Biochemical and biomechanical properties of tendons in two commercial types of chickens.

The quality of the attachment of meat to bone is often reported to be insufficient by more and more poultry's consumers. This is particularly true for thigh meat in broilers. The aim of this study was to compare muscle to bone attachment (namely, tendons) from a biomechanical and a biochemical point of view in 50 standard (S) and 50 Label Rouge (LR) chickens. Carcasses weighted around 1.7 kg in the two groups. Two tendons were harvested and proceeded for passive stretch tests, prior to cooking or not, to determine main mechanical characteristics (maximum load, stiffness and longitudinal strain). Biochemical parameters such as dry matter percentage, total collagen content, collagen solubility and sulphated glycosaminoglycans (sGAGs) content were also determined. Results showed that biomechanical values differ largely between the two studied tendons. For a given tendon, the values were also different between the two groups of chickens mainly after cooking. The results clearly showed that, mainly after cooking, the mechanical resistance of tendon to stretch was better in LR than in S chickens. LR chickens were reported to have tendons with higher collagen and sGAGs contents associated with a lower collagen solubility. These differences may explain biomechanical differences observed for the two types of tendons and could be due to increased age and/or higher physical activity of LR chickens.

High postmortem temperature in muscle has very similar consequences in two turkey genetic lines.

In the present study, we artificially generated pale, soft, exudative turkey meat by holding muscles immediately after death at 40 degrees C for 6 h. Two genetic types (BUT9 and Label) were compared. When muscles were kept at 40 degrees C, BUT9 muscles exhibited higher lightness values than Label muscles. Drip, thawing, and cook losses were higher for muscles held at 40 degrees C, compared with those held at 4 degrees C, regardless of genetic type. A significant decrease in meat tenderness was found for muscles kept at 40 degrees C. For both genetic types, protein extractabilities either with low ionic strength or high ionic strength buffer decreased for muscles held at 40 degrees C. These fractions were analyzed by using SDS-PAGE, and proteins that differed from the 4 degrees C and 40 degrees C treatments were identified using a matrix-assisted laser desorption ionization time-of-flight mass spectrometer. We reported the alteration of various proteins, such as alpha-actinin, myosin heavy chain, myokinase, phosphorylase, and ATP synthase.

Serum sphinganine and the sphinganine to sphingosine ratio as a biomarker of dietary fumonisins during chronic exposure in ducks.

Sphinganine concentration (Sa) and sphinganine to sphingosine ratio (Sa/So) are sensitive biomarkers of fumonisin B1 (FB1) exposure in animals and have been proposed to reveal FB1 exposure in humans. They correlate with liver and kidney toxicity and often precede signs of toxicity. However, the use of Sa and Sa/So is confusing during chronic exposure. Indeed, some authors report altered sphingolipids metabolism, whereas others fail to demonstrate significant effect. The aim of this study was to investigate the kinetics of Sa and Sa/So in the serum of ducks over a 77-day exposure to 0, 2, 8, 32 and 128 mg FB1/kg feeds. Serum biochemistry was also investigated to reveal hepatotoxicity. The results obtained indicate that the kinetics of sphingolipids and serum biochemistry are closely linked with the duration of the exposure. After a strong and rapid increase Sa and Sa/So decrease then stabilize. The lowest investigated dose able to determine a detectable effect is 2 mg/kg feeds, the Sa/So ratio being the most sensitive biomarker of FB1 exposure.

Effects of fumonisins on liver and kidney sphinganine and the sphinganine to sphingosine ratio during chronic exposure in ducks.

Sa and the Sa/So ratio are very sensitive biomarkers of exposure to fumonisins in several species. We previously demonstrated that increases in Sa and in the Sa/So ratio in serum were less pronounced when ducks ingested fumonisins for more than 7 weeks than when animals were exposed for only 1-2 weeks [S.T. Tran, D. Tardieu, A. Auvergne, J.D. Bailly, R. Babilé, S. Durand, G. Benard, P. Guerre, Serum sphinganine and the sphinganine to sphingosine ratio as biomarker of dietary fumonisins during chronic exposure in ducks, Chem. Biol. Interact., in press]. The aim of this study was to investigate the kinetics of Sa and of the Sa/So in both liver and kidney of ducks that have been previously tested for Sa and the Sa/So ratio in serum. Analysis were performed on treatment days 0, 7, 14, 28 and 77 in five groups of ducks fed fumonisins obtained from an extract of Fusarium verticillioides culture material by daily gavage to obtain an exposure equal to 0, 2, 8, 32 and 128 mg FB1/kg feed. Sa and the Sa/So ratio in tissues were then correlated with Sa and the Sa/So ratio previously obtained in serum. The amounts on sphinganine 1-phosphate (Sa1P) and sphingosine1-phosphate (So1P) in the liver were also investigated. On day 7 of treatment, 2mg/kg FB1 in the feed were sufficient to increase Sa and the Sa/So ratio in liver (by 165 and 148%, respectively) and kidney (by 193 and 104%, respectively). At a rate of 128 mg/kg FB1 in the feed, a very high increase in Sa concentration was observed in both liver and kidney without mortality and/or signs of necrosis (respective increase of 2034 and 3768%). Although the precise mechanism of the resistance of ducks to fumonisin-induced hepatotoxicity is still uncertain, it might be linked to the rate at which the sphingoid bases sphinganine and sphingosine are converted to their 1-phosphate or other metabolite and eliminated from target tissues.

