A trial was conducted to evaluate the effect of in ovo injection of prebiotic and synbiotics on growth performance, meat quality traits (cholesterol content, intramuscular collagen properties, fiber measurements), and the presence of histopathological changes in the pectoral muscle (PS) of broiler chickens. On d 12 of incubation, 480 eggs were randomly divided into 5 experimental groups treated with different bioactives, in ovo injected: C, control with physiological saline; T1 with 1.9 mg of raffinose family oligosaccharides; T2 and T3 with 1.9 mg of raffinose family oligosaccharides enriched with different probiotic bacteria, specifically 1,000 cfu of Lactococcus lactis ssp. lactis SL1 and Lactococcus lactis ssp. cremoris IBB SC1, respectively; T4 with commercially available synbiotic Duolac, containing 500 cfu of both Lactobacillus acidophilus and Streptococcus faecium with the addition of lactose (0.001 mg/embryo). Among the hatched chickens, 60 males were randomly chosen (12 birds for each group) and were grown to 42 d in collective cages (n = 3 birds in each 4 cages: replications for experimental groups). Broilers were fed ad libitum commercial diets according to age. In ovo prebiotic and synbiotic administration had a low effect on investigated traits, but depend on the kind of bioactives administered. Commercial synbiotic treatment (T4) reduced carcass yield percentage, and the feed conversion ratio was higher in T3 and T4 groups compared with other groups. The abdominal fat, the ultimate pH, and cholesterol of the PS were not affected by treatment. Broiler chickens of the treated groups with both slightly greater PS and fiber diameter had a significantly lower amount of collagen. The greater thickness of muscle fibers (not significant) and the lower fiber density (statistically significant), observed in treated birds in comparison with those of the C group, are not associated with histopathological changes in the PS of broilers. The incidence of histopathological changes in broiler chickens from examined groups was low, which did not affect the deterioration of meat quality obtained from these birds.

Due to selection for increased body weight modern broilers are 3-4 times heavier as compared with chickens of the laying type. The muscle mass is mainly determined by the total number of muscle fibres (hyperplasia), their thickness (hypertrophy) and different fibre types. Hyperplasia occurs during either embryogenesis or the early posthatching period. Skeletal muscles originate from the dermatomyotome, which differentiates into four myogenic cell populations: myotomal cells, embryonic myoblasts, fetal myoblasts and satellite cells; the latter are the adult myoblasts, present within adult skeletal muscles to serve as a cell source for both muscle regeneration and self-renewal. Pax3 keeps migrated precursor cells non-differentiated, thereby controlling transcription of the MyoD gene, whereas Pax7 is a significant regulator of the satellite cell population. Manipulation of temperature and light quality and quantity have been proposed as methods of both pre-and postnatal myogenesis stimulation. Being thermogenic stimulants, both thyroid and adrenal hormones substantially stimulate metabolism. Shortterm exposure of embryos to increased temperature between days 16 and 18 of incubation directly influences the proliferation and differentiation of muscle fibres, which manifest themselves in increased hyperplasia. Ultraviolet radiation is an effective means for disinfection of hatching eggs, resulting in a change of embryonic mortality rate during breeding. Especially, green light influences both body weight and the satellite cell number in the first days posthatch, thereby enhancing the growth of embryos, and causing a significant increase in both muscle and body weight. In ovo green stimulation probably enhances the proliferation and differentiation of myoblasts, subsequently causing an increase in muscle weight. The present paper highlights the possibilities of enhancing growth and development of skeletal muscles in birds by manipulation of many aspects of their regulation, thereby contributing to a further increase in production efficiency.

Capillary rarefaction is present in early stages of CKD. These changes are independent of blood pressure and progression of CKD. We suspected that muscle function has a big impact on microvasculature as capillaries rarefaction has been reduced more in locomotor than postural skeletal muscle.

