The nutrient-nutrient interactions within a food matrix may alter the postprandial stimulation of myofibrillar protein synthesis rates (MPS). We have previously shown that a protein- and lipid-rich food matrix has greater anabolic potential compared to the ingestion of a low-fat, protein-rich food matrix. Objectives: Thus, this study aimed to investigate the effects of consuming a high-fat pork (HFP) compared to low-fat pork (LFP) product and a carbohydrate control drink (CHO) on postexercise stimulation of MPS. Hypothesis: We hypothesized that the ingestion of HFP and LFP would increase MPS compared to CHO. We further hypothesize that the ingestion of HFP will further potentiate the stimulation of MPS than the LFP condition. Methods: In a semi-crossover design, 16 physically-active adults (25±5; BMI: 25.0 ± 2.3 kg·m -2 ; 12M, 4 F) underwent primed constant infusions of L-[ ring - 13 C 6 ]phenylalanine and performed an acute bout of resistance exercise. Following resistance exercise, participants ingested either HFP (81% lean; 266 kcal, 20 g protein, and 20.6 g fat), LFP (95% lean; 120 kcal, 20 g protein, 4.4 g fat), or CHO (266 kcal, 0 g protein, 0 g fat, 73.3 g carbohydrate; Gatorade). During their second trial, participants were randomly assigned to one of the two remaining conditions in a counterbalanced fashion (resulting in n = 10 per condition). Repeated blood and muscle samples were collected at rest and throughout the 5 h postexercise recovery period for measurement of plasma amino acid concentrations and MPS. Data were analyzed using linear fixed effects models with time and group as fixed factors and Bonferroni post hoc analysis when significant ( P < 0.05) differences were detected. Results: Plasma essential amino acid (EAA) and leucine concentrations increased after ingestion of HFP and LFP (both P < 0.001), with greater peak plasma EAA and leucine concentrations in LFP treatment compared to HFP ( P = 0.018 and P = 0.027, respectively) and CHO (both P < 0.001). Incremental area under the curve (iAUC) for plasma EAA and leucine concentrations did not differ between LFP and HFP ( P = 0.350 and P = 0.361, respectively), however, both conditions resulted in significantly higher iAUC as compared to CHO treatment (both P < 0.001). Both HFP and LFP stimulated MPS above resting values ( P = 0.028 and P < 0.001, respectively). Postexercise MPS was significantly greater in LFP (0.095 ± 0.029 %·h -1 ) compared to HFP (0.065 ± 0.024 %·h -1 ; P = 0.030) and CHO (0.052 ± 0.033 %/h -1 ; P < 0.001). Conclusions: LFP ingestion immediately after resistance exercise results in greater stimulation of MPS than HFP and CHO. Our findings indicate that the nutrient profile of protein-rich foods uniquely modulates postexercise muscle anabolism compared to the protein content alone in healthy adults. This study was funded by the National Pork Board (project no. #22-040). This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Choline is vital in a variety of physiological processes that influence brain development, growth, and carcass characteristics in birds and mammals. In this study, we investigated the influence of graded supplemental choline chloride on growth performance, carcass quality, and liver characteristics in grow-finish pigs. Pigs (672 barrows and 588 gilts) were obtained from a commercial nursery facility at 8 weeks of age and assigned to treatment based on body weight and sex, with 21 same-sex pigs comprising a replicate pen. Each dietary treatment was provided to 15 replicate pens, with 8 pens of barrows and 7 pens of gilts per each of 4 dietary treatments, which included: 1) C0, basal diet containing 0% of supplemental choline chloride; 2) C300, C0 + 0.06% supplemental choline chloride, to provide 300 mg/kg of choline ions; 3) C600, C0 + 0.12% supplemental choline chloride, to provide 600 mg/kg of choline ions; and 4) C900, C0 + 0.17% supplemental choline chloride, to provide 900 mg/kg of choline ions. Feed and water were provided ad libitum throughout the study, and pigs were managed using standard commercial practices. Data were analyzed by two-way ANOVA using the MIXED procedure of SAS, with factors including dietary treatment and sex. There was no dietary impact (P > 0.05) on growth performance. Pigs receiving intermediate levels of supplemental choline had higher (P < 0.05) tenderloin weights compared with other dietary treatments. Furthermore, and as expected, sex differences were denoted in both growth performance and carcass characteristics. Overall, graded supplementation of choline chloride did not significantly alter growth performance or carcass characteristics of pigs raised in a commercial setting.

