Factors influencing embryo transfer success in alpacas—A retrospective study

Challenges for Animal Health and Production in the Tropics and Mediterranean for the next 55 years

Tropical Animal Health and Production is a journal founded 55 years ago. It is dedicated to the publication of results of original research, investigation, and observation in all fields of animal health, welfare and production which may lead to improved health and productivity of livestock and better utilization of animal resources in tropical, subtropical and similar environments. Research is in strong alignment with the United Nations' Sustainable Development Goals, particularly No Poverty, Zero Hunger, and Good Health and Well-being. To celebrate its 55th anniversary, the editorial board has composed this Editorial article in an effort to address the major challenges that animal and veterinary scientists in the tropics and adjacent regions will address over the next 55 years. The task is accomplished in a systematic fashion addressing the topic species by species (cattle, small ruminants, pigs, poultry, camelids, etc.) and in the context of different groups of health challenges encompassing production, vector-borne, parasitic and transboundary diseases. Challenges are difficult and complex, and the solutions herein proposed may be difficult to implement. It aims to be an informed overview of the major difficulties the sector will experience in the near future, ultimately suggesting tools to address them. Only time will tell if they are accurate, effective or implementable. Nevertheless, Tropical Animal Health and Production Editorial Board, secretariat, reviewers and authors will certainly do their best to contribute to the advancement of animal health and production in the Tropics and the Mediterranean.

Body condition scoring in alpacas (Vicugna pacos) and llamas (Lama glama) - a scoping review

Assessment of the body condition score (BCS) is an important tool to check the nutritional status of an animal, and thus can provide important information in herd management, but also in the veterinary examination of individual animals. In dairy farming, BCS has been recognized as an important parameter for a long time already, but over the years body condition scoring has also become more important for other species. Especially in South American camelids (SACs: alpacas and llamas), whose dense coat can hide a poor nutritional status for a long time, regular assessment of the BCS is recommended by different authors and organizations. To date, there are several instructions for the assessment of the BCS in SACs, which, however, differ significantly in some points. For a consistent approach, a total of 35 instructions for the BCS in SACs were compared in a scoping review. The spine, especially the lumbar vertebrae as well as the ribs were identified as the two main body sites recommended for assessing the BCS. Furthermore, the area between the front and rear leg and the pelvis were mentioned frequently; however, these body sites were discussed controversially. The paralumbar fossa, shoulder, and udder were only mentioned sporadically. Among the various scales, the 1-5 scale was mentioned most frequently, with the optimal BCS being 3. Nonetheless, physiological fluctuation due to breed, age, sex, pregnancy, and lactation have to be considered. The BCS should be assessed each time the animals are handled, but at least monthly. In contrast to body weight, the BCS reflects the nutritional status of an animal even after a single examination. The review showed that much of the available information on the assessment of BCS in SACs is based on practical experience rather than scientific evidence. Indeed, some of the assumptions made there might still have to be verified or modified.

Age-Related Differences in Testosterone Concentration and Its Relation to Testicular Biometrics, Hemodynamics, and Fertility in Alpacas (Vicugna pacos)

The goal of this study was to investigate the age-related differences in testosterone concentration and its relation to testicular biometrics, testicular blood flow, and fertility in alpacas (Vicugna pacos). Fifteen alpaca males with different ages (young (YM; ~12-14 mo.), n = 5; intermediate (IM; ~24 mo.), n = 5; and old (OM; ≥36 mo.), n = 5) were enrolled in the study. Blood samples were taken from each alpaca male and the circulating plasmatic testosterone concentration (TC; ng/mL) was determined using ELISA analysis. The testicular traits related to bio-morphometric parameters (the length (L), width (W), area (A), and volume (TV)) were assessed using B-mode ultrasonography. Pulse-wave/power Doppler ultrasonography was used to obtain the circulatory dynamic values (testicular hemodynamics) before the beginning of natural service mating. Significant differences were observed in TC among the age groups, increasing as the age of the males increased (2.47 ± 0.31, 8.45 ± 1.53, and 22.66 ± 2.15 for YM, IM, and OM, respectively; p < 0.05); however, no differences were observed regarding the testicular B-mode ultrasonographic parameters (L, W, and A) (p > 0.05). Positive correlations were observed between TV and testicular L, W, and A (r = 0.96, r = 0.95, and r = 0.96, respectively; p ≤ 0.001). Pulse-wave-Doppler-derived parameters such as the pulsatility index (PI) and the resistive index (RI), as well as the total vascularity area (TVA) assessed by power Doppler, were similar in all of the age groups studied (p > 0.05). General linear model (GLM) analysis showed a relationship between TC and TV (OR = 0.95; p = 0.04), as well as between TC and TVA (OR = 0.99; p= 0.02). Finally, no differences were observed regarding the pregnancy rate among the different age groups (p > 0.05). In conclusion, TC increased as the age of the alpaca males increased. Although TC was related to TV and TVA, the pregnancy rates obtained from individuals belonging to the different age groups were similar, indicating that TC, TV, and TVA were not determining factors in assessing the potential age-related fertility differences in alpaca males.

