Leaner Carcasses Research Articles

Quality and Processability of Meat in Polish Native Pigs – A Review

Abstract The primary aim of pig breeding efforts is to produce animals characterized by outstanding performance, including also fattening and slaughter performance traits. However, improved carcass leanness and reduced carcass fatness, especially intramuscular fat content, have led to a deterioration of pork quality and processability. Due to the growing frequency of meat defects and the limited potential use of such meat in the production of premium products this constitutes a considerable problem for the meat industry. The breeds superior in terms of meat quality are native pig breeds, such as those kept in Poland, i.e. Pulawska (Pul), Zlotnicka Spotted (ZS) and Zlotnicka White (ZW) pigs. The aim of this paper is to present a review of research results concerning quality and processability of meat produced by the Polish native pig breeds. The presented results indicate that pigs of local breeds exhibit a low level of performance traits (daily gain, carcass leanness, backfat thickness) while maintaining very good parameters of meat quality and processability (muscle composition and physical properties, fatty acids profile, sensory traits). Thus, they are used as a source material for premium products. In view of the small size of local populations and higher production costs in Poland it is a niche production. Therefore, the current aim of breeding indigenous breeds is both to maintain a safe population size and genetic diversity and to increase popularity of their meat and processed meat products among consumers. This objective is attained, among other things, thanks to efforts to reduce cost of their production through optimization of environmental conditions and wider use of less expensive traditional feed formulations, which make it possible to fully utilize the potential of local pork resources.

162 Effect of molasses-based liquid supplement vs. corn-based dry supplement on beef cattle feedlot performance, carcass characteristics, and intestinal length

Abstract Molasses-based liquid supplements contain sugars that can be fermented into butyrate, the primary source of energy for gastrointestinal (GIT) epithelial cells and may improve gut health and enhance beef cattle performance. The aim of this study was to examine how a molasses-based liquid supplement, in contrast to a dry-based supplement, impacts the performance, carcass characteristics, and intestinal length of beef cattle. Crossbred steers [n = 60; body weight (BW) = 381.7 ± 1.3 kg] were divided into 10 pens (5 pens per treatment; 6 steers per pen) and were assigned to one of two treatment groups: dry, which consisted of a 10% ground corn-based dry supplement, or liquid, which included a 10% liquid molasses-based supplement. All the steers were fed a high-forage diet (56%) and were transitioned to a high-grain diet (7%) on d 1 of the experiment. The animals were on feed for an average of 122 d and had ad libitum access to feed and water. Steers were weighed every 21 to 28 d, and feed intake, average daily gain (ADG), and gain to feed ratio (G:F) were assessed both overall and for two distinct periods: the initial period (IP) from d 0 to 69, and the subsequent or second period (SP) from d 70 until slaughter. Intestinal length was measured at the time of slaughter. Data analysis was performed using the GLIMMIX procedure of SAS. Body weight and ADG did not differ between treatments in either period, or overall (P ≥ 0.41). However, it is noteworthy that feed intake was greater for steers that received the dry supplement during both periods as well as across the entire study (P ≤ 0.04). In terms of G:F, steers provided with the liquid supplement demonstrated a tendency for improved efficiency in the second period (P = 0.09) and an overall greater efficiency (P = 0.04) compared with those receiving the dry supplement. Intestinal length exhibited no difference for both the small and large intestine (P ≥ 0.57). For carcass data parameters no differences were observed for hot carcass weight, dressing %, or %KPH (P ≥ 0.24). Fat depth tended to be greater (P = 0.06), and yield grade (P = 0.01) and marbling score (P = 0.03) were greater for the steers fed the dry supplement. Rib-eye area was greater (P = 0.03) for the liquid supplement group. Therefore, these findings suggest feeding a liquid based supplement to steers on a 93% concentrate diet decreases intake, maintains BW, and improves feed efficiency and carcass leanness compared with steers fed a dry supplement. However, the improvement in efficiency as a result of feeding a liquid based supplement was not caused by an increase in absorptive capacity through increased intestinal length.

Is bovine somatotropin an alternative strategy to overcome the detrimental effects of high-gain diets on prepubertal Holstein × Gyr heifers?

