The objective was to evaluate the effect of feeding narasin (Skycis; Elanco Animal Health, Greenfield, IN) on growth performance and carcass characteristics of finishing pigs sold in a 3-phase marketing system. Pigs ( = 1,232) were housed in 56 single-sex pens (22 pigs/pen) divided into 2 even blocks based on initiation of treatment. Each treatment × sex combination was replicated 14 times. Pigs were fed either 0 mg/kg narasin (control) or 15 mg/kg narasin for up to 85 d of finishing (initiated at an average of 52.95 kg BW). In each pen, 18% (4 pigs per pen) of pigs were sold in the first marketing group (Day 64 of dietary treatment), 50% (11 of the original 22) were sold in the second marketing group (Day 78), and 32% (the remaining 7 pigs) were sold in the third marketing group (Day 85). Data were analyzed as a randomized complete block design with pen as the experimental unit. The model included the fixed effects of diet, sex, and their interaction. Block and replicate nested within block were random variables. Carcass data from pigs in marketing group 3 of block 2 was not collected due to inclement weather. Narasin had no effect on growth performance traits ( ≥ 0.15) in phases 1 (Days 1-28) or 2 (Days 29-56), regardless of sex. Barrows fed narasin had a 2.0% greater overall (Day 0-85) ADG than barrows fed the control diet ( < 0.01), but ADG of gilts was not different due to diet ( = 0.69). Regardless of sex, narasin improved ( = 0.03) feed efficiency (G:F) by 1.3% throughout the 85-d feeding period. There were no effects ( ≥ 0.21) of narasin on carcass composition in marketing groups 1 and 2. Narasin-fed barrows in marketing group 3 had 0.9 percentage units lower ( < 0.01) estimated carcass lean compared with barrows fed control diets (51.0 vs. 52.0%); no difference existed in gilts ( = 0.21). This is likely due to narasin-fed barrows of marketing group 3 tending ( = 0.06) to have 7.7% greater fat depth than control barrows of marketing group 3. Pooled effects (across all 3 marketing groups) of feeding narasin tended ( = 0.08) to reduce loin depth by 1.1% (60.00 vs. 60.66 mm), but there were no effects on fat depth ( = 0.24) or estimated carcass lean ( = 0.11). Overall, narasin can be used during the last 85 d of feeding to increase feed efficiency of barrows and gilts with minimal impact on carcass composition.

Objectives were to investigate the effects of prolonged gestational and/or postnatal heat stress on performance and carcass composition of market weight pigs. Pregnant gilts were exposed to gestational heat stress (GHS, 28°C to 34°C, diurnal) or thermal neutral (18°C to 22°C, diurnal) conditions during the entire gestation or during the first or second half of gestation. At 14 wk of age (58 ± 5 kg), barrows were housed in heat stress (32°C, HS) or thermal neutral (21°C, TN) conditions. Feed intake and BW were recorded weekly, and body temperature parameters were monitored twice weekly until slaughter (109 ± 5 kg). Organs were removed and weighed, and loin eye area (LEA) and back fat thickness (BF) were measured after carcass chilling. Carcass sides were separated into lean, separable fat, bone, and skin components and were weighed. Moisture, lipid, and protein content were determined in the LM at the 10th rib. Data were analyzed using a split plot with random effect of dam nested within gestational treatment. Carcass measurements included HCW as a covariate to control for weight. Planned orthogonal contrast statements were used to evaluate the overall effect of GHS in the first half, second half, or any part of gestation. Gestational heat stress did not alter postnatal performance or most body temperature parameters (P > 0.10). However, ADFI in the finishing period was increased (P < 0.05) in response to GHS, particularly in pigs receiving GHS in the first half of gestation. Gestational heat stress during the first half of gestation decreased head weight as a percent of BW (P = 0.02), whereas GHS in the second half of gestation decreased bone weight as a percent of BW (P = 0.02). Heat stress reduced ADG, BW, and HCW (P < 0.0001). Lean tissue was increased in HS pigs on both a weight and percentage basis (P < 0.0001), but LEA was similar to TN carcasses (P = 0.38). Carcasses from HS barrows also had less carcass separable fat (P < 0.01) and tended to have less BF (P = 0.06) compared with those from TN barrows, even after controlling for HCW. However, percent intramuscular fat did not differ between treatments (P = 0.48). The LM from HS carcasses had a greater moisture to protein ratio (P = 0.04). HS barrows also had decreased heart (P < 0.001) and kidney (P < 0.0001) as a percent of BW compared with TN pigs. In summary, GHS may affect head and bone development, subsequently affecting carcass composition. Chronic HS during finishing results in longer times to reach market weight and a leaner carcass once market weight is achieved.

