Higher protein intake during resistance training does not potentiate strength, but modulates gut microbiota, in middle-aged adults: a randomized control trial.

Protein intake above the recommended dietary allowance (RDA) and resistance training are known anabolic stimuli to support healthy aging. Specifically, protein supplementation after resistance exercise and nightly are strategies to maximize utilization of protein intake above the RDA in healthy adults. As such, the primary objective was to examine the efficacy of protein supplementation and nutritional counseling resulting in either moderate (MOD: ∼1.0 g·kg-1·day-1) or higher (HIGH: ∼1.6 g·kg-1·day-1) protein intake during resistance training on strength (one-repetition maximum, 1-RM; isokinetic and isometric peak torque) in healthy middle-aged adults. Exploratory analyses include diet-exercise effects on lean body mass (LBM), clinical biomarkers, gut microbiota, and diet composition. In all, 50 middle-aged adults (age: 50 ± 8 yr, BMI: 27.2 ± 4.1 kg/m2) were randomized to either MOD or HIGH protein intake during a 10-wk resistance training program (3 × wk). Participants received dietary counseling and consumed either 15 g (MOD) or 30 g (HIGH) of protein from lean beef in the immediate postexercise period and each evening. Maximal strength (1-RM) for all upper and lower body exercises significantly increased with no effect of protein intake (P < 0.050). There was a main effect of time for LBM (P < 0.005). Cardiovascular, renal, or glycemic biomarkers were not affected by the intervention. Gut microbiota were associated with several health outcomes (P < 0.050). In conclusion, higher protein intake above moderate amounts does not potentiate resistance training adaptations in previously untrained middle-aged adults. This trial was registered at clinicaltrials.gov as NCT03029975.NEW & NOTEWORTHY Our research evaluates the efficacy of higher in comparison with moderate animal-based protein intake on resistance exercise training-induced muscle strength, clinical biomarkers, and gut microbiota in middle-aged adults through a dietary counseling-controlled intervention. Higher protein intake did not potentiate training adaptations, nor did the intervention effect disease biomarkers. Both diet and exercise modified gut microbiota composition. Collectively, moderate amounts of high-quality, animal-based protein is sufficient to promote resistance exercise adaptations at the onset of aging.

Development of Intrinsically Labeled Eggs and Poultry Meat for Use in Human Metabolic Research.

BACKGROUND: Stable isotope amino acids are regularly used as tracers to examine whole-body and muscle protein metabolism in humans. To accurately assess in vivo dietary protein digestion and absorption kinetics, the amino acid tracer is required to be incorporated within the dietary protein food source (i.e., intrinsically labeled protein). OBJECTIVE: We assessed the practicality of producing eggs and poultry meat intrinsically labeled with l-[5,5,5-(2)H3]leucine through noninvasive oral tracer administration. METHODS: A specifically formulated diet containing 0.52% leucine was supplemented with 0.3% l-[5,5,5-(2)H3]leucine and subsequently fed to 3 laying hens (Lohmann LSL Whites) for 55 d. On day 55, the hens were slaughtered and their meat, bones, and organs were harvested to determine tissue labeling. In Expt. 1, 2 healthy young men [mean ± SEM age: 22 ± 1.5 y; mean ± SEM body mass index (BMI; in kg/m(2)): 23.7 ± 0.5] ingested 18 g l-[5,5,5-(2)H3]leucine-labeled egg protein. In Expt. 2, 2 healthy young men (mean ± SEM age: 20.0 ± 0.0 y; mean ± SEM BMI: 26.4 ± 3.1) ingested 28 g l-[5,5,5-(2)H3]leucine-labeled poultry meat protein. Plasma samples (Expts. 1 and 2) and muscle biopsies (Expt. 1) were collected before and after labeled-food ingestion. RESULTS: High tracer labeling [>20 mole percent excess (MPE)] in the eggs was obtained after 7 d and maintained throughout the feeding protocol (P < 0.05). Over a 55-d period, ∼850 g egg protein (145 eggs) was produced, with a mean ± SEM tracer enrichment of 22.0 ± 0.8 MPE. Mean ± SEM l-[5,5,5-(2)H3]leucine enrichment in the meat was 9.6 ± 0.1 MPE. In Expts. 1 and 2, the consumption of labeled eggs and poultry meat protein increased plasma l-[5,5,5-(2)H3]leucine enrichment, with mean ± SEM peak values of 6.7 ± 0.1 MPE and 4.0 ± 0.9 MPE, respectively. The mean ± SEM 5-h postprandial increase in myofibrillar l-[5,5,5-(2)H3]leucine enrichment after egg ingestion in healthy young men was 0.051 ± 0.008 MPE (Expt. 1). CONCLUSION: We demonstrated the feasibility of producing intrinsically labeled eggs and poultry meat for use in human metabolic research.

Reductions in expression of growth regulating genes in skeletal muscle with age in wild type and myostatin null mice.

