Mitochondrial respiratory and antioxidative enzyme activities in broiler meat in relation to age and gender of the animals

Colour is an important quality parameter of broiler meat influencing the consumer buying behaviour. The alterations of the colour after slaughter are related to the oxidative status of the tissue. This in turn is influenced by an interaction between the mitochondria and the antioxidative enzymes. In this study, breast muscles were collected from hens and cocks of a commercial line slaughtered at the ages of 28 and 41 day. Analysis of the activities of superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GR) was performed with samples obtained 20 min and 48 h after slaughter (post mortem, p.m.), whereas the mitochondrial respiratory activity was analysed in permeabilised breast muscle fibres collected 20 min p.m. The carcass characteristics of breast muscle and leg weight as well as breast yield were significantly higher, and the leg yields lower, in the 41-day-old broiler. The 28-day-old hens and cocks had comparable carcass characteristics (P > 0.05), whereas 41-day-old cocks had significantly higher carcass, breast and leg weight in comparison to the hens. The pH20 min p.m. and the L*48 h p.m. were significantly higher, and the a* and b* values of the 20 min and 48 h p.m. samples as well as the drip loss were significantly lower in the 41-day-old broiler. Mitochondrial respiratory rates were comparable (P > 0.05) between the 28- and 41-day-old cocks and hens. The same result could be found with regard to the activities of the SOD, GPx and GR except for lower activities of the SOD20 min p.m. and higher of the GR48 h min p.m. in the 41-day-old broiler. The concentrations of thiobarbituric acid-reactive substances were generally higher in the breast muscles of the 41-day-old broiler. Assorting the data according to their mean pH20 min p.m. indicates a positive influence of higher pH values (>6.34) on the mitochondrial function, whereas a low pH20 min p.m. results in tendentially and significantly higher activities of the antioxidative enzymes and drip loss values. These results indicate a relation between the meat quality and the oxidative metabolism as well as antioxidative capacity of the meat.     

Effect of rearing system and mixing at loading on transport and lairage behaviour and meat quality: comparison of outdoor and conventionally raised pigs

The effect of raising pigs outdoors or conventionally in a barren environment was investigated with respect to behaviour during a 3 to 4 h journey and a 2 h lairage, blood chemistry at slaughter and meat quality characteristics. Pigs were either kept in farm pen groups or were mixed at loading and kept in the groups, so formed, until slaughter. Non-mixed outdoor pigs settled more quickly during transport and lay down to a greater extent at the end of the journey and lairage period compared with conventionally raised pigs. Mixing led to fewer pigs sitting and lying during transport for conventionally raised pigs, where nearly 80% were still standing at the end of the journey. Mixing had no effect on pig posture in the lairage. Outdoor pigs were less aggressive than conventionally raised pigs especially during lairage and had a lower frequency of unacceptable skin damage in the rear and shoulder area. Aggressive interactions were almost exclusively confined to mixed groups and occurred mainly between pigs from different farm pens, i.e. between unfamiliar animals. Mixing at loading led therefore to higher levels of unacceptable skin damage. Cortisol concentrations in slaughter blood were not affected by rearing system or mixing, but mixed, conventionally raised pigs had higher plasma creatine kinase (CK) activities than non-mixed ones (1132 v. 761 U/l, respectively, P < 0.05). Outdoor pigs had similar CK activities, irrespective of mixing (682 and 771 U/l for mixed and non-mixed, respectively). Muscle pH early post mortem was highest in outdoor pigs and muscle temperature lower, but no pig showed pH values below 6.0. Ultimate pH values were both higher (Semimembranosus (S)) and lower (Semispinalis capitis (SC)) than in conventionally raised pigs, and outdoor pigs tended to have a lower frequency of higher than normal pH values. Internal reflectance (MQM) values in Biceps femoris (BF) were highest in outdoor pigs but the incidence of pale, soft and exudative (PSE) meat was low, varying between 0% and 1% for experimental groups. In general, the effects of rearing system and mixing on meat quality measurements taken early post mortem or the day after slaughter were slight, but the trends seen support the CK results, and show that conventionally raised pigs may have found mixing pre-slaughter to be more physically stressful than outdoor pigs did.     

