Effect of fast freezing then thaw‐aging on meat quality attributes of lamb M. longissimus lumborum

The objective of this study was to determine the effect of two different freezing rate then thaw‐aging regimens on the quality attributes of lamb loins. The loins were randomly allocated to one of five different freezing/thawing/aging regimes: fast‐(FF1A0) and slow‐(SF1A0) frozen only; fast‐(FF1A2) and slow‐(SF1A2) frozen then thaw‐aged for 14 days; aged for 14 days never frozen (A2). FF1A2 samples had a significantly higher water‐holding capacity compared to the slow frozen regardless of further aging periods. FF1A2 samples had lower (p < 0.05) shear force values than A2 and higher (p < 0.05) water‐holding capacity compared to the SF1A2. Fast freezing resulted in more intracellular cryo‐damage, whereas slow freezing resulted in extracellular cryo‐damage. FF1A0 and SF1A0 samples had lower (p < 0.05) myofibrillar proteins degradation. This study demonstrated that fast freezing then thaw‐aging can result in an improved water‐holding capacity and tenderness through the minimization of extracellular ice crystal formation, reduction in purge and drip losses, and improved proteolysis in thawed lamb.     

水果提取物对羔羊生长性能、抗氧化及肉品质的影响

本研究旨在研究日粮添加水果提取物对羔羊生长和屠宰性能、组织器官抗氧化及肉品质的影响.试验将60只体重接近的羔羊随机分为2组,每组6个重复,每个重复5只.在为期4周的饲养期间,对照组饲喂基础日粮,处理组饲喂基础日粮+150?mg/kg水果提取物.结果:粮添加150?mg/kg水果提取物对羔羊屠宰率、热胴体重、冷胴体重、内...     

Physico‐chemical characteristics of Longissimus lumborum muscle in goats subjected to halal slaughter and anesthesia (halothane) pre‐slaughter

This study assessed the effect of halal slaughter and anesthesia pre‐slaughter followed by bleeding on meat quality characteristics of goats. Eleven male Boer cross goats were divided into two groups and subjected to either halal slaughter (HS) or anesthesia with halothane and propofol pre‐slaughter (AS). At pre‐rigor, HS had significantly lower (P < 0.05) muscle pH and glycogen than AS. However, no significant difference was observed in the pH and glycogen content between the treatments on 1, 3 and 7 days post mortem. The drip loss of HS was significantly lower (P < 0.05) than that of AS at all aging periods. Treatment had no effect on sarcomere length, myofibrillar fragmentation index and shear force values, loss of thiol groups and degradation of major myofibrillar proteins. It can be concluded that HS did not have deleterious effect on meat quality traits of goat when compared to AS.     

CLA发酵豆粕对羔羊生长性能、胴体性能和肉品质的影响

选择120只健康、体重(11.77±0.70)kg的黄淮白山羊公羔,随机分为4组,每组6个重复,每个重复5只。对照组饲喂基础日粮,试验Ⅰ、Ⅱ、Ⅲ组分别用2.5%、5.0%和7.5%CLA发酵豆粕等量替代基础日粮中普通豆粕,预饲期为10 d,正式试验期为30 d。结果表明:CLA发酵豆粕对黄淮白山羊公羔的生长性能均无显著影响(P>0.05);试验Ⅲ组的胴体骨重显著高于对照组和试验Ⅰ组(P<0.05),试验Ⅲ组的骨肉比极显著高于对照组和试验Ⅰ组(P<0.01),其他胴体性能无显著差异(P>0.05);CLA发酵豆粕对黄淮白山羊公羔的肉品质而及羔羊肌肉的化学指标均无显著影响(P>0.05)。     

Effects of dietary energy level on growth performance,blood parameters and meat quality in fattening male Hu lambs