Changes in lipid composition of hepatocyte plasma membrane induced by overfeeding in duck.

This experiment was carried out to examine the influence of overfeeding ducks with corn on the lipid composition of hepatocyte plasma membrane. Seventy-day-old male Mule ducks (Cairina moschata x Anas platyrhynchos) were overfed with corn for 12.5 days in order to induce fatty livers. The cholesterol and phospholipid contents were approximately 50% higher in hepatocyte plasma membranes from fatty livers compared to those of lean livers obtained from non-overfed ducks. However, the cholesterol/phospholipids molar ratio did not differ between both groups. Overfeeding induced a significant change in phospholipid composition of hepatocyte plasma membrane with a decrease in phosphatidylcholine proportion and conversely an increase in phosphatidylethanolamine. The fatty acid profile of phospholipids was also altered. In fatty hepatocyte plasma membrane, the overall proportion of polyunsaturated fatty acids (PUFA) was decreased and this was due to the decrease of some of, but not all, the PUFA. In addition, the proportions of oleic acid and n-9 series unsaturated fatty acids were higher in fatty than in lean liver membranes. This study provides evidence that overfeeding with a carbohydrate-rich corn-based diet induces a de novo hepatic lipogenesis in Mule duck which predominates over dietary lipid intake to change the lipid composition of the hepatocyte plasma membrane.

Chronic effects of fumonisin B1 on ducks.

Partially purified fumonisin B1 (FB1) was orally administrated for 77 d to 5 groups of 8 mule ducks starting at 7 d of age; the concentrations corresponded to 5 diets containing 0, 2, 8, 32, and 128 mg of FB1/kg of feed. No mortality was observed, and no effects on feed consumption and body weight gain were observed at the end of the treatment period. But, surprisingly, FB1 ingested at 32 and 128 mg/kg led to decreased body weight from d 28 to 63 and from d 7 to 63, respectively. FB1 had no effect on the relative weight of heart and breast muscle, whereas a significant increases in the relative weights of gizzard, spleen, and liver were measured in ducks receiving 32 and 128 mg of FB1/kg of feed without evidence of detectable microscopic modification of these organs. FB1 had no significant effect of the serum aspartate aminotransferase and gamma-glutamyltransferase levels but increased serum total protein, cholesterol, alanine aminotransferase, lactate dehydrogenase, alkaline phosphatase levels when 128 mg of FB1/kg of feed was given. Serum, liver, and kidney sphinganine to sphingosine ratio was significantly increased in ducks fed 8 to 128 mg of FB1/kg of feed. The biggest increase was observed in kidneys, suggesting that this organ is the most sensitive to detect FB1-induced disruption of sphingolipid metabolism.

Modification of glycolyzing enzymes lowers meat quality of turkey.

This paper presents the results of a study on meat quality and protein alterations of fast glycolyzing (FG) and normal glycolyzing (NG) turkey breast muscles. In a commercial processing plant, 34 breast muscles were sampled at 20 min postmortem from a large flock: 17 samples showing the lowest pH(20min) (6.04 +/- 0.09; FG) and 17 showing average pH(20min) (6.47 +/- 0.01; NG). Over a 9-d storage period at 4 degrees C, L* values did not differ between the 2 groups. The FG group showed higher drip, thawing, and cook loss values, and lower processing yield than the NG group. Warner-Bratzler shear force values of cooked meat were higher in the FG group than in the NG group. The FG meat presented a lower protein extractability with low ionic strength buffer than the NG meat. No differences in SDS-PAGE banding patterns were detectable for the different protein extracts between the 2 groups. On the contrary, when SDS-PAGE gels were performed on basic proteins, they showed differences in banding intensity for 2 proteins: glyceraldehyde-3-phosphate dehydrogenase and aldolase A.