Physiological response and carcass and meat quality of suckling lambs in relation to transport time and stocking density during transport by road

To evaluate the effect of stocking density and transport time on physiological responses and meat quality, 72 male suckling lambs were transported by road to the slaughterhouse at three different stocking densities (0.12, 0.20 or 0.25 m2/lamb) and two transport times (5 h or 30 min). Blood samples were collected pre-transport at the farm and after unloading in the slaughterhouse to measure levels of cortisol, creatine kinase (CK) and lactate dehydrogenase (LDH). After slaughter, the weights of the hot carcass, liver and spleen were recorded and pH in Musculus longisimus thoracis et lumborum (L), Musculus semitendinosus (ST) and Musculus psoas major (PM) were determined. Colour, water-holding capacity (WHC), texture and thiobarbituric acid-reactive substances (TBARS) values were measured in samples of L, at 24 h post mortem and after 5 days of ageing. Cortisol and LDH were higher in suckling lambs transported for 30 min than those transported for 5 h. Stocking density did not affect blood parameters studied. Transport time significantly affected some carcass quality parameters, but stocking density had no significant effect. Suckling lambs transported for 5 h had lower liver weights and dressing percentages than those transported for 30 min. Transport time influenced pH values, with lambs subjected to the longer journey showing the lowest pH at 0 h in the three muscles studied, with the lowest final pH in L and PM. The PM lambs transported at high density (0.12 m2/lamb) had the lowest pH at 24 h. Transport time and stocking density did not greatly affect colour and texture parameters. The meat from lambs transported for 30 min had higher WHC than meat from lambs transported for 5 h. Animals transported for longer journeys showed higher lipid oxidation after 5 days of ageing than those transported for 30 min. Loading and initial transport caused significant stress response in suckling lambs, that stress response was reduced over the time course of the journey.     

Effects of Altitude on Antioxidative System in Leaves and Roots of Plantago major

Antioxidative systems were investigated in leaves and roots of Plantago major L. which were collected from Mahan Mountain at different altitudes. The content of glutathione (GSH) in reduced form was increased in leaves and roots with the increasing altitude. The activities of peroxidase (POX) and superoxide dismatase superoxide dismutase (SOD) in roots also increased as the altitude was increased, while that in leaves they declined at higher altitude. Analyses of isozymes of SOD and POX in leaves and roots showed that high altitude (3 300 m) induced the SOD isozymes 8 and POX isozyme 5 in roots, which appeared to be required for protection against lower temperature and higher light intensity as altitude was increased. The present study suggested that high altitude had affected differently the antioxidative system in leaves and roots.     

海拔高度对大车前叶和根中抗氧化系统的影响

以甘肃马衔山（ 海拔３７５０ ｍ）自然生长的大车前（ Ｐｌａｎｔａｇｏ ｍａｊｏｒ Ｌ．） 为材料,通过检测比较不同海拔高度下大车前根和叶中抗氧化保护系统的变化,探讨植物对于高寒环境的适应机理。结果表明,随着海拔的升高（ 从１６００ ｍ～３３００ ｍ） ,根中还原型谷胱甘肽（ＧＳＨ）含量增加,过氧化物酶（ＰＯＸ）和超氧化物歧化酶（ＳＯＤ） 活性显著升高,叶中的ＰＯＸ和ＳＯＤ活性则逐渐降低。高海拔区（３３００ ｍ）根中出现了特异性酶带ＰＯＸ５ 和ＳＯＤ８。这种趋势可能有利于根的越冬,而对叶片的越冬不利,这与多年生植物大车前的自然生长状况相一致     

