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Withdrawal of red meat from the usual diet reduces albuminuria and improves serum fatty acid profile in type 2 diabetes patients with macroalbuminuria.

BACKGROUND: Replacement of red meat in the diet with chicken has reduced the urinary albumin excretion rate (UAER) and serum cholesterol in microalbuminuric type 2 diabetes patients. The effects of withdrawing red meat are unknown in the more advanced stages of diabetic nephropathy. OBJECTIVE: Our objective was to assess the effects of replacing red meat in the usual diet (UD) with chicken (CD) and of consuming a lactovegetarian low-protein diet (LPD) on renal function, fatty acid, and lipid profile in macroalbuminuric type 2 diabetes patients. DESIGN: A crossover controlled trial was conducted in 17 type 2 diabetes patients with macroalbuminuria (24-h UAER > or = 200 microg/min). Each patient followed the UD, CD, and LPD in a random order for 4 wk. After each diet, glomerular filtration rate, UAER, serum fatty acid, lipid profile, glycemic control, anthropometric indexes, and blood pressure were measured. RESULTS: UAER [median CD: 269.4 (range: 111-1128) microg/min; LPD: 229.3 (76.6-999.3) microg/min; UD: 312.8 (223.7-1223.7) microg/min; P < 0.01] and mean (+/-SD) non-HDL cholesterol (CD: 3.92 +/- 0.99 mmol/L; LPD: 3.92 +/- 0.93 mmol/L; UD: 4.23 +/- 1.06 mmol/L; P = 0.042) were lower after CD and LPD than after UD. Compared with the UD, an increase in serum total polyunsaturated fatty acids was also observed (CD: 39.8 +/- 2.6%; LPD: 39.7 +/- 4.4%; UD: 37.3 +/- 3.1%; P = 0.029). CONCLUSION: In macroalbuminuric patients with type 2 diabetes, withdrawing red meat from the diet reduces the UAER.

Aged↗

Proposed structures for an amino-dimethylimidazofuropyridine mutagen in cooked meats.

New analytical data allow the structure of a potent mutagen previously reported present in cooked meats to be proposed. The mutagen was isolated from a fried mixture of beef, creatine and milk, simulating a meat recipe previously shown to produce this compound. High-resolution mass spectra indicate a mol. wt of 202 and the formula C10H10N4O. Mutagenic activity was 10,000 TA1538 revertants per microgram in the Ames Salmonella test. From the NMR data, peaks showing an amino group at 6.812 p.p.m. and an N-methyl group at 3.520 p.p.m. were found, typical for the amino-imidazo structure commonly found in cooked meats. Additional signals at 2.440 p.p.m. (three protons), 7.653 (one proton) and 6.531 (one proton) were observed. A structure of 2-amino-(1 or 3),6-dimethylfuro[2,3(or 3,2)-e]imidazo- [4,5-b]pyridine was proposed based on the mass and NMR spectral data and comparison to literature compounds. The methylimidazofuropyridine reported here is probably related to another mutagen in cooked meats with a mol. wt of 216 with an additional methyl group on either the furan or pyridine rings.

Animals↗

Red meat and colon cancer: dietary haem, but not fat, has cytotoxic and hyperproliferative effects on rat colonic epithelium.

High intake of red meat is associated with an increased risk of colon cancer. It has been suggested that fat from red meat is responsible, because high fat intake increases the concentration of cytotoxic lipids in the colon. Experimental studies have not unequivocally supported such a role for fat, however. Recently, we showed that dietary haem, which is abundant in red meat, increased colonic cytotoxicity and epithelial proliferation. In this study, we wanted to clarify whether dietary fat affects colon cancer risk by itself or by modulating the detrimental effects of haem on the colonic epithelium. Rats were fed control or haem-supplemented diets with 10%, 25% or 40% of the energy derived from fat for 14 days. Faeces were collected for biochemical analyses. Colonic cytotoxicity was determined from the degree of lysis of erythrocytes by faecal water. Colonic epithelial proliferation was measured in vivo using [(3)H]thymidine incorporation. Increasing the fat content of the control diets stimulated faecal disposal of both fatty acids and bile acids. It also increased the concentration of fatty acids, but not that of bile acids, in faecal water in control rats. The cytolytic activity of faecal water and colonic epithelial proliferation were unaffected. Dietary haem increased faecal cation content and cytolytic activity of faecal water at all fat levels, suggesting that the colonic mucosa was exposed to high amounts of luminal irritants. This effect was smaller in rats on the low-fat diet. Dietary haem also increased colonic epithelial proliferation at all fat levels. The haem-induced effects were independent of fatty acids or bile acids in the faecal water. In western societies, 30-40% of ingested energy is supplied by dietary fat, so our results suggest that the association between consumption of red meat and risk of colon cancer is mainly due to its haem content, and is largely independent of dietary fat content.

