Male Alpacas Research Articles

Unilateral maxillary mass on a 4-year-old male alpaca.

Unilateral maxillary mass on a 4-year-old male alpaca.

Intra-horn insemination in the alpaca Vicugna pacos: Copulatory wounding and deep sperm deposition.

Alpacas (Vicugna pacos) are reported to be the rare mammal in which the penis enters the uterus in mating. To date, however, only circumstantial evidence supports this assertion. Using female alpacas culled for meat, we determined that the alpaca penis penetrates to the very tips of the uterine horns, abrading the tract and breaking fine blood vessels. All female alpacas sacrificed one hour or 24 hours after mating showed conspicuous bleeding in the epithelium of some region of their reproductive tract, including the hymen, cervix and the tips of each uterine horn, but typically not in the vagina. Unmated females showed no evidence of conspicuous bleeding. Histological examination of mated females revealed widespread abrasion of the cervical and endometrial epithelium, injuries absent in unmated females. Within one hour of mating, sperm were already present in the oviduct. The male alpaca's cartilaginous penis tip with a hardened urethral process is likely responsible for the copulatory abrasion. The entire female reproductive tract interacts with the penis, functioning like a vagina. Alpacas are induced ovulators, and wounding may hasten delivery of the seminal ovulation-inducing factor beta-NGF into the female's blood stream. There is no evidence of sexual conflict in copulation in alpaca, and thus wounding may also be one of a variety of mechanisms devised by mammals to induce a beneficial, short-term inflammatory response that stimulates blastocyst implantation, the uterine remodeling associated with placental development, and thus the success of early pregnancy.

Fiber quality and fertility in male alpacas in the Cusco region of Peru.

High testosterone levels might be associated with coarser fiber in alpacas, affecting fiber quality. In the husbandry systems employed in the Andes, males with higher libido might have an increased frequency of successful matings than males with lower libido. This study aimed to determine some of the factors affecting fiber quality in Peruvian alpacas and to evaluate the association between fiber quality and male mating behavior. The study population consisted of 189 adult male alpacas at La Raya, Cusco, Peru, at 4,400 m above sea level, belonging to the National University of San Marcos, Lima, and the National University of San Antonio Abad of Cusco. Fiber samples were collected from male alpacas in September 2015; body condition score (BCS) was evaluated. After washing and drying, the fiber samples were analyzed using an Optical Fiber Diameter Analyser 2000; linear regression analysis between predictor variables (location of alpacas, age, BCS, and fiber color) and fiber quality outcomes was conducted. Fertility data were available only for some males belonging to San Marcos University, consisting of hand-written records from the breeding season January to April 2015; individual fertility quotients were calculated for each male. Age was associated with fiber quality, young alpacas having the finest fibers (p < 0.05). An increased BCS was associated with increased fiber length, fiber diameter and spinning fineness, but decreased comfort factor (p < 0.05). White fibers were thinner (p = 0.05) than colored fibers, with lower comfort factor and spinning fineness. A significant association between the fertility quotient and fiber curvature was observed (p = 0.018). These results suggest that careful selection of breeding individuals and attention to husbandry could result in improved fiber quality among alpaca herds in Peru. However, it would be advisable to increase the number of males studied, using more reliable methods for evaluating male fertility and pregnancy diagnosis than were available for this study.

Predictive characteristics of male fertility in alpacas with special reference to seminal NGF

Recent studies document the LH-releasing pathway of nerve growth factor (NGF) in male camelids and that the LH response to seminal NGF is associated with elevated plasma testosterone concentration. Results provide rationale for the hypothesis that NGF in semen is associated with male fertility. In Experiment 1, the association between the amount of NGF in the ejaculate and characteristics of the male reproductive system was examined in alpacas. The concentration of NGF was measured by radioimmunoassay in semen samples collected from male alpacas (n = 47) and correlated with sperm morphology and motility, and measurements of the male reproductive anatomy. Most ejaculates had NGF concentrations that, based on previous studies, triggered ovulation in female camelids, however, we only found a positive correlation between NGF concentration with sperm concentration, thread formation and total NGF, and a negative correlation with pH. In Experiment 2, a retrospective analysis was carried out to determine if breeding performance during the previous season was related to recent concentrations of seminal NGF in male alpacas (n = 22). Birth rates tended to be correlated with sperm concentration and total amount of NGF in the ejaculate (P = 0.09). Experiment 3 was a prospective study to determine the relationship between seminal NGF (n = 8 male alpacas) and ovulation and pregnancy rates in a breeding trial. No association was detected between seminal NGF concentration and ovulation rate, pregnancy rate, or LH response in the female. We conclude that among the breeding males used in our study, the abundance of seminal NGF was correlated with sperm concentration and thread formation, however, it was not predictive of male fertility in alpacas. Examination of males not previously selected as breeding stock may be expected to include a broader range of seminal NGF and provide a more comprehensive understanding of the relationship between seminal NGF and male fertility.

