No abstract

The increase in human consumption of turkey meat and the shift in the poultry market from whole birds to further processed meat products increases the visibility of meat alterations (e.g., heterogenic color, drip loss, petechial hemorrhages) at retail. Changes in poultry meat quality have been related to the intensive growth of the current turkey strains. Considering this, the main objective of this investigation was to evaluate the meat quality and muscle structure of commercially available turkey strains with different growth properties but similar breast yields. Toms (n = 120) of 4 different turkey strains (British United Turkeys Big 6, Kelly Broad-Breasted Bronze, Kelly Wrolstad, Kelly Super Mini; n = 30 per strain) were reared in an experimental barn under similar environmental and feeding conditions and were slaughtered at 22 wk of age in a commercial slaughterhouse. The strains Big 6 and Broad-Breasted Bronze belong to the fast-growing (FG) turkey strain and the other 2 to the slow-growing (SG) turkey strain. The carcass weights, as estimated by video imaging, differed significantly (P < 0.05) between the SG and FG groups. The breast yields (percentage of carcass weight) of the investigated strains were similar. Except for the significantly (P < 0.05) greater protein concentration in the musculus pectoralis superficialis of the SG birds, the musculus pectoralis superficialis had nearly similar fat and ash contents. Plasma lactate concentrations were similar in the investigated turkey strains but the creatine kinase activities were greater in the FG turkeys at the time of slaughter. Determination of the different meat quality parameters [pH, electrical conductivity, color (L a b), drip loss, shear force] did not result in clear differences between the SG and FG turkey strains. There were larger muscle fibers in the FG in comparison with the SG strains, but no differences could be determined in the capillary density and incidence of degenerated or giant fibers, except for a higher rate in the Wrolstad strain. The present results are contradictory to the opinion that turkeys with faster growth have worse meat quality.

This study investigated the effect of vibration on bone healing and muscle in intact and ovariectomized rats. Thirty ovariectomized (at 3 months of age) and 30 intact 5-month old female Sprague-Dawley rats underwent bilateral metaphyseal osteotomy of tibia. Five days later, half of the ovariectomized and of the intact rats were exposed to whole-body vertical vibration (90 Hz, 0.5 mm, 4 × g acceleration) for 15 min twice a day during 30 days. The other animals did not undergo vibration. After decapitation of rats, one tibia was used for computed tomographic, biomechanical, and histological analyses; the other was used for gene expression analyses of alkaline phosphatase (Alp), osteocalcin (Oc), tartrate-resistant acid phosphatase 1, and insulinlike growth factor 1. Serum Alp and Oc were measured. Mitochondrial activity, fiber area and distribution, and capillary densities were analyzed in M. gastrocnemius and M. longissimus. We found that vibration had no effect on body weight and food intake, but it improved cortical and callus densities (97 vs. 99%, 72 vs. 81%), trabecular structure (9 vs. 14 trabecular nodes), blood supply (1.7 vs. 2.1 capillaries/fiber), and oxidative metabolism (17 vs. 23 pmol O2/s/mg) in ovariectomized rats. Vibration generally increased muscle fiber size. Tibia biomechanical properties were diminished after vibration. Oc gene expression was higher in vibrated rats. Serum Alp was increased in ovariectomized rats. In ovariectomized rats, vibration resulted in an earlier bridging; in intact rats, callus bridging occurred later after vibration. The chosen vibration regimen (90 Hz, 0.5 mm, 4 × g acceleration, 15 min twice a day) was effective in improving musculoskeletal tissues in ovariectomized rats but was not optimal for fracture healing.

The effect of daidzein (D), 4-methylbenzylidene camphor (4-MBC) or estradiol-17b-benzoate (E 2 ) on muscle of osteoporotic rats during fracture healing was studied. After performing a metaphyseal tibia osteotomy in 96 osteoporotic 5-month-old female Sprague-Dawley rats, they received daily 50 mg D, 200 mg 4-MBC or 0 . 4 mg E 2 per kg body weight, or soy free (SF) diet up to 36 and 72 days. Mitochondrial activity, fiber area, and capillary density were analyzed in M. gastrocnemius. Osseous callus bridging of fracture was observed in half of the rats after 36 days. By day 72, fracture was healed in most of the animals. State 3 mitochondrial respiration significantly enhanced in E 2 , 4-MBC and D groups versus SF after 36 days (30, 32 and 32 vs 23 pmol O 2 /s per mg). It declined after 72 days, however, in E 2 group it was still at a higher level versus SF (25, 23 and 21 vs 20 pmol O 2 /s per mg). Size of fast oxidative glycolytic (FOG) and fast glycolytic (FG) fibers, capillary density did not differ significantly between the groups, however, at day 36 an increase in D and 4-MBC groups was detectable. FOG diameter was 64, 66, 68, and 58 mm and FG diameter was 88, 98, 95, and 89 mm in SF, D, 4-MBC, and E 2 groups. The ratio of capillaries to muscle fiber was 1 . 1, 1 . 4, 1 . 3, and 1 . 1 in SF, D, 4-MBC and E 2 groups by day 36. D and 4-MBC react similar to estrogen thereby improving oxidative cell metabolism in severe osteoporotic rats. The level of mitochondrial activity was higher, though no significant morphological differences could be shown.

No abstract