Effect of slaughter age on foal carcass traits and meat quality

Meat has played a crucial role in human evolution and is an important component of a healthy and well-balanced diet due to its nutritional richness. Recent studies have shown that horsemeat may be considered as an alternative to other meat (such as beef or pork), and it may have a positive effect on human health from a nutritional point of view. This research was conducted to characterize the carcass measurement, meat quality (chemical composition, colour characteristics and textural traits) and nutritional value (fatty acid and amino acid composition) of foals slaughtered at 8 and 11 months of age (8 and 11 m groups). For this study, a total of 21 foals (10 and 11 animals from the 8 and 11-m groups, respectively) were used. The results obtained showed a positive influence on carcass characteristics with an increase in slaughter age, because 11 m animals had slightly higher values of live (275 v. 247 kg) and carcass weights (148 v. 133 kg), length of leg (72.86 v. 69.85 cm) and carcass (100.41 v. 96.30 cm) and perimeter of leg (97.68 v. 89.22 cm) compared with animals from the 8-m group. Regarding meat quality, only Fe-haeme and cholesterol content in chemical composition and luminosity (L*) in colour parameters showed significant differences. Foals from the 8-m group had the highest content of cholesterol (0.47 v. 0.28 mg/100 g of meat) and luminosity values (39.66 v. 37.88) and the lowest content of ash (1.20% v. 1.40%). In fatty acids content, only five out of 23 fatty acids showed differences between the two groups. However, an interesting change in the fatty acid profile occurred with an increase in the slaughter age. Foals from the 8-m group had the highest values of α-linolenic acid and n-3 fatty acids and the lowest values of linoleic and n-6 fatty acids, which is an interesting fact from a health point of view. Finally, slaughter age had no statistical influence on textural properties or amino acid content. As a main conclusion, animals slaughtered at 8 months of age had higher nutritional quality meat (with higher content of n-3 fatty acids) than meat from foals slaughtered at 11 months of age. The slaughter of animals at 8 months of age also reduced production costs because they ate a smaller amount of commercial fodder.     

Pigs' aggressive temperament affects pre-slaughter mixing aggression, stress and meat quality

Pre-slaughter stress has a negative impact on animal welfare and on meat quality. Aggressive behaviour when pigs are mixed together for transportation to, or on arrival at, the abattoir is an important factor in pre-slaughter stress. Aggressiveness of pigs varies between individuals in the population, and this study investigated its effects on stress and meat quality at slaughter. We mixed pigs at a young age to identify individuals of high (H) or low (L) aggressive temperament using the previously validated approach of lesion scoring. To contrast extremes of social stress single-sex groups of eight pigs were mixed according to their aggressiveness in HH, HL or LL combinations or left unmixed (U) prior to transport and slaughter (n = 271). Each treatment was replicated in at least two groups in each of four slaughter batches. Mixing per se had little effect, but mixed groups composed of aggressive pigs (HH) had more carcass skin lesions and higher levels of plasma cortisol at slaughter and had loin muscle samples with higher pH at 24 h, and lower redness (a*) and yellowness (b*) compared to the other treatments. Females had higher levels of plasma cortisol at slaughter, a more rapid decline in pH post-slaughter and greater lean content of meat. Lactate and creatine kinase (CK) levels and meat pH were affected by the interaction of sex and treatment. Genetic factors, dam and sire line composition, and halothane locus (ryanodine receptor 1, RYR1) genotype, also affected a number of production and meat quality parameters as expected. Additionally, 'commercially normal' levels of social stress were studied in four further slaughter batches with no manipulation of group composition (n = 313). In these pigs, the proportion of unfamiliar pigs and group size of lairage groups explained limited variation in lesion scores at slaughter, but earlier aggressiveness did not. High numbers of skin lesions on the carcass were associated with high levels of cortisol and lactate and low glucose at slaughter, but not with meat quality measures. When stress and meat quality measures were compared for all pigs, high lactate was associated with low early pH and high drip loss, while high cortisol and CK were associated with high pH at 24 h and changes in meat colour. In conclusion, mixing pigs of above average aggressiveness resulted in greater aggression and stress, and changes in meat quality parameters, consistent with the effects of pre-slaughter stress on muscle chemistry.     

Increasing the incubation temperature between embryonic day 7 and 10 has no influence on the growth and slaughter characteristics as well as meat quality of broilers

