Use of fecal progesterone metabolites as an alternative method of pregnancy diagnosis in the llama and alpaca

摘要

Pregnancy in the llama and alpaca can be confirmed by rectal palpation (RP), transrectal (TRU) and/or transabdominal (TAU) ultrasound, behavioural (BEH) changes in the female when exposed to the male, and alterations in progesterone concentrations (P4) when a corpus luteum (CL) is formed secondary to ovulation. RP in the llama is accurate from 30+ days of gestation but requires appropriate animal restraint, careful skilled palpation, and has the potential for rectal tears. Size limitations in the alpaca usually preclude RP for pregnancy diagnosis (PD) in the alpaca. TRU and TAU are highly accurate means of PD in the hands of a skilled operator from approximately 30 to 90 and 90 - 180 + days of gestation, respectively. The primary limitation of TRU and TAU are equipment expenses and the need for adequate restraint. BEH changes in the female following ovulation is an inexpensive, rapid method, and can be >90% accurate in multiparous females. False positives are most commonly associated with persistent CLs in animals that have lost a pregnancy but have not had a resumption of ovarian activity, and equivocal behavioural responses by some females. P4 determinations do not require the presence of a male but do necessitate adequate restraint, collectionof blood samples, and the expense associated with the measurement of serum P4. We have recently developed an alternative method of pregnancy diagnosis for situations in which it is not possible to adequately restrain animals, e.g. evaluation of reproductive activity in wild camelid populations, and as an alternative method of pregnancy determination by owners. Fecal samples are collected and dried prior to extraction of progesterone metabolites and measurement by ELISA. Comparison of serum P4 and fecalprogesterone concentrations have demonstrated that fecal progesterone concentrations lag changes in serum P4 concentrations by 12 - 24 hrs and provide an accurate means of pregnancy diagnosis in the llama.