Figure 1.

A schematic representation of the experimental protocol, including treatment groups and pre-treatment sampling to confirm anestrous status and the intermittent blood sampling to quantify serum progesterone, insulin, and triiodothyronine in Criollo x Saanen-Alpine yearling goats (n = 32) supplemented with Glutamate (GLUT) or control (CONT) under natural photoperiodic conditions during the anestorous season (March to April) in northern Mexico (26°LN). Note: Intermittent blood samplings were performed to evaluate serum progesterone (P4; twice per week), while insulin (INS) and triiodothyronine (T3) were collected every two weeks. Hormones were quantified using radioimmunoassay. Ovarian activity was defined to occur when serum P4 concentrations were ≥1.0 ng/mL.