BACKGROUND:There is considerable variation in the anabolic action of ingesting protein-dense foods on the stimulation of postprandial myofibrillar protein synthesis rates (MPS) despite ingesting similar amounts of protein and essential amino acids (EAA). OBJECTIVES:This study aims to determine the effects of consuming high-fat pork (HFP), low-fat pork (LFP), or a carbohydrate control (CHO) on the MPS response. METHODS:In a semicrossover design, 16 physically active adults (25 ± 5 y; 25.0 ± 2.3 kg/m2; 12M, 4F) received primed-constant infusions of L-[ring-13C6]phenylalanine and performed an acute bout of resistance exercise. Following exercise, participants ingested either HFP (266 kcal, 20 g protein, 20.6 g fat), LFP (120 kcal, 20 g protein, 4.4 g fat), or CHO (266 kcal, 0 g protein, 0 g fat, 73.3 g carbohydrate). Repeated blood and muscle samples were collected at rest and throughout 0-5 h postexercise recovery to measure plasma variables and MPS. Linear mixed-effects models with time and condition as fixed factors were used to detect differences. RESULTS:Both HFP and LFP conditions increased MPS above postabsorptive values (P = 0.028 and P < 0.001, respectively), with LFP eliciting a greater postexercise MPS {0.106 ± 0.026 %/h [95% confidence interval (CI): 0.088, 0.118]} than HFP [0.072 ± 0.027 %/h (95% CI: 0.057, 0.087); P = 0.030] and CHO [0.056 ± 0.035 %/h (95% CI: 0.41, 0.71); P < 0.001]. The absolute change in MPS from basal was significantly correlated with peak EAA and leucine concentrations (r = 0.4638, P = 0.017; r = 0.4211, P = 0.032). CONCLUSIONS:LFP stimulated MPS more than HFP or CHO conditions. Our work demonstrated that other nutrients in the food matrix, beyond total ingested protein or EAAs, can impact the regulation of MPS in healthy adults. This trial was registered at clinicaltrials.gov as NCT05876299.

The LCORL-NCAPG locus is a major quantitative trait locus (QTL) on bovine chromosome 6 (BTA6) that influences growth and carcass composition in cattle. To further understand the molecular mechanism responsible for the phenotypic changes associated with this locus, twenty-four Charolais-sired calves were selected for muscle transcriptome analysis based on alternative homozygous LCORL-NCAPG haplotypes (i.e., 12 “QQ” and 12 “qq”, where “Q” is a haplotype harboring variation associated with increased growth). At 300 days of age, a biopsy of the longissimus dorsi muscle was collected from each animal for RNA sequencing. Gene expression analysis identified 733 genes as differentially expressed between QQ and qq animals (q-value < 0.05). Notably, LCORL and genes known to be important regulators of growth such as IGF2 were upregulated in QQ individuals, while genes associated with adiposity such as FASN and LEP were downregulated, reflecting the increase in lean growth associated with this locus. Gene set enrichment analysis demonstrated QQ individuals had downregulation of pathways associated with adipogenesis, alongside upregulation of transcripts for cellular machinery essential for protein synthesis and energy metabolism, particularly ribosomal and mitochondrial components. The differences in the muscle transcriptome between QQ and qq animals imply that muscle hypertrophy may be metabolically favored over accumulation of fat in animals with the QQ haplotype. Our findings also suggest this haplotype could be linked to a difference in LCORL expression that potentially influences the downstream transcriptional effects observed, though further research will be needed to confirm the molecular mechanisms underlying the associated changes in phenotype.

