content of bacon from IC barrows increased as time of slaughter ASD increased ( < 0.05), regardless of age at slaughter. Additionally, there were no differences in sensory attributes of bacon across management strategies. For the evaluation of sex effects in Objective 2, lipid oxidation was greater ( < 0.05) in IC barrows compared with PC barrows but was not different than gilts ( > 0.05). After 12 wk of frozen storage, lipid oxidation values for IC barrows, PC barrows, and gilts were still below 0.5 mg malondialdehyde/kg of meat, the threshold at which trained panelists may deem a food to be rancid. In conclusion, bacon shelf life characteristics were not altered by the immunological castration management strategy and bacon from IC barrows was similar to bacon from gilts. Therefore, bacon from IC barrows would result in shelf life and sensory quality similar to PC barrows and gilts.

Effects of pelleting diets without or with distillers' dried grains with solubles on growth performance, carcass characteristics, and gastrointestinal weights of growing-finishing barrows and gilts.

Pigs (192 total) were blocked by age and stratified by initial BW (25.75 ± 2.29 kg) into pens (2 barrows and 2 gilts per pen). Within blocks, pens were randomly allotted to treatments in a 2 × 2 factorial arrangement, with 2 diet forms (meal vs. pellet) and 2 distillers' dried grains with solubles (DDGS) inclusion levels (0 vs. 30%). Pigs were weighed at the beginning of the experiment and at the end of each feeding phase (d 35, 70, and 91) and daily feed allotments were recorded. Pigs were slaughtered at the end of the 91-d experiment, and full gastrointestinal (GI) tract and GI tract component weights were recorded immediately following evisceration. Carcass characteristics and meat quality were determined after a 24-h chill. Overall ADG was increased ( < 0.01) 3.2% when pigs were fed pelleted diets rather than meal diets, but there was no effect ( = 0.46) of DDGS inclusion on overall ADG. Overall ADFI of meal-fed pigs fed 30% DDGS was 4.7% greater ( < 0.01) than that of pigs fed 0% DDGS in meal form, but overall ADFI did not differ ( ≥ 0.19) between DDGS inclusion level in pellet-fed pigs (diet form × DDGS inclusion, < 0.01). When fed meal diets, pigs fed 0% DDGS had 2.7% greater ( = 0.02) overall G:F than pigs fed 30% DDGS; however, there was no difference ( = 0.42) in overall G:F between DDGS inclusion levels in pigs fed pelleted diets (diet form × DDGS inclusion, < 0.03). Pigs fed pelleted diets had 2.9% heavier HCW ( = 0.01), 10.4% greater 10th-rib back fat ( = 0.01), and 1.8 percentage units less estimated lean percentage ( = 0.04) than meal-fed pigs. Full GI tracts of pigs fed pelleted diets were 0.33 percentage units less ( = 0.03) of the ending live weight than that of meal-fed pigs due to decreased ( < 0.01) GI tract contents. Inclusion of DDGS increased ( = 0.03) full GI tract weight, large intestine weight ( < 0.01), and GI tract contents ( = 0.02). Severity of parakeratosis of the pars esophagea was greater ( < 0.01) in pellet-fed pigs than in meal-fed pigs, but the magnitude of the difference was likely not great enough to negatively affect drop credit of stomachs. In conclusion, feeding pelleted diets improved growth performance and increased carcass weight and fatness without causing the development of gastric lesions that would reduce the value of the stomach to packers. Furthermore, inclusion of DDGS in diets reduced HCW and dressing percent and increased GI tract and GI tract contents weight but had no effect on gastric lesion development or LM quality.

Effects of feeding pelleted diets without or with distillers dried grains with solubles on fresh belly characteristics, fat quality, and commercial bacon slicing yields of finishing pigs.