Avian embryogenesis can be manipulated by alteration of the temperature during incubation of the brooding egg. Investigations in turkeys showed that a higher temperature during early embryogenesis positively affects the myogenesis accompanied with a higher muscle fibre number (MFN). The aim of this study was to transfer this result to broiler and to investigate if an alteration of the temperature also affects the meat quality after slaughter of the birds. Therefore brooding eggs of the Cobb 500 broiler genetic were either incubated at 37.5°C during the whole incubation period (at normal temperature (NT)), or at 38.5°C during embryonic day (ED) 7 to 10 (at high temperature (HT)). After hatch the chicks were sexed and reared up to an age of 36 days in an experimental stable. Growth and feed conversion properties were determined during this period. After slaughter different meat quality characteristics as well as the muscle microstructure were analysed. The hatch rate and chick weight did not differ between the broiler of the NT and HT group. After 36 days the final body weights and the cumulative feed conversion rates were not different in the NT and HT groups. No differing results were obtained with regard to the slaughter, breast and leg weights of the NT and HT animals. Considering the gender of the animals no differences in the slaughter characteristics could be determined although the carcass and breast weights of the HT cocks were tendentially higher. The muscle fibre areas and MFNs in the breast muscles of the NT and HT cocks did not differ significantly and were in the range of the HT hens. Only the NT hens had significantly larger muscle fibres and less MFN than the other animals. With regard to the meat quality characteristics no clear differences of the pH, electrical conductivity (EC) and colour (L*a*b*) values were found. The L*a*b* values in the investigated breast muscles of all broilers usually increased during ageing. The increase of the incubation temperature had no impact on the hatch, growth, slaughter and meat quality characteristics of the broiler except for the tendentially higher carcass and breast weights of the HT cocks. However, the decrease of the fibre areas in the HT hens is an interesting effect of using a higher incubation temperature, which needs to be considered when implicating further investigations.     

Genetic parameters of meat quality traits in two pig breeds measured by rapid methods

To study genetic variation in meat quality traits measured by rapid methods, data were recorded between 2005 and 2008 on samples of M. longissimus dorsi (LD) in Landrace (n = 3838) and Duroc (n = 2250) pigs included in the Norwegian pig breeding scheme. In addition, ultimate pH levels in the glycolytic LD (loin muscle) and M. gluteus medius (GM, ham muscle), and in the oxidative m. gluteus profundus (GP, ham muscle) were recorded as an extended data set (n = 16 732 and n = 7456 for Landrace and Duroc, respectively) from 1998 to 2008. Data were analysed with a multi-trait animal model using AI-REML methodology. Meat from Duroc had considerably more intramuscular fat (IMF), less moisture and protein, appeared darker with higher colour intensity and had lower drip loss than meat from Landrace. The heritability estimates (s.e. 0.01 to 0.07) for pH in LD (0.19 and 0.27 for Landrace and Duroc, respectively), GM (0.12 and 0.22) and GP (0.19 and 0.38), drip loss (0.23 and 0.33), colour values: L* (lightness) (0.41 and 0.28), a* (redness) (0.46 and 0.43), b* (yellowness) (0.31 and 0.33), IMF (0.50 and 0.62), muscle moisture (0.31 and 0.50) and muscle protein content (0.40 and 0.54) in LD all demonstrated moderate-to-high genetic variation for these traits in both breeds. Near infrared spectroscopy and EZ-DripLoss are modern technologies used in this study for the determination of chemical components and drip loss in meat. These methods gave higher heritabilities than more traditional methods used to measure these traits. The estimated genetic correlations between moisture and IMF in Duroc, and pH and drip loss in Duroc were both -0.89. Interesting differences between the two breeds in numerical value of some genetic correlations were observed, probably reflecting the differences in physiology and selection history between Landrace and Duroc. The estimated genetic correlation between drip loss and pH was much stronger in Duroc than in Landrace (-0.89 and -0.63, respectively). This might be due to the high pH in Duroc, whereas Landrace had a lower pH closer to the iso-electric point for muscle proteins. The positive genetic correlation between the L* value in meat and IMF in Duroc (0.50) was an effect of differences in visible marbling, rather than meat colour. For Landrace, this correlation was negative (-0.20). IMF content showed favourable genetic correlations to drip loss (-0.36 and -0.35 for Landrace and Duroc, respectively).     

