Ovulation and corpus luteum function in the llama (Lama glama).
85 sexually mature ♀ llamas aged 3-6 yr were used in a series of tests at the Patacamaya Experiment Station, Bolivia. In an experiment involving 33 mated and 20 control ♀♀, it was found that ovulation is normally copulation-induced in this species, although ovulation without copulation occasionally occurred at the height of the breeding season. Both during 22 Nov.-27 Dec. and during 22 Nov.-1 May, there were highly significant differences in number of ovulations between mated and non-mated ♀♀. Season did not affect ovulation in animals mated from Nov. to May, but ovulation, when it occurred in non-mated ♀♀ (3 of 20), did so in late Nov.-early Dec. during the early part of the breeding season. Four of 10 ♀♀ ovulated when mated during the luteal phase. Re-ovulation was induced in 1 out of 3 of the ovulating ♀♀ mated 14 days after the 2nd ovulation. Two of 6 ♀♀ not ovulating at the 1st luteal-phase mating ovulated at a 2nd-luteal-phase mating 28 days later. The corpora lútea were well formed 4 days post coitum, reached a max. size on day 8, and decreased in size rapidly to day 16 and more slowly thereafter. Ovulation was induced in 0, 50, 75 and 100% of animals receiving 12.5, 25, 50 and 500 I.U. of HCG resp. during the breeding season.