Incidence of histomonosis in turkeys in France since the bans of dimetridazole and nifursol.

Between April 2003 and March 2005, 113 outbreaks of histomonosis were recorded in standard turkey farms in France, and 15 cases were recorded in turkey breeding centres. Most of the cases were in north-west France, the principal farming area for turkeys. The majority of the cases occurred during the hottest months, from April to September. Large numbers of cases occurred among birds from four to eight weeks of age, but there were some cases in three-week-old birds and some in birds up to 17 weeks of age. In most of the standard turkey flocks the mortality was less than 10 per cent, but it was above 30 per cent in nearly 20 per cent of the outbreaks. In the breeding flocks, the average mortality was 60.2 per cent. The size of the flocks, the sex of the birds and the age at which the first clinical signs appeared did not seem to influence the mortality.

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.

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.

Effect of stunning current frequency on carcass downgrading and meat quality of turkey.

The objective of this study was to determine the effect of frequency of a 150 mA water-bath stunning current on turkey hen carcass and meat qualities. Fifty turkey hens were subjected to water-bath stunning with alternating current of various frequencies: 50 Hz (n = 12), 300 Hz (n = 14), 480 Hz (n = 12), and 600 Hz (n = 12); the duration of stunning was 4 s for each bird. Carcass defects such as engorged wing veins, red wing tips, and hemorrhages were recorded. Turkey meat quality traits (M. Pectoralis major) were assessed based on rigor mortis development, color, drip loss, cooking loss, tenderness, and cooking yield of cured products. The data showed that frequencies of 480 Hz and 600 Hz are associated with an increased rate of postmortem pH decline (during bleeding). This effect is most likely due to the occurrence of vigorous wing flapping during the first 3 min poststunning. Under the experimental conditions of the present work, the increase in rate of pH decline after stunning at 480 and 600 Hz did not induce carcass and meat quality defects. However, before any recommendation is given, the influence of stunning frequency on turkey meat quality needs to be evaluated under industrial conditions.

Effect of current frequency during electrical stunning in a water bath on somatosensory evoked responses in turkey's brain.

Somatosensory evoked responses (SEP) in a turkey's brain were determined after water-bath stunning with a 150-mA (constant current) delivered with 50, 300 or 600 Hz, or with 75 mA, delivered with 50-Hz alternating current (AC) in order to evaluate the effectiveness of stunning. Ninety-four BUT 9 turkey hens 12 weeks of age were surgically implanted with EEG recording and left wing nerve stimulating electrodes 4 hours before stunning. They were individually stunned by immersion of the head and upper part of the neck in a water bath for 4 s. Using a 150-mA current, all birds stunned at 50 Hz showed cardiac arrest and a flat EEG immediately after the stun with no SEP recovery. The incidence of cardiac arrest at stunning decreased with increasing current frequency but SEP were lost in all birds. In birds that survived the stun, the duration of SEP abolition was on average 69 and 34 seconds at 300 and 600 Hz, respectively. Stunning with a 75-mA AC, delivered with 50 Hz, induced cardiac arrest in 32 per cent of turkeys. SEP were abolished in only 71 per cent of the birds that survived the stun, with an average duration of SEP of 66 seconds. The results indicate that increasing the frequency of a 150-mA AC current leads to a decreased stunning efficiency. A current of 75 mA per bird is unacceptable since 29 per cent of the birds do not show SEP abolition.

The effect of current frequency during waterbath stunning on the physical recovery and rate and extent of bleed out in turkeys.

Two experiments were carried out to evaluate the influence of the frequency of a sinusoidal stunning current (150 mA, 4 s) on the physical recovery of turkey hens and toms and on the rate and extent of blood loss. In the first experiment, physical recovery of 72 hens and 78 toms was estimated after stunning with one of five different frequencies. The incidence of cardiac arrest after stunning at 50, 300, 480, 550, and 600 Hz was, respectively, 100, 60, 30, 30, and 0% in hens and 53, 38, 0, 0, and 0% in toms. In hens, time to return of corneal reflex and neck tension and the onset of wing flapping decreased as frequency increased. In contrast to hens, about half of the toms stunned at 50 Hz did not show cardiac arrest. In these animals, recovery after 50 Hz was significantly longer than recovery at the four other frequencies. In the second experiment, 50 hens and 53 toms were bled out by a unilateral neck cut 10 s after stunning with one of four different frequencies (50, 300, 480, and 600 Hz). The rate and extent of blood loss within 3 min, relative to live weight, increased as stunning frequency increased. Large differences in the rate and extent of blood loss were observed between turkeys stunned at 50 or 300 Hz, according to the occurrence of cardiac arrest: cardiac activity was associated with significantly higher rate and extent of blood loss in both sexes. Overall, the results suggest that the duration of unconsciousness decreases as stunning frequency increases.

Comparison between two statistical models for prediction of turkey breast meat colour.

The aims of the present study were: (1) to determine the relevant objective measurements which could express visual assessment of turkey meat colour; and (2) to use these variables for the early prediction of the colour development of turkey breast meat. The colour of the meat was assessed subjectively by an expert at a processing plant at 24 hr post mortem, using a four-category scale (score a: light-pale meat, score b: light pink meat or normal meat, score c: dark meat, score d: very dark meat). Objective measurements included meat pH, temperature, dielectric loss factor, pigment concentration, L(∗) (lightness), a(∗) (redness) and b(∗) (yellowness) colour coordinates determined at different times post mortem. Colour coordinates and pH were chosen as relevant variables when measured at 1 and 4 hr post mortem and were used in prediction models. Linear analysis (canonical discriminant analysis) showed that the efficiency of prediction was 15%. A non-linear analysis (neural network) gave better prediction; the colour of the meat being correctly predicted for 70% of the muscles.