This experiment was conducted to investigate the effects of different dietary energy levels on growth performance, slaughter traits, meat quality and blood biochemical parameters in fattening male Hu lambs. Sixty lambs were fed five iso-protein diets which contained different levels of metabolizable energy in a completely randomized design for 70 days. At the end of study, fifteen lambs were harvested for further study. With the increase in dietary energy level, the daily weight gain and dry matter intake extremely increased (p < .001), and feed conversion ratio decreased significantly (p < .01). The live weight before slaughter (LWBS) and carcass weight had a significant increase (p < .05), non-carcass fat ratio and routine indexes of meat quality had no significant difference. Almost no effect was observed for the amino acid profile except for glycine concentration decreased (p < .05) in longissimus dorsi (LD) muscle. The concentrations of C17:0, C18:3n-3 and n-3 PUFA (p < .01) significantly decreased with the increasing dietary energy levels, and the ratio of ∑n-6/∑n-3 (p < .01) increased, whereas the concentrations of C18:1n-9t (p < .05) decreased in LD muscle and C18:1 (p < .01) increased in biceps femoris (BF) muscle. There were no obviously differences for diameter, area and density of muscle fibres. The relative expression of MyHC-IIa and MyHC-IIx decreased significantly (p < .05) in BF muscle, and the relative expression of MyHC-IIa displayed an obviously decreasing trend (p < .10) in LD muscle. These results suggest that increasing the dietary energy level can improve the growth performance and slaughter traits, and influence meat quality and fatty acid profiles in different muscle tissues of fattening male Hu lambs. These results provide a theoretical basis for developing Hu sheep nutritional standards and designing feed formulations.     

Involvement of μ/m‐calpain in the proteolysis and meat quality changes during postmortem storage of chicken breast muscle

The objective of this study was to investigate the role of calpain isotypes, especially poultry‐specific μ/m‐calpain in the proteolysis and meat quality changes of chicken breast muscle during postmortem storage. Calpain activity was detected by casein zymography, while the degradation of titin, desmin and Troponin‐T was analyzed by sodium dodecyl sulfate – polyacrylamide gel electrophoresis and western blot. Meat quality indicators such as water holding capacity and tenderness were also studied. The correlation analysis between calpain activity, proteolysis and the changes in meat quality indicators indicated that there were strong correlations for μ‐calpain during the first 12 h of storage, while such strong correlations for μ/m‐calpain were only found in samples stored from 12 h to 7 days. Our study suggested that μ‐calpain played a major role in meat quality changes while μ/m‐calpain could also be involved but played a limited role in the proteolysis and meat quality changes during 12 h to 7 days postmortem storage of chicken breast muscle.     

The effect of sex on the quality of meat from farmed pheasants (Phasianus colchicus)

The present study aimed to investigate the influence of sex on the quality of meat from farmed pheasants. Male (roosters, n = 18) and female (hens, n = 18) pheasants were slaughtered at 25 weeks of age. The breast muscles (Pectoralis major) were cut out from chilled carcasses and analyzed to determine the proximate chemical composition, fatty acid profile, and physicochemical and sensory properties of meat. Chemical analyses revealed that the meat of male had higher (p ≤ .05) content of collagen, Na, Cu, and Zn, whereas meat from females had higher (p ≤ .05) concentrations of total nitrogen of water‐soluble compounds, nitrogen of water‐soluble non‐protein compounds, K, and Mn. The meat of male was characterized by greater (p ≤ .05) cooking loss. A sensory evaluation revealed that meat from females had lower (p ≤ .05) taste intensity and aroma desirability. Meat from male and female pheasants revealed differences in the content of minerals as well as low‐molecular‐weight water‐soluble nitrogen compounds, which may affect the flavor of cooked meat. Irrespective of these differences, the analyzed pheasant meat was characterized by high quality, which indicates that it could offer an attractive alternative to other types of meat.     