Expression profile of genes related to pregnancy maintenance in Dromedary Camel during the first trimester

So far, few signals involved in embryo-maternal dialogue have been identified in pregnant she-camel. Our objective was to investigate expression profiles of genes relevant to uterine extracellular matrix remodeling (ITGB4, SLCO2A1, FOS, and JUN), uterine tissue vascularization, and placental formation (VEGFA, PGF, and PDGFA), embryonic growth and development (IGF1 and PTEN), plus cell death of uterine tissue (BCL2) in early pregnant versus non-pregnant she-camels. Forty genital tracts (20 pregnant and 20 non-pregnant) and blood samples were collected from abattoirs. Total RNA was extracted from uterine tissues and qRT-PCR was conducted for candidate genes. Serum concentrations of progesterone (P4) and estradiol17-β (E2) were measured. Expression of ITGB4, FOS, and PGF genes increased (P < 0.001) in the right uterine horn of pregnant versus non-pregnant she-camels. Moreover, JUN, SLCO2A1, VEGFA, and PTEN mRNAs were up-regulated (P < 0.001) in various segments of uterine tissues in pregnant groups. The PDGFA transcript was over-expressed (P < 0.001) in both uterine horns of pregnant groups. Additionally, IGF1 was higher (P < 0.001) in the right horn and the uterine body of pregnant groups, and expression of BCL2 was increased (P < 0.001) in the pregnant uterine body. Moreover, serum concentrations of P4 were higher (P < 0.001) and E2 lower (P < 0.05) in pregnant she-camels. Taken together, the fine-tuning of genes related to implantation, matrix formation, vascularization, and placental formation is highly required for successful pregnancy in she-camels.

Factors affecting outcomes of embryo transfer in dromedary camels: a retrospective study

The present study aimed to use a comprehensive approach for evaluating 12 factors related to embryo quality (shape, size and transparency), donors (age, ET type, number of recovered embryos and day of uterine flushing), recipients (age), males (age and individual variations), and environment (season and year) which could affect the outcome of ET in terms of pregnancy (PR) and pregnancy losses in dromedary camels. During three breeding seasons, 116 donors females were mated repeatedly at 12 to 14-day intervals by fertile camel males (n=33) without stimulation of the ovaries (WSPO). Superovulation (SPO ET) regimen was applied for each donor female twice or thrice per season. In the occasions of applying superovulation regimen, donor females having an ovulatory follicle were mated instead of GnRH administration and superovulation regimen was applied 4 days post-mating (MIX ET). The uteri of all donor females were flushed at Day 8 or 9 post-mating and a total of 2095 embryos were recovered and transferred individually to 924 recipient females. Pregnancy diagnoses were conducted at Day 10 after ET (Days 18 to 19 of gestation) by using progesterone assay and by transrectal ultrasonography (TRU) at Days 30 and 60 of gestation. By using logistic regression analysis, transparency of embryos and age of recipient females had significant effects on PR at Days 18 to 19 (P< 0.01), 30 (P < 0.01) and 60 (P < 0.01; P < 0.05, respectively) of gestation. The shape of embryos had significant effects on the PR at Days 30 (P < 0.05) and 60 (P < 0.01) of gestation. Type of ET and the breeding season (year) had significant (P< 0.05) effects on the PR at Day 30, while day of flushing had the same effect on PR at Day 60. Regarding the pregnancy losses, transparency and shape of the embryo, type of ET, breeding season had significant (P<0.05) effect on the late embryonic mortalities (LEM) and shape and season of year had significant (P<0.01 and P< 0.05, respectively) effect on LEM/early fetal mortalities (EFM). Regarding male individual factor, there was a tendency for a significant (P =0.055) effect of camel males on the PR at Days 18 to 19 and rate of LEM. In conclusion, transferring a spherical, transparent or a large-sized embryo (> 750 µm) into recipient females aging between 8 and 11 y could greatly improve the PR from Days 18 to 60 of gestation. Also, embryo recovered from donor females with Mix ET type or embryos sired by certain camel male or at Day 8 post mating of the donor could improve the two-month PR. In addition, transferring a transparent or spherical-shaped embryo or embryos recovered from donor females with SPO or Mix ET could reduce the pregnancy losses during the first two months of pregnancy.