Abstract Prior research and public perception of pork suggest breed influence visual characteristics like color and size and palatability traits like tenderness and flavor of pork chops. Therefore, the objective of this study was to assess consumer perception of visual appeal and palatability of pork loin chops from three sire lines cooked to two different degrees of doneness (DOD). Boneless pork loins from three sire lines (Duroc, Berkshire, and Synthetic) were aged to 14 d post-mortem. Loin quality was then measured, and 2.54-cm chops were frozen from each loin. Chops from each sire line were overwrap-packaged in sets of two and displayed in a retail case with two representative packages per sire line. Panelists rated each package for color, marbling, and size on a just about right (JAR) scale and then indicated their overall liking of each package. Chops from each sire line were cooked to either 63°C or 71°C, cut into 1-cm cubes and two samples from each chop were served to each consumer. Panelists rated 6 samples, each sire line and DOD, for tenderness, flavor, and juiciness on a JAR scale and then rated overall liking. Data were analyzed as a randomized complete block design (RCBD) in SAS 9.4 with panelist age range serving as an influence effect for all panel data. Berkshire chops did not differ (P > 0.08) in redness from other chops, but required 0.13 kg less force to shear, and had a 16.23 cm2 smaller LEA compared with Synthetic and Duroc chops (P < 0.02). Duroc chops had the greatest marbling (P < 0.04) but did not differ in visual color score from other treatments (P > 0.10). There were no differences in consumer visual evaluations (P > 0.45), with traits from all sire lines averaging between 43 and 57 (JAR = 50). Sire line also did not alter visual liking (P = 0.94). There were tendencies for interactions (P > 0.09) between DOD and sire line for consumer sensory evaluation. In general, consumers rated Berkshire chops cooked to 63°C more favorably than other sire line and DOD combinations. Consumers rated chops with different DOD similarly for tenderness and flavor, but tended to score juiciness of chops cooked to 63°C closer to JAR (P = 0.07). Duroc chops were the least tender and least acceptable (P < 0.05). Berkshire chops were juicer than Duroc and Synthetic chops (P < 0.02). Overall, consumers scored all chops between 3.1 and 12.3 units below the JAR line (100-unit scale) regardless of sire line or DOD for tenderness, juiciness, and flavor with overall acceptability within 10 units of neither like nor dislike, which may be indicative of consumers general negative perceptions of pork loin chops.

The objective of this research was to determine the effects of mid-gestational maternal inflammation on performance, carcass characteristics, and meat quality of offspring. Pregnant gilts were administered either lipopolysaccharide (LPS; n = 7) or saline (CON, n = 7) from days 70 to 84 of gestation. Gilts assigned to the LPS treatment were administered an intravenous injection of reconstituted LPS every other day with a beginning dose of 10 mu g LPS/kg body weight and subsequent doses increasing by 12%, while CON gilts received intravenous injections of comparable volumes of saline. Gilts farrowed naturally, and at day 66 of age, a total of 59 pigs, both barrows and gilts began a 3-phase feeding regimen designed to meet or exceed nutrient requirements for growing-finishing pigs. Pigs were weighed on days 0, 35, 70, and 105 of the finishing trial to determine average daily gain, average daily feed intake, and gain-to-feed ratio (G:F). On day 106, pigs were slaughtered under the supervision of the U.S. Department of Agriculture Food Safety Inspection Service. Ending live weight, hot carcass weight, and dressing percentage were determined. The left side of carcasses was weighed and fabricated to determine carcass cutting yields. The semitendinosus was collected for histological samples. Fresh belly characteristics and loin quality were measured. Two chops were collected for Warner-Bratzler shear force and proximate analysis. No differences (P >= 0.13) between LPS and CON pigs were observed for growth performance in phases 1, 2, 3, or overall (days 0 to 105) performance with the exception of overall G:F reduced in CON pigs compared with LPS pigs (P = 0.03). There was a tendency for carcass yield to be reduced (P = 0.06; 0.82% units) in LPS pigs compared with CON pigs. Additionally, longissimus muscle area tended to be reduced (P = 0.10) 2.27 cm2 in LPS compared with CON pigs. Loin chop quality traits including instrumental color, subjective color, marbling, firmness, pH, and drip loss were not different (P >= 0.09) between LPS and CON pigs. Fresh belly characteristics were not different (P >= 0.22) between LPS and CON pigs. There were no differences in primal and subprimal weights, except that LPS pigs tended to have a reduction (P >= 0.07) in tenderloin and Canadian back weights compared with CON pigs. Furthermore, LPS pigs had no differences (P >= 0.25) in muscle fiber composition or size; however, LPS pigs tended (P = 0.10) to have a 13% reduction in estimated muscle fibers number compared with CON pigs. In summary, mid-gestational inflammation did not result in reduced meat quality, growth performance, or carcass yields of offspring. An acute maternal inflammatory challenge during mid-gestation tended to reduce muscle fiber number in the offspring, but did not impact growth performance, carcass characteristics, or overall pork quality. Gestation is a crucial time for communicating the outside environment to the fetus. Any influence on the fetus during gestation may have lifelong effects on the offspring. Most muscle fiber formation occurs in the beginning of the third trimester of gestation. Therefore, maternal inflammation during this period may be detrimental to fetal muscle development, which can ultimately stunt growth potential and influence carcass characteristics and meat quality. A majority of previous research that investigates maternal inflammation as a result of innate immune activation focuses on neuropsychiatric disorders in the offspring, offering little relevance to animal agriculture. The influence of maternal infection on long-term growth performance, carcass characteristics, and meat quality has received little attention. Therefore, the objective of this study was to elucidate the impact of maternal inflammation on offspring growth, efficiency, carcass characteristics, and pork quality. The gestational challenge resulted in pigs that tended to have fewer total muscle fibers. However, gestational inflammation did not have an impact on overall growth performance, carcass characteristics, or pork quality of the offspring.