Feeding high-gain diets and an inadequate energy and protein ratio during pre-puberty may lead to impaired growth and mammary gland development of heifers. Thus, frequent application of bovine somatotropin (bST) may prevent future losses in productivity, improve mammary development and animal performance. We aimed to evaluate the effects of bST on digestibility, performance, blood metabolites, mammary gland development, and carcass composition of high-performance prepubertal Holstein × Gyr heifers. Thirty-four Holstein × Gyr heifers with an average initial body weight of 218 ± 49 kg and 14 ± 4 months of age were submitted to an 84-day trial evaluating the effects of no bST or bST injections. Treatments were randomly assigned to each animal within one of the tree blocks. The bST did not influence digestibility or performance parameters. Regarding blood results, IGF1 concentration presented an interaction between treatment and day, where bST heifers had the highest IGF1 concentration. Heifers receiving bST also showed increased ribeye area; however, only an experimental day effect for backfat thickness was observed, with greater accumulation of carcass fat on day 84. Heifers receiving bST had lower pixels/mm² on parenchyma, characteristic of greater parenchymal tissue. Moreover, heifers on bST treatment also had reduced pixels/mm2, characteristic of reduced fat pad tissue. Lastly, bST injections did not influence liver and muscle gene expression, nor most genes evaluated in mammary gland tissue, except for IGFBP3 expression, which was greater for bST heifers. In summary, we confirm the efficacy of bST injections to overcome the detrimental effects of high-gain diets on mammary gland growth and to improve lean carcass gain of prepubertal Holstein × Gyr heifers.

Beef production systems with dairy × beef heifers based on forage and semi-natural grassland

ABSTRACT Beef production on semi-natural grassland provides meat and nature conservation of biodiverse habitats. In this study, heifers born to a dairy cow and an Angus (ANG) or Charolais (CHA) sire were allocated to a HIGH or LOW production system, varying in indoor feed intensity, number of summers on grass and slaughter age. CHA crosses had higher liveweight gain, conformation score, and proportion of high-value retail cuts than ANG crosses, which had higher scores for fatness and marbling. The LOW system gave lower liveweight gain and carcasses with lower fatness scores than the HIGH system. CHA-LOW had leaner carcasses than the other groups. Per kilogram salable meat produced, ANG-HIGH, CHA-HIGH, ANG-LOW, and CHA-LOW resulted in 18, 15, 58, and 46 m2 grazed semi-natural grassland. These results indicate that dairy × beef heifers can be used for nature conservation grazing of semi-natural grassland while still achieving acceptable performance and market-oriented carcass characteristics.

The effects of dietary net energy on grow-finish performance and carcass characteristics of market gilts managed with immunological suppression of ovarian function and estrus (Improvest).

The objective was to determine the effects of net energy (NE) during the grow-finish period on live performance and carcass characteristics of market gilts managed with immunological suppression of ovarian function and estrus (Improvest®; IMP) compared with market gilts not managed with Improvest (CON). The 104-d study began when 1,008 gilts (11wk old; average starting weight of 30.8kg) were allocated by weight to 48 pens with 21 gilts/pen. Half of the pens were randomly selected to be managed with Improvest while the other half of the pens were not managed with Improvest. Three dietary programs differing in their NE were formulated over five dietary phases (according to standardized ileal digestible lysine requirements) to provide an average of 2,218 kcal/kg (low NE), 2,343 kcal/kg (medium NE), or 2,468 kcal/kg (high NE). The experiment was designed as a 2 × 3 factorial with main effects of Improvest management and NE. For the overall study period, there were no significant interactions (P ≥ 0.20) for average daily feed intake (ADFI), average daily gain (ADG), or Gain:Feed (G:F). There were also no significant interactions between Improvest management and NE (P ≥ 0.30) for carcass characteristics. However, IMP gilts consumed more feed (6.8% greater ADFI; P < 0.01), grew faster (5.0% greater ADG; P < 0.01), were less efficient (1.8% lower G:F; P < 0.01), heavier (3.5kg hot carcass weight; P < 0.01), and fatter (1.9mm greater backfat thickness and 1.26% less predicted lean carcass yield; P < 0.01). No difference (P = 0.21) in carcass dressing percentage between IMP and CON gilts was reported. For the overall study period, gilts fed low NE and medium NE diets consumed more feed compared with gilts fed high NE diets (6.8% more ADFI for low NE and 5.7% more for medium NE; P < 0.01), and gilts fed low NE diets grew 2.5% slower (P < 0.01) than gilts fed medium NE diets, while gilts fed high NE diets were intermediate and not different from the other NE treatments. This resulted in gilts fed Low NE diets being the least efficient (3.8% lower G:F than medium NE and 7.1% lower G:F than High NE; P < 0.01). Overall, these data indicate that typical Improvest response levels were sustained at each of the NE treatments evaluated in this study as there were no significant interactions for Improvest management and NE; however, consideration should still be provided to the known production impacts of low NE diets.

Genetic merit of sires for ad libitum residual feed intake affects feed efficiency of restricted-fed heavy pigs but not body weight gain tissue composition.

