Progress in reducing the pale, soft and exudative (PSE) problem in pork and poultry meat

SUMMARY The chick embryo, developing in the egg, is an ideal system in which to
investigate the effects of incubation environment on the development of the
embryo. We show that raising the temperature of the eggs by just one degree,
from 37.5°C to 38.5°C, during embryonic days (ED) 4–7 causes
profound changes in development. We demonstrate that embryonic movement is
significantly increased in the chicks raised at 38.5°C both during the
period in which they are at the higher temperature but also 4 days after their
return to the control temperature. Concomitant with this increase in embryonic
activity, the embryos raised at higher temperature grow to significantly
heavier weights and exhibit significantly longer leg bones (tibia and tarsus)
than the controls from ED12 onwards, although mineralization occurs normally.
Additionally, the number of leg myonuclei is increased from ED12 in the
embryos raised at the higher temperature. This is likely to promote greater
leg muscle growth later in development, which may provide postural stability
to the chicks posthatch. These changes are similar to those seen when drugs
are injected to increase embryonic activity. We therefore believe that the
increased embryonic activity provides a mechanism that can explain the
increased growth of leg muscle and bone seen when the eggs are incubated for 3
days at higher temperature.

In ovo temperature manipulation influences embryonic motility and growth of limb tissues in the chick (Gallus gallus)

Thermal manipulations during broiler embryogenesis improves post-hatch performance under hot conditions

Satellite cells (SCs) represent a distinct lineage of myogenic progenitors responsible for the postnatal growth, repair and maintenance of skeletal muscle. Distinguished on the basis of their unique position in mature skeletal muscle, SCs were considered unipotent stem cells with the ability of generating a unique specialized phenotype. Subsequently, it was demonstrated in mice that opposite differentiation towards osteogenic and adipogenic pathways was also possible. Even though the pool of SCs is accepted as the major, and possibly the only, source of myonuclei in postnatal muscle, it is likely that SCs are not all multipotent stem cells and evidences for diversities within the myogenic compartment have been described both in vitro and in vivo. Here, by isolating single fibers from rat flexor digitorum brevis (FDB) muscle we were able to identify and clonally characterize two main subpopulations of SCs: the low proliferative clones (LPC) present in major proportion (∼75%) and the high proliferative clones (HPC), present instead in minor amount (∼25%). LPC spontaneously generate myotubes whilst HPC differentiate into adipocytes even though they may skip the adipogenic program if co-cultured with LPC. LPC and HPC differ also for mitochondrial membrane potential (ΔΨm), ATP balance and Reactive Oxygen Species (ROS) generation underlying diversities in metabolism that precede differentiation. Notably, SCs heterogeneity is retained in vivo. SCs may therefore be comprised of two distinct, though not irreversibly committed, populations of cells distinguishable for prominent differences in basal biological features such as proliferation, metabolism and differentiation. By these means, novel insights on SCs heterogeneity are provided and evidences for biological readouts potentially relevant for diagnostic purposes described.

/pdf/clonal-characterization-of-rat-muscle-satellite-cells-5d3whae0uw.pdf

Clonal characterization of rat muscle satellite cells: proliferation, metabolism and differentiation define an intrinsic heterogeneity.

Skeletal muscle development in vertebrates – also termed myogenesis – is a highly integrated process. Evidence to date indicates that the processes are very similar across mammals, poultry and fish, although the timings of the various steps differ considerably. Myogenesis is regulated by the myogenic regulatory factors and consists of two to three distinct phases when different fibre populations appear. The critical times when myogenesis is prone to hormonal or environmental influences depend largely on the developmental stage. One of the main mechanisms for both genetic and environmental effects on muscle fibre development is via the direct action of the growth hormone–insulin-like growth factor (GH–IGF) axis. In mammals and poultry, postnatal growth and function of muscles relate mainly to the hypertrophy of the fibres formed during myogenesis and to their fibre-type composition in terms of metabolic and contractile properties, whereas in fish hyperplasia still plays a major role. Candidate genes that are important in skeletal muscle development, for instance, encode for IGFs and IGF-binding proteins, myosin heavy chain isoforms, troponin T, myosin light chain and others have been identified. In mammals, nutritional supply in utero affects myogenesis and the GH–IGF axis may have an indirect action through the partitioning of nutrients towards the gravid uterus. Impaired myogenesis resulting in low skeletal myofibre numbers is considered one of the main reasons for negative long-term consequences of intrauterine growth retardation. Severe undernutrition in utero due to natural variation in litter or twin-bearing species or insufficient maternal nutrient supply may impair myogenesis and adversely affect carcass quality later in terms of reduced lean and increased fat deposition in the progeny. On the other hand, increases in maternal feed intake above standard requirement seem to have no beneficial effects on the growth of the progeny with myogenesis not or only slightly affected. Initial studies on low and high maternal protein feeding are published. Although there are only a few studies, first results also reveal an influence of nutrition on skeletal muscle development in fish and poultry. Finally, environmental temperature has been identified as a critical factor for growth and development of skeletal muscle in both fish and poultry.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/206BDBB6C6B14E90931BEFD103651B8E/S1751731110002089a.pdf/div-class-title-advances-in-research-on-the-prenatal-development-of-skeletal-muscle-in-animals-in-relation-to-the-quality-of-muscle-based-food-i-regulation-of-myogenesis-and-environmental-impact-div.pdf

Advances in research on the prenatal development of skeletal muscle in animals in relation to the quality of muscle-based food. I. Regulation of myogenesis and environmental impact.

1. The effect of manipulating egg incubation temperature for short periods on turkey muscle development was determined using the M. semitendinosus, a thigh muscle, as the model. 2. Experiment 1. Eggs were incubated at a control temperature of 37·5°C. For a 4-d period of 0 to 4, 5 to 8, 9 to 12, 13 to 16, 17 to 20 or 21 to 24 embryonic days (ED) eggs were transferred to either 38·5 or 35·5°C. A regime of 38·5°C at 5 to 8 and 9 to 12 ED caused an increased myonuclei number and muscle fibre number, respectively. 3. Experiment 2. Eggs were incubated at a control temperature of 37·5°C. At 5 to 8 ED eggs were transferred to 38·5 or 35·5°C. Temperature-manipulated embryos showed a delay in differentiation (myogenin expression) of the semitendinosus muscle compared to controls. 4. Manipulating the incubation temperature for 4 d in early incubation alters muscle development in the turkey with no observation of deformities or reduction in hatchability. We speculate that this increase in temperature may result in an...

A. Somaiya

Papers

In ovo temperature manipulation influences post-hatch muscle growth in the turkey.