Carcass and meat quality traits of rabbits under heat stress

Rabbits are very sensitive to heat stress because they have difficulty eliminating excess body heat. The objective of the current study was to evaluate the effects of heat stress on slaughter weight, dressing percentage and carcass and meat quality traits of rabbits from two genetic groups. Ninety-six weaned rabbits were used: half were from the Botucatu genetic group and half were crossbreds between New Zealand White sires and Botucatu does. They were assigned to a completely randomized design in a 2 × 3 factorial arrangement (two genetic groups and three ambient temperatures: 18°C, 25°C and 30°C) and kept under controlled conditions in three environmental chambers from 5 to 10 weeks of age. Slaughter took place at 10 weeks, on 2 consecutive days. Meat quality measurements were made in the longissimus muscle. Actual average ambient temperature and relative humidity in the three chambers were 18.4°C and 63.9%, 24.4°C and 80.2% and 29.6°C and 75.9%, respectively. Purebred rabbits were heavier at slaughter and had heavier commercial and reference carcasses than crossbreds at 30°C; however, no differences between genetic groups for these traits were found at lower temperatures. No genetic group × ambient temperature interaction was detected for any other carcass or meat quality traits. The percentages of distal parts of legs, skin and carcass forepart were higher in crossbred rabbits, indicating a lower degree of maturity at slaughter in this group. The percentage of thoracic viscera was higher in the purebreds. Lightness of the longissimus muscle was higher in the purebreds, whereas redness was higher in the crossbreds. Slaughter, commercial and reference carcass weights and the percentages of thoracic viscera, liver and kidneys were negatively related with ambient temperature. Commercial and reference carcass yields, and the percentage of distal parts of legs, on the other hand, had a positive linear relationship with ambient temperature. Meat redness and yellowness diminished as ambient temperature increased, whereas cooking loss was linearly elevated with ambient temperature. Meat color traits revealed paler meat in the purebreds, but no differences in instrumental texture properties and water-holding capacity between genetic groups. Purebred rabbits were less susceptible to heat stress than the crossbreds. Heat stress resulted in lower slaughter and carcass weights and proportional reductions of organ weights, which contributed to a higher carcass yield. Moreover, it exerted a small, but negative, effect on meat quality traits.     

Immunocastrated male pigs: effect of 4 v. 6 weeks time post second injection on performance,carcass quality and meat quality

Immunocastration or vaccination against boar taint can be used as alternative for surgical castration of male piglets. The vaccine is administrated twice. After the second vaccination (V2), the pigs behave like barrows instead of boars and their feed intake increases which may result in a lower lean meat percentage. The timing of V2 is therefore crucial to find the right balance between the advantages of entire males and barrows. In this study, we evaluated the effect of time post second injection within the advised time frame (4 v. 6 weeks before slaughter) on behaviour, performance, carcass and meat quality of immunocastrated male pigs. In total, 180 animals (hybrid sow×Piétrain): 60 gilts, 60 male pigs vaccinated 6 weeks before slaughter (IM-6) and 60 male pigs vaccinated 4 weeks before slaughter (IM-4), all slaughtered at comparable slaughter weights. After 20 weeks of age, IM-6 showed more inactive behaviour at the expense of playing and aggressive behaviour. Daily feed intake (DFI), daily gain (DG) and feed conversion ratio (FCR) did not differ significantly between IM-6 and IM-4. Gilts had a lower DFI and DG in the late finishing phase and a higher FCR overall compared with both IM groups. Gilts showed a higher lean meat content compared with both IM groups. Earlier vaccination increased dressing percentage, which could partly be explained by the lower weight of the gastrointestinal tract, but not by testes weight. Meat quality traits and palatability did not differ significantly between IM-6 and IM-4. Vaccination of immunocastrates at 6 compared with 4 weeks before slaughter improved the calmness in the stable and the dressing percentage, while maintaining performance and carcass characteristics.     

The oxidative stress caused by salinity in two barley cultivars is mitigated by elevated CO2

Changes in antioxidant metabolism because of the effect of salinity stress (0, 80, 160 or 240 m M NaCl) on protective enzyme activities under ambient (350 μmol mol⁻¹) and elevated (700 μmol mol⁻¹) CO₂ concentrations were investigated in two barley cultivars ( Hordeum vulgare L., cvs Alpha and Iranis). Electrolyte leakage, peroxidation, antioxidant enzyme activities [superoxide dismutase (SOD), EC 1.15.1.1; ascorbate peroxidase (APX), EC 1.11.1.11; catalase (CAT), EC 1.11.1.6; dehydroascorbate reductase (DHAR), EC 1.8.5.1; monodehydroascorbate reductase (MDHAR), EC 1.6.5.4; glutathione reductase (GR), EC 1.6.4.2] and their isoenzymatic profiles were determined. Under salinity and ambient CO₂, upregulation of antioxidant enzymes such as SOD, APX, CAT, DHAR and GR occurred. However, this upregulation was not enough to counteract all ROS formation as both ion leakage and lipid peroxidation came into play. The higher constitutive SOD and CAT activities together with a higher contribution of Cu,Zn-SOD 1 detected in Iranis might possibly contribute and make this cultivar more salt-tolerant than Alpha. Elevated CO₂ alone had no effect on the constitutive levels of antioxidant enzymes in Iranis, whereas in Alpha it induced an increase in SOD, CAT and MDHAR together with a decrease of DHAR and GR. Under combined conditions of elevated CO₂ and salinity the oxidative damage recorded was lower, above all in Alpha, together with a lower upregulation of the antioxidant system. So it can be concluded that elevated CO₂ mitigates the oxidative stress caused by salinity, involving lower ROS generation and a better maintenance of redox homeostasis as a consequence of higher assimilation rates and lower photorespiration, being the response dependent on the cultivar analysed.     