The study aimed at evaluating how sires, classified for their additive genetic effects on residual feed intake (RFI) of ad libitum-fed progeny, influence growth performance, tissue accretion, and gain composition in restricted-fed offspring (96-168 kg body weight, BW). A total of 416 purebred C21 Goland pigs, offspring of 23 sires, were randomly allocated to three feeding groups: ad libitum, restricted medium-protein, or restricted low-protein. Empty BW, body lipid mass and body protein mass were estimated from individual BW and backfat measures using literature equations. Residuals of a linear regression of average daily feed intake on average empty BW, body lipid and protein daily gains were used as estimates of individual RFI in ad libitum-fed pigs. Additive genetic effects of sires on RFI of ad libitum-fed pigs were estimated with a linear animal model and solutions of the model were used to allocate the sires to low- (LRFI), medium- (MRFI), or high-RFI (HRFI) groups. Restricted-fed progeny of LRFI sires exhibited reduced average daily feed intake (-3%) compared to MRFI and HRFI progeny. This indicates that LRFI progeny make a more efficient use of energy intake and implies that variation in RFI across families, assessed under ad libitum feeding, is related to the across-family variation in feed efficiency detected under restricted feeding. LRFI progeny exhibited also a lower feed conversion ratio (-11%), partially resulting from of a 3% increase in growth rate compared with HRFI. Thus, LRFI progeny consumed less feed, while growing at a similar or slightly higher rate than MRFI or HRFI. No significant differences across sire classes were observed for daily tissue accretion and gain composition. Hence, we can hypothesise that efficient sires would not affect carcass leanness of heavy pig progeny fed restricted.

Effects of slaughter weight on carcass characteristics, meat quality, and metabolomics profiling in the longissimus dorsi muscle of Tianfu finishing pigs.

In order to investigate the effect of slaughter weight (SW) on carcass characteristics and meat quality, we measured the carcass characteristics, meat quality, and amino acid metabolomics characteristics of longissimus dorsi (LD) muscle from Tianfu finishing (TF) pigs. Based on SW, 13 pigs were divided into three groups (100-kg group, 125-kg group, and 150-kg group with 3, 5, 5 pigs in each group, respectively). Raising SW to 125 kg or 150 kg increased average backfat thickness (P < 0.01) and intramuscular fat content (P < 0.01), and decreased shear force (P < 0.01). A total of 231 amino acid metabolome from three amino acid classes identified with metabolomics were analyzed, and 93 differentially expressed metabolites (DEMs) were identified (69 up-regulated DEMs and 24 down-regulated DEMs). The DEMs, including urea, 3-iodo-L-tyrosine, N-glycyl-L-leucine, and N, N-dimethylglycine with amino acid metabolism, were significantly induced (P < 0.01). KEGG pathway analysis showed that these DEMs were significantly enriched (P < 0.01) in 135 metabolism pathways, including pathways related to amino acid metabolism, such as arginine and proline metabolism, glycine, serine and threonine metabolism, alanine, aspartate and glutamate metabolism, tryptophan metabolism, and beta-alanine metabolism. Our research findings provided new insights into the impact of SW on amino acid distribution and theoretical support for genetic breeding of meat quality of TF pigs. However, raising SW to 125 kg, or more, decreased the carcass leanness of live TF pigs and had no benefits to pork quality attributes.

Effects of Dam and Sire Breeds on Lamb Carcass Quality and Composition in Pasture-Based Systems.

This study explored the impacts of sire and dam breed on carcass quality and composition in a pasture-based system and the use of DXA to rapidly rank carcasses for leanness. Southdown (SD) and Suffolk (SF) ewes were mated to Texel (TX) or SD rams to produce seventy-nine lambs. Lambs were raised on pasture-based systems with limited grain supplementation. Lamb birth weight was greater (p < 0.01) for TX, regardless of dam breed. Lambing rate was lower (p < 0.01) for SD than SF ewes. Circulating myostatin concentrations were greater (p < 0.05) on d 42 than d 75 or d 110 but did not differ by sire breed. Texel-sired lambs had greater (p < 0.01) carcass weight, ribeye area and quality grade compared to SD-sired. Total and primal fat mass as predicted from DXA was higher (p < 0.05) in carcasses from SD than TX sires. Muscles from TX lambs had greater (p < 0.05) polyunsaturated fatty acid (PUFA) composition than SD-sired. Shear force values were influenced (p < 0.01) by dam breed, muscle cut and postmortem age but not by sire breed. The use of TX sires in pasture-based systems improved carcass leanness and muscle PUFA concentrations without altering tenderness.