Animals↗

Method for the analysis of thyreostats in meat tissue using gas chromatography with nitrogen phosphorus detection and tandem mass spectrometric confirmation.

An analytical method not requiring a mercury column cleanup step is described for the isolation and detection of four thyreostatic agents in meat tissue. The use of these growth promotants in livestock has been banned by regulatory agencies. The meat tissue is homogenized with acetonitrile-water, centrifuged, and the supernatant is partitioned with petroleum ether. The acetonitrile-water is concentrated and then passed through a silica-gel column. The solvent is then removed and the residue derivatized with N-methyl-N-(trimethylsilyl)-trifluoroacetamide. The total amount of organic solvent used for the analysis is merely 35 mL. The derivatized thyreostats are detected and quantitated by gas chromatography (GC) equipped with a nitrogen-phosphorus detector. Percent recoveries from fortified meat tissue (n = 6) at the 0.1-microg/g (parts per million) level are 93.5 +/- 2.9 for 2-thiouracil, 90.3 +/- 3.0 for tapazole, 87.5 +/- 2.9 for 6-methyl-2-thiouracil, and 85.1 +/- 5.8 for 6-n-propyl-2-thiouracil. For the confirmation of analyte identities, GC-tandem mass spectrometry with an ion-trap instrument is used. The estimated minimum level for a reliable measurement is 0.050 microg/g in meat tissue.

Animals↗

Gender differences in the consumption of meat, fruit and vegetables are similar in Finland and the Baltic countries.

BACKGROUND: Women's diets are healthier than men's. Finnish women eat more fruits and vegetables but less meat than men. Gender differences may be larger in the Baltic countries, which represent Eastern European transition societies than in Finland, a society characterized by the Scandinavian welfare ideology and a high degree of gender equality. METHODS: The data are based on questionnaires to random samples of adults in Finland, Estonia, Latvia and Lithuania. The data provide a way of addressing gender differences at the turn of the century in the economically and culturally different countries. The purpose is to explore whether the consumption of foods classified as masculine or feminine-meat, fruits and vegetables-follow a similar gender pattern in Finland and the Baltic countries. RESULTS: Men ate meat more often while women ate fruits and vegetables. A high educational level was associated with frequent consumption of fruits and vegetables. Educational differences in the consumption of meat were few and inconsistent. The consumption of fruits and vegetables was more common in urban areas except in Finland. Gender differences were similar in all countries throughout age and educational groups and in rural and urban areas. CONCLUSION: The consistent association of gender and food and the similarity of gender patterning in population subgroups point to the stability of masculine versus feminine food habits. The similarity suggests that food habits contribute equally to the gender gap in health in the Baltic countries as they do in Finland.

Adult↗

Rapid bioassay for the determination of dioxins and dioxin-like PCDFs and PCBs in meat and animal feeds.