Serum steroid and thyroid hormone concentrations in healthy domestic male and female alpacas.

Alpacas are high quality fiber producing animals, kept for production purpose and as pets. Endocrine imbalances from adrenal glands, gonads, or thyroid gland may result in coat abnormalities in domestic animals and affect reproduction. Contrary to many domesticated animals, information on hormone concentrations in alpacas is scarce. The purpose of this study was to provide steroid and thyroid hormone values in domestic alpacas. Blood was collected from healthy male (35 intact, 2 castrated) and female (48 non-pregnant, 3 pregnant) alpacas from local farms in Tennessee. Adrenal, reproductive, and thyroid hormones were analyzed. There were no significant differences in median concentrations of progesterone, estradiol, thyroxine (T4), and triiodothyronine (T3) between intact male and female non-pregnant alpacas. Median concentrations of testosterone, androstenedione, 17-hydroxyprogesterone, and cortisol were significantly higher in intact male alpacas compared to female non-pregnant alpacas. This information provides adrenal, gonadal, and thyroid hormone concentrations in alpacas to help with diagnosis of endocrine disorders.

Diet Digestibility and Partitioning of Nutrients in Adult Male Alpacas Fed a Blend of Oat Hay and Alfalfa Pellets at Two Levels of Intake

Alpacas are well adapted to consume the poor-quality forages present in the arid conditions of the Andean Altiplano. However, studies focusing on understanding the relationship between diet digestibility and intake are scarce. The aim of this study was to evaluate the effects of two levels of dry matter intake (DMI) on a metabolic body weight (BW0.75) basis. The effects of a maintenance level of intake and an ad libitum level of intake (40 and 50 g of dry matter (DM) per kg of BW0.75, respectively) on the apparent diet digestibility and partitioning of specific nutrients (energy, carbon (C), and nitrogen (N)) of alpacas that were fed a blend of oat hay and alfalfa pellets (70:30 ratio as a percentage on a fed basis) were evaluated. Five adult intact male alpacas (BW = 62.9 ± 8.09 kg at the beginning of the study) were fed with the experimental diet and trained to be allocated in metabolism crates for 30 days. After the completion of this phase, two separate experiments for each level of intake were carried out, each lasting for twenty-six days (with the final five days taken for samples and raw data collection). In both experiments, the animals responded differently in terms of nutrient supply and changes in BW (−140 and 100 g/d for the maintenance and ad libitum levels of intake, respectively). Oat hay consumption was rather similar in both experiments, which may be explained by a reduced ingredient selectivity at the ad libitum level of intake. Diet digestibility was similar in both experiments, despite the greater fecal output of nutrients with the increased level of diet intake. In line with this, diet metabolizability, calculated as the ratio between metabolizable energy (ME) and gross energy (GE) contents, indicated a similar energy utilization of the diet. The apparent digestibility of the organic matter (OMD) ranged from 655 to 669 g/kg DM. Water consumption at the ad libitum level of intake was 21% higher than the observed mean at the maintenance level of intake. Fecal outputs of dietary energy, C, and N accounted for the largest source of excreted nutrients, regardless of the level of intake. The N retention increased from 0.439 at the maintenance level of intake, to 0.473 g of DM/kg BW0.75 when the alpacas were fed ad libitum.

