Long-term betacarotene supplementation positively affects serum triiodothyronine concentrations around puberty onset in female goats

The effect of betacarotene (BC) supplementation on serum triiodothyronine (T3) levels over time in prepubertal goats was evaluated. Goats (n = 17; 3 months old; 7/8 Saanen-Alpine; 26° NL) were randomly assigned to one of the following two groups: 1) the betacarotene group, supplemented daily with 50 mg of BC (n = 9; live weight [LW]: 17.3 ± 1.0 kg; body condition score [BCS]: 3.34 ± 0.12), or 2) the control group (CC; n = 8; LW: 16.1 ± 1.0 kg; BCS = 3.17 ± 0.12). The initial mean LW (16.7 ± 1.0 kg) and BCS (3.31 ± 0.12) were similar (p > 0.05) in both groups. Whereas BC supplementation did not affect the onset of puberty (215.7 vs. 226.7 ± 6.6 days; p > 0.05) for the BC and CC, respectively, increases in serum T3 during the second half of the experiment were observed in the BC supplementation group (p < 0.05). As the LW and serum T3 levels increased, the natural photoperiod decreased, revealing a negative correlation (p < 0.05) between the variables; the observed values were r = −0.94 for LW and photoperiod and r = −0.41 for T3 and photoperiod. Long-term BC supplementation was not associated with a precocious onset or an increased percentage of goats reaching puberty. Long-term BC supplementation positively affected the release pattern of triiodothyronine over time, suggesting a potential role of BC as a thyroid-activating molecule; these results might possess clinical significance.