Over the past several years, the numerous contamination incidents have raised concerns over the presence of halogenated aromatic hydrocarbons, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), and related chemicals in foods and feeds. Here we applied a sensitive recombinant mouse hepatoma cell (H1L1.1c2) bioassay for the determination of dioxins and dioxin-like polychlorinated dibenzofurans (PCDFs) and biphenyls (PCBs) in meat and animal feeds. These cells responded to TCDD-like chemicals with dose-dependent induction of firefly luciferase activity, and the minimal detection limit of TCDD in the cell was 16 fg. Induction equivalency factors determined for pure TCDD-like polychlorinated dibenzo-p-dioxins (PCDDs), PCDFs, and PCBs in the bioassay were well-correlated with the World Health Organization's toxic equivalency factors. To determine the applicability of the bioassay system to detect those compounds presence in meat and feed samples, cell bioassays for 17 TCDD-like PCDDs and PCDFs congeners-spiked lipid extracted from beef or animal feed were performed. Mean recoveries of TCDD-like chlorinated PCDDs and PCDFs congeners from spiked beef or feed fat ranged from 61.2 to 122.3%. Within-laboratory coefficients of variation for analysis as index of precision were lower than 5.2%, and the calculated limits of detection and quantitation were 0.33 and 1 pg toxicity equivalency quantity (TEQ)/0.5 g fat, respectively. Correlation between bioassay- and high-resolution gas chromatography-mass spectrometry (HR-GC-MS)-determined TEQs for 10 meat samples was 0.85, with 1.2 times higher in bioassay than HR-GC-MS. The correlation between bioassay- and HR-GC-MS-determined TEQs in 10 animal feed products was 0.81, with 2.1 times higher in bioassay than HR-GC-MS. Overall, these results demonstrated that the recombinant cell bioassay can be used for the rapid detection and quantitation of PCDDs and dioxin-like PCDFs and PCBs in meats and animal feeds.

Animal Feed↗

65Copper absorption by women fed intrinsically and extrinsically labeled goose meat, goose liver, peanut butter and sunflower butter.

Absorption of stable 65Cu incorporated intrinsically or extrinsically into foods was studied in women fed a diet marginal in Cu content. Isotopic enrichment was 73.1 +/- 1.0 atom percent 65Cu in goose breast meat, 74.9 +/- 0.5 atom percent in goose liver, and 55-69.5 atom percent in two crops of peanuts. Seven women were fed a basal diet containing 1.25 mg Cu/d. At 4-wk intervals, they were fed test meals over a 3-d period; each set of meals contained one of the labeled test foods in amounts with similar copper content. Absorption of 65Cu from intrinsically labeled liver was (mean +/- SD) 65 +/- 4%; extrinsic liver, 65 +/- 10%; E/I = 1.00 +/- 0.16. 65Cu absorption from intrinsically labeled goose breast meat was 54 +/- 6%; extrinsic meat, 52 +/- 10%; E/I = 0.97 +/- 0.18. 65Cu absorption from intrinsically labeled peanut butter was 58 +/- 15%; extrinsic peanut butter, 54 +/- 10%; E/I = 0.93 +/- 0.11. 65Cu absorption from extrinsically labeled sunflower butter was 50 +/- 2%. There were no differences in absorption of intrinsic and extrinsic Cu from these foods. Absorption of Cu was significantly higher from goose liver than from goose meat or sunflower butter (P less than 0.05). With a dietary intake of 1.25 +/- 0.20 mg Cu/d, Cu balance, exclusive of surface losses, was essentially zero (0.01 +/- 0.13 mg/d) in the seven subjects.

Animals↗

Prevention of mutagen formation in heated meats and model systems.

Possible means for preventing mutagen formation in cooked meats and in heated model systems are described. One way to reduce mutagenicity in cooked meats is to control cooking temperature, time and method. Another way is to increase water content or to avoid loss of water in meats during cooking. Addition of an excessive amount of reducing sugars to meats before cooking is effective in minimizing mutagen formation, which may be due to suppression of generation of the pyrazine cation radical Maillard intermediate of heterocyclic amines. Addition of a small amount of ascorbate or erythorbate is also effective, which may be the result of scavenging the intermediary pyrazine cation radical.

Animals↗

Nested case-control study of tumors of the hemopoietic and lymphatic systems among workers in the meat industry.