BACKGROUND: Genes that decline in expression with age and are thought to coordinate growth cessation have been identified in various organs, but their expression in skeletal muscle is unknown. Therefore, our objective was to determine expression of these genes (Ezh2, Gpc3, Mdk, Mest, Mycn, Peg3, and Plagl1) in skeletal muscle from birth to maturity. We hypothesized that expression of these genes would decline with age in skeletal muscle but differ between sexes and between wild type and myostatin null mice. RESULTS: Female and male wild type and myostatin null mice (C57BL/6J background) were sacrificed by carbon dioxide asphyxiation followed by decapitation at d -7, 0, 21, 42, and 70 days of age. Whole bodies at d -7, all muscles from both hind limbs at d 0, and bicep femoris muscle from d 21, 42 and 70 were collected. Gene expression was determined by quantitative real-time PCR. In general, expression of these growth-regulating genes was reduced at d 21 compared with day 0 and d -7. Expression of Gpc3, Mest, and Peg3 was further reduced at d 42 and 70 compared with d 21, however the expression of Mycn increased from d 21 to d 42 and 70. Myostatin null mice, as expected, were heavier with increased biceps femoris weight at d 70. However, with respect to sex and genotype, there were few differences in expression. Expression of Ezh2 was increased at d 70 and expression of Mdk was increased at d 21 in myostatin null mice compared with wild type, but no other genotype effects were present. Expression of Mdk was increased in females compared to males at d 70, but no other sex effects were present. CONCLUSIONS: Overall, these data suggest the downregulation of these growth-regulating genes with age might play a role in the coordinated cessation of muscle growth similar to organ growth but likely have a limited role in the differences between sexes or genotypes.

Effect of photoperiod on the feline adipose transcriptome as assessed by RNA sequencing.

BACKGROUND: Photoperiod is known to cause physiological changes in seasonal mammals, including changes in body weight, physical activity, reproductive status, and adipose tissue gene expression in several species. The objective of this study was to determine the effects of day length on the adipose transcriptome of cats as assessed by RNA sequencing. Ten healthy adult neutered male domestic shorthair cats were used in a randomized crossover design study. During two 12-wk periods, cats were exposed to either short days (8 hr light:16 hr dark) or long days (16 hr light:8 hr dark). Cats were fed a commercial diet to maintain baseline body weight to avoid weight-related bias. Subcutaneous adipose biopsies were collected at wk 12 of each period for RNA isolation and sequencing. RESULTS: A total of 578 million sequences (28.9 million/sample) were generated by Illumina sequencing. A total of 170 mRNA transcripts were differentially expressed between short day- and long day-housed cats. 89 annotated transcripts were up-regulated by short days, while 24 annotated transcripts were down-regulated by short days. Another 57 un-annotated transcripts were also different between groups. Adipose tissue of short day-housed cats had greater expression of genes involved with cell growth and differentiation (e.g., myostatin; frizzled-related protein), cell development and structure (e.g., cytokeratins), and protein processing and ubiquitination (e.g., kelch-like proteins). In contrast, short day-housed cats had decreased expression of genes involved with immune function (e.g., plasminogen activator inhibitor 1; chemokine (C-C motif) ligand 2; C-C motif chemokine 5; T-cell activators), and altered expression of genes associated with carbohydrate and lipid metabolism. CONCLUSIONS: Collectively, these gene expression changes suggest that short day housing may promote adipogenesis, minimize inflammation and oxidative stress, and alter nutrient metabolism in feline adipose tissue, even when fed to maintain body weight. Although this study has highlighted molecular mechanisms contributing to the seasonal metabolic changes observed in cats, future research that specifically targets and studies these biological pathways, and the physiological outcomes that are affected by them, is justified.

Defining a Haplotype Encompassing the LCORL-NCAPG Locus Associated with Increased Lean Growth in Beef Cattle.

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.

Effects of supplemental methionine sources in finishing pig diets on growth performance, carcass characteristics, cutting yields, and meat quality.

Supplemental methionine (Met) is widely used within the swine industry; however, data are limited regarding the effect of Met sources on carcass cutability and meat quality. The objective was to determine the effects of L-Met (LM, 99%), DL-Met (DLM, 99%), or calcium salt of DL-Met hydroxyl analog (MHA, 84%) in finishing pig diets on carcass characteristics and meat quality. At 9 weeks of age, pigs (N = 240) were allocated to 60 single-sex pens for a four-phase finishing trial that lasted 104 d. Pigs were fed a common grower diet until day 56 where pens were randomly allotted to one of the three experimental diets. For the remaining 7 wk of the finisher phase, pigs (BW = 79.9 ±â€…0.80 kg) were fed diets containing LM, DLM, or MHA, with the supplemental Met source providing 25% of standardized ileal digestible (SID) Met + cysteine (Cys) requirement based on 65% bioefficacy for MHA in comparison with LM or DLM. One pig per pen was slaughtered at the study conclusion (on day 104), and the left sides of carcasses were fabricated into subprimal cuts to determine carcass-cutting yields. Loin quality including proximate composition and shear force were measured. Hot carcass weight was not different (P = 0.34) between treatments (LM 104.5 kg; DLM 103.0 kg; MHA 101.5 kg), moreover, loin eye area was not different (P = 0.98) between treatments (LM 52.65 cm²; DLM 52.49 cm²; MHA 52.81 cm²). Boneless carcass-cutting yield was not different (P = 0.56) between treatments (LM 54.97 kg; DLM 54.82 kg; MHA 54.52 kg). Loin pH was not different (P = 0.24) between treatments (LM 5.45; DLM 5.48; MHA 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 (6.68%) treatments. Shear force was not different (P = 0.85) between treatments (LM 3.03 kg; DLM 3.06 kg; MHA 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 (18.50%) treatments. These data suggest that only minimal differences in carcass cutability and meat quality can be attributed to Met source in finishing pig diets when using 65% bioefficacy for MHA relative to L-Met or DL-Met.