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.

The objective was to determine the effects of maternal inflammation on offspring muscle development and postnatal innate immune response. Sixteen first-parity gilts were randomly allotted to repeated intravenous injections with lipopolysaccharide (LPS; n = 8, treatment code INFLAM) or comparable volume of phosphate buffered saline (CON, n = 8). Injections took place every other day from gestational day (GD) 70 to GD 84 with an initial dose of 10 mu g LPS/kg body weight (BW) increasing by 12% each time to prevent endotoxin tolerance. On GD 70, 76, and 84, blood was collected at 0 and 4 h postinjection via jugular or ear venipuncture to determine tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and IL-1 beta concentrations. After farrowing, litter mortality was recorded, and the pig closest to litter BW average was used for dissection and muscle fiber characterization. On weaning (postnatal day [PND] 21), pigs were weighed individually and 2 barrows closest to litter BW average were selected for another study. The third barrow closest to litter BW average was selected for the postnatal LPS challenge. On PND 52, pigs were given 5 mu g LPS/kg BW via intraperitoneal injection, and blood was collected at 0, 4, and 8 h postinjection to determine TNF-alpha concentration. INFLAM gilt TNF-alpha concentration increased (P < 0.01) 4 h postinjection compared to 0 h postinjection, while CON gilt TNF-alpha concentration did not differ between time points. INFLAM gilt IL-6 and IL-1 beta concentrations increased (P = 0.03) 4 h postinjection compared to 0 h postinjection on GD 70, but did not differ between time points on GD 76 and 84. There were no differences between INFLAM and CON gilts litter mortality outcomes (P >= 0.13), but INFLAM pigs were smaller (P = 0.04) at birth and tended (P = 0.09) to be smaller at weaning. Muscle and organ weights did not differ (P >= 0.17) between treatments, with the exception of semitendinosus, which was smaller (P < 0.01) in INFLAM pigs. INFLAM pigs tended (P = 0.06) to have larger type I fibers. INFLAM pig TNF-alpha concentration did not differ across time, while CON pig TNF-alpha concentration peaked (P = 0.01) 4 h postinjection. TNF-alpha concentration did not differ between treatments at 0 and 8 h postinjection, but CON pigs had increased (P = 0.01) TNF-alpha compared to INFLAM pigs 4 h postinjection. Overall, maternal immune activation did not alter pig muscle development, but resulted in suppressed innate immune activation.