One hundred ninety-two pigs were blocked by age and stratified by initial BW (25.7 ± 2.3 kg) into pens (2 barrows and 2 gilts/pen), and within blocks, pens were assigned randomly to 1 of 4 treatments in a 2 × 2 factorial arrangement, with main effects of diet form (meal vs. pelleted) and distillers dried grains with solubles (DDGS) inclusion (0% vs. 30%). Pigs were slaughtered after a 91-d feeding trial, and carcasses were fabricated after a 24-h chilling period. Belly dimensions and flop distance were measured, and an adipose tissue sample from each belly was collected for fatty acid analysis. Bacon was manufactured at a commercial processing facility before being returned to the University of Illinois Meat Science Laboratory for further evaluation. Although bellies from pigs fed pelleted diets were 5.3% heavier ( < 0.01) than bellies from meal-fed pigs, belly weight as a percentage of chilled side weight ( = 0.55) and fresh belly dimensions ( ≥ 0.11) were not affected by diet form. Slab bacon weight and cooked yield were greater ( ≤ 0.01) for bellies from pellet-fed than meal-fed pigs. Despite pellet-fed pigs having a 3.1-unit greater iodine value (IV) than meal-fed pigs, there was no effect ( ≥ 0.16) of diet form on commercial bacon slicing yields. Bacon slabs from pellet-fed pigs produced more ( < 0.01) total bacon slices, but 3.1% fewer ( < 0.01) slices per kilogram than slabs from meal fed pigs. Inclusion of 30% DDGS reduced belly thickness ( < 0.001), flop distance ( < 0.001), and initial belly weight ( = 0.04) by 0.32 cm, 4.97 cm, and 2.85, respectively, and increased ( < 0.001) belly fat IV by 7.1 units compared with bellies from pigs fed 0% DDGS. Feeding 0% DDGS produced more ( < 0.01) total bacon slices than feeding 30% DDGS. Distillers dried grains with solubles inclusion had no effect on slice yields ( ≥ 0.14) or slices per kilogram ( = 0.08). Overall, bellies from pellet-fed pigs were heavier and had greater IV but did not differ in commercial slicing yields from meal-fed pigs. Feeding pigs 30% DDGS produced thinner, softer bellies with greater IV, but slicing yields were not different from bellies of pigs fed 0% DDGS. Thus, swine producers can feed pelleted diets, without or with 30% DDGS, without negatively affecting commercial bacon slicing yield.

Effects of supplementing zinc or chromium to finishing steers fed ractopamine hydrochloride on growth performance, carcass characteristics, and meat quality.

Objectives were to determine the effects of feeding ractopamine hydrochloride (RAC) with zinc (Zn) and chromium (Cr) on feedlot growth performance, carcass characteristics, and meat quality. Steers ( = 179; initial BW = 533 ± 94 kg) were blocked by BW and allotted to 30 pens, and pens were randomly assigned 1 of 5 treatments: (1) control (CONT), (2) RAC only (RO), (3) RAC + Zn (RZ), (4) RAC + Cr (RC), or (5) RAC + Zn + Cr (RZC). Trace minerals were fed from d 0 to 63 to target 1 g of Zn/steer·d (KemTRACE Zn; Kemin Industries, Inc., Des Moines, IA) and 3 mg Cr/steer·d (KemTRACE Chromium; Kemin Industries, Inc.) for Zn and Cr treatments, respectively. Dry-rolled corn, 0.605 kg/steer, was removed from the diet and 400 mg RAC, per 0.605 kg of ground corn carrier, was top dressed per steer immediately following feed delivery to pens fed RAC. There were no effects ( ≥ 0.45) of trace mineral supplementation on DMI, ADG, or G:F before RAC feeding. There were also no treatment effects ( ≥ 0.46) over all 63 d of the trial on DMI, ADG, or G:F. Despite the lack of differences in live performance, steers fed RO and RC averaged 0.10 kg/d greater ( = 0.10) carcass ADG than steers fed RZC and CONT, while steers fed RZ were intermediate and not different. Steers fed RO had the greatest ( = 0.09) carcass G:F, while steers fed CONT had the least carcass G:F, 0.0875 and 0.0774, respectively. Steers fed RO and RC averaged 5.5 kg heavier ( = 0.09) HCW than steers fed RZC and CONT, while steers fed RZ were intermediate and not different. There were no treatment effects ( ≥ 0.32) on LM area, 12th rib fat, marbling score, KPH, carcass yield, or USDA yield grade and distribution. However, carcasses from steers fed RC had the greatest ( = 0.10) percentage grading USDA Select. There were no treatment effects ( ≥ 0.20) on shear force, intramuscular fat, pH, a*, and b*. Steaks from steers fed RO and RC had 11.4% greater ( = 0.08) cook loss than steaks from steers fed CONT and RZC, whereas steaks from steers fed RZ were intermediate and not different. Also, steaks from steers fed RC had 2.11 units greater ( = 0.03) L* values (i.e., were lighter) than steaks from steers fed RZ; steaks from steers fed CONT, RO, and RZC were intermediate. In feedlot steers, the addition of both Cr and Zn supplementation did not improve growth performance or meat quality when fed in combination with 28 d of RAC supplementation; however, RAC, fed alone or in combination with Cr, did increase HCW.