The effect of chronic, non-pathogenic maternal immune activation on offspring postnatal muscle and immune outcomes.

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 µg 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)-α, interleukin (IL)-6, and IL-1ß 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 µg LPS/kg BW via intraperitoneal injection, and blood was collected at 0, 4, and 8 h postinjection to determine TNF-α concentration. INFLAM gilt TNF-α concentration increased (P < 0.01) 4 h postinjection compared to 0 h postinjection, while CON gilt TNF-α concentration did not differ between time points. INFLAM gilt IL-6 and IL-1ß 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-α concentration did not differ across time, while CON pig TNF-α concentration peaked (P = 0.01) 4 h postinjection. TNF-α concentration did not differ between treatments at 0 and 8 h postinjection, but CON pigs had increased (P = 0.01) TNF-α compared to INFLAM pigs 4 h postinjection. Overall, maternal immune activation did not alter pig muscle development, but resulted in suppressed innate immune activation.

Maternal inflammation or immune activation impacts fetal development and subsequently the offspring's postnatal performance. In particular, maternal immune activation may be detrimental to fetal muscle development and alter postnatal immune responses, both of which are vital in determining livestock efficiency. However, understanding the relationship between maternal immune activation and offspring development is difficult as many models use a live pathogen. This introduces many confounding factors, including increased mortality, persistent postnatal infection, and potential copathogens. Therefore, the objective of this study was to determine the effect of maternal inflammation on offspring muscle development and postnatal inflammatory response using repeated injections of a nonpathogenic immune stimulant. Each injection successfully induced an inflammatory response as indicated by increased rectal temperature and circulating inflammatory markers. The gestational challenge did not result in increased litter mortality. Further, muscle development was not altered in piglets exposed to gestational inflammation. However, when challenged with the same immune stimulant given to the dams, pigs exposed to maternal inflammation had a remarkably suppressed immune response compared to controls. Overall, maternal inflammation independent of infection affected offspring immune function, but not muscle development.

Effects of feeding high oleic soybean oil to growing-finishing pigs on growth performance and carcass characteristics.

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. The 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 pigs raised in two separate blocks (144 pigs each) were assigned to one of four 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% not only 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.

Feeding pigs supplemental fat to increase caloric density is a common practice in the swine industry and can result in improved feed efficiency. However, high oleic soybean oil (HOSO), a relatively new feed ingredient, has not been extensively researched in pig diets. HOSO differs from conventional soybean oil in that it contains an increased proportion of oleic acid, a monounsaturated fatty acid. Therefore, our goal was to investigate the use of HOSO in the diets of pigs in the weeks leading up to marketing. A total of 288 pigs were fed one of four diets that differed in their source of fat. One diet contained 25% dried distiller's grains with solubles (DDGS), while the other three had graded levels of HOSO (2%, 4%, or 6%). Pigs were fed diets for the last 14 wk leading up to slaughter. Pigs fed the highest level of HOSO grew more efficiently and were heavier than those fed the diet containing DDGS. However, pigs fed 6% HOSO were also fatter and yielded a reduced percentage of boneless meat cuts than those fed DDGS.

Maternal immune activation and dietary soy isoflavone supplementation influence pig immune function but not muscle fiber formation.

The goals of this study were to determine the impact of maternal PRRSV infection on offspring muscle and immune development and the potential of dietary soy isoflavones to mitigate those effects. Thirteen first-parity gilts ("gilts") were randomly allotted into one of three treatments: not infected and fed a diet devoid of isoflavones (CON), infected with porcine reproductive and respiratory syndrome virus (PRRSV) and fed the control diet (POS) or that supplemented with 1,500 mg/kg soy-derived isoflavones (ISF). Gilts were inoculated with PRRSV intranasally on gestational day (GD) 70. After farrowing (GD 114 ± 2), 1-2 offspring ("pigs") closest to the average litter weight were selected either at birth (3 ± 2 d of age) or weaning (21 ± 2 d of age) to determine body, muscle, and organ weights as well as muscle cell number and size. Four weaned pigs of average body weight within each litter were selected for postnatal immune challenge. At PND 52, pigs were injected with 5 µg/kg BW lipopolysaccharide (LPS) intraperitoneally. Serum was collected at 0, 4, and 8 h following LPS administration to analyze tumor necrosis factor alpha (TNF-α). At PND 59, pigs were administered a novel vaccine to elicit an adaptive immune response. At PND 59, 66, and 73, peripheral blood mononuclear cells were isolated and T-cell populations determined by flow cytometry. Both POS and ISF pigs exhibited persistent PRRSV infections throughout the study (PND 1-73). At PND 3, whole body, muscle, and organ weights were not different (P > 0.22) between groups, with the exception of relative liver weight, which was increased (P < 0.05) in POS compared with CON pigs. At PND 21, ISF pigs had reduced (P ≤ 0.05) whole body and muscle weights, but greater (P < 0.05) kidney weight compared with CON, and greater (P < 0.05) relative liver weight compared with CON and POS. Muscle fiber number and size were not different (P > 0.39) between groups at birth or weaning. After LPS administration, TNF-α was greatest in ISF pigs (P < 0.05) at both 0 and 8 h post-challenge. At the peak time-point of 4 h post-challenge, ISF pigs had the greatest concentration of TNF-α and CON pigs had the lowest, with POS pigs being intermediate (P = 0.01). After vaccination, ISF offspring had shifts in T-cell populations indicating an impaired immune response. These data indicate that maternal PRRSV infection may impact offspring organ growth and immune function, particularly when the dam is supplemented with isoflavones.