Pregnancy and parturition in dromedary camels II. Incidence, timing and factors affecting early pregnancy loss (EPL) and the outcome of twin pregnancies

In this paper, we described the incidence of early pregnancy loss (EPL) both after natural mating and embryo transfer, evaluated risk factors, and summarized the outcome of twin pregnancies throughout gestation in dromedaries under reproductive care. Data were collected over seven breeding seasons at the world's largest camel dairy farm (study 1). In addition, we determined the timing of EPL and monitored serum progesterone (P4) concentration between Days 13-70 of gestation during one breeding season (study 2). In the first study, out of 2970 pregnancies, 507 cases (17.1%) of EPL were diagnosed with transrectal ultrasonography. The rate of EPL after natural mating and embryo transfer was 16.1% (n = 422 out of 2616) and 24.0% (n = 85 out of 354), respectively. Twin pregnancies were detected in 215 cases (7.2% of all gestations), and 57 of those (26.5%) underwent complete EPL. Almost half of the early losses (n = 243; 47.9%) occurred before 30 d of gestation. Another 43.2% (n = 219) of EPL was diagnosed during the next month, and 8.9% (n = 45) occurred after 60 d of gestation. Multivariable mixed effects logistic regression models revealed that the breeding season (year) and twin pregnancy were the most important exposure variables affecting the rate of EPL (P < 0.001). The effect of some male camels was also demonstrated while other factors, such as type of breeding, age category, month of mating, breed/ecotype and reproductive history did not prove to have a significant influence. In the second study, the overall rate of EPL was 24.5% (n = 34 of 139). There was no difference in the incidence of EPL between ET recipient (24.2%, n = 23 of 95) and mated (25%, n = 11 of 44) camels. Weekly rate of EPL ranged from 0.9% to 4.8% with a decreasing tendency, and approx. 41% of the animals (n = 14 of 34) had some ultrasonographic signs of impending EPL 1 week before the final diagnosis. Mean serum P4 concentration in camels with subsequent EPL was 5.3 ± 0.1 ng/ml compared to 5.6 ± 0.04 ng/ml in normal pregnant dromedaries. Day of gestation and future EPL influenced serum P4 levels (P < 0.001) with an interaction between the two fixed factors (P < 0.05). At the time of the final diagnosis of EPL, mean serum P4 concentration was 2.8 ± 0.44 ng/ml. Although twinning had an unfavorable prognosis with a total pregnancy loss of 36.7%, it was not entirely detrimental for the final outcome of gestation as two-thirds of twin pregnancies (n = 136 out of 212) resulted in the birth of a live calf.

New Insights Into the Role of β-NGF/TrKA System in the Endometrium of Alpacas During Early Pregnancy

One striking reproductive feature in South American camelids is that more than 90% of gestations are established in the left uterine horn (LUH). This phenomenon could be related to a differential vascular irrigation of the LUH. An increase of vascularization in llama endometrium was observed after systemic administration of Beta Nerve Growth Factor (β-NGF), a neurotrophin present in the uterus and placenta of various mammals that is involved in pregnancy development. We hypothesized that the β-NGF signaling pathway is related to embryo implantation in the LUH in camelids. The aim of this study was to characterize the spatial expression of β-NGF and its high-affinity receptor, TrKA, between LUH and right uterine horn (RUH) of non-pregnant (NP) and early pregnant alpacas (15 and 30 days of gestation, 15 and 30P, respectively). In addition, β-NGF, TrKA, and Vascular Endothelium Growth Factor A (VEGFA) temporal gene expression patterns and counting of blood vessels were evaluated among groups. The β-NGF and TrKA were localized in the luminal, glandular, and vascular epithelium of the alpaca uterus and in the embryonic membranes of the 30-days-old conceptus. β-NGF and TrKA immunosignal were stronger in 15P females than that of NP and 30P. In addition, TrKA signal was higher in the LUH luminal epithelium of NP and 15P alpacas than that of NP-RUH and 15P-RUH. β-NGF mRNA relative abundance was higher in the 30P-RUH than that of NP-RUH; whereas TrKA mRNA abundance only differed between 15P-RUH and NP-LUH. VEGFA mRNA relative abundance was higher in NP females compared to the LUH of 15P and 30P alpacas, and lower to their right counterparts. The number of vessels per field was higher in 15P than that of 30P. A positive correlation was observed between the number of vessels per field and β-NGF immunosignal in 15P-LUH. In contrast, the area occupied by vessels was higher in 30P alpacas than of NP and 15P females. The changes of β-NGF/TrKA expression pattern in the peri-implantation endometria between LUH and RUH and their localization in the extraembryonic membranes support the implication of the neurotrophin during implantation and pregnancy development in South American Camelids.