Severe anaemia secondary to a perforated gastric ulcer in a male alpaca

BackgroundAnaemia is a common condition in alpacas and attributable to a variety of causes. Severe anaemia with a packed cell volume (PCV) less than 10% is frequently diagnosed, usually due to blood loss resulting from haemonchosis. Many South American camelids (SACs) also suffer from gastric ulcers, which are often associated with anaemia in other species. However, in alpacas and llamas, gastric ulcers usually do not lead to anaemia due to blood loss according to the current literature. There are no detailed clinical and laboratory data on this condition in the scientific literature so far.Case presentationWe report on the case of a nine-year-old male alpaca that was presented to the clinic with suspected forestomach acidosis. The animal showed clinical signs of colic, hypothermia, tachypnea, tachycardia, pale mucous membranes, and died shortly after admission to the clinic. Laboratory diagnosis revealed a markedly decreased haematocrit (0.13 l/l), leucopaenia with band neutrophils, azotaemia, hypocalcaemia, hyperphosphataemia and vitamin D deficiency. Post-mortem examination revealed multiple ulcers in the first and third compartment with perforation of one ulcer in the first compartment, resulting in intraluminal blood loss and purulent peritonitis.ConclusionsTo the authors’ knowledge, this is the first detailed description of clinical and laboratory data of severe anaemia due to a perforated gastric ulcer in a SAC. Although the current literature suggests that severe blood loss due to gastric ulcers does not occur in SACs, this condition should be considered as a possible differential diagnosis in anaemic animals. Clinical indicators can be colic and pale mucous membranes.

Are alpacas especially protective of lambs? An insight into alpaca guardian behaviour towards sheep using an arena preference test

Alpacas are increasingly used as a guardian species in Australian sheep flocks in an effort to improve lamb survival rates. Yet little is documented about the role and mechanisms of alpaca guarding behaviours within this environment. The first phase of this study, evaluated the temperament of 44 alpacas by assessing their behaviour when individuals were separated from herd mates. Tests included agitation while in an isolation enclosure, flight speed and behaviour in observation arena tests. The second phase of the study evaluated alpaca responses to different auditory, olfactory and visual cues representative of young lambs, adult sheep (ewes) and other novel stimuli. Alpacas (n = 24) which had not previously been exposed to sheep were individually presented with stimuli in a test arena. Behavioural responses were recorded over 2 min and analysed to compare differences between stimuli type (lamb/ewe/other) and stimuli cue form (live animal/auditory only/olfactory only/visual only). In phase one of this study alpacas exhibited little agitation while retained in an isolation enclosure with 67% of animals demonstrating a low agitation score. Females appeared to have a more ‘reactive’ temperament than males, exhibiting significantly faster flight speeds (P < 0.01) and more frequent pacing behaviour (P < 0.01) in the observational pen. In the arena test both male (n = 12) and female (n = 12) alpacas consistently exhibited greater attraction towards the lamb stimuli type (for all cue forms) compared to the ewe and other atypical stimuli (P < 0.05 for all comparisons). Alpacas showed the greatest attraction towards the live lamb compared to visual (P < 0.01), auditory (P < 0.01) and olfactory lamb cues (P < 0.001). Both male and female alpacas demonstrated similar response times and there were no significant differences between alpaca sex in the total time spent reacting to the lamb and ewe stimuli. This study demonstrates that alpacas exhibit a greater attraction towards or interest in young vulnerable animals such as lambs and supports the available anecdotal evidence that the use of alpacas as livestock guardians may be useful in improving lamb survival rates.

Surgical correction of a bilateral lateral luxation of the patella in an adult alpaca

AbstractA bilateral lateral luxation of the patella was diagnosed in an 8‐year‐old, 54 kg, neutered, male alpaca presented with hindquarter weakness progressing to periods of prolonged recumbency over the last 2 weeks. The patient underwent a correction of the condition using a block recess trochleoplasty combined with a medial imbrication on both hindlimbs, performed 15 days apart. Postoperative radiographs confirmed the correct repositioning of the patella. Immediately after the second surgery, the alpaca was able to get up and move freely. No postoperative complications occurred, and the alpaca was discharged from the clinic 15 days after the second surgery. Two years after discharge, the alpaca is doing well with no recurrence of the luxation. Considering the quick recovery and the safe and relatively simple procedure, this technique may be considered an option in unilateral or bilateral patellar luxations in alpacas.