Temporal changes in liver tissue metabolome of lambs fed low‐quality roughage

Early experience with low‐quality roughage may induce adaptations in ruminants’ metabolism. This study was conducted to explore the variation in the hepatic metabolomes of lambs fed low‐quality roughage beginning early in life. Five lambs were fed Sudan grass hay (crude protein (CP): 4.6% of the dry matter (DM), neutral detergent fiber, 68.5% of DM) for 6 months during time periods P1, P2 and P3, which consisted of 2 months each. The metabolizable energy (ME) and CP intake satisfied lambs’ maintenance requirements in P1 and P2, but the ME intake was 78.5% of the maintenance ME requirement in P3. Liver metabolomics was carried out in P2 and P3 by the capillary electrophoresis and time‐of‐flight mass spectrometry system. Eight amino acids and six amino acid metabolism‐related metabolites were altered between P2 and P3. Several intermediates of glycolysis/gluconeogenesis decreased, while nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide phosphate increased in P3. Taurocholic acid and taurine increased, while glycocholic acid decreased in P3. The results suggested that amino acid utilization and the efficiency of glycolysis/gluconeogenesis might be adjusted to accommodate the low‐quality roughage fed to the lambs during early stages of life. The composition of bile acids might also be optimized to promote the efficiency of lipid absorption.     

Changes of microbial spoilage,lipid‐protein oxidation and physicochemical properties during post mortem refrigerated storage of goat meat

Examined was the effect of post mortem refrigerated storage on microbial spoilage, lipid‐protein oxidation and physicochemical traits of goat meat. Seven Boer bucks were slaughtered, eviscerated and aged for 24 h. The Longissimus lumborum (LL) and Semitendinosus (ST) muscles were excised and subjected to 13 days post mortem refrigerated storage. The pH, lipid and protein oxidation, tenderness, color and drip loss were determined in LL while microbiological analysis was performed on ST. Bacterial counts generally increased with increasing aging time and the limit for fresh meat was reached at day 14 post mortem. Significant differences were observed in malondialdehyde (MDA) content at day 7 of storage. The thiol concentration significantly reduced as aging time increased. The band intensities of myosin heavy chain (MHC) and troponin‐T significantly decreased as storage progressed, while actin remained relatively stable. After 14 days of aging, tenderness showed significant improvement while muscle pH and drip loss reduced with increase in storage time. Samples aged for 14 days had higher lightness (P < 0.05) and lower (P < 0.05) yellowness and redness. Post mortem refrigerated storage influenced oxidative and microbial stability and physico‐chemical properties of goat meat.     

Effects of feeding frequency on meat quality traits and Longissimus muscle proteome in finishing pigs

Sixty‐four barrows with an initial body weight of 59.8 ± 2.1 kg were allocated to one of the two feeding frequency regimes (had free access to diet and fed two meals per day). Pigs had free access (FA) to feed were fed on an ad libitum basis during the 8‐week experimental period. Pigs fed twice daily (M2) were allowed to consume their meals in 2 h. Pigs fed twice daily had lower average daily feed intake (p < 0.01) and average daily gain (p < 0.1), but a greater G:F (p < 0.05) than FA pigs. Lower perirenal fat deposition, hot carcass weight, intramuscular fat content (p < 0.05) and dressing percentage (p < 0.1) were found in M2 pigs compared with FA pigs. Activities of citrate synthase, β‐hydroxylacyl‐CoA dehydrogenase and lactate dehydrogenase were greater in the Longissimus muscle (LM) of M2 pigs compared with FA pigs (p < 0.05). Proteomic analysis revealed that expression abundances of proteins involved in glucose metabolism, energy production and lipid utilization were upregulated, but expression levels of proteins participating in protein and amino acid metabolism, stress response and redox homeostasis were downregulated in the LM of M2 pigs than those in FA pigs (p < 0.05). In conclusion, the less meal frequency impairs growth rate, has marginal effects on carcass and meat quality traits and affects expression abundances of proteins in the LM of finishing pigs.     

Effect of alfalfa (Medicago sativa L.) saponins on meat color and myoglobin reduction status in the longissimus thoracis muscle of growing lambs

The effect of alfalfa saponins (AS) supplementation on the meat quality especially the color for growing lamb was investigated. Fifty Hu male lambs with body weights (BW, 19.21 ± 0.45 kg) were divided into five groups and supplemented AS with 0, 500, 1,000, 2,000, and 4,000 mg/kg of dietary dry matter intake. After 90 days, all lambs were slaughtered. The longissimus thoracis muscle in lamb displayed significant changes in the content of intramuscular fat, especially n-3 polyunsaturated fatty acids, and drip loss within AS treatment (p < .05) between control and treatments groups. Redness (a*) significantly improved in both 0-day and 7-day storage with the AS supplementation coupled with the percentage of met-myoglobin reduction (p < .05). The redness (a*) change may result from improved met-myoglobin reducing activity, antioxidant enzymes, lactate dehydrogenase, and succinate dehydrogenase (p < .05) by AS supplementation in muscle. These enzymes may help to protect mitochondria function and reduce met-myoglobin, which bring a bright and red meat color.     