Gestational health challenges may influence growth performance and immunity of offspring pigs during postnatal life. In particular, porcine reproductive and respiratory syndrome virus (PRRSV) is endemic in the U.S. herd, but its effects on surviving offspring pigs are largely unknown. Further, dietary supplementation with soy isoflavones lessened the severity of PRRSV infections in weaning and growing pigs. Therefore, the goals of this study were to determine the impact of maternal PRRSV infection on offspring muscle and immune development and the potential of isoflavones to mitigate those effects. Isoflavone supplementation reduced viral load in dams 21 d after infection, but did not alter clinical illness indicators. Pig mortality was increased by PRRSV infection in dams, and surviving pigs were infected with PRRSV throughout the study. Interestingly, muscle and organ weights were not different among treatments at birth, but infected litters were lighter at weaning, likely due to postnatal infection. Muscle fiber number and size did not differ between treatments. Pigs born to infected dams had slower responses during innate immune stimulation and then failed to mount a proper vaccine response during adaptive immune stimulation. Overall, maternal infection altered offspring immune responses but not muscle fiber development. Isoflavone supplementation did not mitigate these effects.

Relationship between Inherent Cooking Rate and Warner-Bratzler Shear Force of Pork Chops Cooked to Two Degrees of Doneness.

The objective was to test inherent cooking rate differences on tenderness values of boneless pork chops when exogenous factors known to influence cooking rate were controlled. Temperature and elapsed time were monitored during cooking for all chops. Cooking rate was calculated as the change in °C per minute of cooking time. Warner-Bratzler shear force (WBSF) was measured on chops cooked to either 63 °C or 71 °C. Slopes of regression lines and coefficients of determination between cooking rate and tenderness values for both degrees of doneness (DoD) were calculated. Shear force values decreased as cooking rate increased regardless of DoD (p ≤ 0.05), however changes in tenderness due to increased cooking rate were limited (ß1 = -0.201 for 63 °C; ß1 = -0.217 for 71 °C). Cooking rate only explained 3.2% and 5.4% of variability in WBSF of chops cooked to 63 °C and 71 °C, respectively. Cooking loss explained the most variability in WBSF regardless of DoD (partial R2 = 0.09-0.12). When all factors were considered, a stepwise regression model explained 20% of WBSF variability of chops cooked to 63 °C and was moderately predictive of WBSF (model R2 = 0.34) for chops cooked to 71 °C. Overall, cooking rate had minimal effect on pork chop tenderness.

Effects of feeding high oleic soybean oil to growing-finishing pigs on loin and belly quality.

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 quality. Objectives of the study were to evaluate the effects of feeding graded levels of high oleic soybean oil (HOSO) on loin and belly quality. A total of 288 pig raised in two separate blocks (144 pigs each) were assigned to one of four 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). Following the conclusion of the feeding trial, 144 pigs were slaughtered at the University of Illinois Meat Science Laboratory. Following fabrication, loins were collected for the evaluation of fresh quality measurements and color stability. Belly quality and fatty acid composition were evaluated using skin-on natural fall bellies. There were no differences (P ≥ 0.11) in pH, visual color, lightness (L*), drip loss, or WBSF among dietary treatments. However, visual marbling was increased (P ≤ 0.01) in loin chops from pigs fed HOSO4 and HOSO6 treatments compared with chops from pigs fed the DDGS dietary treatment. Additionally, loin chops were more red (a*) (P ≤ 0.01) from pigs fed HOSO diets when compared with pigs fed DDGS. Extractable lipid was decreased (P ≤ 0.01) in fresh loin chops from pigs fed DDGS and HOSO2 diets compared with pigs fed HOSO6. There were no differences (P ≥ 0.75) in trained sensory tenderness, juiciness, or flavor for loin chops from pigs fed different dietary treatments. Pork fatty acid composition was altered by dietary HOSO inclusion, with pigs fed DDGS having (P ≤ 0.01) the greatest concentration of C16:0 and was decreased with increasing levels of HOSO inclusion. Inversely, the percentage of C18:1n-9 was least (P ≤ 0.01) in pigs fed DDGS and increased with increasing levels of HOSO inclusion. Pigs fed DDGS produced wider (P ≤ 0.03) and thinner (P ≤ 0.04) bellies with reduced flop distance compared with pigs fed HOSO diets. Overall, HOSO diets did not negatively affect fresh loin quality or sensory traits of loin chops. Furthermore, feeding HOSO to swine resulted in bellies containing greater percentages of oleic acid and reduced percentages of palmitic and linoleic acid.

