Effect of maternal undernutrition during late pregnancy on hormonal status and metabolic changes in neonatal lambs

Abstract

The study investigated the consequences of maternal undernutrition during late pregnancy on hormonal status and metabolic changes in neonatal lambs. Four ewes out of twenty-eight multiparous ewes mated at a synchronized oestrus were slaughtered at day 90 of pregnancy to collect fetal blood to serve as an initial comparison group. Twenty-four animals were divided into three groups and offered 0.18 MJ ME·kg<sup>–0.75</sup>per day (restricted group 1, RG1), 0.33 MJ ME·kg<sup>–0.75</sup>per day (restricted group 2, RG2), and control group (ad libitum CG) during late pregnancy, respectively. Immediately after parturition, blood was collected from the neonatal lambs in each group and analyzed for growth hormone (GH), insulin-like growth factor I (IGF-I), IGF-II, insulin (INS), thyroxine (T<sub>4</sub>), triiodothyronine (T<sub>3</sub>), glucose (GLU), nonesterified fatty acids (NEFA), and total amino acid (TAA), respectively. The results indicated that the maternal undernutrition during late gestation decreased the average lamb birth weight in both RG1 (P < 0.01) and RG2 (P < 0.05) compared to CG. During the late fetal development period, the concentrations of T4, INS, and IGF-I of neonatal lambs in CG were increased (P < 0.05) compared to those at day 90 of pregnancy; the secretions of T<sub>4</sub>, INS, and IGF-I in RG1 and RG2 during restriction were suppressed. The neonatal INS concentrations in RG1 and RG2 were decreased (P < 0.05), but the neonatal GH concentration in RG1 was greater than that of CG (P < 0.05). The GLU concentrations of neonatal lambs in RG1 were lower than those of CG (P < 0.05). However, the neonatal NEFA (P < 0.05) and TAA (P < 0.01) concentrations in RG1 were greater than those of CG. Thus, maternal undernutrition can change the hormonal and metabolic status of neonatal lambs, which may have significant implications on postnatal growth and adult health.