PSV-23 Characterization of Katahdin Lamb Carcasses in a Traditional Lamb Marketing Context

Abstract The Katahdin breed has grown in popularity in the US, but it is relatively unknown if their carcasses conform to expectations of the traditional commodity lamb industry. Purebred Katahdin wethers (n = 223) were sourced from the genetic reference flock at the U.S. Meat Animal Research Center over two consecutive years. The flock is enrolled in the National Sheep Improvement Program (NSIP) and estimated breeding values (EBV) were available on standard production traits. Lambs were assigned to one of three groups per year based on body weight (BW) and fed a common finishing diet through harvest at similar end BW (51.3 ± 5.6 kg) but varying age (223.8 ± 32.2 d). Lambs were harvested at a commercial processor, hot carcass weight (HCW) was recorded, dressing percentage (DP) was calculated, and carcasses were chilled for 24 h. Carcasses were then ribbed and 12th rib backfat thickness (BFT), and loin muscle area (LMA) were measured. Traits were analyzed in mixed models with fixed class effects of finishing group (6 levels) and rearing type (single or multiple), a linear covariate of harvest age, and a random effect of sire (n = 16). There were no differences in BW, HCW, BFT, and LMA between rearing types but lambs reared as multiples had greater DP than those reared as singles (P = 0.02; Table). End BW increased while DP decreased with lamb harvest age (P ≤ 0.03). Pearson correlation coefficients were estimated between traits including post-weaning weight (PWWT) NSIP EBV. There was a strong, positive correlation between HCW and BFT (0.52) and HCW and BWT (0.54; P &amp;lt; 0.001). In contrast, HCW was only moderately correlated to LMA (0.35; P &amp;lt; 0.001). The PWWT EBV is the best genetic predictor of post-weaning lamb growth and was moderately correlated with end BW (0.38), HCW (0.35), and LMA (0.35; P &amp;lt; 0.001). Traditional markets prefer carcasses to be 29.5 – 36.3 kg HCW and &amp;lt; 6.4 mm BFT; 91% and 51% of Katahdin carcasses were below the HCW and BFT thresholds, respectively. Katahdins are capable of producing lean carcasses that conform to packer ideals for BF when fed to harvest BW of the present study, which may reduce excess fat trimming during fabrication. However, HCW observed in the present study may suggest greater suitability for non-traditional (i.e., ethnic) markets. Lower correlations between carcass traits in Katahdin compared with past research in Western white-faced lambs may highlight important biological differences in growth and fat deposition among divergent breed types. Crossbreeding Katahdin ewes with terminal sire breeds and within breed selection will improve growth and carcass traits without exceeding HCW thresholds commonly reached in wool sheep but should be considered in tandem with other breeding objectives.

Genomic background of biotypes related to growth, carcass and meat quality traits in Duroc pigs based on principal component analysis.

As the swine industry continues to explore pork quality traits alongside growth, feed efficiency and carcass leanness traits, it becomes imperative to understand their underlying genetic relationships. Due to this increase in the number of desirable traits, animal breeders must also consider methods to efficiently perform direct genetic changes for each trait and evaluate alternative selection indexes with different sets of phenotypic measurements. Principal component analysis (PCA) and genome-wide association studies (GWAS) can be combined to understand the genetic architecture and biological mechanisms by defining biological types (biotypes) that relate these valuable traits. Therefore, the main objectives of this study were to: (1) estimate genomic-based genetic parameters; (2) define animal biotypes utilizing PCA; and (3) utilize GWAS to link the biotypes to candidate genes and quantitative trait loci (QTL). The phenotypic dataset included 2583 phenotypic records from female Duroc pigs from a terminal sire line. The pedigree file contained 193,764 animals and the genotype file included 21,309 animals with 35,651 single nucleotide polymorphisms (SNPs). Eight principal components (PCs), accounting for a total of 99.7% of the population variation, were defined for three growth, eight conventional carcass, 10 pork quality and 18 novel carcass traits. The eight biotypes defined from the PCs were found to be related to growth rate, maturity, meat quality and body structure, which were then related to candidate genes. Of the 175 candidate genes found, six of them [LDHA (SSC1), PIK3C3 (SSC6), PRKAG3 (SSC15), VRTN (SSC7), DLST (SSC7) and PAPPA (SSC1)] related to four PCs were found to be associated with previously defined QTL, linking the biotypes with biological processes involved with muscle growth, fat deposition, glycogen levels and skeletal development. Further functional analyses helped to make connections between biotypes, relating them through common KEGG pathways and gene ontology (GO) terms. These findings contribute to a better understanding of the genetic relationships between growth, carcass and meat quality traits in Duroc pigs, enabling breeders to better understand the biological mechanisms underlying the phenotypic expression of these traits.

