To investigate temporal changes in capillarization and increases in mitochondrial enzyme activity, rabbit tibialis anterior muscles underwent chronic low-frequency stimulation for up to 50 days. Capillary density (CD), capillary-to-fiber ratio (C/F), intercapillary distance (ICD), and mean capillary area (MCA), as well as several other parameters of capillarization, were examined. In addition, tissue levels of mRNA specific to vascular endothelial growth factor (VEGF) were assessed by reverse transcriptase-polymerase chain reaction. Citrate synthase (CS) activity, a marker of aerobic-oxidative metabolic potential, was measured in the same muscles. Significant increases in CD and C/F, respectively, and decreases in ICD and MCA were observed after 2 days. These changes reached stable maxima by 14 days. The increases in capillarization occurred in a fiber-type-specific manner, affecting type IId fibers before types IIda and IIa. VEGF mRNA levels increased in a bimodal time pattern with a first elevation (2.5-fold) after 1 day and a second (9-fold) after 6–8 days. Increases in CS were first noted after 8 days. Obviously, increases in capillarization as induced by enhanced contractile activity precede increases in the aerobic-oxidative potential of energy metabolism.

We examined satellite cell content and the activity of satellite cell progeny in tibialis anterior muscles of young (15 weeks) and aging (101 weeks) Brown Norway (BN) rats, after they were exposed for 50 days to a standardized and highly reproducible regime of chronic low-frequency electrical stimulation. Chronic low-frequency electrical stimulation was successful in inducing fast-to-slow fiber-type transformation, characterized by a 2.3-fold increase in the proportion of IIA fibers and fourfold and sevenfold decreases in the proportion of IID/X and IIB fibers in both young and aging BN rats. These changes were accompanied by a twofold increase in the satellite cell content in both the young and aging groups; satellite cell content reached a level that was significantly higher in the young group (p <.04). The total muscle precursor cell content (i.e., satellite cells plus progeny), however, did not differ between groups, because there was a greater number of satellite cell progeny passing through the proliferative and differentiative compartments of the aging group. The resulting 1.5-fold increase in myonuclear content was similar in the young and aging groups. We conclude that satellite cells and satellite cell progeny of aging BN rats possess an unaltered capacity to contribute to the adaptive response.

In contrast to conventional methods for the determination of meat chemical composition and quality, near infrared spectroscopy (NIRS) enables rapid, simple and simultaneous assessment of numerous meat properties. The present article is a review of published studies that examined the ability of NIRS to predict different meat properties. According to the published results, NIRS shows a great potential to replace the expensive and time-consuming chemical analysis of meat composition. On the other hand, NIRS is less accurate for predicting different attributes of meat quality. In view of meat quality evaluation, the use of NIRS appears more promising when categorizing meat into quality classes on the basis of meat quality traits for example discriminating between feeding regimes, discriminating fresh from frozen-thawed meat, discriminating strains, etc. The performance of NIRS to predict meat properties seems limited by the reliability of the method to which it is calibrated. Moreover, the use of NIRS may also be limited by the fact that it needs a laborious calibration for every purpose. In spite of that, NIRS is considered to be a very promising method for rapid meat evaluation. &nbsp; &nbsp;

This study aimed to evaluate the effect of hydrolysable tannin supplementation on morphology, cell proliferation and apoptosis in the intestine and liver of fattening boars. A total of 24 boars (Landrace × Large white) were assigned to four treatment groups: Control (fed commercial feed mixture) and three experimental groups fed the same diet supplemented with 1%, 2% and 3% of hydrolysable tannin-rich extract. Animals were housed individually with ad libitum access to feed and then slaughtered at 193 d of age and 122 ± 10 kg body weight. Diets supplemented with hydrolysable tannin affected the morphometric traits of the duodenum mucosa as reflected in increased villus height, villus perimeter and mucosal thickness. No effect was observed on other parts of the small intestine. In the large intestine, tannin supplementation reduced mitosis (in the caecum and descending colon) and apoptosis (in the caecum, ascending and descending colon). No detrimental effect of tannin supplementation on liver tissue was observed. The present findings suggest that supplementing boars with hydrolysable tannins at concentrations tested in this experiment has no unfavourable effects on intestinal morphology. On the contrary, it may alter cell debris production in the large intestine and thus reduce intestinal skatole production.