Abstract Numerous studies have shown genetic variation at the LCORL-NCAPG locus is strongly associated with growth traits in beef cattle. However, a causative molecular variant has yet to be identified. To define all possible candidate variants, Charolais-sired calves (n = 34) were whole genome sequenced including 17 homozygous for a long-range haplotype associated with increased growth (QQ), and 17 homozygous for potential ancestral haplotypes for this region (qq). The Q haplotype was refined to an 814-kb region between chr6:37,199,897-38,014,080 and contained 218 variants not found in qq individuals. These variants include an insertion in an intron of NCAPG, a previously documented mutation in NCAPG (rs109570900), two coding sequence mutations in LCORL (rs109696064 and rs384548488), and 15 variants located within ATAC peaks that were predicted to affect transcription factor binding. Notably, rs384548488 is a frameshift variant likely resulting in loss of function for long isoforms of LCORL. To test the association of the coding sequence variants of LCORL with phenotype, 405 cattle from five populations were genotyped. The two variants were in complete linkage disequilibrium. Statistical analysis of the three populations that contained QQ animals revealed significant (P < 0.05) associations with genotype and birth weight, body weight, carcass weight, hip height, and average daily gain. Additionally, an RNAseq analysis was performed using 22 of the Charolais-sired calves. This, in conjunction with the WGS data, was used to run an eQTL analysis, which revealed 256 genes whose expression were impacted by eQTL in the region (FDR < 0.05). These findings affirm the link between this locus and growth in beef cattle and describe DNA variants that define the haplotype. However, further studies will be required to define the true causative mutation.

Abstract The ability to modify the genomes of livestock species has previously been limited by low efficiency and the high cost associated with reagents and the generation of edited live animals (e.g., via somatic cell nuclear transfer). However, the CRISPR/Cas9 system has shown promise by improving specificity and efficacy, while decreasing costs associated with reagent acquisition and potentially live animal production (e.g., via direct editing of embryos). Given these potential improvements there are still a limited number of well-characterized genes for targeting. Nonetheless, there are two genes where molecular variation in different species has shown highly significant effects on increased lean growth and reduced adiposity, insulin-like growth factor 2 (IGF2) and myostatin (MSTN). In pigs, a G-to-A substitution in intron 3 of IGF2 (g.3072G >A) disrupts a conserved binding site for the transcriptional repressor ZBED6 allowing for increased postnatal IGF2 expression. This increased expression is associated with increased lean muscle yield and intramuscular fat deposition, while decreasing backfat. In livestock species other than the pig, numerous loss-of-function mutations in MSTN have been reported. MSTN is a known early regulator of myoblast differentiation, negatively regulating myoblast fusion into myotubes. This results in muscle hyperplasia causing the commonly referred to “double-muscling” phenotype. Animals of this phenotype have significantly increased skeletal muscle mass, improved feed conversion, and decreased fat deposition. These mutations have the potential to act synergistically as demonstrated by generation of a mouse line possessing both IGF2 overexpression and MSTN loss-of-function mutations. Within this line, wild-type (WT) mice have an average body weight (BW) of 19.64 ± 1.89 g at 11 wk of age. In comparison, IGF2 overexpression, MSTN loss-of-function, and the combination of both mutations have average BW of 23.54 ± 2.31 g, 26.14 ± 2.35 g, and 31.43 ± 2.39 g, respectively (P < 0.0001). Based on these results in mice we have initiated editing of both genes in cattle. Two male fetal fibroblast cell lines were generated from d 75 fetuses from high genetic merit Angus matings. Four CRISPR guide RNAs have been designed for both genes and assayed for their in vitro cleavage efficiencies. All guide RNAs exceeded 60% cleavage efficiency. CRISPR/Cas9 ribonuclear protein complexes were electroporated into each cell line. Targeted modifications will be confirmed through sequencing, and successfully modified cell lines will undergo somatic cell nuclear transfer to produce live animals.

The objective was to characterize the effects of increasing carcass weight on pork carcass characteristics and yields from traditional and alternative fabrication methods, as well as evaluate the size of novel retail cuts. Pigs (n = 85) were slaughtered and divided into 3 hot carcass weight (HCW) categories: Average (99 to 109 kg), Heavy (116 to 126 kg), and Very Heavy (134 to 144 kg). Loin muscle area (LMA) and back fat depth were measured on all carcasses. Paired right and left sides were fabricated traditionally and alternatively (shoulder separation at the 4th/5th rib), respectively. From the alternative side, the serratus ventralis (SV) was removed from the cellar-trimmed butt, and the triceps brachii (TB) was removed from the picnic shoulder. All individual primals and subprimals were weighed for yield calculations. Data were analyzed using the MIXED procedure in SAS including the main effect of weight class, with sex and sire line as fixed blocking effects. Differences were considered significant at P ≤ 0.05. Regardless of fabrication method, whole primal and subprimal weights increased (P < 0.01) in heavier carcass weight classes compared with lighter classes, but when expressed as a percentage of chilled side weight, these increases did not often translate into meaningful differences in distribution of carcass weight. While the alternative shoulder-loin separation reduced loin and belly length, loins and bellies from heavier carcasses weighed more than those from carcasses typically produced in the U.S. pork industry today. Serratus ventralis weight was increased (P < 0.01) approximately 0.28 kg from Average to Very Heavy, while the TB weight was increased (P < 0.01) approximately 0.24 kg from Average to Very Heavy. At heavier weights, alternative fabrication of carcasses yielded novel cuts from the shoulder including the SV and TB that were of size to warrant further exploration as retail offerings.