Feeding pigs supplemental fat to increase caloric density is a common practice in the swine industry. However, dietary fats are also a key determinant of pork fat composition and may influence product quality. High oleic soybean oil (HOSO), a relatively new feed ingredient, differs from conventional soybean oil in that it contains an increased proportion of oleic acid, a monounsaturated fatty acid. However, HOSO has not been extensively researched in pig diets. Therefore, our goal was to investigate the use of dietary HOSO on fresh belly and loin quality. A total of 144 pigs, fed one of four diets that differed in fat source, were slaughtered at the University of Illinois Meat Science Laboratory. One diet contained 25% dried distiller's grains with solubles (DDGS), while the other three had graded levels of high oleic soybean oil (2%, 4%, or 6%). Pigs were fed diets for the last 14 weeks leading up to slaughter. Pigs fed HOSO produced thicker, firmer bellies and fat tissue containing a decreased proportion of polyunsaturated fatty acids compared with DDGS-fed pigs. Feeding HOSO had little impact on fresh loin quality and palatability compared with feeding an industry-reference diet containing DDGS.

Differences in carcass chilling rate underlie differences in sensory traits of pork chops from pigs with heavier carcass weights.

Pork hot carcass weights (HCW) have been increasing 0.6 kg per year, and if they continue to increase at this rate, they are projected to reach an average weight of 118 kg by the year 2050. This projection in weight is a concern for pork packers and processors given the challenges in product quality from heavier carcasses of broiler chickens. However, previous work demonstrated that pork chops from heavier carcasses were more tender than those from lighter carcasses. Therefore, the objective was to determine the effects of pork hot carcass weights, ranging from 90 to 145 kg with an average of 119 kg, on slice shear force and sensory traits of Longissimus dorsi chops when cooked to 63 or 71 °C, and to assess if differences in chilling rate can explain differences in sensory traits. Carcasses were categorized retrospectively into fast, medium, or slow chilling-rates based on their chilling rate during the first 17 h postmortem. Loin chops cut from 95 boneless loins were cooked to either 63 or 71 °C and evaluated for slice shear force and trained sensory panel traits (tenderness, juiciness, and flavor) using two different research laboratories. Slopes of regression lines and coefficients of determination between HCW and sensory traits were calculated using the REG procedure in SAS and considered different from 0 at P ≤ 0.05. As hot carcass weight increased, chops became more tender as evidenced by a decrease in SSF (63 °C ß = -0.0412, P = 0.01; 71 °C ß = -0.1005, P < 0.001). Furthermore, HCW explained 25% (R2 = 0.2536) of the variation in chilling rate during the first 5 h of chilling and 32% (R2 = 0.3205) of the variation in chilling rate from 5 to 13 h postmortem. Slow- and medium-rate chilling carcasses were approximately 12 kg heavier (P < 0.05) than fast chilling carcasses. Slice shear force of chops cooked to 63 and 71 °C was reduced in slow and medium chilling compared with fast chilling carcasses. Carcass temperature at 5 h postmortem explained the greatest portion of variation (R2 = 0.071) in slice shear force of chops cooked to 63 °C. These results suggest that carcasses tend to chill slower as weight increases, which resulted in slight improvements in sensory traits of boneless pork chops regardless of final degree of doneness cooking temperature.

Pork carcass weights have increased year over year for at least the past 25 yr. The poultry industry has experienced similar increases in carcass weights in the recent past. The increases in broiler carcass weights have resulted in detrimental impacts on quality. Contrary to the poultry industry, increases in pork carcass weights have resulted in a general improvement in pork quality, including tenderness. The underlying cause of these improvements has not been explained. In the present study, chilling rate was associated with carcass weights, particularly during the first 5 h postmortem. In fact, carcass temperature measured in the Longissimus dorsi muscle at 5 h postmortem was the most predictive of instrumental tenderness values when boneless pork chops were cooked according to UDSA guidelines for whole-muscle pork products. The metabolic conversion of muscle to meat is most active during this initial chilling period. Therefore, chilling rate, which is associated with carcass weight, may be influencing the conversion of muscle to meat and provide some explanation as to why heavy carcasses result in more tender pork chops.

Comparison of beta-ligands used in cattle production: structures, safety, and biological effects.

