Phosphoproteome analysis of sarcoplasmic and myofibrillar proteins in bovine longissimus muscle in response to postmortem electrical stimulation.

Protein phosphorylation changes of the sarcoplasmic and myofibrillar proteins in beef longissimus muscle in response to electrical stimulation (ES) was investigated. Sarcoplasmic and myofibrillar proteins purified from muscle samples taken at 0, 3 and 10h after ES were separated on SDS-PAGE and stained with phosphorous and protein specific stains. There was a significant effect of ES on phosphorylation of total sarcoplasmic and myofibrillar proteins (P<0.05). However, although there an instant effect of ES on the phosphorylation level of the myofibrillar proteins, the ES effect on the sarcoplasmic proteins (P<0.05) was first observed after 3h. Several protein bands were analyzed by LC-MS/MS, revealing that the major glycolytic proteins, including glycogen debranching enzyme, glycogen phosphorylase and 6-phosphofructokinase probably are affected by ES together with different heat shock proteins. This work gives an insight into the regulation of the glycolytic enzymes and muscle contraction on application of electrical stimulation.

A comparative study of beef quality after ageing longissimus muscle using a dry ageing bag, traditional dry ageing or vacuum package ageing.

The objective of this study was to investigate beef quality of longissimus muscle after ageing in dry ageing bags, traditional dry ageing or vacuum for 8 or 19 days. Lower ageing weight loss, odour score and microbial growth were found in meat aged in dry ageing bags than after traditional dry ageing. The sensory panel detected no differences for most of the sensory attributes between samples using the two dry ageing methods, except for the odour of the cutting surface. The dry-aged steaks had more umami and butter fried meat taste compared with vacuum-aged steaks. Ageing time affected most of the sensory traits in this study, which improved as ageing time increased from 8 to 19 days. In a consumer test, meat aged for 21 days in dry ageing bags was preferred than the samples aged in vacuum. This may be due to the higher tenderness and juiciness obtained during storage in dry ageing bags than meat aged in vacuum.

Consumer preference and effect of correct or misleading information after ageing beef longissimus muscle using vacuum, dry ageing, or a dry ageing bag.

The objective of this study was to determine which ageing treatment of beef was sensorially preferred by consumers and how their preference changed when given information about the ageing treatment used. Longissimus thoracis et lumborum from four young bulls were randomly assigned three ageing treatments: dry ageing, vacuum ageing and ageing in a highly moisture permeable bag (bag dry-ageing); each was aged at 1.6 °C for another 13 days. A preference test (171 consumers) with questions about overall liking, tenderness, and juiciness was performed. Thereafter, a deceptive test (61 consumers) was performed with two taste samples, the first taste sample with correct information about ageing treatment and the second with false information. In the preference test, consumers preferred dry ageing and bag dry-ageing to vacuum ageing. In the deceptive test, dry ageing was preferred, but the information given influenced preference.

Meat quality, microbiological status and consumer preference of beef gluteus medius aged in a dry ageing bag or vacuum.

This study investigated meat quality and consumer preference after ageing beef gluteus medius in a water vapour-permeable dry-ageing bag or in vacuum for 14 days. Higher ageing and trim losses but lower thawing loss, cooking loss and water content were found in samples aged in dry ageing bags compared to those aged in vacuum. Samples aged in dry ageing bags had higher total bacteria and yeast counts but lower lactic acid bacteria counts than those aged in vacuum, both before and after trimming. Meat aged in dry ageing bag was more tender and juicier and overall preferred by consumers compared with samples aged in vacuum. Female participants outperformed the males in detecting differences in palatability. No differences were found in pH, smell, shear force, colour, Enterobacteriaceae, and mould counts. Thus, by using a dry ageing bag, it is possible to produce dry-aged meat in a more controlled condition without negative effects on sensory or other quality attributes.

Association of polymorphisms at DGAT1, leptin, SCD1, CAPN1 and CAST genes with color, marbling and water holding capacity in meat from beef cattle populations in Sweden.

The objective of this study was to investigate the associations of single nucleotide polymorphisms (SNPs) at five candidate genes with meat pH, color, marbling and water holding capacity (WHC) in young bulls from five beef breeds (n=243) in Sweden. The UASMS2 polymorphism at the leptin gene and the SNPs at the Stearoyl-CoA desaturase 1 gene (SCD1.878) and µ-calpain gene (CAPN1:c.947) were associated with variation in meat color traits after 6days of exposure to air. The K232A polymorphism at the diacylglycerol O-acyltransferase 1 (DGAT1) gene and the CAPN1:c.947 SNP were associated with level of beef marbling. There was no association between the SNP at the calpastatin gene (CAST:c.155) and meat quality traits, nor was there any association of the tested SNPs with WHC traits and pH value.

