Supplementing dietary betaine during late gestation increases plasma betaine and methionine concentrations in pregnant Merino ewes but not neonatal lambs

Abstract

Supplementing dietary betaine during pregnancy has improved vigour and post-natal survival rates to day seven in twin lambs, potentially due to improvements in the circulating metabolite profile of these animals. This study determined whether maternal betaine supplementation during late gestation would increase circulating levels of betaine, creatinine and other amino acids in ewes and their newborn lambs, leading to subsequent improvements in lamb viability and growth. Twenty-five single-bearing Merino ewes received dietary betaine at either 0 (Control, CTL), 2 (Low Betaine, LB) or 4 g/day (High Betaine, HB) from day 125 of gestation (dG 125) until parturition (150.7 ± 0.6 days). Blood samples were collected from the ewes prior to feeding (0 h), and at 2, 4, 6, 8 and 24 h post-feeding on dG 125 and dG 140 prior to feeding and from the lamb within 2 h after birth. Lamb viability measures were taken at 2, 24 and 72 h and day 7 post-partum, marking (⁓30 days of age) and weaning (⁓104 days of age). Betaine supplementation at LB and HB increased plasma betaine levels at 6, 8 and 24 h post-feeding on dG 125 (P < 0.05) and tended to increase plasma betaine on dG 140 (P = 0.085). Plasma methionine levels increased at 2 and 4 h post-feeding on dG 125 relative to baseline levels (0 h) in LB ewes, yet remained unchanged in HB ewes. On dG 125, creatinine levels were higher in CTL ewes compared with betaine-supplemented ewes at 4 and 8 h post-feeding (both P < 0.05). While plasma betaine and methionine levels were unchanged in neonatal lambs, plasma concentrations of glutamine and lysine were higher (P < 0.05) in HB lambs compared to CTL and LB lambs. HB lambs tended to be heavier at marking (P = 0.057) and were heavier at weaning compared to CTL and LB lambs (P < 0.05). This study indicated that betaine supplementation increased plasma betaine and methionine levels in ewes, but not in neonatal lambs. Further research is warranted to determine whether higher levels of betaine supplementation increase neonatal concentrations.