Effects of chromium supplementation to feedlot steers on growth performance, insulin sensitivity, and carcass characteristics.

Objectives were to determine the effects of chromium propionate supplementation on growth performance, insulin and glucose metabolism, and carcass characteristics of beef cattle. Steers ( = 34) were stratified by BW and assigned to 1 of 2 treatments: 1) no supplemental Cr (Cont) or 2) 3 mg supplemental Cr·steer·d (CrP). Both supplements, Cont and CrP, were delivered via 0.454 kg ground corn top-dressed on the basal diet. There was no effect ( ≥ 0.45) of CrP on ADG, DMI, G:F, or final BW. However, steers fed CrP needed more ( = 0.10) days on feed (DOF) to achieve the same carcass back fat (BF) as steers fed Cont. There were no effects ( ≥ 0.41) of CrP on HCW, BF, or KPH. Steers fed CrP had increased ( = 0.01) dressing percentage (DP) and tended to have a 4.21 cm greater LM area ( = 0.15), decreased marbling scores ( = 0.11), and decreased intramuscular fat ( = 0.11) compared to steers fed Cont. There were no differences ( ≥ 0.25) in quality or yield grade distributions. A glucose tolerance test was conducted early (21 DOF) and late (98 DOF) in the finishing phase. There was a feedlot treatment (FT) × time × DOF interaction ( = 0.08) for glucose concentrations, but no other interactions ( ≥ 0.21) for glucose or insulin concentrations. There were no FT × DOF interactions ( ≥ 0.21) for insulin area under the curve (iAUC), insulin:glucose ratio, insulin or glucose baseline, or peak insulin or glucose concentrations. At 21 DOF, steers fed CrP had decreased glucose area under the curve (gAUC; = 0.01), decreased glucose clearance rate (; = 0.02), and increased glucose half-life (T; = 0.07) compared to steers fed Cont; however, by 98 DOF, no differences were observed between treatments. At 98 DOF, all steers, regardless of treatment, had increased ( < 0.01) peak glucose and insulin, , iAUC, insulin:glucose ratio, and baseline insulin when compared to values at 21 DOF, but gAUC and T decreased ( < 0.01). Although steers fed CrP tended ( = 0.11) to have increased baseline glucose concentrations compared to steers fed Cont, CrP supplementation did not affect ( ≥ 0.17) other measures of glucose or insulin. Results of this study indicate that CrP increased DP and tended to increase LM area but tended to decrease intramuscular fat, with no effect on growth performance. With increased DOF, all steers became more insulin resistant, using more insulin to clear less glucose, and these effects were not mitigated by CrP supplementation.

Ham and belly processing characteristics of immunological castrated barrows (Improvest) fed ractopamine hydrochloride (Paylean).

Effects of sex class (physically castrated, PC or immunologically castrated, IC) and diet (0 or 5mg/kg ractopamine hydrochloride, RAC) on characteristics of ham and bellies were determined from pigs slaughtered in three groups with similar ending live weights. One carcass per pen per marketing group (n=8) was selected to evaluate further processing characteristics. Data were analyzed as a 2×2 factorial design with a split plot in time and fixed effects of sex, diet, marketing group, and their interactions. IC fresh bellies were thinner (P<0.01) and softer (P<0.01) than PC bellies. IC hams and bellies were leaner (P<0.05) than those from PC pigs. RAC feeding did not affect (P>0.05) fresh ham or belly characteristics but decreased (P<0.01) fat in cured PC bellies. Marketing group affected (P<0.05) fresh quality, processing characteristics, and composition of hams and bellies. Immunological castration and RAC produced leaner finished products but did not alter processing yield of hams or bacon.

Effects of marketing group on the quality of fresh and cured hams sourced from a commercial processing facility.