Technologies that increase the efficiency and sustainability of food animal production to provide meat for a growing population are necessary and must be used in a manner consistent with good veterinary practices, approved labeled use, and environmental stewardship. Compounds that bind to beta-adrenergic receptors (ß-AR), termed beta-adrenergic receptor ligands (ß-ligands), are one such technology and have been in use globally for many years. Though all ß-ligands share some similarities in structure and function, the significance of their structural and pharmacological differences is sometimes overlooked. Structural variations in these molecules can affect absorption, distribution, metabolism, and excretion as well as cause substantial differences in biological and metabolic effects. Several ß-ligands are available for use specifically in cattle production. Ractopamine and zilpaterol are beta-adrenergic agonists approved to increase weight gain, feed efficiency, and carcass leanness in cattle. They both bind to and activate ß1- and ß2-AR. Lubabegron is a newly developed selective beta-adrenergic modulator with unique structural and functional features. Lubabegron displays antagonistic behavior at the ß1- and ß2-AR but agonistic behavior at the ß3-AR. Lubabegron is approved for use in cattle to reduce ammonia emissions per unit of live or carcass weight. Additionally, lubabegron can withstand prolonged use as the ß3-AR lacks structural features needed for desensitization. Due to these unique features of lubabegron, this new ß-ligand provides an additional option in cattle production. The individual properties of each ß-ligand should be considered when making risk management decisions, as unique properties result in varying human food safety profiles that can determine appropriate safe ß-ligand use.

The Effect of Cooking Method and Cooked Color on Consumer Acceptability of Boneless Pork Chops.

The objective was to determine the effects of sous-vide cooking and degree of doneness on consumer eating experience of pork chops when cooked color was expected to differ. The hypothesis was consumers would prefer a cooked brown color and would rate grilled chops more acceptable than sous-vide chops. Chops were cooked to 63 °C or 71 °C using either an open-hearth grill or a sous-vide device. Participants evaluated four samples for tenderness, juiciness, flavor, and overall acceptability. Participants rated a greater percentage of chops cooked sous-vide at 63 °C as tender (82.82%), juicy (55.83%) and acceptable (60.34%) compared with all other cooking method and degree of doneness combinations. Participants rated a greater percentage of sous-vide chops as tender and acceptable compared to grilled chops. Participants rated a greater percentage of chops cooked to 63 °C as tender, juicy, flavorful, and acceptable when compared to 71 °C. Even when participants could visualize cooked color, they preferred chops cooked to 63 °C compared with chops cooked to 71 °C. Overall, participants preferred chops cooked to 63 °C compared to 71 °C regardless of the cooking method and preferred chops cooked to 63 °C using the sous-vide cooking method the most among all treatments.

Effects of feeding lubabegron on gas emissions, growth performance, and carcass characteristics of beef cattle housed in small-pen environmentally monitored enclosures during the last 3 mo of the finishing period.

The development of technologies that promote environmental stewardship while maintaining or improving the efficiency of food animal production is essential to the sustainability of producing a food supply to meet the demands of a growing population. As such, Elanco (Greenfield, IN) pursued an environmental indication for a selective ß-modulator (lubabegron; LUB). LUB was recently approved by the United States Food and Drug Administration (FDA) to be fed to feedlot cattle during the last 14 to 91 d of the feeding period for reductions in gas emissions/kg of unshrunk final BW and HCW. A 4 × 2 factorial arrangement of treatments was used with the factors of dose (0.0, 1.38, 5.5, or 22.0 mg·kg-1 DM basis) and sex (steers or heifers). Three 91-d cycles were conducted (112 cattle/cycle) with each dose × sex combination being represented by a single cattle pen enclosure (CPE; 14 cattle/CPE) resulting in a total of 168 steers and 168 heifers (n = 6 replicates/dose). There were no interactions observed between dose and sex for any variable measured in the study (P ≥ 0.063). Five gases were evaluated for all pens based on CPE concentrations relative to ambient air: NH3, CH4, N2O, H2S, and CO2. Cumulative NH3 gas emissions were reduced by feeding cattle 5.5 and 22.0 mg·kg-1 LUB (P ≤ 0.023) and tended (P = 0.076) to be lower for the cattle fed 1.38 mg·kg-1 LUB compared with the negative controls (CON). The cumulative NH3 gas emission reductions of 960 to 1032 g, coupled with HCW increases (P ≤ 0.019) of 15 to 16 kg for all LUB doses vs. CON, led to reductions in NH3 gas emissions/kg HCW for all three LUB treatments (P ≤ 0.004). Similar to HCW, reductions in NH3 gas emissions/kg of unshrunk final BW were observed for all LUB doses (P ≤ 0.009) and were attributable to both decreases in NH3 gas emissions and numerical increases in BW. Dose had no effect on cumulative emissions or emissions standardized by BW or HCW for the other four gases (P ≥ 0.268). LUB is a novel tool to reduce emissions of NH3 gas per kilogram of unshrunk live BW and hot carcass weight.

Characterizing the amount and variability of intramuscular fat deposition throughout pork loins using barrows and gilts from two sire lines.

