Effects of birth weight and postnatal nutrition on neonatal sheep: II. Skeletal muscle growth and development.

Abstract

This study investigated effects of birth weight and postnatal nutrition on growth and development of skeletal muscles in neonatal lambs. Low (L; mean +/- SD 2.289 +/- .341 kg, n = 28) and high (H; 4.840 +/- .446 kg, n = 20) birth weight male Suffolk x (Finnsheep x Dorset) lambs were individually reared on a liquid diet to grow rapidly (ad libitum fed, ADG 337 g, n = 20) or slowly (ADG 150 g, n = 20) from birth to live weights (LW) up to approximately 20 kg. At birth, weight of semitendinosus (ST) muscle in L lambs was 43% that in H lambs; aggregate weights of ST and seven other dissected muscles were similarly reduced. In ST muscle of L lambs, mass of DNA, RNA, and protein were also significantly reduced to levels 67, 60, and 34%, respectively, of those in H lambs. However, myofiber numbers of ST, tibialis caudalis, or soleus muscles did not differ between the L and H birth weight lambs and did not change during postnatal growth. During postnatal rearing, daily accretion rate of dissected muscle was lower in L than in H lambs. Accretion of muscle per kilogram of gain in empty body weight (EBW) was reduced in the slowly grown L lambs compared with their H counterparts, although the difference was less pronounced between the rapidly grown L and H lambs. Throughout the postnatal growth period, ST muscle of L lambs contained less DNA with a higher protein:DNA ratio at any given muscle weight than that of H lambs. Slowly grown lambs had heavier muscles at any given EBW than rapidly grown lambs. Content of DNA and protein:DNA ratio in ST muscle were unaffected by postnatal nutrition, but RNA content and RNA:DNA were greater and protein:RNA was lower at any given muscle weight in rapidly grown lambs. Results suggest that myofiber number in fetal sheep muscles is established before the presumed, negative effects of inadequate fetal nutrient supply on skeletal muscle growth and development become apparent. However, proliferation of myonuclei may be influenced by fetal nutrition in late pregnancy. Reduced myonuclei number in severely growth-retarded newborn lambs may limit the capacity for postnatal growth of skeletal muscles.

Influence of gestational maternal feed restriction on growth performance and meat quality of rabbit offsprings

“…This concept implies that a stimulus or insult acting during critical periods of growth and development may result in developmental adaptations that permanently change the structure, physiology and metabolism of the offspring (Barker, 1995). Maternal undernutrition may impact upon offsprings' growth efficiency and body composition (Greenwood et al, 2000;Caton et al, 2009) and is crucial for both skeletal muscle (Greenwood et al, 2000) and adipose tissue development (Taylor and Poston, 2007).…”

Nutritional and developmental effects on the intrinsic properties of muscles as they relate to the eating quality of beef

“…In cattle, fetal growth restriction to about half normal growth during the period 232-271 days of gestation resulted in a 7.8% increase in muscle DNA content, compared with a 99.5% increase during normal fetal growth (Ferrell 1991). In this regard, it has been demonstrated that the number of satellite cells , replication of satellite cell nuclei (Greenwood et al 1999b) and subsequent accumulation of muscle DNA (Robinson 1969;Beermann 1983;Greenwood et al 2000) can be reduced by prenatal and/or early postnatal growth retardation with potential longer-term consequences for growth, body composition and body size (Widdowson 1971;Greenwood et al 1998).…”

“…In ruminants, the influence of growth retardation on subsequent growth and development is important during late gestation (Everitt 1967;Greenwood et al 1998Greenwood et al , 1999bGreenwood et al , 2000. It has been demonstrated in various species that the number of myonuclei or the DNA content in muscle can be reduced by undernutrition during early life, but this influence diminishes as the age when the nutritional restriction is .…”

“…imposed increases (e.g. Winick and Noble 1966;Robinson 1969;Greenwood et al 2000). In cattle, fetal growth restriction to about half normal growth during the period 232-271 days of gestation resulted in a 7.8% increase in muscle DNA content, compared with a 99.5% increase during normal fetal growth (Ferrell 1991).…”

“…The number of myonuclei and DNA content in muscle are correlated with muscle growth (Greenwood et al 2000) and are believed to be the primary determinants of muscle growth potential and mature muscle mass. In postnatal mammals, nuclei are incorporated into myofibres from satellite cells located adjacent to the sarcolemma.…”