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To clarify the physiological prerequisites for the course of energy metabolism post mortem, 80 pigs consisting of four females from each of 20 litters of crossbreeds (Duroc as sireline and Danish Landrace×Danish Large White as dam line) were within litter allocated to four different treatments (A, B, C and D) to provide a large variation in the concentration of the key metabolites glycogen, ATP and creatine phosphate at the time of stunning. (A) no stress before stunning, (B) physical stress consisting of treadmill running (3.8 km/h for 10 min) immediately before stunning, (C) intermediate reduction of glycogen at stunning achieved by application of adrenaline (0.2 mg/kg live weight 15-18 h before stunning), and (D) maximal reduction of glycogen achieved by application of adrenaline (0.3 mg/kg live weight 15-18 h before stunning) and treadmill running (3.8 km/h for 5 min). Compared with resting values (measured in samples taken in the pen the day before slaughter by needle biopsy), longissimus muscle glycogen (16, 13, 57 and 66% for A, B, C and D, respectively), creatine phosphate (17, 22, 12 and 9% for A, B, C and D, respectively) and ATP levels (10, 15, 38 and 31% for A, B, C and D, respectively) measured immediately before stunning were all reduced by the treatments. Stunning caused a rather uniform reduction in creatine phosphate level in all the models. Glycogen concentrations were also further reduced in treatments A, C and D, but not in B, and although ATP levels increased in all the models during stunning, this was only significant for the B model. Consequently, the effect of CO(2) stunning on glycogen and ATP levels depends on pre-slaughter handling. It was also shown that an inverse relationship between ultimate pH and glycogen concentration at the time of stunning existed only when glycogen levels at stunning were below 53 mmol/kg (r=0.88, P<0.001). The validity of this threshold value is discussed. Furthermore, the possibility to standardise the physiological prerequisites of the post mortem pH decreases represents a potent tool to investigate metabolic causes of variations in meat quality characteristics.

Early post mortem metabolism and structural changes from 3 to 24 h, together with pH, temperature and impedance Py development were investigated in 37 Duroc×Landrace×Large White (DLY) pigs covering a range of drip loss from 2.2 to 12.6%. Multivariate statistical analysis was used to assess the impacts of different metabolites, pH and temperature, impedance, cytoskeletal protein degradation and extracellular cross-sectional area on drip loss. Taken as single factors, the concentration of lactate could explain 80% of the variation in drip, inosine monophosphate (IMP) and adenosine triphosphate (ATP) concentration explained 71 and 68%, respectively, whereas inosin and glycogen levels explained only 59 and 60%. The extracellular area was found to explain 39% of the variation in drip. The area between fibres provided more significant information than did the area between fibre bundles. The degradation of the cytoskeletal proteins was not related to drip loss. Impedance Py development over 24 h could explain 66% of the variation in drip, whereas pH and temperature explained 85 and 87%, respectively. A model including all measured variables could explain 83% of the variation in drip. However, only pH, temperature, impedance, [ATP](1 h) and [lactate](1 h and 2 h) were significant in relation to drip. By reducing the variables in the multivariate analysis, 89% of the variation in drip could be explained by a model containing only pH(2 h) and temperature(1 min). To explain variation in drip loss, pH and temperature measurements at significant time points were sufficient. Variation in post-mortem metabolites did, however, explain why variation in pH and temperature occurred. Development of drip channels was ruled by pH and temperature while impedance development was highly correlated to pH. This multi-faceted study shows those parameters, which can best be used to indicate or predict WHC, as well as those indicating the basic mechanism underlying variations in drip.