246 Evaluation of the Complete Replacement of Soybean Meal by Rapeseed Meal on Performance and Carcass Composition of Grow-Finishing Pigs

Abstract The aim of this experiment was to evaluate the effects of replacing soybean meal (SBM) by rapeseed meal (RSM) as main protein source in diets for grow-finishing pigs. The trial included a total of 1,248 crossbred boars and gilts [Pietrain x (Landrace x Large White), with an initial body weight (BW) of 38.3 ± 5.29 kg (Mean ± SD)], distributed in 96 pens of 13 pigs. Pens were randomly distributed in 2 dietary treatments, balanced by BW, block and sex within each of the 8 slurry pits. The inclusion of SBM and RSM in the growing diets was 13.8% and 20.0%, whereas in the finishing diets (days 52-91) was 10.5% and 14.4%, respectively. Diets were formulated to have the same net energy (NE) value and crude protein differences were below 0.5%. To achieve isoenergetic diets, the inclusion of animal fat was increased by 2.4% and 1.7% in RSM diets compared with SBM for the growing and finishing phases, respectively. Standardized ileal digestible (SID) Lys was kept at 0.95% and 0.86% in the growing and finishing phases, respectively. Performance variables were analyzed by using a linear mixed model with treatment and sex as fixed effects and initial BW as covariate, while pit was included as a random effect. Individual carcass data were analyzed in a linear mixed model with treatment, sex and marketing group as fixed effects, and hot carcass weight as a covariate, and pen within a pit as random effect. During the growing phase, pigs showed lower ADFI when fed the RSM diet (1.68 vs. 1.62 kg; P = 0.002) that resulted in decreased ADG (0.842 vs. 0.803 kg; P = 0.015), but FCR was not affected (2.00 vs. 2.02; P = 0.459). Contrarily, in the finishing phase, ADFI was not significantly reduced (1.98 vs. 1.95 kg; P = 0.586) but less FCR was observed when feeding RSM (2.59 vs. 2.49; P = 0.007). Final BW was not significantly affected (112.0 vs. 110.7 kg; P = 0.404), but hot carcass weight tended to be less in RSM fed pigs (92.2 vs. 91.3 kg; P = 0.078). No significant differences were reported on carcass yield (P = 0.815), carcass leanness (P = 0.850) or backfat thickness (P = 0.850). In conclusion, feeding growing pigs diets without SBM might negatively affect their performance during the growing phase, but those effects can be partly counteracted in the finishing phase without modifying carcass composition.

71 Effects of Late Gestational Nutrient Restriction on Calf pre-Weaning Growth, Backgrounding and Feedlot Performance, and Carcass Composition

Abstract Fall-calving Hereford-SimAngus heifers [single-sired; BW: 451 ± 28 (SD) kg; BCS: 5.4 ± 0.7] bred to a single sire were individually fed 100% (control; CON; n = 12) or 70% (nutrient restricted; NR; n = 13) of NASEM metabolizable energy and metabolizable protein requirements for maintenance, pregnancy, and growth from day 160 of gestation to calving. Post-calving, all females were fed chopped tall-fescue hay supplemented to meet lactational nutrient requirements in Calan gates to constrain diets of calves to milk only until day 147, then pen-fed in drylots until weaning at day 242 ± 3 (SD). Post-weaning, calves were fed a tall fescue hay-based backgrounding diet in the same large drylots for 53 ± 12 d, then moved to partially covered pens with GrowSafe feeding systems in 2 groups and fed a corn-based feedlot diet (formulated to be 18.3% CP, 1.21 Mcal NEg/kg, DM basis; 89% DM) for 255 ± 3 d (similar days on feed rather than carcass endpoint). Cattle were harvested in a commercial plant, and camera carcass grading was performed. Data were analyzed with maternal treatment, calving date, and calf sex (when P &amp;lt; 0.25) as fixed effects; feedlot group was included for feedlot and carcass measures. We previously reported that birth weight was not affected (P = 0.72), but NR decreased (P &amp;lt; 0.04) milk production by 15%. Calves born to NR dams had reduced ADG from birth to day 147 (P = 0.02), day 147 to weaning (P = 0.08), and birth to weaning (P = 0.003), resulting in NR calves having 13% lighter (P = 0.004) weaning weight. Backgrounding ADG was not affected (P = 0.80) by maternal treatment; thus, feedlot entry BW was 11% less (P = 0.009) in NR calves. On day 28, 56, 84, and 112 on feed, NR calves weighed less (P ≤ 0.09) than control. Final BW was not affected (P = 0.91) by maternal treatment. Feedlot ADG was greater for NR calves from day 168 to slaughter (P = 0.02) and the overall feeding period (P = 0.03), but not before day 168 on feed (P ≥ 0.22). Calves born to NR dams had less (P = 0.02) dressing percentage, but improved (P = 0.02) yield grade and backfat thickness. Hot carcass weight, ribeye area, marbling score, and KPH were not affected (P ≥ 0.26) by maternal treatment. Percent prime, yield grade ≤ 2, and yield grade ≥ 4 were not affected (P ≥ 0.29) by maternal treatment. Overall, late gestational nutrient restriction decreased growth pre-weaning but increased late finishing growth, without affecting backgrounding or early feedlot growth. These cattle had leaner carcasses after similar days on feed, suggesting that late gestational nutrient restriction altered growth patterns or body composition.