NaCl胁迫对菜用大豆种子膨大过程中抗氧化系统及渗透调节物质的影响

采用蛭石栽培试验,在100mmol.L-1 NaCl胁迫下,对耐盐性不同的两个菜用大豆品种种子膨大、抗氧化系统及渗透调节物质进行了研究。结果显示:(1)耐盐品种‘绿领特早’种子干质量及大小的增加在NaCl胁迫15d时未受显著影响,而盐敏感品种‘理想高产95-1’种子的膨大受到了显著抑制。(2)NaCl胁迫导致菜用大豆种子超氧阴离子(O2.-)、过氧化氢(H2O2)及丙二醛(MDA)的过量积累,但‘绿领特早’种子的相对积累量均低于‘理想高产95-1’。(3)与‘理想高产95-1’相比,‘绿领特早’在NaCl胁迫期间维持了相对较高的超氧化物歧化酶(SOD)、抗坏血酸过氧化物酶(APX)及谷胱甘肽还原酶(GR)活性,以及较高的抗坏血酸(AsA)、可溶性蛋白和可溶性糖含量;胁迫中期维持了相对较高的过氧化物酶(POD)活性,胁迫后期维持了相对较高的过氧化氢酶(CAT)活性;胁迫前中期维持了相对较高的谷胱甘肽(GSH)含量。研究发现,‘绿领特早’种子在NaCl胁迫期间能够保持较高且协调平衡的保护酶SOD、POD、CAT活性和较高的AsA-GSH循环效率,同时维持了较强的渗透调节能力,有效抑制了O2.-和H2O2的过量积累,进而有效降低了细胞膜质过氧化程度,这可能是其耐盐性较强的重要原因之一。     

Effect of age and carcass weight on quality traits of m. rectus abdominis from Charolais heifers

In practice cattle may be slaughtered at different combinations of age and weight. As each of these factors could affect meat quality traits, the present work aimed to identify which combination can be expected to increase overall meat quality of m. rectus abdominis of Charolais heifers. Totally, 40 heifers were slaughtered either at 26±1 or at 36±1 months of age. Young heifers were sampled at two different carcass weights (349±12 and 394±8 kg). Old heifers were also sampled at two different carcass weights (397±6 and 451±9 kg). The m. rectus abdominis was excised 24 h postmortem to determine metabolic enzyme activities, myosin heavy-chain isoform proportions, lipid contents, collagen content and collagen solubility. Shear force measurements were evaluated on raw and broiled meat after 14 days of ageing. Meat quality traits scored between 0 and 10 by sensory analysis. Increasing slaughter age from 26 to 36 months had no impact on either raw/broiled shear force (0.31⩽P⩽0.47) and/or meat quality traits (0.62⩽P⩽0.91) or on physicochemical properties of heifer’s meat samples. Increasing carcass weight for a similar slaughter age of 26 months had also impact neither on meat quality traits (0.52⩽P⩽0.91) nor on muscular properties. On the contrary, increasing carcass weight for a similar slaughter age of 36 months had induced a decrease of muscular shear force (raw muscle; P=0.009) and a concomitant decrease of total collagen content (P=0.03). Nevertheless, no significant impact on meat quality traits was revealed by the sensorial panel (0.13⩽P⩽0.49). Metabolic enzyme activities (0.13⩽P⩽0.86) and myosin heavy-chain proportions (0.13⩽P⩽0.96) were not significantly impacted by slaughter age and carcass weight. Thus, the impact of increasing carcass weight and/or slaughter age in young Charolais heifers has a limited impact on meat quality traits and associated muscular characteristics. Modulating heifer’s cycles (age and/or carcass weight in the studied range) appears to be a way to answer to the numerous marketing chains, without penalising meat quality traits.     