Workers in the meat industry are exposed to viruses that cause leukemia and lymphoma in cattle and chickens, and also to carcinogenic chemical agents. This case-control study, nested in a cohort of members of a meatcutters' union in Baltimore, Maryland, investigated whether occupational exposures are associated with death from tumors of the hemopoietic and lymphatic systems. Cases of these tumors represent all deaths which occurred in the cohort between 1949 and 1980. Excess risks of tumors of the hemopoietic and lymphatic systems were observed throughout the meat industry, except in meatpacking plants. Slaughtering activities involving heavy exposure to oncogenic viruses were strongly associated with these tumors, especially with lymphomas. Thus, elevated risks were observed for butchers who killed animals (odds ratio (OR) = 5.3, 95% confidence interval (CI) 1.0-27.0); workers in chicken-slaughtering plants (OR = 3.3, 95% CI 0.8-13.1); and workers in cattle/sheep/pig abattoirs (OR = 2.8, 95% CI 0.8-9.5). Among supermarket workers, wrapping meat (mainly a female activity) was associated with increased risk of tumors of the hemopoietic and lymphatic systems (OR = 3.8, 95% CI 1.0-14.3), with the odds of both lymphomas and tumors of the myeloid stem cell being elevated. On the other hand, meatcutting in supermarkets (almost exclusively a male activity) was associated with multiple myeloma; the odds ratio for men was 18.0 (95% CI 1.6-207.5), with no myeloma cases being recorded in women. These associations persisted after limited control for exposures outside the industry that have also been observed to be associated with excess risk, such as exposure to pesticides, working/living on pig farms, and exposure to X-rays. The findings provide evidence that workers in the meat industry may be at elevated risk of tumors of the hemopoietic and lymphatic systems. Further studies with larger sample sizes are needed to identify more conclusively which exposures play an etiologic role in the occurrence of the different histologic types of these tumors.

Adult↗

A comparison of high current and low voltage electrical stunning systems on broiler breast rigor development and meat quality.

Experiments were conducted to compare the effects of a high current (HC) stunning system to a low voltage (LV) stunning system on broiler carcass and meat quality. A total of 360 broiler chickens were individually stunned using either 125 mA, 50 Hz, constant AC for 5 s (HC) or using 10.5 V, 500 Hz pulsed DC for 10 s (LV). Birds were individually weighted, killed by conventional neck cut, bled for 150 s, and reweighed to determine blood loss. Breast fillets (Pectoralis major) were removed from the carcass immediately after picking (0 h) or after aging for 24 h in a static ice-water slush. Breast muscle pH was determined at both 0 and 24 h. Raw breast meat color (CIELAB) and cooked breast meat Allo-Kramer shear values were determined on samples held at 2 C for 48 h. The LV stunning treatment significantly increased (P < 0.05) blood loss (4.0 vs 3.7%) and significantly reduced initial muscle pH (6.47 vs 6.67) when compared to the HC stunning treatment. There were no significant differences between the stunning systems for 24 h pH, raw breast color, and Allo-Kramer shear. High current stunning reduced initial blood loss and delayed early rigor development compared to the LV treatment, but appeared to have little effect on final meat quality.

Animals↗

Moderate excess of dietary protein increases breast meat yield of broiler chicks.