PSI-A-10 Correlations of NR3C1 Gene Expression with Pork Quality and Carcass Characteristics

Abstract Genetic control of carcass and meat quality traits is of great interest to the pork industry, and Hypothalamic-Pituitary-Adrenal (HPA) activation has been reported to have an inverse relationship with lean carcass growth traits in swine. The objective of this study was to determine if transcript abundance of the glucocorticoid receptor (NR3C1) in liver is associated with carcass trait variation. The liver is a key player in energy partitioning towards muscle or adipose accretion, and hepatic glucocorticoid receptors that bind cortisol are known to play a role in glucose metabolism. We hypothesized that NR3C1 expression levels are associated with differences in pork quality and carcass traits. We collected liver tissue from 18 gilts at slaughter (avg. BW =127 kg, age at slaughter = 164 d). Additionally, we collected measurements of carcass traits including dressing percentage, loin muscle area, 10th-rib backfat depth, subjective color and marbling scores, Minolta Colorimeter measures of L*, a*, b*, 45-min and ultimate pH, and driploss (Table 1). We extracted RNA from liver samples using a Qiagen miRNeasy kit and performed qRT-PCR using a TaqMan assay to quantify NR3C1 transcript abundance, with ACTB and HPRT1 as reference genes. Pearson correlation analysis was conducted between the carcass traits and NR3C1 expression. While liver NR3C1 transcript abundance was not significantly correlated with a majority of these traits, it was found to have a significant positive correlation with dressing percentage (r = 0.606, t = 3.05, P = 0.008). In conclusion, transcript abundance of NR3C1 in liver does not appear have a relationship with carcass merit and meat quality, but does have a positive relationship with dressing percentage. Further investigation into tissue-specific expression of NR3C1 may reveal the molecular mechanisms underlying the reported associations between HPA activation and differences in pork quality and carcass traits.

Nutritional strategies to reduce growth of pigs during emergency situations

Multiple feeding strategies have been shown to reduce growth in emergency situations. Feeding low protein diets decreased average daily gain (ADG) up to 71% depending on the degree of restriction and resulted in decreased carcass leanness. Feeding excess methionine decreased ADG up to 67%, with limited effects on carcass leanness. Feeding methionine in the diet above 2% may result in body weight loss. Feeding calcium chloride or ammonium chloride decreased ADG up to 98% depending on the dietary electrolyte imbalance imposed and can result in leaner carcasses and potentially poorer meat quality as measured by color, pH, and tenderness.

Estimating energy utilization in laying hens: what are the best response criteria?

An experiment was conducted to evaluate the effects of varying dietary energy on the performance and energy storage in laying hens from 36 to 52 wk of age. A total of 252 Hy-Line W-36 laying hens were housed in cages with 3 birds per cage and 12 replicate cages per treatment. Birds were control fed 1 of 7 experimental diets ranging in dietary energy from 2,750 to 3,050 kcal/kg with a 50 kcal/kg difference among each of the diets. Egg production, energy intake, feed intake, egg weight, egg mass, and feed efficiency were calculated every 2 wk so that performance data could be analyzed every 2 wk using repeated measures analysis. Hens were weighed every 4 wk for repeated measures analysis and carcass total, lean, and fat mass were determined at 52 wk using dual X-ray absorptiometry. Correlations between dietary energy and energy intake with performance parameters, and body composition were generated. Dietary energy (kcal/kg) was significantly correlated with all performance parameters except hen housed egg production (HHEP; P = 0.07) and lean carcass mass (P = 0.60). For dietary energy, the highest correlations were total carcass mass (r = 0.60) and carcass fat mass (r = 0.54). Energy intake (kcal/d) was significantly correlated with all performance parameters except feed intake (P = 0.18). The highest correlations were between energy intake and total carcass mass (r = 0.63) or body weight (r = 0.51). These results suggest that dietary energy has a more pronounced effect on body mass and fatty tissue over the short run (16-wk period) before direct performance responses are observed. Therefore, hen body weight and composition can be used as a more sensitive measurement of shorter-term hen energy status than egg production or feed efficiency.