COMPARISON OF COMMERCIAL DILUENTS AND TRACE ELEMENTS ON FRESH ALPACA SEMEN (LAMA PACOS)

The reproduction of alpacas is a research subject of interest in recent times since their condition and morphology do not cause an impact on the Andean-habitat territories. The collection of semen from male alpacas by artificial vagina is the methodology used for the best extraction of seminal material. However, conservation methods are not fully defined, therefore, analyzing the semen conservation on male alpacas with the inclusion of trace elements and commercial diluents were the subject of interest in the study. Seven male alpacas were taken, with reproductive ages between 3 - 5 yrs. with an average weight of 60 ± 1.64 kg of BW. Distributed in two random homogeneous experimental groups (SSO, male alpacas semen without trace elements, and SCO, male alpacas semen with trace elements) to analyze the macroscopic and microscopic characteristics of the commercial trace elements administration. In addition, were subjected to a dilution procedure with two types of registered commercial diluents (Triladyl® and AndroMed®) and a laboratory-generated diluent (Tris Yema + Glycerol ). The semen conservation process was analyzed and compared to the trace elements application and has no difference, even though there is heterogeneous research on semen conservation. The authors recommended making more scientific contributions to the inclusion of trace elements and diluents in the fresh semen of male alpacas.

Fusobacterium necrophorumandActinomycesspp. masseter muscle abscessation in an adult alpaca

AbstractThere are few documented cases of facial abscesses due to masseter abscess formation in South American camelids. Facial swellings in South American camelids have been reported and are frequently due to apical tooth root infections. Masseter abscess has been described in people. However, this lesion has not previously been described in South American camelids. This case report describes the clinical signs, diagnostic procedures and pathological findings in adult male Huacaya alpaca suffering from a masseter abscess caused byFusobacterium necrophorumandActinomycesspp. The mass was delimited by computed tomography and removed under general anaesthesia. The histopathology of the mass revealed severe focally extensive suppurative inflammation, which infiltrated and effaced the skeletal muscle. Bacterial cultures revealed that the abscess was caused byFusobacterium necrophorumandActinomycesspp. Once removed, the alpaca was started on antimicrobial therapy and did fully recover at the farm.

Serum anti-Müllerian hormone concentrations in female alpacas: variations during the reproductive cycle and correlation with ovarian superstimulation response

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 &gt; 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 &lt; 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.

Design, operation, and validation of metabolism crates for nutrition studies in alpacas (Vicugna pacos)

Metabolism studies in farm animals require reliable measurements of feed intake and water consumption, as well as the accurate collection of feces and urine. When designing metabolism crates, aspects such as: animal behavior, minimization of injury risks, and animal cleanliness should be considered. In the present study, morphometric measures taken from 30 Huacaya male alpacas (five years old) were the basis for designing an initial prototype of metabolism crates, which was built largely of metal for strength and durability, and has replaceable parts. Two of these metabolism crates were built and tested with experimental animals sequentially allocated in pairs during five days each. Based on the observed performance, both length and width of metabolism crates were adjusted (2.00 × 0.55 m respectively) for an up-graded design, which was tested during the validation phase. These features provided greater comfort and ease of handling of the experimental animals. Metabolism crates are illustrated by photos and drawings, which give dimensions and details of construction. At the end, five units were built. Validation of metabolism crates comprised the evaluation of animal performance of five alpacas fed at maintenance level of intake in terms of: daily feed intake and water consumption, fecal and urine excretion, and diet digestibility over a two-week experimental period. Data were analyzed by descriptive statistics. Overall, both dry matter intake per kg of metabolic body weight (DMI: 42.7 ± 1.29 g/kg BW0.75), and water consumption (100 ± 7.1 ml/kg of BW0.75), which was equivalent to 2.3 times the observed DMI (kg/d), were in line with a number of previous studies conducted with alpacas for this feeding regime. Due to differences mainly related to diet composition, direct comparisons with studies in the literature in terms of fecal production and diet digestibility are difficult to draw. However, these results appear to be in line with expected performance for the given diet (70:30 oat hay and alfalfa pellets on a fed basis). Same applies to urine volume (428 ± 34.2 ml/d), which in the present study represented 19% of the daily water consumption. It is concluded that proposed metabolism crates are suitable for conducting nutritional studies with alpacas.

Use of antimicrobial impregnated calcium sulphate beads in the surgical management of mandibular osteomyelitis in an 8‐year‐old huacaya alpaca

AbstractAn 8‐year‐old male huacaya alpaca presented for a left mandibular swelling that was not responsive to antimicrobial treatment. A computed tomography scan was obtained, confirming the presence of a lytic bone destruction and primary mandibular osteomyelitis. Surgical debridement of the area was performed and the surgical site was packed with antibiotic‐loaded calcium sulphate beads to provide local antibiotic delivery and support new bone formation. The surgical intervention and implantation of the beads were well tolerated, and no postsurgical issues were reported over the following 12 months. A follow‐up computed tomography scan was performed 14 months after surgery and this revealed near‐complete restoration of bone architecture and no evidence of active bone destruction. A combination of surgical debridement and antibiotic‐loaded calcium sulphate beads is a viable and cost‐reasonable option for the treatment of osteomyelitis in camelids.