No abstract

Muscle fibre formation takes place during embryonic development and is regulated by the MyoD gene family, which consists of four genes, MYOD1, myogenin, MYF5 and MRF4. A relationship was studied between MYOD1, myogenin and MYF5 genotypes and microstructural characteristics of the m. longissimus lumborum in pigs – crosses: Pietrain × (Polish Large White × Polish Landrace). The data included 115 unrelated animals slaughtered at about 105 kg live body weight. Within 45 min after exsanguination, samples were taken from the m. longissimus lumborum, frozen in liquid nitrogen and later analysed for the diameter of slow-twitch oxidative, fast-twitch oxidative and fast-twitch low-oxidative fibres, their proportion in a bundle, the proportion of pathological changes and number of fibres per unit area. The RYR1 and MyoD genotypes were determined using the PCR-RFLP technique. A significant or highly significant relation was observed between the diameter of all types of muscle fibres and genotype RYR1 – the highest values were recorded for homozygotes TT (genetically stress-sensitive). A relation between MyoD genotypes and microstructural characteristics of the m. longissimus lumborum was analysed on a group of 93 animals of the genotype CC or CT at locus RYR1. Sex appeared to have no significant effect on the muscle microstructural traits in this group of animals. The content of fast-twitch oxidative fibres (FTO) was significantly related to the MYF5 genotype, whereas that of fast-twitch low-oxidative fibres (FT) was affected by the MYOD1 and MYF5/DdeI genotypes. The proportion of angular fibres in a bundle was related to MYF5/HinfI genotype. The results showed that MyoD genes could be considered as candidate genes for some microstructural characteristics of m. longissimus lumborum in pigs.  

No abstract

An association between genotypes at the porcine loci MSTN (GDF8) and CAST and microstructural characteristics of m. longissimus lumborum : a preliminary study AbstractThe aim of the study was to evaluate the association between the microstructure characteristics of longissimus lumborum (LL) muscle and the genotype at porcine loci MSTN and CAST. The study was carried out on 132 unrelated pigs -93 crosses of Pietrain and (Polish Large White x Polish Landrace) and 39 Stamboek castrated males. Crosses Pi x (PLW x PL), with an equal proportion of castrated males (n=46) and females (n=47), were of genotype CC or CT at the locus RYR1, whereas Stamboek pigs were of genotype CC at this locus. The diameters of slow-twitch oxidative (STO), fast-twitch oxidative (FTO) and fast-twitch glycolytic (FTG) fibers, their per cent share in a bundle and number of fibers per 1 mm 2 were determined. Moreover, the analyses covered the frequency of occurrence of pathological fibers, including giant and angular fibers. The parameters examined, characterising the microstructure of LL muscle, were not found to be related to the presence of the C→T polymorphism in exon 3 of the MSTN gene, identified by enzyme TaqI. However, it was shown that the diameters of the STO, FTO and FTG fibres in the LL muscle were significantly smallest in the Stamboek pigs with genotype FF at locus CAST compared to both the remaining genotypes. Among the crosses Pi x (PLW x PL) this genotype was not observed. The content of FTG fibres in a bundle proved to be related to the CAST genotype in Stamboek pigs. The frequency of pathological fibres in the LL muscle was the lowest in pigs with genotype EE at the locus CAST, but only in the case of the crosses Pi x (PLW x PL) was this relation statistically significant. The studies should be continued to determine whether such relations occur in other pig breeds. The frequency of pathological fibres affects meat quality and thus the polymorphism of the CAST gene could be of importance in selection.

Abstract. The aim of the present study was to compare the histological structure of muscles in wild boars, pigs and wild boar/domestic pig hybrids by determining the percentage of different muscle fibre types and diameters and the intramuscular fatty tissue content of the Musculus longissimus lumborum (LL). The study involved 24 males representing three groups: wild boars (6 animals), pigs (12 animals: 6 of Polish Landrace and 6 of Duroc breeds) and wild boar/domestic pig hybrids (6 animals). Wild boar/domestic pig hybrids were obtained by crossing DU pigs with wild boars. Samples of the LL were frozen in liquid nitrogen. Frozen muscle samples were cut into 10- μm sections. These were later placed on a glass slide and stained using different histochemical reactions: NADH-TR and myofibrillar ATP-ase activity to distinguish muscle fibre types and Oil Red staining to determine the intramusuclar fatty tissue content. The highest proportion of slow twitch oxidative fibres and fast twitch oxidative fibres, being indicative of high meat value, was characteristic of wild boar muscles. The lowest diameters of all three muscle fibre types, associated with the largest number of fibres in the analysed area, suggest that the meat had the most delicate structure. Compared to wild boars, wild boar/domestic pig hybrids showed a decrease in the percentage of oxidative fibres and an increase in the percentage of glycolytic fibres. The diameters of all muscle fibre types in this group of animals were similar to those obtained in pigs.