Effect of ultimate pH on the physicochemical and biochemical characteristics of turkey breast muscle showing normal rate of postmortem pH fall.

This experiment aimed to study the effect of ultimate pH (pH(u)) on the biochemical and physicochemical characteristics of turkey breast muscle with normal rate of postmortem pH fall. Five hundred turkey toms (12 wk old, 10 kg live weight) were randomly chosen from a commercial flock. At 24 h postmortem, 64 birds were randomly selected within the subgroup showing pH higher than 6.0 at 20 min postmortem and pH(u) lower than 6.1. These pH levels were used to exclude pale, soft, and exudative (PSE) meat and dark, firm, and dry (DFD) meat, respectively. The pH(u) was significantly correlated with luminance (L*; r = -0.37) and yellowness (b*; r = -0.36) at 24 h postmortem, drip losses (r = -0.56 to -0.62), thawing loss (r = -0.47), 80% compression (r = -0.29), yield of curing and cooking (r = 0.37), glycolytic potential at slaughter (r = -0.44) and lactate at 24 h postmortem (r = -0.47). Significant correlations were found between drip losses and compression test on cooked meat (r = 0.27 to 0.34). Cooking loss was correlated with WB shear force (r = 0.32). These results show that when PSE defects are excluded, the intensities of the correlations between pH(u) and meat quality traits are lower than those usually reported. The present data also indicate that the level of glycogen at time of slaughter poorly explains the variability in pH(u). Thus, further research is needed to identify the mechanisms explaining pH(u) variation in poultry muscle.

Breed differences in the biochemical determinism of ultimate pH in breast muscles of broiler chickens--a key role of AMP deaminase?

The biochemical determinism of ultimate pH (pHu) was studied in the pectoralis muscle of broiler chickens. Thirty birds of 3 genetic types (a fast-growing standard (FG), a slow-growing French "Label Rouge" (SG), and a heavy line type (HL)) were kept under conventional breeding methods until the usual marketing age (6, 12, and 6 wk for FG, SG, and HL birds, respectively). The birds were divided into 3 different antemortem treatment groups: minimum stress, shackling for a longer time (2 min), and heat stress (exposure to 35 degrees C for 3.5 h and shackling for 2 min before stunning). The birds were slaughtered on the same day. The pHu differed (P < 0.001) among the 3 genetic types, ranking as follows: FG (5.95+/-0.01) > HL (5.85+/-0.02) > SG (5.73+/-0.02). In SG and HL birds, pHu was strongly correlated with muscle glycogen content at slaughter (r = -0.74 and -0.82; P < 0.01 respectively), whereas this correlation was weak in FG birds. Regardless of genetic type, neither buffering capacity nor lactate accumulation significantly contributed to pHu variations (P > 0.05). The activity of adenosine monophosphate deaminase (AMPd) was significantly higher in FG chickens (0.98+/-0.31; P < 0.05) than in HL and SG birds (0.46+/-0.24 and 0.34+/-0.18, respectively). Significant correlations were found between AMPd activity, pHu, and glycolytic potential (GP) at slaughter (r = 0.34 and -.29; P < 0.01, respectively). Further research is needed to study in more detail the role of AMPd in the determinism of pHu, particularly in fast-growing broilers.

Electrocorticogram spectral analysis and somatosensory evoked potentials as tools to assess electrical stunning efficiency in ducks.

1. Fast Fourier transformations (FFTs) of electrocorticogram (ECoG) signals and averaging of somatosensory evoked potentials (SEPs) were used for assessing the impact of electrical stunning of ducks in a waterbath set to deliver a constant current of 150 mA, 600 Hz alternating current (AC) for 4 s. The effectiveness of stunning was determined on the basis of induction of epileptiform activity in the ECoG followed by a decrease in total power content to less than 10% of pre-stun values and abolition of SEPs. 2. One out of 10 birds was killed by the stun. FFT analysis of the ECoG signals of the remaining 9 birds showed that only one bird had a decrease of the total power to less than 10% of the pre-stun values for up to 70 s post-stun. The SEPs were retained in 6 out of 9 ducks and and 4 of them retained the evoked responses throughout the post-stun period. In the two birds showing abolition of SEPs, this was associated with a decrease in the total power content to below 10% of the pre-stun value. 3. The present experiment confirmed that the abolition of SEPs and the decrease of the total power below 10% of the pre-stun value for assessing unconsciousness after an electrical stunning in various species are also applicable to ducks. Based on this, it is concluded that electrical waterbath stunning of ducks using 150 mA of 600 Hz AC is ineffective.

