Histological characterization of hemorrhages in muscles of broiler chickens.

Hemorrhages in meat of broiler chickens are major quality defects. The objective of our study was to characterize the various types of hemorrhages in thigh and breast muscles with respect to their morphological appearance, location, and origin. Chickens were stunned using a water-bath stunner and were either exsanguinated and fixed or perfused with fixative. The morphological appearance of the hemorrhages was determined by the type of tissue in which they were found and by the amount of extravasating blood. Origins of hemorrhages were found only at sites of rupture of venous structures, such as postcapillary venules and small collecting veins. The absence of significant leukocyte infiltration strongly indicated that muscle tissue damage and hemorrhage occurred within the 24 h preceding stunning and slaughter. The locations and types of hemorrhages indicate different underlying mechanisms.

Hemoglobin and myoglobin content in muscles of broiler chickens.

The two main heme proteins, hemoglobin and myoglobin, are important factors determining meat quality aspects such as color and hemorrhage. The extent of hemorrhage in muscle tissue can probably be determined by measuring the hemoglobin content. The objective of this study was twofold: 1) to develop a specific and reproducible method to quantify the hemoglobin and myoglobin content in muscle tissue of broiler chickens, and 2) to study the effect of hemorrhage on the hemoglobin content in muscle tissue. We tested several methods to determine the total heme, hemoglobin, and myoglobin content in broiler chicken muscles on their specificity, sensitivity, and reproducibility. Methods based on immunological techniques appeared to be very specific and sensitive. The results obtained applying these methods on muscle tissue extracts were, however, not reproducible due to concentration effects. A combination of spectrophotometric analysis of the total heme protein concentration and measurement of the myoglobin concentration, applying size exclusion chromatography, proved to be a reliable and reproducible method to determine the hemoglobin and myoglobin content in chicken muscles. The total heme, hemoglobin, and myoglobin contents were related to muscle type. Extensive hemorrhage increased the hemoglobin content.

The effect of thermal preslaughter stress on the susceptibility of broiler chickens differing with respect to growth rate, age at slaughter, blood parameters, and ascites mortality, to hemorrhages in muscles.

In this study we investigated the occurrence of hemorrhages in four groups of electrically stunned broilers, differing with respect to growth rate, age at slaughter, hemodynamic parameters, and ascites mortality. In addition, the effect of three thermal preslaughter conditions on hemorrhage occurrence in thigh and breast muscles was studied. Broilers were either reared at a thermoneutral or low temperature regimen, and were either restricted in their feed consumption or consumed feed ad libitum. Prior to slaughter the broilers were exposed for 2 +/- 0.5 h to either cold (4 +/- 2 C, RH 100%), moderate (19 +/- 2 C, RH: 70 to 80%), or warm (30 +/- 2 C, RH: 60 to 70%) conditions. There was no effect of rearing group, nor was there an interaction between rearing group and preslaughter condition on hemorrhage scores in the thighs or breasts. Preslaughter conditions only affected hemorrhage scores in the left thigh. Scores were highest in broilers exposed to moderate preslaughter conditions. These data indicate that the cause of hemorrhages in muscles is multifactorial. Hemorrhage severity was not diminished in broilers retarded in growth. Pathological hemodynamic adaptations to low rearing temperatures, leading to ascites, did not increase hemorrhage severity, neither upon exposure to moderate nor to cold or warm preslaughter conditions.

Susceptibility of broiler chickens to hemorrhages in muscles: the effect of stock and rearing temperature regimen.