Effects of concentrate or ryegrass-based diets (Lolium multiflorum) on the meat quality of lambs grazing on semi-natural pastures

Abstract

With the objective of studying the effects of production systems on meat quality, 75 Norwegian White Sheep lambs were subjected to one of the following treatments: continuous grazing on a semi-natural lowland pasture until slaughtering (Control); continuous grazing followed by either stall-feeding on concentrate and grass silage or grazing ryegrass pasture for 44 or 24 days before slaughtering (Conc44, Conc24, Rye44, Rye24). Loin samples of M. longissimus dorsi including the subcutaneous fat were analysed for sensory attributes and fatty acid composition. Compared with the control group, a lower intensity of acid taste (P<0.05) and a lower content of C18:3n-6 fatty acids (P<0.001) were observed in the Conc44 group. The n-6/n-3 ratio was higher (P<0.001) in meat tested from the concentrate treatments compared to the ryegrass treatments. These findings indicate that the fattening of lambs on improved pastures or a concentrate-based diet prior to slaughter may alter meat characteristics.     

Effects of grass forage species and long‐term period of low quality forage diet feeding on growth performance,nutrient utilization and microbial nitrogen yield in growing wether lambs

Six growing lambs were used to evaluate the feeding value of two forage‐based diets in a long‐term feeding period by measuring body weight (BW) gain, digestibility, nitrogen (N) retention and microbial N (MBN) yield. The animals were fed imported low‐quality timothy hay (TH) with concentrate diet (THD) or imported low‐quality Italian ryegrass straw (IR) with concentrate diet (IRD) for 9 months. The forages were offered at 2% BW, and concentrate was fed at 40% of forage intake. The BW gain averaged 82.6 and 66.2 g/day for THD and IRD, respectively, without showing significant difference. Average forage intake (% BW) was significantly greater for IR than for TH, although it was not affected by feeding periods. The digestibility did not differ between diets or periods. The numerically greater (P = 0.06) ratio of retained N to absorbed N for IRD than that for THD was prominent. Neither diet nor period had significant effect on MBN supply and efficiency of MBN synthesis. The results suggest that the IR‐based diet can be also used for long‐term periods of feeding to growing ruminant animals as a grass hay‐based diet without any detrimental effects on nutrient utilization and growth performance.     

Long‐term ingestion of low amylose/amylopectin ratio diet affects aspects of meat quality by changing muscle fibre characteristics in growing‐finishing pigs

Amylose plays important role in body health. It is controversial whether changing dietary amylose/amylopectin ratio (DAR) will improve meat quality in growing‐finishing pigs. A total of 48 Duroc × Landrace × Large White castrated male pigs (initial body weight 49.8 ± 2.8 kg) were randomly allotted to two treatments, and fed ad libitum either with a low DAR diet (LR, amylose/amylopectin: 12/88) or a high DAR diet (HR, amylose/amylopectin: 30/70) for 68 days. Feed intake was recorded every day, body weight was weighed at 46th and 68th day to calculate average daily gain (ADG), average daily feed intake (ADFI) and Feed:gain ratio. Blood was collected at ?30 min (fasting 12 hr), 60, 90, 120, 180 min postprandial at 64th day and then serum was obtained by centrifugation of blood at 1,500× g at 4°C. After pigs were slaughtered, samples such as longissimus dorsi, iliopsoas and semitendinosus were collected. Density, diameter and types of muscle fibres were analysed. Results showed that ADG, ADFI, Feed:Gain ratio, cross‐sectional area of longissimus dorsi muscle, backfat thickness, colour scores were not affected by DAR. Ingestion of LR diet increased the fasting glucose (p < 0.05) and insulin (p < 0.05) concentrations in serum. The drip loss and firmness were decreased significantly in LR vs. HR animals (p < 0.05). Densities of muscle fibre in longissimus dorsi, iliopsoas and semitendinosus were greater in LR pigs (p < 0.05). Moreover, ingestion of LR diet significantly increased myosin heavy chain (MyHC) IIa mRNA level and decreased MyHC IIb gene expression in longissimus dorsi muscle (LM) (p < 0.05). Therefore, intake of diet low in amylose/amylopectin ratio induces a better meat quality (lower drip loss and lower firmness), which could attribute to smaller myofibres, a shift to slower and/or more oxidative fibres.     