Feed and water supplementation with powdered hydrolyzable tannins from chestnut represents a valuable alternative strategy to antibiotics in animal nutrition. In this study, we evaluated the effects and safety of a water-soluble form of chestnut tannin (WST) in an in vitro model of chicken small intestinal epithelial cells (CSIEC). A chicken cell culture was established, and WST in concentrations of 0.025, 0.05, 0.1, and 0.2% were tested for cytotoxicity, cell proliferation, metabolic activity, production of reactive oxygen species, intracellular antioxidative potential, genotoxicity, and influence on the epithelia cell cycle. The tested concentrations showed a significant (P < 0.05) greater proliferative effect on CSIEC than the control medium (maximal proliferation at 0.1% WST as determined by optical density measurements). The 0.2% concentration of WST was cytotoxic, causing significantly higher (P < 0.05) nitric oxide and hydrogen peroxide production but with no short-term genotoxicity. Although increasing the concentration caused a decline in the metabolism of challenged cells (the lowest at 0.1% WST), metabolic activity remained higher than that in control cells. The antioxidant potential was 75% better and significantly (P < 0.05) higher in the 0.1% WST cultured cells compared to control. In conclusion, the cultured CSIEC are useful tools in basic and clinical research for the study of intestinal physiology, as they retain physiological and biochemical properties and epithelial morphology close to the original tissue and, in many ways, reflect the in vivo state. Our results indicate that WST exert a beneficial effect on intestinal epithelia, since they: i) stimulate proliferation of enterocytes; ii) increase antioxidative potential; iii) have no genotoxic effect; and iv) do not affect cellular metabolism. Our results reinforce the importance of WST as promising candidates for further evaluation and use in commercial broiler farm production.

No abstract

Prediction ability of near infrared (NIR) spectroscopy for intramuscular fat content (IMF) determination was studied. The material comprised 126 muscle samples; 46 pig longissimus dorsi and semitendinosus and 34 beef longissimus dorsi muscle samples. The IMF content was chemically determined in duplicate using two different chemical methods; fat extraction according to Folch et al. and Soxhlet extraction with hydrolysis according to SIST ISO 1443. Folch extraction underestimated IMF content compared to Soxhlet extraction with hydrolysis (-0.32%, P < 0.0001). Similar repeatability was obtained for Folch and Soxhlet extraction with hydrolysis (0.17% and 0.18%, respectively, P < 0.0001). Sample spectra were scanned from 400–2500 nm by the NIR Systems model 6500 spectrophotometer (Silver Spring, MD, USA) and analysed by WinISI II on minced and intact (pork only) samples. Modified partial least squares regression was used to develop models and to obtain calibration statistics: coefficient of determination in calibration( R2 C) and cross-validation ( R2 CV) and standard error in calibration ( SEC) and cross-validation ( SECV). We prepared different models (for a single muscle/common, by applying NIR spectrum or the whole spectrum, on intact and minced samples). Obtained models proved the remarkable prediction ability of NIR spectroscopy to determine IMF content ( R2 CV between 0.84 and 0.99; SECV between 0.14% and 0.53%) and confirms the potential of NIR spectroscopy to replace laborious chemical procedures. Regarding the factors studied, calibrations were less accurate for intact than for minced samples; the use of an NIR spectrum compared to the whole spectrum had no important effect on the prediction ability. According to calibration statistics, the prediction using a common equation for several muscles seems more reliable than the equations within the muscle, but the latter showed lower bias.

Dynamics of myofiber differentiation/maturation in porcine skeletal muscle is associated with domestication, breeding and rearing conditions. This study was aimed to comparatively elucidate the age-dependent myosin heavy chain (MyHC) isoform expression and transition pattern in domestic and wild pig (WP) skeletal muscle from birth until adulthood. Domestic pigs (DPs) of Large White breed raised in conventional production system were compared with WPs reared in a large hunting enclosure. Muscle samples for immuno/enzyme histochemistry were taken from the longissimus dorsi muscle within 24 h postmortem at 24 to 48 h, 21 to 23 days, 7 months and~2 years postpartum. Based on the antibody reactivity to MyHCs (NCL-MHCs, A4.74, BF-F3) and succinate dehydrogenase activity, myofibers were classified into I, I/IIa, IIa, IIx and IIb types. In addition, foetal MyHC expression was determined with the use of F158.4C10 antibody. Maturation of the longissimus dorsi muscle in the WP was characterized by an accelerated transformation of the fast to slow MyHC during the first hours postpartum, followed by differentiation towards oxidative myofibers in which type I, IIa and IIx MyHCs predominated. In the DP, the transformation shifted towards glycolytic myofibers that expressed MyHC-IIb. The expression of foetal MyHC was higher in the DP than in the WP at 1 day of age, and the decline in the foetal MyHC during the first 3 weeks was more rapid in the WP than in the DP denoting an accelerated early postnatal muscle maturation in WP than DP piglets. All foetal MyHC-positive myofibers co-expressed IIa isoform, but not vice versa. The intense myofiber hypertrophy was evident from 3 weeks until 7 months of age. In this period, the myofiber crosssectional area increased up to 10-and 20-fold in the WP and the DP, respectively. In the DP, the hypertrophy of all myofiber types was more pronounced than in the WP, particularly the hypertrophy of IIx and IIb myofibers. To summarize, the comparison between growing DP with wild ancestors showed that genetic selection and rearing conditions lead to substantial changes in the direction and intensity of postnatal MyHC transformation as evidenced by different proportion of individual myofiber types and differences in their hypertrophic potential.