In this study, the effect of genetic constitution (stock) and rearing temperature on the occurrence of hemorrhages in thighs and breasts of water bath stunned broilers was investigated. Particular attention was given to the relation between the susceptibility for hemorrhages, body composition, and adaptations in blood variables induced by low rearing temperatures. A factorial experiment was performed with five parental stocks, differing with respect to growth rate, feed conversion, and body composition, and two temperature regimens (thermoneutral and below the zone of thermoneutrality). Hemorrhage scores in thighs were dependent on rearing temperature, not on stock, and were highest in broilers reared at low temperatures. In all stocks, high scores in the thighs were accompanied by an increased carbon dioxide pressure and bicarbonate and triiodothyronine concentration of the venous blood, and by an increased relative heart weight, hematocrit, and blood loss at slaughter. Hemorrhage scores in breasts were dependent on stock, confounded with day of scoring. An effect of rearing temperature was present only for the leanest, slow-growing stock having the lowest feed conversion ratio at thermoneutral rearing conditions. Scores in breasts were related neither to body composition nor to metabolic and hemodynamic adaptations to low rearing temperatures. It is concluded that high hemorrhage scores in thighs are related to hemodynamic and metabolic adaptations to an increased need for energy and oxygen caused by low rearing temperatures. Hemorrhage scores are not related to stock-dependent differences.

The effects of alternative electrical and mechanical stunning methods on hemorrhaging and meat quality of broiler breast and thigh muscles.

Five trials were conducted to determine the effects of various alternative stunning and restraining methods on the quality of chicken broiler meat. The stunning methods used were electrical whole-body and head-only stunning with different voltages (25 vs 100 V) and frequencies (50 vs 200 Hz), and mechanical captive bolt stunning. Before being stunned, the broilers were restrained either by shackling them by the feet, restraining their heads while they were standing, or placing them in a cone. Convulsions during and after stunning were subjectively scored. At 1 d post-mortem, the pH, color, and the intensity and number of hemorrhages, of breast and thigh muscles were measured. Convulsions were, in order of increasing intensity, observed after whole-body stunning using 50 Hz, whole-body stunning using 200 Hz, head-only stunning, and captive bolt stunning. No differences in ultimate pH were measured. A consistent difference in color was observed between whole-body and head-only stunning. Head-only stunning resulted in darker and more red (P < or = 0.01) breast muscles. Head-only and captive bolt stunning resulted in hemorrhages that were located more distal in the breast muscle than those observed after whole-body stunning. Captive bolt stunning (in a cone) resulted in fewer (P < or = 0.01) hemorrhages in breast and thigh muscles than whole-body stunning (100 V, 50 Hz, shackled), and in a similar level of hemorrhaging as electrical head-only stunning (25 V, 200 Hz, in a cone).

Hemorrhages in muscles of broiler chickens: the relationships among blood variables at various rearing temperature regimens.

Hemorrhages in muscle tissue can be considered as major quality defects of broiler carcasses. They can be induced by stunning, especially electrical stunning. The underlying mechanism, however, is considered to be multifactorial. In this study, the effect of blood circulation disturbances on the severity of hemorrhages induced by electrical stunning was investigated. The disturbances were evoked in two genetically different, fast-growing broiler strains, Ross and Hybro, by rearing the broilers at low ambient temperatures. The broilers were slaughtered by two different electrical stunning methods. Broilers reared at low temperatures showed changes in blood variables and heart weight known to be associated with blood circulation disturbances. There was no effect of rearing temperature on hemorrhage severity. Ross broilers, being the most susceptible to low temperatures, had less severe hemorrhages than Hybro broilers. There was, however, a clear effect of the stunning method on hemorrhage severity. Whole body stunning caused more severe hemorrhages than head stunning in thigh and breast muscles. These results suggest that factors interfering with blood circulation have little or no effect on the occurrence of hemorrhages induced by electrical stunning.

Chilling pig carcasses: Effects on temperature, weight loss and ultimate meat quality.