Maintaining muscles at a high post-mortem temperature induces PSE-like meat in turkey.

The aim of the present study was to validate an experimental model which surely generates pale, soft, exudative (PSE) turkey meat. Immediately after exsanguination, Pectoralis major (n=15) were kept at various temperatures (4, 20 or 40 °C) for 6 h. All the muscles were then stored at 4 °C for 9 days. They had the same rate of pH fall. L(∗) values were higher in the 40 °C treatment muscles than in the two other treatment muscles between 1 and 9 h. Drip loss of the 40 °C treatment muscles was higher than in the two other treatment muscles. However, thawing and cook loss were not significantly different between treatments. Cooked meat from the 40 °C treatment muscle was tougher than the two other treatment muscles. Napole yield was lower for these muscles. Myofibrillar protein extractability was lower in the 40 °C treatment muscle whatever the considered time. We showed that the 40 °C treatment muscles were similar to PSE muscles.

Effects of the rate of muscle post mortem pH fall on the technological quality of turkey meat.

1. This experiment evaluated the influence of the rate of post mortem pH fall on the processing ability of turkey meat. 2. Four hundred and twenty male turkeys from a selected pure line (grand-parental female line, BUT Ltd) were slaughtered at 16 weeks of age in a commercial plant and pH was measured in the Pectoralis superficialis (PS) and Ilio tibialis (IT) muscles, at 20 min post mortem. Three groups of PS muscle differing in pH20 and two groups of IT muscle differing in pH20 were constituted and processed as cured-cooked white meat and turkey ham, respectively. 3. The technological yield was lower in the groups showing the lowest pH20 (97.4% at pH20 5.90 vs 98.6 and 98.3% at pH20 6.24 and 6.55, respectively, for white meat and 97.2% (pH20 6.28) vs 98.3% (pH20 6.56) for turkey hams). The groups showing the lowest pH20 also showed higher drip loss in commercially packed products. 4. Acceptability tests of processed products were carried out in the commercial plant. Texture and taste of white meat were better in the highest pH group but the overall impression was similar in the lowest and the highest pH groups (mean scores of 4.2 and 4.1, respectively), due to better colour in the former (mean scores of 4.4 for the lowest pH20 group vs 4.0 and 3.9 for the medium and highest pH20 groups, respectively). 5. For turkey hams, the meat processed from the highest pH group got the best score for all items.

The use of near-infrared reflectance spectroscopy in the prediction of the chemical composition of goose fatty liver.

The use of near-infrared reflectance spectroscopy (NIRS) on a meat product is described in this report. The aim of the study was to develop calibration equations to predict the chemical composition of goose fatty liver (foie gras) with lipid contents greater than 40% of the fresh pate. Spectra of 52 foie gras samples were collected in the visible and NIR region (400 to 2,498 nm). Calibration equations were computed for DM, CP, lipids and fatty acids using modified partial least-squares regression. R2 values were high for the total lipid content (0.805) and DM (0.908) but were low for ash (0.151) and relatively low for protein content (0.255). For the major fatty acids, R2 ranged from 0.886 for palmitic acid to 0.988 for oleic acid. Oleic acid, the main fatty acid of the liver, and the stearic acid had higher R2 values than the less represented fatty acids. This study suggests that the NIRS technique can be used to predict lipid content and the fatty acid composition of goose fatty livers, but calibration must be built on a larger number of samples to generate accurate predictions.

Post mortem muscle metabolism and meat quality in three genetic types of turkey.

1. A standard (FG, fast-growing), a black local or 'label', type (SG, slow-growing) turkey line, and the crossbreed between these two lines were compared for muscle post-mortem metabolism and related meat quality traits. 2. Ninety male turkeys (30 of each genetic type) were raised under the same experimental conditions until slaughter at 16 weeks of age. 3. Live weights at 16 weeks of age differed significantly (7.8, 6.0 and 4.2 kg, for the FG, crossbred and SG lines, respectively). Collagen content of Pectoralis superficialis (PS) muscle was higher in SG birds than in the other two types. 4. The rate of post-mortem glycogen depletion and lactate accumulation in PS and Ilio tibialis (IT) muscles were similar in the 3 lines, as were the rate and extent of post-mortem pH fall in PS muscle. In IT muscle, however, SG birds showed a slight but significantly faster pH decline. 5. Colour measurements indicated a paler breast muscle and a higher degree of myoglobin oxidation in SG birds at 24 h post mortem, than in both other lines. But these differences had disappeared after 4 and 7 d post mortem 6. SG birds showed higher drip loss and instrumentally-assessed toughness in breast muscle, compared with crossbred and FG birds. FG birds, however, had the lowest yield of breast meat after curing-cooking. 7. No marked differences in post-mortem metabolism were found between the three lines. However, differences in water-holding capacity of fresh and cured-cooked meat suggest that factors other than the rate and extent of post-mortem pH fall may contribute to the respective characteristics of these lines.