An update of the predicted lean yield equation for the Destron PG-100 optical grading probe.

The objective was to update the equation used for prediction of pork carcass leanness with the Destron PG-100 optical grading probe. A recent cutout study (completed in 2020-2021) consisting of 337 pork carcasses was used for this research. An updated equation was generated using a calibration dataset (N = 188 carcasses) and prediction precision and prediction accuracy of the new equation was evaluated using a validation dataset (N = 149 carcasses). The updated equation was generated using forward stepwise multiple regression selection techniques in PROC REG of SAS, and the same parameters as the existing equation were used to fit the model. The updated Destron equation [89.16298 - (1.63023 × backfat thickness) - (0.42126 × muscle depth) + (0.01930 × backfat thickness2) + (0.00308 × muscle depth2) + (0.00369 × backfat thickness × muscle depth)] and the existing Destron equation [68.1863 - (0.7833 × backfat thickness) + (0.0689 × muscle depth) + (0.0080 × backfat thickness2) - (0.0002 × muscle depth2) + (0.0006 × backfat thickness × muscle depth)] were similar in their prediction precision for determination of carcass lean yield (LY), with the updated equation R2 = 0.75 and root mean square error (RMSE) = 1.97 and the existing equation R2 = 0.75 and RMSE = 1.94. However, when prediction accuracy was evaluated using the variance explained by predictive models based on cross-validation (VEcv) and Legates and McCabe's efficiency coefficient (E1), the updated equation (VEcv = 67.97%; E1 = 42.41%) was much more accurate compared with the existing equation (VEcv = -117.53%; E1 = -69.24%). Furthermore, when accuracy was evaluated by separating carcasses into 3% carcass LY groupings ranging from less than 50% LY to greater than 62% LY, the existing equation correctly estimated carcass LY 8.1% of the time, while the updated equation correctly estimated carcass LY 47.7% of the time. In an effort to further compare the abilities of the updated equation, comparisons were made with an advanced automated ultrasonic scanner (AutoFom III), which scans the entire carcass. The prediction precision of the AutoFom III was R2 = 0.83 and RMSE = 1.61, while the AutoFom III correctly estimated carcass LY 38.2% of the time and prediction accuracy calculations for the AutoFom III were VEcv = 44.37% and E1 = 21.34%). Overall, refinement of the Destron PG-100 predicted LY equation did not change prediction precision, but substantially improved prediction accuracy.

Comparison of an advanced automated ultrasonic scanner (AutoFom III) and a handheld optical probe (Destron PG-100) to determine lean yield in pork carcasses.

This study compared the accuracy of two methods for predicting carcass leanness (i.e., predicted lean yield) with fat-free lean yields obtained by manual carcass side cut-out and dissection of lean, fat, and bone components. The two prediction methods evaluated in this study estimated lean yield by measuring fat thickness and muscle depth at one location with an optical grading probe (Destron PG-100) or by scanning the entire carcass with advanced ultrasound technology (AutoFom III). Pork carcasses (166 barrows and 171 gilts; head-on hot carcass weights (HCWs) ranging from 89.4 to 138.0 kg) were selected based on their fit within desired HCW ranges, their fit within specific backfat thickness ranges, and sex (barrow or gilt). Data (n = 337 carcasses) were analyzed using a 3 × 2 factorial arrangement in a randomized complete block design including the fixed effects of the method for predicting lean yield, sex, and their interaction, and random effects of producer (i.e., farm) and slaughter date. Linear regression analysis was then used to examine the accuracy of the Destron PG-100 and AutoFom III data for measuring backfat thickness, muscle depth, and predicted lean yield when compared with fat-free lean yields obtained with manual carcass side cut-outs and dissections. Partial least squares regression analysis was used to predict the measured traits from image parameters generated by the AutoFom III software. There were method differences (P < 0.01) for determining muscle depth and lean yield with no method differences (P = 0.27) for measuring backfat thickness. Both optical probe and ultrasound technologies strongly predicted backfat thickness (R2 ≥ 0.81) and lean yield (R2 ≥ 0.66), but poorly predicted muscle depth (R2 ≤ 0.33). The AutoFom III improved accuracy [R2 = 0.77, root mean square error (RMSE) = 1.82] for the determination of predicted lean yield vs. the Destron PG-100 (R2 = 0.66, RMSE = 2.22). The AutoFom III was also used to predict bone-in/boneless primal weights, which is not possible with the Destron PG-100. The cross-validated prediction accuracy for the prediction of primal weights ranged from 0.71 to 0.84 for bone-in cuts and 0.59 to 0.82 for boneless cut lean yield. The AutoFom III was moderately (r ≤ 0.67) accurate for the determination of predicted lean yield in the picnic, belly, and ham primal cuts and highly (r ≥ 0.68) accurate for the determination of predicted lean yield in the whole shoulder, butt, and loin primal cuts.

