Abstract
The aim of the study was to induce deep pectoral myopathy (DPM) lesions in 42 to 45-day-old broiler chickens of the Ross 308 and Flex genetic lines, kept under standard intensive breeding management conditions applied in Poland, and to assess the degree of myopathy. A total of 110 and 120 carcasses, respectively, were examined. The study method consisted of the exposure of the birds to a stress factor (forced wing flapping) at specific time intervals prior to slaughter and at different durations of the stress factor. As a result of the conducted experiment, DPM symptoms appeared in the examined chickens. The symptoms of the progressing anomaly were divided into four stages. The first stage was characterised by the occurrence of bloody extravasations, stage II was characterised by a pale pink colour of muscles, stage III - greening of the muscle tissue, while stage IV was connected with necrosis and white-grey-green colour of muscles. The application of the forced wing flapping several days before slaughter (1, 3 d) resulted in the incidence of earlier symptoms of myopathy - stages I and II. Stimulation of wing flapping 5, 7, and 14 d before slaughter caused subsequent DPM stages (i.e. stages III and IV). In the group of the youngest birds subjected to the stress factor at 21 d before slaughter, DPM lesions were not found. Moreover, the longer the duration (15-60 s) of the stress factor, the greater the intensity of this phenomenon was observed. Bilateral DPM symptoms occurred more frequently than unilateral symptoms. Recorded results show that increased wing flapping is a significant factor inducing DPM in 42 to 45-day-old broiler chickens. These investigations indicated a possibility to determine the degree of DPM lesions depending on the passage of time from the induction of the anomaly to the slaughter of birds.
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