Histopathological and ultrastructural alterations of turkey skeletal muscle.

The pectoralis thoracicus and biceps femoris muscles were obtained from 30 18-wk-old Large White turkey males at the time of slaughter. The birds had no observable mobility or postural problems, and the meat appeared normal. Samples were processed for histology, histochemistry, and electron microscopy. Degenerative features were found in muscle from 10 of the 30 birds. Four of the 10 had alterations in both muscles. The degenerative changes included scattered focal necrosis, hypercontraction of muscle fibers, infiltration by mononuclear cells, formation of fibrous tissue scars, and Z-band streaming. These structural alterations appear to be related to muscle ischemia.

Distribution of capillaries in normal and ischemic turkey skeletal muscle.

Capillary to fiber relationship was studied in musculi biceps femoris and musculi pectoralis thoracicus from 20 normal and 10 ischemic turkeys. Capillary density, the number of capillaries surrounding a fiber, capillary to fiber ratio, intercapillary distance, and fiber area were measured. The muscles from the ischemic group had significantly lower (P less than .05) values for capillary density and capillary to fiber ratio and significantly higher intercapillary distance than those from the normal group. There was no evidence of larger muscle fiber size in the ischemic versus normal birds. It is suggested that the occurrence of muscle ischemia in the domestic turkey is due to alterations in capillarity and reduced vasodilatation, resulting from lack of exercise.

Incidence of microscopically detectable degenerative characteristics in skeletal muscle of turkey.

1. The incidence of microscopically detectable degenerative characteristics in 5 skeletal muscles (m. pectoralis thoracicus, m. supracoracoideus, m. biceps femoris, m. semitendinosus, m. femorotibialis medius) of turkeys was investigated. 2. Samples were obtained from 30 Large White turkey males 14, 16 and 18 weeks old. Hyaline degeneration, infiltration of mononuclear cells and necrotic fibres were observed. 3. Individual fibres varied greatly in size and muscle fibre nuclei were often shrunken and pyknotic. 4. Weak and/or uniform reaction for Ca++-ATPase and SDH in all types of muscle fibres and loss of alkaline phosphatase activity in cell membranes were noted. A positive reaction for acid phosphatase occurred in regions of perivascular infiltration and in necrotic muscle fibres. The majority of muscle fibres possessed high activity for phosphorylase a and b. 5. Based on the use of fluorescein alpha-bungarotoxin conjugate, motor end-plates appeared to be morphologically intact. Direct immunofluorescence with anti-chicken IgG showed positive reaction in muscle fibres undergoing necrosis and in the involved connective tissue. 6. Degenerative changes varied with age and were most marked in the oldest birds. 7. Because gross degenerative symptoms were absent from both the birds and the meat from them, the condition appears to be either different from or a precursor to the degenerative myopathy characterised by other authors.

Influence of maternal frame size and nutritional restriction on growth and development of the postnatal lamb.

Pregnant ewes (large frame [LF] and small frame [SF]) were nutritionally stressed in early gestation (EGS), late gestation (LGS) or fed 100% of NRC requirements (unstressed, US) throughout gestation. Lambs (128) from these ewes were slaughtered at birth, weaning (18 kg), 41 kg or 55 kg. Sixty-four lambs received a 13% protein diet from weaning to either 41 or 55 kg. Lambs from SF ewes were fatter at 55 kg, had a higher numerical yield grade and a lower percentage of carcass protein. Lambs from US ewes were youngest at slaughter and had the most carcass weight and protein per day of age at 55 kg. The LGS lambs had the lowest percentage of lean and carcass protein at 41 and 55 kg. However, at birth these lambs had the highest concentration of RNA and DNA in muscle. The EGS lambs had the lowest quality grade, carcass weight per day of age and fat percentage. Muscle DNA and RNA at birth was lowest in EGS lambs. However, EGS lambs produced the highest lean percentage and highest percentage carcass protein at 41 and 55 kg. Shortest metacarpals and metatarsals were also found in these lambs at weaning and 41 kg. Although frame size had little effect on carcass characteristics, the effects of nutritional stress in the first 80 d of gestation were apparent in lambs slaughtered at 31 kg. Stress in the last 50 d of gestation had more effect on lambs slaughtered at 55 kg.

Influence of delayed bleeding on sensory characteristics of beef.

Sensory characteristics of bovine longissimus dorsi and biceps femoris muscles from 30 heifers exsanguinated 0, 3 or 6 min after stunning and 36 steers exsanguinated 0, 3 or 30 min after stunning were evaluated to determine if delayed bleeding influenced palatability. More blood was retained in carcasses of animals where exsanguination was delayed after stunning than in control animals, but no consistent differences existed for total pigment or per cent hemoglobin in muscle. Tenderness, juiciness, flavor, shear values and cooking loss were not affected by treatment.