Two factorial experiments were carried out to evaluate the effects of dietary protein level, expressed as energy to protein (E:P) ratio, on yields of carcass and breast and on abdominal fat pad weight of male broiler chicks at 43 and 57 d of age. Two diets similar in their energy content and differing markedly in their protein content, in which the E:P ratios were lower and identical to the NRC (1994) recommendations, were used in Experiment 1. Four diets, the combination of two energy and two protein levels, in which the E:P ratios were lower and identical to the recommendations, were used in Experiment 2. There were no differences in feed intake or weight gain until 42 d of age between broilers fed the diets with the low and those fed the recommended E:P ratio. However, feed efficiency of the former was consistently and significantly (P < 0.05) higher. The high-energy diets did not affect feed intake but significantly improved weight gain between 7 and 28 d of age and feed efficiency until 42 d of age. In both experiments, carcass yield was not affected by dietary E:P ratio at 43 d of age; however, at 57 d of age it was increased significantly by the low E:P ratio in Experiment 1 and in birds fed the high energy diet in Experiment 2. On a factorial basis, the effect of the low E:P ratio on increasing yield was significant only in Experiment 1. The high dietary energy level increased carcass yield only at 43 d of age, but on a factorial basis its effect was significant. Carcass yield was significantly (P < 0.001) higher at 57 than at 43 d of age. In both experiments, breast meat yield was negatively correlated with dietary E:P ratio, a significant factorial effect. The difference in this variable between broilers fed the diets containing the low and the recommended E:P ratio was significant, at both ages in Experiment 1, and only at 57 d of age in Experiment 2. Breast meat yield was not affected by dietary energy level, and it was significantly (P < 0.001) higher at 57 than at 43 d of age. Relative abdominal fat pad weight was increased significantly by increasing dietary E:P ratio. Dietary energy level and age did not affect this variable. The relationship between abdominal fat pad weight and breast meat yield within the treatments tended (in most of the cases not significantly) to be negative. However, this negative relationship was significant, at both ages, when the analysis was carried out with the pooled data at each age. It is concluded that the optimal E:P ratio for maximal breast meat yield for broiler chicks, particularly at 57 d of age, may be below the NRC (1994) recommendations.

Aging↗

n-3 enrichment of chicken meat using fish oil: alternative substitution with rapeseed and linseed oils.

Two sequential experiments were conducted to assess the effect of replacing a fish oil diet with vegetable oil diets on broiler chicken performance and fatty acid (FA) composition and sensory traits of broiler meat. A diet enriched with 8.2% fish oil (FO) was fed to the birds throughout the 5-wk growth period (T1), the same basal diet being supplemented with 8.2% linseed oil (LO, Experiment 1) or rapeseed oil (RO, Experiment 2) in three different periods: the last week before slaughtering at 35 d (T2), the last 2 wk (T3), and throughout the experiment (T4). A sensory evaluation of the meat was carried out and its FA profile was determined. Performance parameters were not significantly different among treatments. Removing FO resulted in lower values of saturated and higher n-6 FA content, the latter because of the increase in linoleic acid in both experiments. The amounts of long-chain n-3 polyunsaturated fatty acids (PUFA) were significantly depressed when FO was replaced. However, replacing FO by LO resulted in minimal effects on total n-3 FA, due to the increase in linolenic acid. The substitution of FO by RO resulted in a decrease in the n-3 FA content, whereas levels of monounsaturated FA (MUFA) increased in direct relation to the larger amounts of oleic acid in the diet. Sensory panelists scored as unacceptable those meats from T1 in both experiments. Replacing 1 (T2) or 2 (T3) wk FO with vegetable oil clearly resulted in the improved sensory quality of meat.

Animal Feed↗

Broiler breast meat color variation, pH, and texture.

Four experiments were conducted to determine the range of breast meat color variation observed in commercial processing plants and its relationship to muscle pH and texture. Boneless, skinless breast fillets were collected weekly from the deboning lines of five commercial processing plants over a 4-wk period. Plant personnel selected breast fillets based on their appearance as being "lighter than normal," "normal," or "darker than normal" in color. Five representative fillets of each appearance classification were transported to a central laboratory for analyses of visual score (1 to 5 with 1 = light, 3 = normal, or 5 = dark), instrumental color, muscle pH, and Allo-Kramer shear (n = 300). Visual scores, lightness (L*), redness (a*), and pH were different (P<0.05) among the three appearance groups, with no significant differences in yellowness (b*). Visual scores averaged 2.4, 3.0, and 3.6, L* was 48.8, 45.6, and 43.1, and pH was 5.63, 5.70, and 5.81 for the lighter, normal, and darker fillets, respectively. There were no significant effects of color group on breast meat texture. Correlations between the color values and pH, however, were all highly significant. These results not only indicate that there are wide variations in breast meat color in commercial production, but they also demonstrate a strong relationship between breast meat color and muscle pH.

Animals↗

Age-related changes in meat tenderness and tissue pentosidine: effect of diet restriction and aminoguanidine in broiler breeder hens.