The physiological condition of the live animal was found to significantly affect colour, lipid oxidation and water holding capacity of chill stored pork chops (M. Longissimus dorsi) in a study, where various pre-slaughter conditions were achieved by the following four treatments: (A) control; (B) subjected to treadmill exercise immediately prior to stunning; (C) given epinephrine injection 15 h prior to slaughter; and (D) given epinephrine injection 15 h before slaughter and further subjected to treadmill exercise immediately before stunning. The treatments resulted in variations in energy metabolites (glycogen, lactate, creatine phosphate, ATP) and ultimate pH (pH(u)), with the lowest pH(u) in chops from treatments A and B, and in significantly different tristimulus colour L(∗)-, a(∗)- and b(∗)-parameters, although the effect of treatment on colour was not consistent during the chill storage period of 6 days. Overall, chops from treatments A and B had significantly higher L(∗)- and b(∗)-values (were paler and less blue) than chops from C and D during storage under conditions typical for retail trade. The initial a(∗)-values were higher (redder) in chops from treatments A and B, but the colour, as judged by the a(∗)-values, was less stable in meat from these treatments compared with treatments C and D. Lipid oxidation, evaluated by thiobarbituric acid reactive substances (TBARS) in the fresh meat, and drip loss, measured after 6 days of storage, were both significantly higher in chops from treatments A and B compared to chops obtained from treatments C and D. Statistical analysis relating the pH and the level of various energy metabolites post-mortem in the individual animals to the measured quality parameters, revealed that pH(u) was the most important factor affecting product quality. In conclusion, over all product quality depends on obtaining a pH(u) in the narrow range where both meat quality parameters such as colour, lipid oxidation and drip loss as well as microbiological aspects have to be considered.

Four spectroscopic instruments, a fibre optical probe (FOP), a visual (VIS) and near infrared (NIR) reflectance spectrophotometer, a reflectance spectrofluorometer and a low-field (1)H nuclear magnetic resonance (LF-NMR) instrument were used to perform measurements on two muscles (longissimus dorsi and semitendinosous) from 39 pigs, 18 of which were carriers of the Halothane gene. Water-holding capacity (drip loss and filter paper wetness) and chemical composition (intramuscular fat and water) of the muscle samples were determined for spectroscopic calibration. Prediction models were established by partial least squares regression to evaluate the potential of using the spectroscopic techniques in an on-line slaughterhouse system. VIS data gave good prediction models, indicating that current industrial colour systems can be advanced into more specific meat evaluation systems by including the entire visible spectral range. The FOP and fluorescence measurements were less successful, and suffered from sampling problems since they measure only a small area. The best regression models were obtained from LF-NMR data for all reference quality measures and yielded a correlation coefficient of 0.75 with drip loss. LF-NMR proved able to distinguish between the two muscles and the results for their longitudinal relaxation times, T(21), were proportional to their average myofibrillar cross-sectional areas reported in the literature.

The objectivity of two of the most widely used methods for differentiation of fibre types, i.e. 1) the myosin ATP-ase method (Brooke and Kaiser, 1970a,b) and 2) the combined method, by which the myosin ATP-ase reaction is used to differentiate between fast and slow twitch fibres and NADH-tetrazolium reductase activity is used to identify the subgroups of fast twitch fibres (Ashmore and Doerr, 1970, Peter et al., 1972), was assessed in muscle samples from horses, calves and pigs. We also assessed the objectivity of the alpha-amylase-PAS preparation for the visualisation of capillaries (Andersen, 1975) in these species. For the purpose of reducing the time costs of histochemical analysis of muscle samples, we have developed an interactive image analysis system which is described. All analyses are performed on this system. In accordance with several other investigations, differences between the two methods of differentiating fibre types were found only for the relative distribution of the fast-twitch fibre subgroups (p < 0.02 and p < 0.05 for the relative number of type IIA and IIB, respectively) whereas when calculated in relative area, only the proportion of type IIA fibres differed significantly (p < 0.05). Significant interaction effects between method and person and method and species were found for the same traits. When methods were analysed separately, the combined method displayed a significant variance component of person for the distribution of type IIA fibres both in relative number and in relative area (p < 0.01 and p < 0.001, respectively). The objectivity of the ATP-ase method was further substantiated by the fact that a higher fraction of the total variance for the relative area distribution of type IIA fibres was explained by the statistical model (72.1% versus 34.2% for the combined method). Although the repeatability of measurements between persons was generally high (> 87%), the impact of differences in pre-requisites (varied degrees of overlap between the fibre types) for performing the differentiation by the combined method raises a question of the reliability of this method. Apparently, no general rules for comparison of results of distribution of the two subgroups of fast twitch fibres by the two methods are applicable. The alpha-amylase-PAS method was found to be a fairly objective method to identify capillaries in muscles from horses, calves and pigs. However, as capillarity described in combination with other traits to give an indication of diffusion characteristics is significantly influenced by person, it is recommended that the same person perform all the analysis of a project. In addition to the methodological results in this study, we have shown that by application of the TEMA image analysis system, which is more rapid compared with the time-consuming traditional method for evaluation of histochemical preparations, analysis of samples from large-scale experiments are now possible.