Microbiological quality of organic chicken meat during refrigerated storage in air and modified atmospheres

ABSTRACT

1. The aim of this study was to assess the incidence of pathogens and the development of spoilage microflora in organic chicken meat originating from a small poultry slaughterhouse and stored for 14 days at 2°C aerobically (control) or in one of two modified atmosphere packaging systems (MAP1: 80% O₂, 20% CO₂ and MAP2: 70% N₂, 30% CO₂).

2. Campylobacter jejuni survived well during storage; and was found on the skin in 95% of samples (262/276).

3. In general, both the skin and meat samples showed a good initial microbiological quality with total viable counts of less than 3 log cfu/g in meat and approximately 5 log cfu/g on skin.

4. No difference was found between breast and thigh samples during the experiment.

5. Shelf life was limited mainly by the development of mesophilic and psychrotrophic microflora on skin which were found at 7-day storage for the control and MAP1 and 10 days for MAP2.     

Differential protein profiles in duck meat during the early postmortem storage period

The present study was designed to investigate proteomic differences in duck breast muscle during the early postmortem storage period. The meat quality was evaluated at 0 hr and 24 hr postmortem at 4°C in Pekin ducks, black Muscovy ducks and Mule ducks. Differentially expressed proteins were detected by two‐dimensional gel electrophoresis (2‐DE) and matrix‐assisted laser desorption ionization‐time‐of‐flight mass spectrometry (MALDI‐TOF/TOF MS) at 0 hr and 24 hr postmortem in the three duck breeds. The results showed that 53 proteins spots were differentially expressed at 0 hr and 24 hr postmortem at 4°C in Pekin ducks, 75 spots in black Muscovy ducks, and 72 spots in Mule ducks. A total of 30 (10 spots for each breed) were selected for identification by mass spectrometry. Seven proteins were identified in Pekin ducks, eight in black Muscovy ducks and seven in Mule ducks. Moreover, the above results obtained by 2‐DE and MALDI‐TOF/TOF MS were confirmed by western blotting. To our knowledge, this study is the first to provide insights into the protein profiles of ducks during postmortem storage and provides a better understanding of the biochemical processes that contribute to duck meat quality.     

Effects of apple pomace‐mixed silage on growth performance and meat quality in finishing pigs

We measured the growth performance and meat quality of 10 crossbred (Yorkshire × Duroc × Landrace) neutered male pigs to evaluate the effects of apple pomace‐mixed silage (APMS). The pigs were divided into two groups and were respectively fed the control feed and the AMPS ad libitum during the experiment. No difference was found in the finished body weight, average daily gain, carcass weight, back fat thickness or dressing ratio between the control and the AMPS treatments, but average dairy feed intake (dry matter) was significantly lower and feed efficiency was significantly higher using the APMS treatment (P < 0.05). With regard to meat quality, the APMS increased the moisture content but decreased the water holding capacity (P < 0.05) compared with the control treatment. Furthermore, the APMS affected the fatty acid composition of the back fat by increasing linoleic acid (C18:2n6), linolenic acid (C18:3) and arachidic acid (C20:0) levels, while decreasing palmitic acid (C16:0), palmitoleic acid (C16:1) and heptadecenoic acid (C17:1) levels, compared with the control treatment. These results indicate that feeding fermented apple pomace to finishing pigs increases the feed efficiency and affects the meat quality and fatty acid composition of back fat.