Insulin like growth factor I plasma concentration assessment during the luteal phase in pregnant and non pregnant llamas

This study aimed to assess the temporal association between plasma Insulin like growth factor I (IGF1) and progesterone (P4) concentration during the luteal phase in pregnant and non-pregnant llamas. On Day 0, sixteen llamas were induced to ovulate either by mating (n = 10) or by a single dose of buserelin (n = 6). All llamas were examined by transrectal ultrasonography every other day from Day 6 until Day 14 post-induction of ovulation to assess corpus luteum diameter. Blood samples were collected every other day from Day 0 until Day 14 postinduction of ovulation to evaluate plasma P4 and IGF1 concentrations. Plasma IGF1 concentration was between 109 and 499 ng/ml, without significant differences between groups (pregnant, mated non-pregnant and induced to ovulate by buserelin). No significant differences were observed in plasma IGF1 concentration between follicular and luteal phase, nor between the different days of the luteal phase. There was no correlation between plasma IGF1 and P4 concentration or corpus luteum diameter. In conclusion, mean plasma IGF1 concentration did not significantly change along the luteal phase and was similar between pregnant and non-pregnant llamas; without showing an association with corpus luteum function.