Effects of proteasome inhibitor, MG132, on proteasome activity and oxidative status of rat liver

In vivo effects of N-benzyloxycarbonyl (Cbz)-Leu-Leu-leucinal (MG132) on chymotryptic-like (ChT-L), tryptic-like, and post-glutamyl peptide hydrolytic-like proteasome activities, protein oxidation, lipid peroxidation (LP), glutathione (GSH) level, as well as on the activity of antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and glutathione-reductase) in the rat liver were studied. The possibility of MG132 provoking the formation of free oxygen radicals was also assayed in primary hepatocytes. The following results were obtained: (1) In vivo, MG132 did not change the spontaneous LP, but increased Fe-induced LP and the amount of oxidized proteins; it decreased the GSH level in liver. From the proteasome activities studied in liver cytosol only ChT-L activity was significantly decreased after MG132 administration. Furthermore, MG132 increased antioxidant enzyme activities of SOD, CAT, and GSH-Px. (2) In vitro, MG132 increased free radical oxygen species in hepatocytes; this effect disappeared in the presence of CAT or mannitol. In conclusion, since nowadays proteasome inhibitors are entering into the swing of laboratory and clinical practice, the present data could provide useful information for MG132 action. Consequently, future in vivo experiments with MG132 could highlight the possibility of its use at different pathological conditions.     

Effects of pre-weaning concentrate feeding on calf performance, carcass and meat quality of autumn-born bull calves weaned at 90 or 150 days of age

A study was conducted to evaluate the effect of pre-weaning concentrate feeding in early-weaned (EW, day 90) or traditionally weaned (TW, day 150) autumn-born beef calves on growth, feed intake and feed efficiency, and carcass and meat quality. Twenty-eight male calves were either EW or TW, and offered a starter concentrate (S) or no additional feed (NS) during the pre-weaning period. Therefore, four management strategies were tested: EWS, EWNS, TWS and TWNS. Growth patterns were affected by management strategy. From day 90 to 150, TWNS calves presented a substantially lower average daily gain (ADG) than their counterparts, which had similar performance. During the finishing phase (from day 150 to slaughter at 450 kg live weight), EWS calves had the lowest ADG. Daily feed intake or efficiency in the finishing phase was unaffected by previous management. Serum IGF-I concentrations at day 90 and slaughter did not differ with management strategy, but early weaning and pre-weaning concentrate feeding increased IGF-I concentrations at day 150. Circulating leptin concentrations were unaffected by age at weaning and pre-weaning concentrate feeding, except for leptin concentrations at slaughter, which were higher in S calves than in NS calves. Total concentrate intake from birth to slaughter and the concomitant feed costs were higher for EWS and EWNS calves than for TWNS and TWS ones. However, cow feed costs were lower for cows whose calves had been early weaned. Concerning carcass quality, early weaning improved dressing percentage and increased fatness score, and particularly TWNS calves presented a poorer conformation. Meat quality was not affected by management strategy. Considering the economic performance, TWS, EWNS and EWS strategies yielded a similar economic margin, whereas TWNS would be the least advisable strategy when calves are fattened in the farm until slaughter.     

猪FUT1基因对肉质和胴体性状的影响

测定139头杂交猪(大白猪和梅山猪)的14个肉质性状和8个胴体性状,用PCR-RFLP方法检测FUT1基因型。分析猪FUT1基因型间肉质和胴体性状差异,发现AA基因型猪3个部位肌肉pH值均比AG基因型的高,其中pH(LD)达到显著水平(P<0.05)。AA基因型猪肌肉系水力显著高于AG猪的系水力(91.02% VS 86.70%,P<0.05)。AA基因型猪的肉色值显著高于AG猪的(P<0.05)。AA基因型猪三个部位肌肉膘厚值均较低,其中最后肋骨膘厚和倒数三四肋骨膘厚分别比AG基因型猪的低4.26 mm和3.96 mm(P<0.05)。AA基因型猪瘦肉率比AG基因型猪的高3.31% (53.46% VS 50.15%,P<0.05)。以上结果表明FUT1基因的AA基因型对肉质和和胴体性状具有显著的正遗传效应,这对于在抗病育种中应用该基因十分有利。     