Occurrence of giant myofibres according to muscle type, pre- or post-rigor state and genetic background in turkeys.

Forty-five male turkeys were bred to 15 weeks of age. At this age, the birds weighed 4, 6 and 8 kg depending on their genetic origin. At 3 min and 24 h post mortem samples from the pectoralis major (PM) and iliotibialis lateralis (ITL) muscles were excised for biochemical and histochemical measurements. At 3 min post mortem, except in the size of the myofibres, no differences in types, shapes or luminance due to glycogen was seen between the three lines in the respective muscles. Birds from the fast growing line had bigger muscle fibres than the two other lines, but the muscles did not present more glycolytic or oxidative enzyme activities. No muscle abnormalities were noticed at this stage. At 24 h post mortem, the presence of giant fibres (GF) was seen which differed proportions according to muscle and in genetic background. The GF were found both in the fast (PM) or mixed type (ITL) muscles. In this latter muscle they were more prevalent in the slow contracting muscle fibres than the other fiber types. It was concluded that the occurrence of the GF is independent of the genetic background of the birds or the type of muscle, but is dependent on the biochemical events occurring during rigor mortis.

Lipid composition of hepatocyte plasma membranes from geese overfed with corn.

Twelve-week-old Landes male geese were overfed with corn for 21 d in order to induce liver steatosis (fatty liver). Lipid composition of hepatocyte plasma membranes from fatty livers was compared to that of lean livers obtained from geese fed a normal diet. The ratio cholesterol/phospholipids was higher in fatty hepatocyte plasma membranes (0.63 vs. 0.47), whereas the phospholipid/protein ratio was less than half. Overfeeding induced changes in fatty acid composition of hepatocyte plasma membranes, including a greater than twofold increase in the percentage of oleic acid (29.7 vs. 13.8%) and a somewhat lesser increase in lauric, palmitic, and palmitoleic acid contents of plasma membrane lipids of fatty livers. A concomitant reduction in the proportion of stearic acid (18.4 vs. 25.1%) was also observed. In fatty livers, the increased ratio of saturated to polyunsaturated fatty acids (PUFA) (1.5 vs. 1.0) was related to a significant decrease in PUFA content. Among all the PUFA, only the eicosatrienoic acid (20:3n-9) percentage was increased by liver steatosis. Overfeeding with corn appeared to induce competition between de novo synthesized and dietary fatty acids incorporated in hepatocyte plasma membranes. This resulted in an accumulation of de novo synthesized monounsaturated and derived fatty acids in plasma membranes from overfed birds. A defect in the incorporation of linoleic acid and linoleic- and linolenic-derived PUFA was observed despite the high proportion of these essential fatty acids in the diet. It was concluded that in overfed palmipeds, de novo hepatic lipogenesis prevails over dietary lipid intake to modulate lipid composition of the fatty liver plasma membrane.

[Relationship between digestive repletion state and hepatic composition in gavaged mule ducks]. / Relation entre l'état de réplétion digestive et la composition hépatique du canard mulard en gavage.

Two batches of male mule ducks were constituted on the basis of the filling state of the crop at slaughter, after being over-fed twice a day for 5 days: no corn in the crop defined 'OV' birds, and corn in the crop defined 'OP' birds. 'OP' animals presented significantly lower daily consumption during the last 3 days of force-feeding. They had a lighter liver weight than 'OV' ducks (178 versus 197 g), lower hepatic lipid percentages (25.0 versus 33.0%), and enhanced hepatic glycogen rates (4.7 versus 2.4%). Metabolic state of animals might explain these variations in hepatic composition. Unadaptation to force-feeding modifies the metabolic inbalance of the overfed animals and consequently induces higher levels of carbohydrate. These results suggest that similar differences between crude fatty livers could be reflected in the quality of the cooked products.