A total of 300 female broiler chickens were reared from day-old to 10 d of age on the same starter diet. Then they were divided into five groups, receiving a control diet (Group 1) relatively rich in fat (14.3%) and unsaturated fatty acids (87.6%) and standardized with respect to vitamins and minerals, supplemented with 100 mg (Group 2) and 500 mg (Group 4) of RRR-alpha-,gamma-,delta-tocopheryl acetate/kg feed (40.6% alpha-, 41.1% gamma-, 18.3% delta-) or 100 mg (Group 3) and 500 mg (Group 5) all-rac-alpha-tocopheryl acetate/kg feed until slaughter at 6 wk of age. No differences between the supplemented groups were observed with respect to weight gain, feed consumption, packed cell volume (PCV), plasma enzyme activities of creatine kinase (CK) and glutathione peroxidase (GSH-Px), fatty acid composition, and enzyme activities of citrate synthase (CS), and total lactate dehydrogenase (LDH), and 3-OH-acyl-coenzyme A-dehydrogenase (HAD) of breast (Pectoralis major) and thigh (Gastrocnemius interna) muscle. Increasing levels of alpha-, gamma-, and delta-tocopherol were found in blood plasma with increasing dietary levels of these tocopherols. Only alpha-tocopherol was detectable in skeletal muscle and in higher concentrations in thigh than in breast muscle. Hemolysis in vitro and plasma activity of aspartate aminotransferase (ASAT) were lower (P < .01) in Groups 2 and 4 than in Groups 3 and 5. Interactions were observed between dietary type and concentration of tocopherols for plasma CK, GSH-Px, Na+, and K+. No measurable excretion of ethane and pentane was observed in any of the groups. The findings indicate that the oxidative stress in the live animals was minimal. The mixture of natural source RRR-alpha-,gamma-,delta-tocopherols was as efficient in protecting the live chickens as the all-rac-alpha-tocopheryl acetate, when provided on a weight basis as judged from the chosen in vivo parameters of vitamin E status.

The development of PSE (pale, soft and exudative) meat is characterized by a rapid decrease in pH post-mortem and/or a low ultimate pH. We investigated some physiological properties of the live muscle (the glycogen content, the non-bicarbonate buffering capacity and 'resting pH'), which could influence both the decrease in pH and the ultimate pH. Measurements were performed on three halothane genotypes, hal(N)hal(N), hal(N)hal(n) and hal(n)hal(n), with their known predispositions for PSE meat. It was demonstrated that the glycogen content in both the groups of double recessive and heterozygous individuals was higher than the levels in the group of homozygous dominant pigs. No difference was found in non-bicarbonate buffering capacity between the groups. The groups with the highest glycogen levels also had the lowest 'resting pH' values. The results indicate that measurement of glycogen content in vivo may be superior to the halothane test in detecting PSE-prone individuals. The lower pH values of carriers of the hal(n) gene further indicate that the characteristic rapid decrease after slaughter may not be as fast as generally accepted, as even very low pH values can be observed in the muscles of live pigs., (Copyright © 1992. Published by Elsevier Ltd.)