While supplemental methionine (Met) is widely used within the swine industry, data are limited regarding the effect of Met sources on carcass cutability and meat quality. The objective was to determine the effects of DL-methionine (DLM, 99%), L-methionine (LM, 99%), or calcium salt of DL-methionine hydroxyanalogue (MHA-Ca, 84%) in finishing pig diets on carcass characteristics and meat quality. Pigs (n = 240) were allocated to 60 single-sex pens. For the final 7 wk of the finisher phase, pigs (BW= 79.9 ± 0.80 kg) were fed diets containing DLM, LM, or MHA-Ca, with the supplemental methionine source providing 25% of the sulfur amino acid requirement. One pig per pen was slaughtered, and left sides of carcasses were fabricated into subprimal cuts to determine carcass-cutting yields. Loin quality including proximate composition and shear force was measured. Data were analyzed using the MIXED procedure of SAS. Hot carcass weight was not different (P= 0.34) between treatments (DLM 103.0 kg; LM 104.5 kg; MHA-Ca 101.5kg), moreover loin eye area was not different (P= 0.98) between treatments (DLM 52.49 cm²; LM 52.65 cm²; MHA-Ca 52.81 cm²). Boneless carcass cutting yield was not different (P = 0.56) between treatments (DLM 54.82 kg; LM 54.97 kg; MHA-Ca 54.52 kg). Loin pH was not different (P = 0.24) between treatments (DLM 5.48; LM 5.45; MHA-Ca 5.45). However, drip loss tended to be reduced (P = 0.11) by the DLM treatment (5.58%) compared with LM (7.03%) and MHA-Ca (6.68%) treatments. Shear force was not different (P = 0.85) between treatments (DLM 3.06 kg; LM 3.03 kg; MHA-Ca 3.10 kg). However, cook loss tended to be reduced (P = 0.06) by the DLM treatment (16.20%) compared with LM (18.18%) and MHA-Ca (18.50%) treatments. These data suggest that only minimal differences in carcass cutability and meat quality can be attributed to methionine sources in finishing pig diets.

Abstract Pigs with an engineered myostatin loss-of-function mutation in exon 3 (-1T) experience perinatal mortality of unknown cause. From 36 litters resulting from matings of sows and boars both heterozygous for the mutation, 240 total piglets were born but only 14% (5/35) of piglets with myostatin loss-of-function mutation survived or were viable beyond postnatal d 3. Thus, the objective was to evaluate the effects of this myostatin loss-of-function mutation on piglet organ and muscle development and blood parameters to determine potential causes of this excess mortality. Blood was collected for complete blood count and then piglets (n = 50) were euthanized at postnatal d 3. Piglets were dissected and longissimus muscle, semitendinosus muscle, heart, liver, lungs, kidneys, pancreas, spleen, stomach, small intestine, large intestine, testicles or female reproductive tract, and tongue were weighed. Front girth, back girth, and snout to rump were measured. Loin samples were used to genotype piglets into one of three groups: wild type (WT; unmutated myostatin, n = 13), heterozygous (HET, n = 21) and myostatin mutant (MKO, n = 10). Data were analyzed as a two-way ANOVA using the MIXED procedure of SAS to determine the effect of sex, genotype, and their interaction. Body weight (P = 0.67) and front girth (P = 0.13) were not different between genotypes, but back girth was reduced (P = 0.04) in MKO by 2.3 cm compared with WT and by 2.1 cm compared with HET piglets. MKO piglets had lighter (P ≤ 0.03) hearts, livers, kidneys, pancreases, spleens, stomachs, and small intestine compared with HET and WT piglets, on both an absolute basis and as a percentage of body weight. In general, compared with other other genotypes, MKO organs were 5 to 19% lighter. Surprisingly, muscle weights, both longissimus and semitendinosus muscles, were not different (P ≥ 0.15) between genotypes, either on an absolute basis or as a percentage of body weight. White blood cell count was not different; however, neutrophil count was increased in MKO compared with other genotypes. These data suggest that underdeveloped or undersized organs in MKO piglets may compromise their survivability. Additionally, increased neutrophil counts may be indicative of a stress response in MKO piglets.