The objective was to characterize the relationship between fresh loin quality with fresh belly or fresh and cured ham quality. Pigs raised in 8 barns representing 2 seasons [cold ( = 4,290) and hot ( = 3,394)] and 2 production focuses [lean ( = 3,627) and quality ( = 4,057)] were used. Carcass characteristics and other meat quality data were collected on 7,684 carcasses. All of the carcasses were evaluated for HCW, LM depth, tenth rib fat depth, leg (ham primal) weight, instrumental color on the gluteus medius and gluteus profundus of the ham face, and subjective loin quality. Instrumental loin color and ultimate pH (≥ 22 h postmortem) were collected on the ventral side of loins along with dimensions and firmness scores of fresh bellies from 50% of the carcasses. Ten percent of the boneless loins and fresh hams were evaluated for slice shear force (SSF) or cured ham characteristics. Correlation coefficients between traits were computed using the CORR procedure of SAS and considered significantly different from 0 at ≤ 0.05. Temperature decline, beginning at 31 min postmortem and concluding at 22 h postmortem, for the longissimus dorsi and semimembranosus muscles were evaluated on 10% of the carcasses. Ultimate loin pH was correlated with dimensional belly characteristics ( ≥ |0.07|; < 0.0001) fresh ham instrumental color ( ≥ |0.03|; ≤ 0.05), and semimembranosus ultimate pH ( = 0.33; < 0.0001). Further, ultimate loin pH was correlated ( ≤ 0.01) with pump retention ( = 0.087) and cooked yield ( = 0.156) of cured hams. Instrumental L*on the ventral surface of the loin was related to L* on both muscles of the ham face ( ≤ 0.0001). Even though significant relationships between the loin, belly, and ham were detected, the variability in belly and ham quality explained by variability in loin quality was poor (≤ 22.09%). Compositional differences between the loin and belly may have contributed to those poor relationships. Additionally, differences in temperature declines during chilling between the loin and ham likely contributed to the weak nature of relationships. Equilibration of longissimus dorsi temperature to ambient cooler temperature occurred at 14 h postmortem ( = 0.0005), yet the semimembranosus had not equilibrated with ambient (equilibration bay) temperature ( < 0.0001) at 22 h postmortem. Using loin quality to draw conclusions about fresh belly and fresh and cured ham quality may be misleading.

Although pork producers typically aim to optimize growth rates, occasionally it is necessary to slow growth, such as when harvest facility capacity is limited. In finishing pigs, numerous dietary strategies can be used to slow growth so pigs are at optimal slaughter body weights when harvest facility capacity and/or access is restored. However, the impact of these diets on pork carcass quality is largely unknown. Thus, this study aimed to evaluate the efficacy of dietary strategies to slow growth in late finishing pigs and evaluate their effects on carcass composition and pork quality. Mixed-sex pigs (n = 897; 125 ± 2 kg BW) were randomly allotted across 48 pens and assigned to 1 of 6 dietary treatments (n = 8 pens/treatment): (1) Control diet representative of a typical finisher diet (CON); (2) diet containing 3% calcium chloride (CaCl2); (3) diet containing 97% corn and no soybean meal (Corn); (4) diet deficient in isoleucine (LowIle); (5) diet containing 15% neutral detergent fiber (NDF) from soybean hulls (15% NDF); and (6) diet containing 20% NDF from soybean hulls (20% NDF). Over 42 d, pen body weights and feed disappearance were collected. Pigs were harvested in 3 groups (14, 28, and 42 d on feed) and carcass data collected. From the harvest group, 1 loin was collected from 120 randomly selected carcasses (20 loins/treatment) to evaluate pork quality traits. Overall, ADG was reduced in CaCl2, Corn, and 20% NDF pigs compared with CON pigs (P &lt; 0.001). However, ADFI was only reduced in CaCl2 and 20% NDF pigs compared with CON (P &lt; 0.001). Feed efficiency was reduced in CaCl2 and Corn pigs compared with CON (P &lt; 0.001). Hot carcass weights were reduced in CaCl2 pigs at all harvest dates (P &lt; 0.001) and were reduced in Corn and 20% NDF pigs at days 28 and 42 compared with CON pigs (P &lt; 0.001). In general, CaCl2 and 20% NDF diets resulted in leaner carcasses, whereas the Corn diet increased backfat by 42 d on test (P &lt; 0.05). Loin pH was reduced and star probe increased in CaCl2 pigs compared with CON pigs (P &lt; 0.05); no treatments differed from CON pigs regarding drip loss, cook loss, color, firmness, or marbling (P ≥ 0.117). Overall, these data indicate that several dietary strategies can slow finishing pig growth without evidence of behavioral vices. However, changes to carcass composition and quality were also observed, indicating quality should be taken into consideration when choosing diets to slow growth.

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.

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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.

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.