Effects of Prenatal Herbal Methionine Supplementation on Growth Indices, Onset of Puberty, Blood Metabolites, and Fertility of Alpine Doelings

This study investigated the effects of prenatal herbal methionine supplementation on growth, puberty onset, reproductive efficiency, and blood metabolites in first-generation G1 Alpine doelings. Sixty pregnant multiparous goats (G0), each with at least three parturitions, were assigned during the last trimester of pregnancy to either herbal methionine (H-MET-G0; 1% Optimethione^®; n = 30) or a control group (CTL-G0; n = 30). Only female offspring (G1 doelings) were studied (H-MET-G1:19; CTL-G1:25) from weaning (45 days old) to 10 months (first breeding). G1 doelings were weighed and monitored weekly for metabolites, IGF-1, insulin, and progesterone. Ovulation of the G1 doelings was induced using vasectomized bucks, followed by breeding with intact bucks. Postweaning growth, age at puberty (H-MET-G1:216 vs. CTL-G1:229 days), and live weight at puberty (H-MET-G1:20.5 vs. CTL-G1:21.0 kg) did not significantly differ (<i>p</i> > 0.05). Age at puberty and conception were negatively correlated with live weight (<i>p</i> < 0.001). First-cycle conception rates were 81% in CTL-G1 and 66% in H-MET-G1, with similar days to conception (<i>p</i> > 0.05). The number of pregnant doelings and the number of kids in utero did not significantly differ (<i>p</i> > 0.05) between treatments. Plasma IGF-1 and insulin levels were significantly higher (<i>p</i> < 0.001) in H-MET-G1 doelings, whereas plasma metabolites related to nutrition showed no differences between groups (<i>p</i> > 0.05). Prenatal herbal methionine supplementation had no carry-over effect on growth, puberty onset, or reproductive efficiency. Age at puberty and conception were negatively correlated with live weight and positively correlated with IGF-1 and insulin levels.