The nonenzymatic glycosylation of tissue protein contributes to the formation of crosslinks that leads to structural and functional deterioration in the long-lived tissue protein, collagen. The accumulation of these crosslinks thus contributes to the objectionable toughness of meat from aged animals, decreases its economic value, and limits its use in whole muscle foods. The objectives of this study were to determine the effectiveness of diet restriction and the crosslinking inhibitor, aminoguanidine (AG), on reducing the accumulation of crosslinks, thereby improving meat tenderness in broiler breeder hens. The glycoxidation product, pentosidine, was also measured in skin (Ps) to determine whether changes in its concentrations correlated with the changes in shear value (SV). Chicks (n = 450) were randomly assigned to four treatment groups from 8 to 125 wk after hatch: ad libitum (AL), diet restricted (DR), AL and DR groups supplemented with 400 ppm AG each (AL+AG and DR+AG, respectively). Shear value was measured with an Instron Universal Mechanical Machine. Skin pentosidine was isolated by reverse phase HPLC. There was an age-related, linear increase in SV (P<0.0001, r = 0.96), which correlated (r = 0.86) with the age-related increase in Ps in AL hens. Diet restriction retarded SV (P<0.0001) over the sampling period. In general, SV values for AL+AG were similar to those measured in DR, whereas no additive effect was observed for AG in DR birds. It was concluded that there was a linear increase in meat toughness (SV) with age that correlates with the accumulation of Ps, and that the decline in meat tenderness can be retarded by DR or AG. Secondly, the effect of DR on accumulation of Ps was so pronounced that AG supplementation did not further enhance this effect.

Age Factors↗

The development of pale, exudative meat in two genetic lines of turkeys subjected to heat stress and its prediction by halothane screening.

Previous research has indicated that seasonal-type heat stress (HS) can contribute to the development of pale, soft, exudative (PSE) meat in fast-growing turkeys and that halothane exposure may identify stress-susceptible animals. This study evaluated the ability of halothane screening to identify stress-susceptible birds prone to developing pale, exudative meat when reared to market age. Two lines of turkeys (n = 292), one selected for rapid overall growth (BODY) and the other for large breast muscle yield (BREAST), were exposed to 3% halothane for 5 min at 2 to 4 wk of age and were raised together until 16 wk of age. Approximately 10% of both BODY and BREAST birds were sensitive to halothane. Between 16 and 20 wk, all of the halothane sensitive (HAL+) and half of the halothane nonresponders (HAL-) were exposed to an HS environment of 30 to 36 C (night/day), whereas the other half of the HAL- birds were kept at an ambient temperature of 13 to 21 C (night/day). All birds were slaughtered at 20 wk of age, and samples were collected for pH, L* value, drip loss, cooking loss, and shear value. The BREAST strain had 5% greater breast percentage than the BODY strain, and there were no differences in ready-to-cook yields between any treatments. The HAL+ HS birds had significantly lower muscle pH (0 h) and significantly higher L* values at 2 h postmortem compared with HAL- HS birds in the BREAST strain; however, there was no difference in L* value at 24 h postmortem. The HAL- HS birds had significantly lower muscle pH (0 h and 2 h) and significantly higher L* values at 2 h postmortem compared with HAL- controls in the BODY strain. The HAL- HS BREAST birds had significantly higher drip loss than HAL- controls. No differences in shear value were found among any treatments. The incidence of PSE (2-h L* values >52) was significantly higher in HAL+ HS birds (34.7%) compared with HAL- HS birds (13.4%). These results suggest that halothane sensitivity early in life is associated with HS susceptibility and the development of pale meat when birds are slaughtered at market age. These results also suggest that halothane screening may be better at predicting the development of PSE meat during HS in the strain selected for large breast yield rather than rapid overall growth.

Animals↗

Acute heat stress-induced alterations in blood acid-base status and skeletal muscle membrane integrity in broiler chickens at two ages: implications for meat quality.