Numerous studies have shown genetic variation at the LCORL-NCAPG locus is strongly associated with growth traits in beef cattle. However, a causative molecular variant has yet to be identified. To define all possible candidate variants, 34 Charolais-sired calves were whole-genome sequenced, including 17 homozygous for a long-range haplotype associated with increased growth (QQ) and 17 homozygous for potential ancestral haplotypes for this region (qq). The Q haplotype was refined to an 814 kb region between chr6:37,199,897–38,014,080 and contained 218 variants not found in qq individuals. These variants include an insertion in an intron of NCAPG, a previously documented mutation in NCAPG (rs109570900), two coding sequence mutations in LCORL (rs109696064 and rs384548488), and 15 variants located within ATAC peaks that were predicted to affect transcription factor binding. Notably, rs384548488 is a frameshift variant likely resulting in loss of function for long isoforms of LCORL. To test the association of the coding sequence variants of LCORL with phenotype, 405 cattle from five populations were genotyped. The two variants were in complete linkage disequilibrium. Statistical analysis of the three populations that contained QQ animals revealed significant (p < 0.05) associations with genotype and birth weight, live weight, carcass weight, hip height, and average daily gain. These findings affirm the link between this locus and growth in beef cattle and describe DNA variants that define the haplotype. However, further studies will be required to define the true causative mutation.

Pork is often viewed as a “middle-of-the-road” option. It is typically less expensive than beef, but more expensive than chicken. While beef cuts, especially steaks, are viewed as luxury items or high-end dining experiences, pork is more of a staple food featured as a variety of fresh and processed products at breakfast, lunch, and dinner. To increase demand for pork and capture more of the high-end market, improving fresh pork loin quality has been a focus of the industry for many years. There is evidence that these efforts have been successful. Compared with pork of the past, fresh pork loins have increased pH and darker color. Additionally, the incidence of tough pork has been reduced and overall pork tenderness improved. However, per capita consumption of pork by the consumers of the United States has not changed. This suggests that consumer acceptance and demand for fresh pork may not depend on intrinsic characteristics such as pH, color, and tenderness. Extrinsic factors like endpoint cooking temperature may have a larger influence on consumer acceptability of fresh pork loin chops. It is possible that, in terms of pork quality, we have been successful in eliminating the problems of the pork industry like pale, soft and exudative pork, but this is not sufficient to reach a consistently excellent eating experience in pork loins.

Feeding growing-finishing pigs supplemental fat is a common practice in the swine industry and can result in improved feed efficiency and reduced feed intake; however, dietary lipids also play a key role in determining pork composition. Objectives of the current study were to evaluate the effects of feeding graded levels of high oleic soybean oil (HOSO) on growth performance and carcass characteristics. A total of 288 pig raised in two separate blocks (144 pigs each) were assigned to 1 of 4 diets containing either 25% dried distiller's grains with solubles (DDGS), 2% high oleic soybean oil (HOSO2), 4% high oleic soybean oil (HOSO4), or 6% high oleic soybean oil (HOSO6). Pigs were housed 4 per pen and fed for 98 d using a 3-phase feeding system. Pigs were individually weighed and feed intake was recorded throughout the trial to calculate average daily feed intake (ADFI) and gain to feed ratio (G:F). A total of 144 pigs were transported to the University of Illinois Meat Science Laboratory and fabricated into primal and subprimal cuts to calculate carcass cutting yields. Differences in growth performance were observed, with pigs fed the DDGS treatment exhibiting greater (P ≤ 0.01) overall ADFI consuming 0.21, 0.18, and 0.28 kg/d more than HOSO2, HOSO4 and HOSO6 diets, respectively. Pigs fed the HOSO6 diet had greater (P ≤ 0.03) overall G:F than pigs fed DDGS and HOSO2 diets, but did not differ (P = 0.12) from pigs fed HOSO4. Furthermore, differences in carcass traits were observed. Hot carcass weight was increased (P ≤ 0.03) in pigs fed the HOSO6 diet compared with pigs fed the DDGS and HOSO2 diets, while pigs fed HOSO4 did not differ (P > 0.05) from either extreme. Additionally, pigs fed HOSO4 and HOSO6 produced fatter (P ≤ 0.01) carcasses with reduced (P ≤ 0.01) standardized fat-free lean. Minimal differences were observed in primal weights expressed as a percentage of chilled side including bone-in Boston butt, trimmed loin, and trimmed ham with primal weights decreasing with increasing inclusion of dietary HOSO. Overall, pigs fed HOSO2 had reduced ADFI with similar backfat thickness and standardized fat-free lean compared with pigs fed the DDGS treatment. However, pigs fed HOSO 4 and 6% had improvements in ADFI and G:F, but also had increased backfat thickness which resulted in reductions in standardized fat-free lean and primal weights expressed as a percentage of chilled side weight.

