Reproductive endocrinology and vaginal cytology of the female llama (lama glama)

Graduation date: 1990Four studies were conducted in the llama (Lama glama) evaluating changes in reproductive physiology, vaginal cytology, and growth. Study I. Temporal changes in vaginal cytology were correlated with alterations in serum estradiol -17β and progesterone concentrations. A 2 * 2 factorial study examined the treatment effects of a) concurrent male exposure without copulation and b) collection of vaginal smears for cytologic examination on serum hormone concentrations. Repeated collection of vaginal samples produced: a) an increase in the relative percentage of cornified cells, b) a decrease in the percentage of intermediate cells; and c) no changes in serum estrogen or progesterone concentrations. The presence of a male did not influence serum estrogen, progesterone or vaginal cytology. Study II. The life-span of the corpus luteum was determined following hCG-induced ovulation and sterile or fertile breedings. Peak plasma progesterone concentrations of 8.5 ± .3 ng/ml at 9,8 ± .8 days following either sterile breeding or hCG administration was observed. Luteal regression, began 10.3 ± .3 and 10.8 ± .8 days following sterile breeding or hCG adminstration, respectively, and was completed by day 12-13 post-stimulation. Following a fertile breeding, progesterone increased significantly by 4 days post-breeding and remained above 2 ng/ml in all animals that subsequently delivered a full term cria. Fertile breedings could be differentiated from sterile breedings or hCG induced ovulation by 15 days post-stimulation by differences in progesterone concentration. Study III. The changes in plasma concentrations of progesterone, estradio1-170, total estrogens, T₃, T₄ and cortisol concentrations during pregnancy, parturition and the early postpartum period were determined in experiment III. Progesterone concentrations were significantly elevated by 5 days postbreeding, remained elevated throughout pregnancy until approximately 2 weeks prior to parturition and declined to < 0.5 ng/ml by the day of parturition. Total estrogen (TE) and estradiol-17β (E₂β) concentrations varied between 6-274 pg/ml and 4-114 pg/ml, respectively, during the first 9 months of pregnancy. Mean TE and E₂β concentrations increased between 9 months and the end of pregnancy with peak mean concentrations of 827 ± pg/ml (TE) and 196 ± 10 pg/ml (E₂β) observed during the last week of pregnancy. E₂β and TE concentrations declined rapidly immediately prepartum. Cortisol concentrations varied between 2.6 and 51.9 ng/ml (14.0 ± 0.5) from conception until 2 weeks prior to parturition when they began to decline. Only a slight increase in glucocorticoid concentrations were observed in association with parturition. Study IV. The growth patterns of the llama from birth to 12 months of age was characterized. Regression analysis revealed a strong positive correlation between log transformed measurements of thoracic circumference and height with body weight. Thoracic circumference was a good predictor of body weight