The effects of acute heat stress (AHS) on indices of respiratory thermoregulation and skeletal muscle damage (myopathy) were examined in broiler chickens at two ages (35 and 63 d of age); the relationships of these responses with changes in meat quality were assessed. Exposure to AHS significantly increased deep-body temperatures, panting-induced acid/base disturbances, and plasma creatine kinase (CK) activities, reflecting heat stress-induced myopathy (HSIM). The extent of the hyperthermia and disturbances in acid/base status and myopathy was significantly (P < 0.05) higher in the older birds. Consistent with AHS-induced alterations in thermoregulatory indices and muscle membrane integrity were changes in breast muscle glycolytic metabolism as indicated by lower muscle pH immediately postslaughter (pHi), increased water loss, and increased incidence of breast muscle hemorrhages. Values of pHi were lower and hemorrhage scores greater in the AHS birds at 63 d; drip losses were significantly higher in the 35-d-old birds. Exposure to AHS did not affect breast meat eating quality, although overall reductions in flavor attributes were observed in the older birds. We concluded that exposure to AHS induced disturbances in blood acid/base status and had a detrimental effect upon skeletal muscle membrane integrity. Muscle from broilers exhibited an increased sensitivity to AHS exposure with age. Alterations in antemortem blood acid/base status and muscle membrane integrity induced by AHS were associated (though not necessarily causally) with adverse effects upon breast meat quality. It is recommended that preslaughter exposure of broiler chickens to AHS should be avoided in order to reduce alterations in muscle metabolism and membrane integrity and undesirable meat characteristics.

Acid-Base Equilibrium↗

Effects of stunning and decapitation on broiler activity during bleeding, blood loss, carcass, and breast meat quality.

Four experiments were conducted to determine the effects of electrical stunning and decapitation on bird activity as well as carcass and meat quality. In Experiment 1, broilers were subjected to one of four stunning and killing methods: no stun and neck cut, stun and neck cut, no stun and decapitation, and stun and decapitation. Birds were scored for severity of physical activity on a scale of 1 to 4 with 1 being no activity and 4 being severe wing flapping and muscular contractions. Carcasses were also scored for red wing tips and broken bones. In Experiments 2 to 4, all birds were stunned prior to neck cut or decapitation. Carcasses were scored as described in Experiment 1 as well as measurements of blood loss, feather removal, and breast meat pH, color, cook loss, and tenderness. Based on carcass activity in Experiment 1, decapitation following stunning was similar to a conventional stun and unilateral neck cut, except there was almost no late activity (after 60 s) observed in the decapitated birds. Decapitation following stunning did not result in any consistent carcass quality defects compared to conventional killing in the four experiments. No differences were found in 24-h lightness values, yellowness, cook yield, tenderness, and ultimate pH between conventionally killed and decapitated birds. Blood loss and breast meat redness were inconsistent. These results indicate that high frequency stunning and decapitation may be an acceptable alternative to conventional slaughter based on carcass and meat quality and by ensuring an irreversible loss of consciousness.

Abattoirs↗

Breast meat quality and composition in unique chicken populations.

The objective of this project was to examine the diversity of breast meat composition and quality traits among unique resource populations. Birds from 5 groups (inbred Leghorn, inbred Fayoumi, commercial broilers, F5 broiler-inbred Leghorn cross, and F5 broiler-inbred Fayoumi cross) were utilized. Contemporary stocks (broilers, inbreds, and crosses) were grown in a single house but in separate pens. Birds were harvested at 8 wk of age. Breast muscle weight, moisture, lipid and protein contents, color, pH, and Kramer shear force values were determined on birds from each group. Breasts from broilers contained lower percentages of protein (P < 0.05) and greater percentages of lipid (P < 0.05) compared with all other groups. The 5 genetic stocks did not differ for Hunter L values or pH. The data indicate that the Leghorn inbred line breasts were a more pure and more intense red color than the crossbred contemporary (P < 0.05). Kramer shear force (kg/g sample) was higher (P < 0.05) in breasts from broilers than in breasts from the inbred lines. Our results demonstrate that the 5 genetic groups differed markedly in breast meat composition and quality characteristics. The described outbred by inbred advanced intercross lines will be useful in searches for genes affecting meat quality traits. Definition of the molecular factors that influence these traits will enhance our ability to make improvements in composition and quality of poultry meats.

Animals↗