Influence of vacuum skin packaging on color stability of beef longissimus lumborum compared with vacuum and high-oxygen modified atmosphere packaging.

The objective of this study was to investigate how color stability of beef is affected by vacuum skin packaging (VSP) compared with vacuum packaging (VP) and high-oxygen modified atmosphere packaging (MAP; 80% O2 and 20% CO2). Longissimus lumborum muscles were aged in vacuum for 7 days and then cut into 2-cm-thick slices and repacked using VSP, VP and MAP for another 7 days. Color stability was measured during the next 5 days in air and samples for α-tocopherol and NADH analyses were obtained at the beginning and end of aerobic storage. Color stability, α-tocopherol and NADH of steaks were affected by packaging methods and storage time in air (P<0.05). Higher a* value was obtained in VSP on day 5 compared with VP. Steaks packed in VSP had better color stability than in VP and their color was similar to MAP at the end (day 5) of storage.

Effects of pelvic suspension of beef carcasses on quality and physical traits of five muscles from four gender-age groups.

Pelvic and Achilles suspension methods for beef carcasses were compared for four gender-age groups (24month bulls, 34month bulls, heifers, and cows) and five muscles [M. longissimus dorsi (LD), M. semimembranosus (SM), M. adductor (AD), M. psoas major (PM), and M. gluteus medius (GM)]. Pelvic suspension increased muscle and sarcomere lengths in the SM, LD, GM, and AD muscles. The following effects were significant (p<0.05). Peak force was reduced by pelvic suspension in the LD and GM of bulls-24 and bulls-34, but not heifers and cows. Furthermore, peak forces decreased for the SM after pelvic suspension in bulls-24, bulls-34, and heifers. For the AD, the only decrease in peak force was for bulls-34. Water-holding capacity increased and purge in vacuum bags decreased for pelvic suspension of all muscles except the PM. Although the effects of pelvic suspension varied somewhat between gender-age groups and muscles, this method of hanging carcasses merits industrial consideration because it improves muscle yields, tenderness, and reduces variation within muscles.

Postmortem changes in pork muscle protein phosphorylation in relation to the RN genotype.

Postmortem changes in pork muscle protein phosphorylation in relation to the RN(-) genotype were investigated using one-dimensional gel electrophoresis and a phosphor specific staining. The phosphorylation levels of several protein bands were found to be affected by the RN(-) genotype and to change during postmortem development. Glycogen phosphorylase, phosphofructokinase, and pyruvate kinase were found in protein bands affected by the RN(-) genotype, and the phosphorylation profile indicates that part of the increased rate and extended pH decline of the RN(-) genotype could be a consequence of phosphorylation of these key enzymes during the postmortem metabolism. The results illustrate that the protein phosphorylation level of the muscle proteins could be interpreted as a global metabolic fingerprint containing information about the activity status of the enzymes in the postmortem metabolism.

Early immunocastration of male pigs with Improvac(®) - effect on boar taint, hormones and reproductive organs.

The aim of this study was to investigate the effect of a vaccine against gonadotropin-releasing hormone (GnRH), Improvac(®) (Pfizer Ltd), administered at a pre- or early pubertal stage on boar taint, hormonal status and reproductive organs. Crossbred male pigs (Swedish Yorkshire dams×Swedish Landrace sires or Swedish Yorkshire sires, n=192) were at birth randomly allocated to four groups: one group of pigs surgically castrated without anaesthesia before age 1 week, a second group of early vaccinated pigs given Improvac at ages 10 and 14 weeks, a third group of standard vaccinated pigs given Improvac at ages 16 and 20 weeks, and a fourth group of entire male pigs. Following the second vaccine injection, antibody titres increased rapidly, accompanied by a rapid decrease in testosterone and a slower decrease of skatole in plasma to the same low levels as for surgically castrated pigs. At slaughter, the levels of androstenone and skatole in adipose tissue were low in surgically castrated and vaccinated pigs, whereas entire male pigs had elevated levels (p<0.001). Similarly, oestradiol was at low levels for surgically castrated and vaccinated pigs, whereas entire male pigs had elevated levels (p<0.001). IGF-1 was lowest for surgically castrated pigs and highest for entire male pigs, with vaccinated pigs at an intermediate level (p<0.001). At slaughter, reproductive organs were small in pigs vaccinated with Improvac, and smaller in pigs vaccinated early (p<0.001). Under our experimental conditions, early vaccination with Improvac can be used as an alternative to the recommended schedule with maintained control of boar taint and testicular secretory activity.

