Llamas and alpacas are important production animals in South America, with increasing interest in other parts of the world. Poor reproductive efficiency combined with several unique anatomical and physiological reproductive features offer challenges in the diagnosis and treatment of infertility in camelids. This review presents an approach to the clinical investigation and common causes of infertility and subfertility in the male and female. The selection of males for breeding should be made based on complete evaluation to eliminate congenital and possibly hereditary disorders. Common disorders of the male reproductive system include testicular hypoplasia, testicular and epididymal cysts and testicular degeneration. Semen evaluation presents some challenges owing to the viscous nature of the ejaculate in these species. Females should be screened for congenital genital defects before breeding. Causes of subfertility in the female are dominated by ovarian and uterine disorders. A systematic clinical approach and the use of endometrial biopsy and advanced techniques, such as laparoscopy, allow early identification of these disorders. Further research is needed for continued understanding of the reproductive pathological processes in these species.

Development of bovine estrus synchronization protocols started in the 1970's. The aim of these protocols has changed progressively from synchronizing estrus to synchronizing ovulation with main goal of performing insemination without heat detection (Timed artificial insemination). The present paper discusses the physiology behind development of these synchronization protocols and reviews of the main protocols used nowadays in dairy herd reproductive management. RESUMENEl desarrollo de los protocolos de sincronización del celo en bovinos comenzó en la década de 1970. El objetivo de estos protocolos ha cambiado progresivamente de la sincronización del celo a la sincronización de la ovulación con el objetivo de realizar la inseminación sin detección de celo (inseminación artificial a tiempo fijo). El presente artículo discute la fisiología detrás del desarrollo de estos protocolos de sincronización y las revisiones de los principales protocolos utilizados hoy en día en el manejo reproductivo del hato lechero.

Steroid response to human Chorionic Gonadotropin (hCG) administration has been used in various species to study testicular function and for diagnostic purposes. In this study, two experiments were conducted to determine serum testosterone concentration response to administration of hCG and its correlation with testicular weight. In the second experiment the relationship between age, testosterone and estrogen response to hCG, and testicular histometry was in pre-pubertal and post-pubertal male alpacas. For experiment 1, males in two age groups (2 to 3 years, n = 9) and (4 to 7 years; n = 15) received 3,000 IU hCG IV, 36 to 48 h before castration. Serum testosterone concentration was determined before (T0), 1 h (T1), 2 h (T2), 8 h (T8), and 24 h (T24) after administration of hCG. Basal concentrations of serum testosterone was significantly different ( P < 0.01) between age groups. Serum testosterone concentrations increased over time and doubled 2 h after treatment. The highest change (250 to 300% increase from T0) was observed at 8 h (3.5 ± 0.3 ng/ml). A significant correlation ( P < 0.01; r = 0.64) was found between serum testosterone concentration and total testicular weight. For experiment 2, 60 males ranging in age from 6 to 60 months were used. Serum testosterone and estrogen was determined in samples taken just prior to and 2 h after administration of 3,000 IU hCG. Basal serum testosterone concentrations were very low (≤0.1 ng/mL) until 9 months of age then increased steadily with age. There was a significant variation amongst males within the same age group. Serum testosterone concentration increased by 2- to 4-fold 2 h after hCG injection ( P ≤ 0.05). Males in the 13 to 14 months of age group had the highest rise. Estrogen concentration increased in response to hCG administration and was detected only in males with high testosterone. We conclude that administration of 3,000 IU of hCG IV can be used reliably to detect testicular tissue and study its steroidogenic activity. The response is correlated with testicular weight and Leydig cell number. Testicular growth and sensitivity to LH stimulation increases between the ages of 13 and 14 months. The aromatizing ability of Leydig cells increased significantly in post-pubertal male alpacas.

Earlier, we validated an anti-Müllerian hormone (AMH) enzyme-linked immunosorbent assay kit for male alpacas. First, wecompared the validation data with another kit. There was a high correlation (R2 = 0.94) between these 2 kits. Second, we used thelatter kit to determine serum AMH concentrations during follicular and luteal phases of the reproductive cycle in female alpacas.There were no differences (p = 0.39) in serum AMH concentrations in alpacas (n = 11) between peak follicular and luteal phases(mean ± SEM, 1.33 ± 0.35 versus 1.18 ± 0.34 ng/ml, respectively). Third, we treated female alpacas (n = 13; 5 - 11 years) after 14-day treatment with decreasing doses of porcine follicle-stimulating hormone. There was no effect (p > 0.05) of day of treatmenton serum AMH concentrations. Number of follicles (7 - 10 mm; mean ± SD [as determined via transrectal ultrasonography]) atend of treatment (12.69 ± 5.25; range: 6 - 24) was positively correlated (R2 = 0.7; p < 0.01) with serum AMH concentrations. Toconclude, the kit tested is usable for female alpacas; serum AMH concentrations were not affected by the cycle stage nor by ovariansuperstimulation treatment. Furthermore, a significant correlation between serum AMH serum concentrations and response to superstimulationsuggested that estimation of serum AMH concentrations may be valuable in determining ovarian follicular reserve.

Alpacas have a high incidence of congenital reproductive tract abnormalities, including ovarian hypoplasia/dysgenesis. Diagnosis of this condition is often challenging. The present study describes the clinical, ultrasonographic, and histologic features of ovarian hypoplasia/dysgenesis syndrome in 5 female alpacas. Additionally, serum AMH levels were compared between female alpacas diagnosed with ovarian hypoplasia/dysgenesis and a group of reproductively sound females (n = 11). The syndrome was suspected based on the presence of an infantile uterus and lack of ovaries by ultrasonography and laparoscopy. All females had normal female karyotype (n = 74 XX), but one presented a minute chromosome. The ovaries from these cases showed 3 main histological classifications: hypoplasia (n = 2), dysgenesis (n = 2), and dysplasia (n = 1). Serum AMH levels in affected females were significantly lower (P &lt; 0.05) than those of reproductively sound control females. In conclusion, Serum AMH level may be helpful in the rapid diagnosis of ovarian hypoplasia/dysgenesis syndrome in alpacas. Furthermore, this syndrome in alpacas presents a variety of histological features. Different mechanisms may be involved in the derangement of ovarian differentiation. Further studies are needed to elucidate the causes of the syndrome.