The objective was to determine the amount and variability of intramuscular fat (IMF) in a pork loin attributable to anatomical chop location, sex, and sire line. Pigs were sired by commercially available terminal Duroc boars selected for meat quality (MQ; n = 96) or lean growth (LG; n = 96) and equally split between barrows and gilts. After slaughter and fabrication, bone-in chops were removed from four locations of each left-side loin (A = 6th rib, B = 10th rib, C = last rib, and D = 4th lumbar vertebrae). An adjacent pair of chops from each location was collected and evaluated for visual color and marbling, subjective firmness, moisture and extractable lipid (IMF) (anterior chop), and Warner-Bratzler shear force (posterior chop). Data were analyzed using the MIXED procedure of SAS as a split-plot design. Homogeneity of variances was tested on raw data using Levene's test of the GLM procedure and found to be heterogeneous. Thus, a two-variance model was fit using the REPEATED statement of the MIXED procedure, grouped by pig. The mivque(0) option of the VARCOMP procedure was used to calculate the proportion of variability that each factor contributed to the total variance. Barrows (3.64%) produced chops with greater (P < 0.01) IMF content than gilts (3.20%), and barrows (2.14) had greater (P < 0.01) IMF variability than gilts (1.23). Chops from MQ pigs (4.02%) exhibited greater (P < 0.01) IMF content than LG (2.82%), and MQ (1.76) had greater IMF variability (P < 0.01) than LG pigs (0.97). Chops from locations A (3.80%) and D (3.77%) had greater IMF than B (3.34%; P < 0.01), and A, B, and D had greater IMF than C (2.77%; P < 0.01). Variances of IMF also differed (A = 1.44, B = 1.59, C = 1.05, and D = 2.18; P = 0.01) across chop locations. Of the variability in IMF, 33.0% was attributed to sire line, 10.16% to chop location, and 4.01% to sex, with 52.83% not accounted for by these three factors. Location A chops were the most (P < 0.01) tender (2.57 kg) and C chops the least (P < 0.01) tender (2.93 kg), while B and D chops were intermediate and not different from each other. No differences in variability (P = 0.40) of tenderness were observed among chop locations (A = 0.31, kg B = 0.24 kg, C = 0.24 kg, and D = 0.23 kg). These results demonstrated that variability in tenderness values did not reflect the variability of IMF. In conclusion, chop location, sex, and sire line all contribute to the amount and variability of pork loin marbling.

Evaluation of the changes in composition of pork chops during cooking.

The objective was to determine the change in extractable lipid concentration during cooking of boneless pork chops to different endpoint temperatures. Pork loins (152 total) were used and three consecutive chops were cut from each loin. Chop 1 was evaluated raw (not cooked) for intramuscular fat (IMF) percentage. Raw IMF percentages were used to categorize the remaining two chops, from each loin, into low, average, and high marbling bins. The low bin included ≤3% IMF, the average bin included 3-4% IMF, and the high bin included ≥4% IMF. Chop 2 was cooked to 63 °C and chop 3 was cooked to 71 °C to evaluate cook loss, Warner-Bratzler shear force (WBSF), and IMF percentage. When cooked to either 63 or 71 °C, high IMF chops maintained greater (P < 0.001) IMF percentage than average and low IMF chops. Additionally, average IMF chops maintained greater (P < 0.001) IMF percentage than low chops, regardless of endpoint cooking temperature. The three marbling categories did not differ in cook loss (P = 0.28) or WBSF (P = 0.23) when chops were cooked to either 63 or 71 °C. However, both WBSF (2.76 kg) and cook loss (18.72%) were decreased (P < 0.001) in chops cooked to 63 °C compared with chops cooked to 71 °C (3.08 kg, 23.45%). Overall, differences in IMF percentages persisted even after cooking. Furthermore, IMF percentage of pork chops did not affect tenderness.

Effect of porcine reproductive and respiratory syndrome virus infection and soy isoflavone supplementation on carcass cutability and meat quality of pigs.

The objective was to evaluate the effects of porcine reproductive and respiratory syndrome virus (PRRSV) infection and dietary soy isoflavone (ISF) supplementation on carcass cutability and meat quality of commercial pigs. Barrows (21 d of age) were randomly allotted to experimental treatments that were maintained throughout the study: noninfected pigs received an ISF-devoid control diet (CON, n = 22) and infected pigs received either the control diet (PRRSV-CON, n = 20) or that supplemented with total ISF in excess of 1,500 mg/kg (PRRSV-ISF, n = 25). Pigs were penned by treatment, with six pigs within a pen. Following a 7-d adaptation, weanling pigs were inoculated once intranasally with either a sham-control (phosphate buffered saline [PBS]) or live PRRSV (1 × 105 tissue culture infective dose [TCID]50/mL, strain NADC20). Pigs were maintained on experimental diets for 166 d after inoculation and then slaughtered (192 or 194 d of age; approximately 120 kg body weight [BW]). At 1-d postmortem, left sides were separated between the 10th and 11th rib for the determination of loin eye area (LEA), backfat (BF) thickness, and loin quality (ultimate pH, instrumental color, drip loss, visual color, marbling, and firmness). Loin chops were aged 14 d postmortem prior to Warner-Bratzler shear force (WBSF) determination. Belly width, length, thickness, and flop distance were determined. Data were analyzed as a one-way ANOVA with pig as the experimental unit. Carcass yield, LEA, BF, and estimated lean percentage did not differ (P > 0.26) among treatments. Loins from CON pigs had increased ultimate pH (P = 0.01), reduced L* scores (P = 0.005) coupled with darker visual color scores (P = 0.004), were firmer (P < 0.0001), and exhibited reduced drip loss (P = 0.01) compared with PRRSV-CON and PRRSV-ISF pigs. However, WBSF did not differ (P = 0.51) among treatments after 14 d of aging. Bellies from CON pigs were more firm compared with bellies from PRRSV-CON and ISF pigs (P < 0.01). These data suggest PRRSV infection did not alter carcass characteristics but may have marginally reduced loin and belly quality. Supplementation with dietary soy isoflavones did nothing to mitigate the detrimental effects of PRRSV infection.