Effects of early vaccination with Improvac(®) on the development and function of reproductive organs of male pigs.

Gonadotropin-releasing hormone (GnRH) vaccine (Improvac(®)) is effective at diminishing boar taint by interfering with testis function. Early pre-pubertal vaccination at 10 and 14 weeks-of-age could be desirable if sufficient and sustained effects could be achieved. Crossbred male pigs (n=24) were randomly assigned to three groups each with eight individuals: an unvaccinated control group, one group vaccinated with Improvac(®) early at ages 10 and 14 weeks, and a third group vaccinated with Improvac at the standard ages of 16 and 20 weeks. The average age at slaughter was 25 weeks. At slaughter, reductions in testes weight and bulbourethral gland length of vaccinated pigs compared with controls were observed (P<0.001), accompanied by lowered testosterone concentrations in peripheral blood (P<0.001). The diameter of tubuli seminiferi was affected; being 18% smaller in standard and 38% smaller in early vaccinated males, compared with controls (P<0.01). Leydig cells in vaccinated pigs became pycnotic, and their number decreased in early vaccinated pigs. Spermatogenesis was disrupted, evidenced by spermatocyte loss among standard vaccinated pigs to severe spermatogenic arrest among early vaccinated pigs. This histological picture was reflected in the absence of epididymal spermatozoa in 5 of 8 early vaccinated pigs and a dramatic reduction in the remaining 3 early vaccinated pigs. Among standard vaccinated pigs, 5% of the spermatozoa were morphologically normal (>70% in controls, P<0.01). Early vaccination caused a more severe disruption of testicular structure and function than standard vaccination, thus providing an alternative for immunocastration of male pigs.

Effect of low-voltage electrical stimulation after dressing on color stability and water holding capacity of bovine longissimus muscle.

The effect of low voltage electrical stimulation after dressing (ES) on color stability and water holding capacity (WHC) of beef was investigated. Nine Swedish red cattle were slaughtered and the left side was electrically stimulated (80 V, 35 s) approximately 30 min after stunning, whereas the other side was not treated and used as control. Color and its stability, WHC, and protein solubility were evaluated on longissimus lumborum muscles from the two sides. ES produced a brighter red color at 24h mainly by increasing the oxygenation capacity of myoglobin (P<0.01), which was attenuated by postmortem aging. ES did not affect WHC, protein solubility and color stability (P>0.05). Therefore, this technology could accelerate meat tenderization without any negative effect on commercial attributes, such as color or drip of bovine longissimus muscle.

Vacuum skin pack of beef--a consumer friendly alternative.

The aim of this study was to assess how beef quality traits are affected by skin packaging compared with vacuum and high-oxygen modified atmosphere packaging (MAP; 80% O(2) and 20% CO(2)). Both M. longissimus dorsi from 6 young bulls were cut and aged in vacuum for 7 days and then cut into 3.5-cm steaks, thereafter either frozen directly day 7 or stored in skin pack, vacuum pack or MAP for an additional 7 or 14 days and then frozen. Warner-Bratzler shear force, loss and colour were measured and sensory analysis was performed. The results showed no differences in shear force, sensory analysis and total loss between steaks packed in skin pack or vacuum, but skin packed steaks had lower purge loss. MAP steaks had lower sensory scores than the other treatments at days 14 and 21. Raw MAP-steaks were bright red, but showed signs of premature browning when cooked.

Influence of vacuum or high-oxygen modified atmosphere packaging on quality of beef M. longissimus dorsi steaks after different ageing times.

The objective of the study was to determine if beef quality parameters differ between steaks in modified atmosphere packaging (MAP; 80% O2and 20% CO2) and in vacuum packaging. Both M. longissimus dorsi (LD) from ten young bulls were cut in steaks day 3 postmortem and frozen either directly or after storage for 5 or 15 days in MAP and/or vacuum. The parameters studied were Warner Bratzler shear force, colour stability, α-tocopherol content, protein oxidation, water holding capacity and sensory attributes. Steaks stored in MAP had higher shear force than steaks stored in only vacuum at all ageing times. Tenderness and juiciness were negatively affected by storage in MAP. Ageing in MAP induced higher levels of metmyoglobin compared with vacuum ageing. In conclusion, high-oxygen MAP negatively influenced shear force, thawing loss, α-tocopherol content and colour stability, as well as the sensory attributes tenderness, juiciness and to some extent meat flavour.

Ageing of large cuts of beef loin in vacuum or high oxygen modified atmosphere--effect on shear force, calpain activity, desmin degradation and protein oxidation.