A comparison of carcass characteristics, carcass cutting yields, and meat quality of barrows and gilts.

Objectives of this research were to compare carcass characteristics, carcass cutting yields, and meat quality for market barrows and market gilts. Commercially-sourced carcasses from 168 market barrows and 175 market gilts weighing an average of 107.44 ± 7.37 kg were selected from 17 different slaughter groups representing approximately 3,950 carcasses. Each group was sorted into percentiles based on hot carcass weight with an equal number of barrows and gilts selected from each quartile so that weight minimally confounded parameters of interest. Carcass lean yield was determined for carcasses following fabrication (i.e. dissection of lean, fat, and bone tissue components) and meat quality measurements were evaluated at the time of fabrication (24 to 72 h postmortem) and following 14-d of postmortem storage. Data were analyzed as a randomized complete block design with carcass serving as the experimental unit, sex (barrow or gilt), the three hot carcass weight quantiles (light [<104 kg]; average [104 to 110 kg]; heavy [>110 kg]), and the interaction between sex and hot carcass weight quantile serving as fixed effects, and producer nested within slaughter event serving as a random effect. Results from the study demonstrated that gilt carcasses were leaner (3 mm less backfat thickness; 3.5 cm2 greater loin muscle area, 1.52% greater merchandized-cut yield, and 2.92% greater dissected carcass lean yield; P < 0.01) than barrow carcasses, while loins from barrows were higher quality (0.43% more intramuscular fat and slightly less shear force; P < 0.01) than loins from gilts. While this study confirms the well-known biological principle that barrow carcasses have greater levels of fat deposition and lower levels of carcass leanness when compared with gilt carcasses, this study provides a much-needed quantification of these differences for the commercial industry that will undoubtedly be useful as new technologies emerge in upcoming years.

'The use of dual energy x-ray absorptiometry (DXA)' to predict the veal carcass composition

The objective of this study was to evaluate the potential of dual energy X-ray absorptiometry (DXA) to estimate the carcass composition of veal calves. A total of 15 newborn Holstein × Gyr male calves were randomly assigned to two dietary treatments: calves fed exclusively milk or fed milk + concentrate ad libitum. Calves were assigned to four slaughter groups (7, 28, 49 and 63 days of age) and after 24 h of chilling carcasses were analyzed by DXA using the enCORE software to obtain fat, lean tissue, and bone mineral content and density. Afterward, carcasses were dissected into lean, fat, and bone tissues that were ground and lyophilized to determine the carcasses chemical composition. The DXA predicted the protein (P < 0.0001, R2 = 0.7290), mineral (P = 0.002, R2 = 0.6119) contents, proportions of muscle (P < 0.001, R2 = 0.6986) and bone of veal carcasses (P < 0.0001, R2 = 0.6982), but not fat (P = 0.9557, R2 = 0.002). In conclusion, the DXA measured values were able to predict veal carcass protein, mineral contents, lean and bones amount but was not precise enough to detect the fat tissue on lean carcasses such as those from veal calves.

Integrating Genome-Wide Association Study with RNA-Sequencing Reveals HDAC9 as a Candidate GeneInfluencing Loin Muscle Area in Beijing Black Pigs.

Loin muscle area (LMA) is an important meat production trait and plays a key role in determining carcass leanness. Genome-wide association study (GWAS) and RNA sequencing (RNA-seq) analysis were used to identify candidate LMA genes in Beijing Black pigs, a popular breed among consumers in northern China. Ten single nucleotide polymorphisms (SNPs) in sus scrofa chromosome (SSC) 9 were significantly associated with LMA. These SNPs were mapped to a 2.90 Mb (84.94-87.84 Mb) region. A total of 11 annotated genes were mapped on this region, namely MEOX2, CRPPA, SOSTDC1, LRRC72, ANKMY2, BZW2, TSPAN13, AGR2, AHR, SNX13, and HDAC9. In addition, RNA-seq analysis was performed between the high- and low-LMA groups, and 329 differentially expressed genes (DEGs) were identified. Further, Kyoto Encyclopedia of Genes and Genomes analysis based on DEGs revealed that the JAK/STAT signaling pathway and oxytocin signaling pathway may be responsible for LMA. Both GWAS and RNA-seq analysis identified the HDAC9 gene, indicating that it may be an important candidate gene affecting LMA in Beijing Black pigs. The findings provide valuable molecular insights into the mechanisms that influence LMA content in pigs, which can be utilized in targeted approaches to enhance meat quality and commercial profitability.