Effects of conventional (4°C, air velocity 0·5 m/s) and forced chilling at -5°C (120 min) or -30°C (30 min) with air velocities of 1, 2 or 4 m/s, followed by conventional chilling till 24 h post mortem on temperatures, meat quality and weight losses, were studied. Experiments were carried out in six batches of six slaughter pigs each (crossbred gilts, weighing 105-110 kg. The subcutaneous temperature decreased very rapidly to values below 0°C when 'ultra' rapid chilling (-30°C) at high air velocities (4 m/s was used. Immediately after rapid chilling, when the carcasses were railed into a conventional chiller, the subcutaneous temperature increased above the air temperature, after which the decline in temperature was continued. Temperature inside the biceps femoris muscle decreased from the start of chilling rather slowly according to an asymptotic curve until ultimate values of 4°C were reached. Theoretically calculated temperatures during slaughter and chilling were comparable with the measured values; indicating that a finite-element calculation method in combination with a cylindrical model for heat transport can be used to predict muscle temperatures for various chilling regimes. Losses in carcass weight, 24 h after conventional and forced chilling at -5°C, were about 2%. After 'ultra' rapid chilling (-30°C) the losses were reduced to 1·3% when air velocity was increased to 4 m/s. Meat quality of the longissimus lumborum muscle was not significantly affected by the various chilling regimes except for the variables related to tenderness. The Warner-Bratzler shear forces were higher (P < 0·05) together with shorter sarcomere lengths (P < 0·10) after 'ultra' rapid chilling at a high (4 m/s) air velocity, indicating an increased risk of cold shortening.

The effect of scalding on subcutaneous and ham temperatures and ultimate pork quality.

Scalding of pig carcasses (n = 34) at 60°C for a period of at least 5·5 to 7·5 min gave satisfactory dehairing results, with the exception of autumn hair for which a longer period (9 mins) was required. Temperature curves were recorded for a subcutaneous position in the ham (n = 26) between the rind and the underlying fat layer. These showed a curve starting at about 30·8°C and increasing to an asymptotic value of 53°C during scalding. Results of calculations with a finite element model of a flat layer of muscle covered with a layer of 1·0 cm fat broadly showed the same temperature increase at about 0·5 cm below the surface as the actual values measured. Immediately after dehairing, about 1·5 mins after finishing scalding, the subcutaneous temperature had already dropped to 46·1 ± 3·0°C, which was considerably higher than the muscle temperature at the same position at a depth of 5 cm under the skin (40·6°C). The heat removal and temperatures during the cooling period after scalding were also calculated. It can be concluded that the increase in temperature due to scalding has only a minor influence on muscle temperature and that meat quality (pH, FOP) is not affected.

Effect of dietary energy, protein, and lysine content on performance and yields of two strains of male broiler chicks.

In a factorial arrangement of treatments Arbor Acres and Ross male broiler chicks were given four diets with 3,200 kcal ME/kg and four diets with 2,880 kcal ME/kg, two CP levels per energy level (23.1 and 33.6% in the high-energy diet and 21.0 and 29.7 in the low-energy diet) and two Lys levels per CP level per energy level (1.20 and 1.36% per CP level in the high-energy diets and 1.08 and 1.22% per CP level in the low-energy diets). The diets were given to 8 wk of age. Weight gain of Arbor Acres chicks was significantly higher (P less than .05) than that of Ross chicks at 6 and 7 wk of age, but feed to gain ratios were also significantly higher (P less than .05) at 6, 7, and 8 wk of age. Weight gain and feed to gain ratios were significantly better (P less than .05) on the high-energy diets than on the low-energy diets at 6, 7, and 8 wk of age. With equal Lys content, the normal-CP diets gave significantly higher gains (P less than .05) than the high-CP diets at 6, 7, and 8 wk of age. With equal CP content, the high-Lys diets gave significantly more gain (P less than .05) than the normal-Lys diets at 6, 7, and 8 wk of age. Oven-ready and breast meat yields of Ross chicks were significantly higher (P less than .001) compared with those of Arbor Acres chicks at 6, 7, and 8 wk of age and yields of edible organs, skin and fat, and remaining carcass were significantly lower (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)