成花光敏感的雌雄性不育苎麻活性氧代谢研究

为研究成花光敏感雌雄不育苎麻(Floral initiation photo-sensitive male and female sertile ramie,SMSFS)的败育与活性氧代谢的关系,对SMSFS及其回复突变株SMSFS(R)花器官的活性氧(ROS)清除酶活性和丙二醛(MDA)含量测定．结果表明：SMSFS蕾的过氧化物酶(POD)、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性明显高于可育株SMSFS(R),而膜脂过氧化产物MDA的含量低于SMSFS(R);与蕾期相比,败育期SMSFS雌雄花除POD活性有所上升,而SOD和CAT活性则显著下降,MDA含量升高并高于开花期可育株．可见活性氧代谢的失衡引起了的膜脂过氧化,与SMSFS雌雄性败育明显相关．     

Behaviour of Merinos divergently selected for multiple rearing ability in response to external stimuli

Data of Merino sheep descended from two divergent selection lines for (H line) and against (L line) multiple rearing ability were collected in three different trials to compare response to stressful situations between lines. Trial 1: the behaviour of 138, 20-month-old sheep born in 2001 and 124, 8-month-old sheep born in 2002 were observed in an arena test. Experimental animals amounted to 111 and 101 for the H line in the respective years. Corresponding numbers for the L line were 27 and 23, respectively. Progeny born in 2001 were accustomed to handling, as the tests were performed shortly after routine performance recording. Lambs born in 2002 were unaccustomed to handling when tested. Progeny from the H line born in 2002 allowed a smaller (P < 0.01) minimum distance between them and the human operator seated between them and a group of similar aged sheep than L line contemporaries. Progeny born in the L line during 2002 defecated more (P < 0.05) frequently than H line contemporaries. No line differences were found in progeny born during 2001. Trials 2 and 3 were designed to test whether the putative line difference in stress response would impact on physical meat quality. Trial 2: a total of 103, 18–20-month-old progeny from the two selection lines were slaughtered during 2001, 2002–2003. Mean slaughter weight, dressing percentage and carcass weight of H line animals were between 5 and 13% higher (P < 0.05) than that of L line animals. There were no differences in cooking loss, drip loss and tenderness between the two lines. As pertaining to the meat colour, L line progeny had less vivid red meat, as seen by their lower (P < 0.05) a* colour reading and chroma values. The L line animals had lower (P < 0.01) initial pH values as measured in the Musculus longissimus dorsi. These results are indicative of susceptibility to acute, short-term stress. Trial 3: 20 progeny of the two selection lines were slaughtered and their muscle pH measured at 11 intervals from 45 min to 48 h post slaughter. As in Trial 1, the initial pH of the L line animals were lower (P < 0.05) than that of H line animals. An opposite tendency was observed by 48 h post slaughter. The obtained results support a hypothesis that divergent selection for ewe multiple ability resulted in adaptations to cope with unfamiliar conditions.     

Constitutively Elevated Levels of Putrescine and Putrescine-Generating Enzymes Correlated with Oxidant Stress Resistance in Conyza bonariensis and Wheat

Changes in ascorbate and glutathione levels and in activities of ascorbate peroxidase, catalase, dehydroascorbate reductase (DHAR), glutathione reductase (GR), glutathione S-transferase (GST), and superoxide dismutase (SOD) were investigated in tobacco mosaic virus (TMV)-inoculated lower leaves and in non-inoculated upper leaves of Nicotiana tabacum L. cv Xanthi-nc. In separate experiments the effects of exogenous salicylic acid (SA) were also studied. Symptom appearance after TMV inoculation was preceded by a slight, transient decline of ascorbate peroxidase, GR, GST, and SOD activities in the inoculated lower leaves, but after the onset of necrosis these activities and the glutathione level substantially increased. Ascorbic acid level and DHAR activity declined and dehydroascorbate accumulated in the inoculated leaves. In upper leaves, the glutathione level and the activities of GR, GST, and SOD increased 10 to 14 d after TMV inoculation of the lower leaves, concomitantly with the development of systemic acquired resistance. From the six distinct SOD isoenzymes found in tobacco leaves, only the activities of Cu,Zn-SOD isoenzymes were affected by TMV. SA injection induced DHAR, GR, GST, and SOD activities. Catalase activities were not modified by TMV infection or SA treatment. It is supposed that stimulated antioxidative processes contribute to the suppression of necrotic symptom development in leaves with systemic acquired resistance.