The objective was: 1) to characterize the effect of marketing group on fresh and cured ham quality, and 2) to determine which fresh ham traits correlated to cured ham quality traits. Pigs raised in 8 barns representing 2 seasons (hot and cold) and 2 production focuses (lean and quality) were used. Three groups were marketed from each barn. A total of 7,684 carcasses were used for data collection at the abattoir. Every tenth carcass was noted as a select carcass for in-depth ham quality analyses. Leg primal weight and instrumental color were measured on 100% of the population. On the select 10% of the population, hams were fabricated into sub-primal pieces, and 3-piece hams were manufactured to evaluate cured ham quality and processing yield. Data were analyzed as a split-plot design in the MIXED procedure of SAS with production focus as the whole-plot factor, and marketing group as the split-plot factor. Pearson correlation coefficients between fresh and cured ham traits were computed. There were no differences ( ≥ 0.15) in instrumental color or ultimate pH ( ≥ 0.14) among fresh ham muscles from any marketing group. The only exception was the semimembranosus of marketing group 2 was lighter than marketing group 1 ( = 0.03) and the dark portion of the semitendinosus muscle from group 1 was lighter than from group 3 ( = 0.01). There were no differences ( ≥ 0.33) in ultimate pH of fresh ham muscles between production focuses, but several muscles from quality focus pigs were lighter in color than ham muscles from lean focus pigs. The lack of differences in fresh ham quality lead to few differences in cured ham quality. Cured hams from the quality focus pigs had greater lipid content ( < 0.01) than hams from lean focus pigs. Cured lightness values of hams from marketing group 1 and 2 were 1.52 units lighter than hams from marketing group 3 ( 0.01). Overall, marketing group did not impact ham quality. Fresh ham quality was not strongly related to cured ham quality. Some correlations were present between fresh and cured ham traits, but those relationships were likely not strong enough to be used as a sorting tool for fresh hams to generate high quality cured hams.

Effects of marketing group and production focus on quality and variability of adipose tissue and bellies sourced from a commercial processing facility.

Objectives were to determine the effects of marketing group on quality and variability of belly and adipose tissue quality traits of pigs sourced from differing production focuses (lean vs. quality). Pigs ( = 8,042) raised in 8 barns representing 2 seasons (cold and hot) were used. Three groups were marketed from each barn with 2 barns per production focus marketed per season. Data were collected on 7,684 carcasses at a commercial abattoir. Fresh belly characteristics, American Oil Chemists' Society iodine value (AOCS-IV), and near-infrared iodine value were measured on a targeted 50, 10, and 100% of carcasses, respectively. Data were analyzed as a split-plot design in the MIXED procedure of SAS 9.4 with production focus as the whole-plot factor and marketing group as the split-plot factor. Barn (block), season, and sex were random variables. A multivariance model was fit using the REPEATED statement with the marketing group × production focus interaction as the grouping variable. Variances for production focus and marketing groups were calculated using the MEANS procedure. Homogeneity of variance was tested on raw data using the Levene's test of the GLM procedure. Among quality focus carcasses, marketing group 3 bellies weighed less ( ≤ 0.03) than those from either marketing group 1 or 2, but there was no difference ( ≥ 0.99) among marketing groups of the lean focus carcasses. There was no effect ( ≥ 0.11) of production focus on fresh belly measures, SFA, or iodine value (IV), but lean focus carcasses had decreased ( = 0.04) total MUFA and increased ( < 0.01) total PUFA compared with quality focus carcasses. Marketing group did not affect ( ≥ 0.10) fresh belly dimensions, total SFA, total MUFA, total PUFA, or IV. Belly weight, flop score, width, and all depth measurements were less variable ( ≤ 0.01); whereas, belly length, total SFA, and total MUFA were more variable ( < 0.0001) in lean focus carcasses than in quality focus carcasses. There was no difference ( ≥ 0.17) in total PUFA or AOCS-IV variability between production focuses. Variance of flop score, total MUFA, and total PUFA were not equal ( ≤ 0.01) among marketing groups. Belly weight, length, width, and depth measurements; SFA; or IV variance did not differ ( ≥ 0.06) among marketing groups. Although a multiple-marketing strategy was effective at minimizing differences in belly characteristics, differences in the variability of these traits exist among marketing groups and are likely dependent on the production system used.