Acute fasciolosis in an alpaca: a case report

BackgroundThe popularity of new world camelids, particularly alpacas, is growing rapidly in Ireland, presenting a clinical challenge to veterinary practitioners who may not have worked with these species previously. To the authors’ knowledge, the clinical course of a case of acute fasciolosis in an alpaca has not previously been reported, and fasciolosis has not been reported at all in alpacas in Ireland, making this case report a valuable addition to the current literature.Case presentationA three-year-old male castrated huacaya alpaca was admitted to UCD Veterinary Hospital with a two-day history of colic and tenesmus. He had been treated with albendazole, dexamethasone and potentiated amoxycillin by the referring veterinary practitioner with no response. On initial clinical exam, sensitivity to abdominal palpation was the only abnormality. However, the alpaca proceeded to show abnormal lying positions, tenesmus and reduced faecal output over the next 24 h. A general blood panel demonstrated moderate anaemia, marked hyperglobulinaemia and moderately increased hepatocellular and hepatobiliary enzyme activity. Abdominal radiography revealed enlargement of the first forestomach compartment without evidence of gastrointestinal obstruction or peritonitis. An abdominal ultrasound exam revealed an elongated, heterogenous mass in the caudoventral abdomen that appeared to be contiguous with the liver. FNA of this mass revealed that it was in fact a liver lobe with biliary stasis and inflammation. Faecal sedimentation demonstrated Fasciola hepatica eggs. In spite of treatment with triclabendazole and supportive treatment including blood transfusion, the alpaca’s condition continued to deteriorate and he was euthanised. On post-mortem exam, acute fasciolosis was diagnosed.ConclusionsThe clinical presentation and course of a case of acute fasciolosis in an individual alpaca is described, including the results of a range of diagnostic tests that were carried out. The final diagnosis is supported by a description of post-mortem findings. This information will serve as a resource for veterinary practitioners involved in the diagnosis and treatment of similar cases.

First report of Eimeria and Entamoeba infection in alpacas (Vicugna pacos) in Shanxi Province, northern China

Intestinal protozoa Eimeria and Entamoeba can infect many animal species including alpacas. However, data on the prevalence and pathogenicity of species of the two genera Eimeria and Entamoeba in alpacas in China is scarce. The current study was carried out to investigate the prevalence of Eimeria and Entamoeba in alpacas in two cities (Taiyuan and Xinzhou) in Shanxi Province, northern China, using PCR-based approaches. Eimeria spp. were only found in Taiyuan city, and the overall prevalence was 1.64%. All samples collected from male alpacas were PCR-negative for Eimeria. Four Eimeria-positive samples were tested positive as Eimeria lamae. The molecular prevalence of Entamoeba in alpacas was 18.03% (66/366), including 16.39% (50/305) in alpacas from Taiyuan city and 26.23% (16/61) from Xinzhou city, respectively. The Entamoeba prevalence in male alpacas (25.00%) was significantly higher than that in female alpacas (15.69%). Entamoeba bovis was the predominant species, and no Entamoeba histolytica infection was detected. Nine unique SSU rRNA gene sequences of Entamoeba were obtained which formed a new cluster. The results showed that sex and location might be the risk factors associated with prevalence of Eimeria spp., and sex might be the risk factor associated with prevalence of Entamoeba spp.. This is the first report of Entamoeba in alpacas worldwide. These findings expand our understanding of the prevalence and genetic diversity of Eimeria and Entamoeba in alpacas.

Rescue and Conservation of Male Adult Alpacas (Vicugna pacos) Based on Spermatogonial Stem Cell Biotechnology Using Atomized Black Maca as a Supplement of Cryopreservation Medium.

