Animal Health

OBJECTIVE: To determine concentrations of estrone sulfate in serum, estrone sulfate in urine, relaxin in serum, and progesterone in serum in pregnant llamas and alpacas and to assess the potential of these hormones as pregnancy indicators. DESIGN: Prospective study. ANIMALS: 19 parous pregnant camelids (8 llamas and 11 alpacas). PROCEDURE: Estrone sulfate concentrations (in serum and in urine) and progesterone concentrations (in serum) were determined by enzyme immunoassay. Relaxin concentrations (in serum) were measured by radioimmunoassay. Serum and urine samples were collected daily for the first 30 days after breeding and, thereafter, once weekly until parturition. RESULTS: Estrone sulfate concentrations (in serum and in urine) peaked twice during pregnancy. The first took place 21 days after breeding and the second during the last month of pregnancy. Relaxin concentrations increased at 3 months of gestation to > 20 ng/mL, decreased at 5 months to 5 ng/mL, then increased from 8 months of pregnancy until parturition. Progesterone concentrations were detectable 4 days after breeding and were maintained > 2 ng/mL throughout pregnancy. CLINICAL IMPLICATIONS: The first increase in estrone sulfate concentration over basal values may indicate early interaction between mother and embryo, whereas the second increase may reflect fetal viability. Use of estrone sulfate concentration to diagnose pregnancy in llamas and alpacas is highly dependent on time of sampling. Relaxin concentration in serum is a superior indicator of pregnancy after the second month in the Ilama and alpaca because its existence is suggestive of interaction between mother and fetus, and concentrations are greater than basal values for a long period of pregnancy. Progesterone is not a direct product of the embryo or fetus and only indirectly confirms a diagnosis of pregnancy. more »

The proportion of female alpacas ovulating, conceiving and remaining pregnant up to 40 days after copulation was evaluated using progesterone concentrations. One hundred and seventy six parous, postpartum alpacas were divided into three groups for breeding at 10, 20, and 30 days postpartum at the La Raya research station, Cusco, Peru. Females were further subdivided into three groups to allow copulation once, twice, or three times at 24-h intervals, within different postpartum times. Blood samples were collected at time of breeding, at Day 7 (ovulation), at Day 21 (conception), and Day 40 (pregnancy) from all females after breeding. Progesterone analysis was performed by enzyme immunoassay. There was significant difference in the proportion of females ovulating at Days 10 (), 20 () or 30 () postpartum; however, frequency of breeding did not increase the number of females ovulating. There was significant difference in the proportion of females conceiving at Days 10 (), 20 (), and 30 () postpartum, compared with females ovulating at the three times of breeding. There was also a significant difference in the number of females in which pregnancy was sustained at Day 40 when bred at 10 (19), 20 (31) and 30 (44) days postpartum. There were significant differences in the concentration of progesterone of ovulating females (4.2 ng ml−1), conceiving females (3.1 ng ml−1) and females remaining pregnant (1.4 ng ml−1), compared with the overall mean of 0.4 ng ml−1 for females that did not ovulate, did not conceive and that experienced embryonic mortality. Altogether, these results suggest that breeding as early as Day 10 postpartum does not yield acceptable fertility rates as compared with breeding on Days 20 or 30 postpartum, and that repeated breeding does not increase the number of females ovulating or conceiving. more »

From spring 1990 to autumn 1993, 44 spring-mated and 82 autumn-mated alpacas at Flock House Agricultural Centre (FH) had their pregnancies monitored by ultrasound every 10–14 days from day 20 to day 120 of gestation. A further 32 autumn-mated alpacas at Tara Hills High Country Research Station (TH) were monitored in 1992. Trans-rectal probes were used in early gestation and trans-abdominal probes in late gestation. As techniques for pregnancy diagnosis in alpacas improved during the experiment, the stage of gestation at which pregnancies were first confirmed became earlier. From spring 1991 onwards most pregnancies were first diagnosed at 20–30 days of gestation. Progesterone concentrations were determined from individual blood samples collected each time alpacas were brought in for pregnancy diagnosis from spring 1991 onwards. Foetal loss from day 30 onwards was 25.7% with the foetal losses after day 120 of gestation being 9.6–16.7% in different mating groups. There were apparent differences in the pattern of foetal loss between autumn- and spring-mated alpacas at FH with foetal losses before day 81 being 17.3% and 2.8% respectively and no significant difference in foetal loss after day 81 of gestation. The younger New Zealand born alpacas had a similar incidence of foetal loss to the older Chilean born alpacas. There was a suggestion at TH that the stress of transport and relocation of a group of alpacas at 212 ± 3 days of gestation precipitated a high incidence of foetal loss. The spring-mated alpacas had a longer gestation length (350.1 ± 2.7 days) than autumn-mated alpacas at FH (340.2 ± 1.9 days). more »