The aim was to investigate the effect of ageing large beef cuts directly in high oxygen modified atmosphere (MA) and how ageing time in vacuum influence meat quality when followed by retail packaging in high oxygen MA. Large cuts (10 cm long) of beef loin (LD) were aged for up to 25 days postmortem in different ageing systems at 4 degrees C. Ageing solely in high oxygen modified atmosphere (MA, 80% O(2)+20% CO(2)) for 5 or 10 days and ageing in vacuum for 5 or 15 days followed by high oxygen MA for 5 or 10 days were compared with ageing in vacuum for 5, 15 and 25 days. Warner-Bratzler shear force, purge and cooking losses, calpain activity and desmin and carbonyl contents were measured. Shear force decreased to the same level when ageing this large beef cut solely in high oxygen MA for 5 or 10 days as when ageing in vacuum. The activity of mu-calpain disappeared, the activity of m-calpain decreased and purge loss increased between 5 and 10 days, but cooking loss and the contents of desmin and carbonyls were unaffected. The ageing time in vacuum before packaging of this large beef cut in high oxygen MA did not affect the ultimate shear force. The m-calpain activity decreased and the content of carbonyls increased compared with solely in vacuum after 15 days of total ageing, but there was no difference in the content of desmin or cooking loss between these ageing systems at the same ageing time.

Perceptual masking of boar taint in Swedish fermented sausages.

Surgical castration of male piglets has traditionally been practiced to avoid development of boar taint in pork meat which can occur if entire male pigs are raised. Boar taint is commonly characterised as exhibiting the odour and flavour of urine and manure. This study involves sensory characterisation of the possibilities to mask boar taint in meat from entire male pigs by fermentation and smoking to maintain high sensory quality in meat products if castration is prohibited. Model and commercial type Swedish fermented sausage products based on low or high levels of boar tainted fat, three different starter cultures and two different levels of smoking were studied. In the model sausages, liquid smoke masked the perception of boar taint. In contrast, the smoking procedure of the commercial sausages was insufficient to totally mask the perception of boar taint. In both the model and commercial sausages, the aroma development from the starter cultures lowered the perception of boar taint but was insufficient for total perceptual masking. Due to the total masking effect of smoking in the model sausages, it was clear that smoke may present a potential solution to remove the perception of boar taint in fermented sausages if the smoking procedure is optimised.

Genome-wide identification of quantitative trait loci in a cross between Hampshire and Landrace II: meat quality traits.

BACKGROUND: Meat quality traits are important in pig breeding programs, but they are difficult to include in a traditional selection program. Marker assisted selection (MAS) of meat quality traits is therefore of interest in breeding programs and a Quantitative Trait Locus (QTL) analysis is the key to identifying markers that can be used in MAS. In this study, Landrace and Hampshire intercross and backcross families were used to investigate meat quality traits. Hampshire pigs are commonly used as the sire line in commercial pig breeding. This is the first time a pedigree including Hampshire pigs has been used for a QTL analysis of meat quality traits. RESULTS: In total, we analyzed 39 meat quality traits and identified eight genome-wide significant QTL peaks in four regions: one on chromosome 3, two on chromosome 6 and one on chromosome 16. At least two of the QTLs do not appear to have been detected in previous studies. On chromosome 6 we identified QTLs for water content in M. longissimus dorsi (LD), drip loss in LD and post mortem pH decline in LD. On chromosomes 3 and 16 we identified previously undetected QTLs for protein content in LD and for freezing and cooking loss respectively. CONCLUSION: We identified at least two new meat quality trait QTLs at the genome-wide significance level. We detected two QTLs on chromosome 6 that possibly coincide with QTLs detected in other studies. We were also able to exclude the C1843T mutation in the ryanodine receptor (RYR1) as a causative mutation for one of the chromosome 6 QTLs in this cross.

Regulation of CYP2A6 protein expression by skatole, indole, and testicular steroids in primary cultured pig hepatocytes.

