PSV-13 Betaine supplementation and nutrient restriction during gestation: Influences on growth in fetal sheep offspring

Abstract Restricted nutrition during gestation can reduce offspring productivity. Supplementation of betaine, a methyl donor, promotes fetal growth and liver function. We hypothesized that nutrient restriction during gestation impairs growth, including organ weights and muscle mass, while betaine supplementation would alleviate these negative effects. To determine if maternal betaine supplementation during gestation would improve growth of offspring of restricted-fed dams, multiparous Dorset ewes (n = 47) were estrus synchronized and bred to one of three rams. Ewes confirmed pregnant with twins (n = 32) and singletons (n = 15) were randomly assigned to one of four diets [100% NRC requirements (CON), 60% NRC (RES), CON+betaine (CON+BET; 2 g/d), and RES+BET] from d 30 to 130 of gestation. Among the twins, there were 27 males (CON-8, RES-5, CON+BET-5, and RES+BET-9) and 37 females (CON-8, RES-9, CON+BET-11, and RES+BET-9). Within singletons, there were 7 males (CON-2, RES-2, CON+BET-2, and RES+BET-1) and 8 females (CON-3, RES-1, CON+BET-1, and RES+BET-3). Dam body weight (BW) was measured weekly from d 30 to d 130 of gestation, and diet adjusted accordingly. Dams were euthanized at d 130 of gestation and fetal BW and tissue weights were collected. Data were analyzed using RStudio with P ≤ 0.05 considered significant and 0.05 < P ≤ 0.10 as tendency. At d 130, dams carrying twin fetuses in the CON group were 11.3% and 19.1% heavier than RES and RES+BET dams, respectively (P ≤ 0.05), and CON+BET dams were 18.4% and 10.5% heavier than RES and BET+RES dams, respectively (P ≤ 0.07). However, dams with singletons showed no significant difference in BW (P ≥ 0.37). Regarding fetal BW for singletons, RES fetuses (3.80 ± 0.28kg) were lighter than CON (4.60 ± 0.21kg), CON+BET (4.72 ± 0.27kg), and RES+BET (4.59 ± 0.24kg; P ≤ 0.03). Whereas in twins, RES+BET fetuses (3.19 ± 0.11kg) were lighter than CON (3.68 ± 0.12kg), RES (3.73 ± 0.14kg), and CON+BET (3.60 ± 0.13kg; P ≤ 0.02). In all fetuses, the livers of male RES (28.0 ± 1.49g) and male RES+BET (27.7 ± 1.44g) tended to be heavier than those of female RES+BET (24.5 ± 1.19g; P ≤ 0.07). In terms of muscle mass, female CON+BET (9.33 ± 0.43g) fetuses tended to have greater longissimus muscle (LM) mass compared with female CON (8.30 ± 0.35; P = 0.06), whereas male RES (9.06 ± 0.44g) tended to have heavier LM than male CON+BET (8.02 ± 0.43g; P = 0.09). There were no observed effects of diet, fetal sex, or fetal number on the weights of heart, kidney, perirenal fat, pancreas, semitendinosus muscle, and triceps brachii muscle (P ≥ 0.11). These findings suggest that betaine supplementation may have a significant role in improving fetal BW in singleton pregnancies, with variable effects in twins. Additionally, betaine supplementation may have sex-specific effects on muscle development.