This is the first time that testicular tissue (n = 44) and isolated testicular cells (n = 51) were cryopreserved from alpaca testes 24 h postmortem. For this purpose, internally designed freezing media and cryopreservation protocols were used. Testicular tissue fragments (25 mg) and isolated testicular cells were frozen in MTDB (trehalose and black maca), MTD (trehalose), MSDB (sucrose and black maca), and MSD (sucrose) media. Isolated spermatogonial cells were cryopreserved in two ways, before and after proliferation in vitro. After cryopreservation, the percentage of cell viability in Group 1 (>50% of cell viability) by trypan blue did not show differences within each group (p > 0.05) but showed significant differences when comparing fragments with isolated cells (p < 0.05). Spermatogonial stem cells (SSC) were identified by flow cytometry as strong Dolichos biflorus agglutinin (sDBA) and mitochondrial activity of SSC as strongly positive for MitoSense (sMitoSense+) in intact mitochondria cells, weakly positive for MitoSense (wMitoSense+) in early apoptosis, and necrosis with 7-Aminoactinomycin-D positive (7-AAD). After freezing, in Group 1M (≥30% sMitoSense+), the fragments did not show differences between the media (p > 0.05), but in the isolated cells frozen in MSDB medium, 63.68 ± 8.90% (p < 0.05). In Group 2M (<30% sMitoSense+), necrosis (7AAD+) in MSDB medium was 27.03 ± 5.80%, and necrosis in isolated cells was 14.05 ± 9.3% with significant differences between these groups (p < 0.05); in sMitoSense+, the isolated cells (34.40 ± 23%) had a higher percentage than the fragments (12.4 ± 5.2) (p < 0.05). On the other hand, MSDB and MSD media were significantly higher for isolated cells than for fragments in sDBA+ (p < 0.05). On the other hand, the SSC (sDBA+) had significant differences (p < 0.05) between fresh cells 7.43 ± 1.3% (sDBA+) compared with those cryopreserved in MSDB medium 1.46 ± 0.34% (sDBA+). Additionally, the proliferated and cryopreserved SSC 6.29 ± 1.17% (sDBA+) did not show significant differences concerning the fresh cells (p > 0.05). In conclusion, the black maca showed antioxidant properties when it was included in the freezing medium and, therefore, improved the SSC's conservation of the alpaca. Furthermore, the proliferation of isolated cells in vitro produces a higher amount of SSC after thawing them for further preclinical or clinical work.

Investigating a method for pharmacologic semen collection in alpacas.

While semen evaluation is standard practice prior to a sale or when infertility is suspected in other species, it is rarely done in camelids due to the difficulties involved in collecting a sample. The reproductive physiology of alpacas differs to that of other domestic animals and is still poorly understood. In the stallion, a technique was developed for semen collection that pharmacologically induces ejaculation without copulation (ex copula). This study investigates whether semen could be reliably collected by ex copula ejaculation in male alpacas. Eleven male Huacaya alpacas were used in this study, and six ex copula treatment protocols were evaluated: (1) saline (control); (2) xylazine only (0.1 mg/kg); (3) xylazine only (0.2 mg/kg); (4) imipramine only (1.0 mg/kg); (5) imipramine (1.0 mg/kg) followed 10 minutes later with xylazine (0.1 mg/kg); and (6) imipramine (2.0 mg/kg) followed 10 minutes later with xylazine (0.1 mg/kg). Each treatment protocol was repeated two to five times. Azoospermic samples obtained from ex copula ejaculation contained numerous epithelial cells but no sperm. A reliable treatment for pharmacologically inducing ejaculation in alpacas remains to be found.

Basal Levels and hCG Responses of Serum Testosterone and Estrogen in Male Alpacas.

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.

Variaciones en el metabolismo energético de la alpaca (Vicugna pacos). Una evaluación por efecto del ayuno prolongado

The study aimed to evaluate the effect of a prolonged fast (5 days) on some blood biochemical componentsinvolved in energy metabolism. Twenty male alpacas of two-year-old were used in two treatments (experimentaland control). Blood samples were taken in the morning for five days to quantify serum glucose, protein and urealevels by spectrophotometry and ketone bodies using semiquantitative test strips. The results show that theaverage of glucose, protein and urea of the alpacas subjected to fasting are different from the control group(P≤0.05). Glucose levels decrease while protein and urea levels increase over time. The presence of acetoacetatewas not detected during the five days of fasting. It is concluded that prolonged fasting in alpacas alters the animal'smetabolic process, both quantitatively and qualitatively, modifying the substrates and products involved inenergy production.