Effects of space allowance and marketing strategy on growth performance of pigs raised to 165 kg.

A total of 976 pigs (PIC 327 × Camborough; PIC, Hendersonville, TN; initially 22.0 ± 1.53 kg body weight [BW]) were used in a 160-d growth study to evaluate the effects of increasing space allowance and varying marketing strategies on growth performance of pigs raised to market weights of ~165 kg. Pens of pigs were blocked by location within the barn and allotted to one of six treatments. Pen served as the experimental unit, and there were eight replicate pens per treatment. The first four treatments consisted of increased initial stocking density and did not utilize topping strategies: (1) 14 pigs/pen (1.17 m2/pig), (2) 17 pigs/pen (0.97 m2/pig), (3) 20 pigs/pen (0.82 m2/pig), and (4) 23 pigs/pen (0.71 m2/pig). The fifth treatment began with 25 pigs/pen (0.66 m2/pig) and had four marketing events with the heaviest 3 pigs/pen removed on day 93, and additional pigs removed to a common inventory of 20 pigs/pen on day 122 and 17 pigs/pen on day 147 with final marketing on day 160. The final treatment began the experiment with 23 pigs/pen (0.71 m2/pig) with three marketing events to achieve a common inventory of 20 pigs/pen on day 108 and 17 pigs/pen on day 147. Pens of pigs were weighed and feed disappearance measured on days 0, 55, 93, 108, 122, 135, 147, and 160. As space allowance decreased from 1.17 to 0.71 m2/pig via increased initial pen inventory (treatments 1 to 4), overall average daily gain (ADG) and average daily feed intake (ADFI) decreased (linear, P < 0.001), while gain:feed ratio (G:F) did not differ (P > 0.05). The treatments with multiple marketing events were compared with each other and with the treatment that began with 0.71 m2/pig and only marketed once at the end of the study. Overall ADG and ADFI were not different (P > 0.05) among these three treatments. Marketing pigs three or four times improved (P < 0.05) G:F compared with the treatment that began the study with 0.71 m2/pig and marketed only once. Reducing floor space allowance for heavy weight pigs decreased intake, which resulted in lower growth rate and final BW, with these reductions occurring before the critical k-value was reached. Total weight gain per pen was maximized with the lowest space allowance and the multiple marketing treatments. Thus, strategic use of pig removals prior to final marketing may allow producers to maximize both number of pigs and total weight marketed through a barn when feeding to heavy weights.

Final internal cooking temperature of pork chops influenced consumer eating experience more than visual color and marbling or ultimate pH.

The objective was to determine the effect of "quality grade" (combination of visual color and marbling) or ultimate pH on consumer eating experience of pork chops cooked to different final internal temperatures. The hypothesis was that consumers would rate a greater percentage of pork chops as acceptable when graded "choice," had a greater ultimate pH, or when cooked to 63 °C compared with chops graded "standard," had a lesser ultimate pH, or when cooked to 71 or 82 °C. Consumers (264 total) were served chops in 1 of 2 experiments. Chops in Exp. 1 were classified as "choice" when NPPC visual color score ≥3 and visual marbling score was ≥2 or "standard" when NPPC scores did not meet the qualifications for "choice" and were cooked to either 63 or 71 °C. Chops in Exp. 2 were categorized as high pH (5.88 to 6.23) or low pH (5.36 to 5.56) and cooked to 63, 71, or 82 °C. Chops were cooked with a sous-vide device (ANOVA Precision Cooker, Anova Applied Electronics, San Francisco, CA) in a water bath. Consumers used a 9-point Likert-type score system where scores 1 through 3 were considered not tender, not juicy, not flavorful, or unacceptable. Scores 4 through 6 were consider neutral for tenderness, juiciness, flavor, and overall acceptability. Scores 7 through 9 were considered tender, juicy, flavorful, and acceptable. Data were organized as a percentage of responses and analyzed using the GLIMMIX procedure of SAS for both experiments with models including treatment (quality grade, ultimate pH, and final internal temperature) and all interactions. Quality grade did not affect (P ≥ 0.30) consumer ratings for any sensory trait. More (P < 0.01) consumers rated chops with a high pH (36.07%) as juicy compared with chops with a low pH (24.29%), but pH category did not alter (P ≥ 0.13) perceptions for tenderness, flavor, or overall acceptability. In both studies, a greater (P < 0.001) percentage of consumers rated chops cooked to 63 °C as acceptable compared with chops cooked to 71 °C. Therefore, internal cooking temperature has a greater impact on consumer eating experience than "quality grade" or ultimate pH.