Effects of birth weight and postnatal nutrition on neonatal sheep: III. Regulation of energy metabolism1,2

Abstract

This study investigated effects of birth weight and postnatal nutrition on regulation of energy metabolism in the neonatal lamb. Low (mean +/- SD 2.289 +/- 0.341 kg, n = 28) and high (4.840 +/- 0.446 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, small newborns had higher plasma concentrations of urea nitrogen (mean +/- SEM 8.31 +/- 0.25 vs 6.39 +/- 0.32 mM, P = 0.002) and somatotropin (ST, 49.1 +/- 17.0 vs 10.8 +/- 4.3 ng/mL, P = .045) and lower IGF-I (36.1 +/- 6.8 vs 157.7 +/- 21.8 ng/mL, P < 0.001) than large newborns. Plasma glucose (1.42 +/- 0.23 vs 2.63 +/- 0.95 mM, P = 0.147) and insulin (0.09 +/- 0.02 vs 0.13 +/- 0.06 ng/mL, P = 0.264) concentrations did not differ. Urea nitrogen concentration in plasma peaked and then declined rapidly in all lambs during the first week postpartum, and plasma ST declined on a body-weight-related basis from birth. During rearing to 20 kg LW, plasma insulin was higher in low- vs high-birth-weight lambs. Lambs fed ad libitum had greater plasma concentrations of glucose, urea nitrogen, insulin, and IGF-I compared to those fed a restricted diet (ADG = 150 g). The results suggest that during the early postpartum period, newborn lambs exhibit the fetal characteristic of high rates of amino acid oxidation. The results also support the notion that, at birth, low-birth-weight lambs are less mature than high-birth-weight lambs in aspects of metabolic and endocrine development, which may enhance their capacity to utilize amino acids for energy production and to support gluconeogenesis during the immediate postpartum period. Being small at birth also resulted in elevated plasma insulin concentrations when adequate nutriment to support moderate or rapid growth was provided postpartum, although it remains to be elucidated whether this more chronic effect persists in the longer term.

Estimation of genetic trends from 1977 to 1998 of body composition and physiological state of Large White pigs at birth

“…However, more interesting was the finding that plasma IGF-1 concentrations were lower in G98 than in G77 piglets despite G98 piglets being heavier at birth, suggesting that IGF-1 level at birth is not correlated with postnatal muscle growth. However, as reported by Greenwood et al (2002) in neonatal sheep, lower plasma IGF-1 concentrations may also be indicative of a lower maturity of the G98 piglets. Similar results were found when piglets from a 'synthetic' line highly selected for muscle growth were compared with Meishan piglets (Herpin et al, 1993).…”

Mortality in Holstein-Friesian calves and replacement heifers, in relation to body weight and IGF-I concentration, on 19 farms in England

“…For example, lambs fed ad libitum had greater plasma concentrations of IGF-I compared to those fed restricted diets (Greenwood et al, 2002), and feeding bull calves a 30% CP, 20% fat milk replacer at increasing levels to achieve target rates of gain of 0.50, 0.95 or 1.40 kg/day elevated IGF-I concentrations (Smith et al, 2002). Similarly, feeding heifer calves high protein and energy diets (milk replacer 30% CP, 4.4 kcal ME/g; calf starter 21% CP, 3.7 kcal ME/g) from 2 to 14 weeks of age increased IGF-I concentrations compared to calves fed either moderate protein and energy, or low protein and energy diets (Brown et al, 2005).…”

Body composition and blood parameters of newborn piglets from Alentejano and conventional (Large White × Landrace) genotype

“…Further, increased body protein at birth, relative liver weight (Herpin et al, 1993;Canario et al, 2007b) and plasma albumin (Stone and Christenson, 1982;Wise et al, 1991) are considered as good indexes of development and maturity. Similarly, level of plasma IGF-1 is considered to be indicative of the maturity of the IGF axis (Greenwood et al, 2002). On these bases, piglets born from Alentejano sows are expected to be more mature at birth than those born from conventional sows.…”