CYP2A6 is one of the enzymes involved in the hepatic metabolism of a naturally produced compound, skatole, in the pig. Low CYP2A6 activity has been linked to excessive accumulation of skatole in pig adipose tissue and development of the phenomenon "boar taint." CYP2A6 activity varies between male and female animals, suggesting the involvement of sex hormones in regulation of the enzyme activity and/or expression. The present study investigated whether pig hepatic CYP2A6 protein expression is regulated by the testicular steroids testosterone, androstenone, or estrone sulfate using primary cultured hepatocytes as a model system. The study has also examined whether CYP2A6 expression can be modulated by the boar taint compounds skatole and indole. The research has established that androstenone inhibits CYP2A6 protein expression at the concentration of 1, 10, and 100 nM by 55, 37, and 44%, respectively. In contrast to androstenone, skatole and indole (final concentrations, 1, 10, and 100 nM) had a stimulatory effect on CYP2A6 expression. The effect of indole was more pronounced than that of skatole (maximum induction by 145 and 70%, respectively). Estrone sulfate and testosterone did not have a significant effect on CYP2A6 protein level. This is, as far as we know, the first communication to report the regulation of pig hepatic CYP2A6 expression by steroids and boar taint compounds. The hormonal modulation of CYP2A6 expression might contribute to gender-related differences in pig hepatic CYP2A6 activity and skatole accumulation in pig adipose tissue.

Long-term effect of vaccination against gonadotropin-releasing hormone, using Improvac, on hormonal profile and behaviour of male pigs.

The objective of this study was to evaluate the long-term effect of a gonadotropin-releasing hormone (GnRH) vaccine, Improvac (Pfizer Ltd.), on the levels of GnRH antibodies, testosterone, estrone sulphate (E1S) and androstenone, as well as skatole and indole in male pigs. Additionally, the long-term effect of immunocastration on social and sexual behaviour was studied. Male pigs were assigned to two treatment groups: a treatment group given two doses of Improvac (n=12) and a control group of entire male pigs (n=12). The pigs were kept either 16 or 22 weeks after vaccination. Blood samples were collected five or six times; prior to both first and second vaccination, then three or four times during the 16 or 22 week period after second vaccination. Immunocastration significantly reduced levels of testosterone and E1S in plasma, and levels of androstenone in fat (P<0.001 for all). Skatole and indole levels in plasma and fat were also lower in immunocastrated pigs than in entire male pigs. These effects lasted up to 22 weeks after the second vaccination. Testis weight and bulbourethral gland length were lower in immunocastrated pigs at slaughter and these pigs showed less social, manipulating and aggressive behaviour than entire male pigs. The immunocastrated pigs remained sexually inactive throughout the study. Our study represents a further step in the evaluation of the effectiveness of Improvac as an alternative to surgical castration of entire male pigs. It shows that Improvac may have an extended effect compared with that currently implied by the directions for use.

Pelvic suspension improves quality characteristics in M. semimembranosus from Swedish dual purpose young bulls.

To study whether pelvic suspension would improve tenderness in comparison with normal hanging from the achilles tendon, carcasses from 34 Swedish red and white young bulls were randomly selected at the slaughter line. The left sides of the carcasses were re-hanged by the pelvic bone before cooling whereas the right sides remained hanging from the achilles tendon. Quality characteristics and length and weight were studied for M. semimembranosus. Tenderness was measured by the Warner-Bratzler shear force method. Purge and cooking loss were determined and sarcomere length was measured. Pelvic suspension considerably affected the shape of M. semimembranosus; the length increased by 38% in comparison with achilles suspension. The elongation of the muscle was parallel with an increase in sarcomere length from 1.6 to 2.9µm. The water-holding capacity was improved because both purge and cooking loss were lower for pelvic suspended carcasses. Tenderness was improved and the coefficient of variation between animals for Warner-Bratzler shear force was reduced from 26% for achilles tendon suspension to 12% for pelvic suspension. Likewise, the within-animal variation for shear force decreased significantly from 13.3% to 10.0%. Therefore, pelvic suspension seems to be a reliable method to reduce texture variability in M. semimembranosus from young bulls.

Significance of storage time on degree of blooming and colour stability of pork loin from different crossbreeds.

The objective was to investigate the effect of ageing time (1 day vs. 8 days postmortem) and sire breed used in the crossbreed (Duroc sired vs. Landrace sired pigs) on blooming ability and colour stability of pork M. longissimus dorsi (LD). The colour was measured during blooming (0, 10, 30, 60, 90min and 24h after cutting) and during subsequent display (1, 2, 3 and 6 days) at 3°C. The contents of deoxymyoglobin (Mb), oxymyoglobin (MbO(2)) and metmyoglobin (MetMb) were calculated. Ageing improved the blooming of LD from both crossbreeds with increased content of MbO(2) and decreased content of Mb, resulting in increased lightness, redness and yellowness. Ageing had smaller effect on colour stability with slightly lower MetMb in aged meat. Crossbreed affected both blooming and colour stability. LD from Landrace-sired pigs bloomed more than LD from Duroc-sired pigs, but more MetMb was formed during subsequent storage, although at a low level in both crossbreeds. The present data show superior colour characteristics of fresh pork aged for 8 days.