Medycyna Wet. 65 (7), 466-471, 2009

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Kijowski J., Kupiñska E., Kaczmarek A., Stangierski J., Popiół A.
Occurrence and characteristics of chicken breast muscles with DPM symptoms
Deep pectoral myopathy (DPM) in m. pectoralis minor is a degeneration occurring in turkeys and broiler chickens. In Poland data were published only on DPM in meat-type turkey breeder hens. However, incidence of DPM was found in chickens slaughtered at week 6-7. The number of such cases is growing with an increased intensification of genetic selection for heavy weight of the breast muscle in chickens. Characteristics of muscles with DPM symptoms in stage I include reddening of muscles with haemorrhages or blood extravasations. In stage II muscle colour from red turns to green, while in the final (III) stage the colour is whitish grey. Texture of DPM muscles is also changed as a result of occurring necrosis. The aim of the study was to determine the frequency of occurrence of DPM symptoms in chickens under Polish conditions, where at present the most commonly used genetic lines are Ross 308 and Cobb 500, slaughtered at the age of 37-45 days. 349 350 chickens from 15 poultry farms were tested. Complete photographic documentation of diagnosed DPM muscles at different stages of this anomaly was prepared at the chicken cutting line in a selected abattoir. Correlations between DPM occurrence and live weight, farm (A-O), poultry house and genetic line were determined. Slaughterhouse economic losses resulting from condemnation of the most valuable muscles were established. The colour of control and DPM muscles was determined in the Hunter scale (L*, a*, b*, ÄE). At the same time analogous traits of m. pectoralis major corresponding to those of tenders with DPM symptoms were analyzed in order to verify whether they underwent any changes. Variation of results was analyzed using Statistica 7.1 software. The following dependencies were found. Frequency of DPM occurrence was dependent on the farm and poultry house, ranging from 0.06 to 0.9%. DPM intensity for Cobb 500 was 2 times higher than that in Ross 308. Atrophy of the minor pectoral muscle was observed. Colour parameter a* best differentiates muscles at different stages of DPM development in relation to the control. For control samples the value of parameter a* was 2.7, for stage I of DPM it was 11.8 (red colour) and for stage II it was – 3.0 (green colour). Based on the analysis of colour, consistency and photographs it may be stated that changes occur also in the major pectoral muscle if the minor pectoral muscle exhibits DPM symptoms. Financial losses for the abattoir slaughtering daily 50 000 chickens due to the condemnation of DPM muscles for the analyzed population of birds amounted to PLN 1047, i.e. approx. EURO 240.
Keywords: chicken broilers, Deep Pectoral Myopathy (DPM), frequency, colour, texture, economic losses