The objective of this study was to determine the effect of chronic inflammation during late gestation on offspring muscle development. Starting at gestational day (GD) 70, first-parity gilts were administered either lipopolysaccharide (LPS, n=7) or saline (CON, n=8) via jugular venipuncture every other day until GD 84. LPS was initially given at 10 µg/kg BW and was increased by 12% each instance of administration. Volume of PBS was increased accordingly. Rectal temperatures of gilts were collected at 0, 2, 3, and 4-h post injection. Gilts farrowed naturally at GD 114 (±2). At postnatal day (PND) 3, the pig closest to the average litter weight was euthanized, and the longissimus dorsi, psoas major, semitendinosus, heart, lungs, liver, and kidneys dissected and weighed. The semitendinosus was frozen in liquid N cooled-methylbutane and sectioned for muscle fiber typing analysis. Data were analyzed as a one-way ANOVA with cohort as a random effect and significance considered at (P ≤ 0.05). Gilts exposed to LPS had a 1.3°C increase in rectal temperature at 3 and 4-h post injection (P < 0.05), indicating successful induction of an inflammatory response. LPS exposure reduced (P = 0.04) the weight of piglets born alive and tended to reduce (P =0.09) the weight of piglets weaned, but did not alter the percent of pigs born alive or survival during the suckling period (P ≥ 0.29). Semitendinosus weight was also reduced (P < 0.01) in LPS pigs, and tended to be reduced (P =0.09) as a percentage of whole-body weight. However, there were no differences between treatments in any other tissues. Further, maternal LPS exposure did not alter fiber type proportions, average fiber area, or estimated number of fibers (P ≥ 0.17). Overall, these data indicate that chronic maternal LPS exposure during late gestation did not reduce offspring muscle fiber formation.

The objective of this study was to characterize the color stability of pork loin chops using fresh quality traits and instrumental measures of discoloration. Boneless pork loins (N=484) were evaluated for quality traits at 11 or 14 d post-mortem. One chop was cut from each loin near the 10th rib for retail display, overwrapped, and displayed under constant fluorescent lighting for 7 d. Objective color, myoglobin redox forms, and subjective visual discoloration traits were evaluated daily. After retail display, chops were categorized based on final visual discoloration (Day 7) as Very Color Stable (VCS; 0% to 5% discoloration), Color Stable (CS; 5% to 10% discoloration), Neutral (10% to 25% discoloration), Color Labile (CL; 25% to 30% discoloration), or Very Color Labile (VCL; >30% discoloration). Quality and color traits were analyzed using the GLIMMIX (visual discoloration) or MIXED (all other measures) procedure of SAS. Retail display data were analyzed as repeated measures. Chops ultimately classified as CS or VCS were darker, redder, and had lesser surface metmyoglobin (P<0.01) than CL and VCL chops at both Day 1 of retail display and throughout display. Stable chops also had generally increased R630/580 values as well as decreased visual discoloration scores and yellowness during display. A group×day interaction was observed for all traits measured during retail display (P<0.0001). No differences in aged loin ventral surface redness were observed between color stability groups (P≥0.16). Overall, chops ultimately classified as CS came from aged loins that were generally darker, redder, and less yellow, with greater pH values, greater marbling scores,and decreased purge loss.