Uterine and Corpus Luteum Blood Flow Evaluation Prior to Uterine Flushing in Llama Embryo Donors

The aim of this study was to assess the uterine blood flow (UBF) and corpus luteum blood flow (CLBF) in llamas 8 days post-mating, using color-Doppler ultrasonography (CDU), to determine the possible relationship between vascularization and the presence of an embryo. Adult females (n = 25) were used to monitor ovarian dynamics by palpation and transrectal ultrasonography until detection of a ≥6 mm growing follicle. Females were randomly assigned to one of two groups: Group I (n = 19), were mated and ovulation was induced by a single dose of buserelin (GnRH analog) that same day (Day 0); and Group II (n = 6), only ovulation was induced (control). On Day 8, UBF and CLBF were evaluated transrectally in both groups. The color-flow images obtained were analyzed with Image J1.52a software to determine the vascularization area and the percentage of corpus luteum with blood flow emission (CLBF%) together with the percentage for each uterine horn (UBF%). Statistical analysis was performed using an ANOVA test. In Group I, uterine flushing was performed to obtain the embryos, thus dividing the females into Group I+ (n = 10), when an embryo was recovered and Group I- (n = 9), when no embryo was recovered. Embryo recovery rate was 52.63% (10/19). In Group I+, UBF% was significantly higher compared to Group I- and Group II (P <0.05). UBF appears to be a good predictor for embryo presence, with an area under the curve (AUC) of 0.9 and an optimal cut-off value of 9.37% (with a sensitivity of 90% and specificity of 88.9%). The CLBF% did not differ between groups (P > 0.05). In conclusion, it is possible to detect a local increase of UBF in the presence of an embryo on day 8 post-mating in llamas. This could be useful to achieve an early pregnancy diagnosis or to decide whether to carry out the uterine flushing in a llama embryo transfer program.

Birth of a Live Cria After Transfer of a Vitrified-Warmed Alpaca (Vicugna pacos) Preimplantation Embryo

The alpaca (Vicugna pacos) is an important species for the production of fiber and food. Genetic improvement programs for alpacas have been hindered, however, by the lack of field-practical techniques for artificial insemination and embryo transfer. In particular, successful techniques for the cryopreservation of alpaca preimplantation embryos have not been reported previously. The objective of this study was to develop a field-practical and efficacious technique for cryopreservation of alpaca preimplantation embryos using a modification of a vitrification protocol originally devised for horses and adapted for dromedary camels. Four naturally cycling non-superovulated Huacaya females serving as embryo donors were mated to males of proven fertility. Donors received 30 μg of gonadorelin at the time of breeding, and embryos were non-surgically recovered 7 days after mating. Recovered embryos (n = 4) were placed individually through a series of three vitrification solutions at 20°C (VS1: 1.4 M glycerol; VS2: 1.4 M glycerol + 3.6 M ethylene glycol; VS3: 3.4 M glycerol + 4.6 M ethylene glycol) before loading into an open-pulled straw (OPS) and plunging directly into liquid nitrogen for storage. At warming, each individual embryo was sequentially placed through warming solutions (WS1: 0.5 M galactose at 37°C; WS2: 0.25 M galactose at 20°C), and warmed embryos were incubated at 37°C in 5% CO₂ in humidified air for 20-22 h in 1 ml Syngro® holding medium supplemented with 10% (v/v) alpaca serum to perform an initial in vitro assessment of post-warming viability. Embryos whose diameter increased during culture (n = 2) were transferred individually into synchronous recipients, whereas embryos that did not grow (n = 2) were transferred together into a single recipient to perform an in vivo assessment of post-warming viability. Initial pregnancy detection was performed ultrasonographically 29 days post-transfer when fetal heartbeat could be detected, and one of three recipients was pregnant (25% embryo survival rate). On November 13, 2019, the one pregnant recipient delivered what is believed to be the world's first cria produced from a vitrified-warmed alpaca embryo.

Semen Handling in South American Camelids: State of the Art

Reproductive biotechnologies such as artificial insemination could be very useful for South American camelids, allowing widespread use of semen from breeding males with desirable genetics. However, artificial insemination is not widely employed in these species and is considered to have low overall efficiency. This is due in part to incomplete knowledge about the physiology of conception in these species, and also to challenges presented by semen collection and handling. Several recent reviews have centered on female camelid reproduction; therefore, in this review, the focus is on semen handling. Various semen collection methods are presented. Different methods of reducing seminal viscosity are compared, such as needling, enzyme treatment, and colloid centrifugation. Use of enzymes remains controversial because of widely differing results among research groups. Colloid centrifugation, particularly single layer centrifugation, has proved to be successful in facilitating development of sperm handling techniques in dromedary camels, and has also been used with llama semen. Therefore, protocols for colloid centrifugation of alpaca semen could be developed in the future.

Modifications of extracellular matrix features in the left and right uterine horns during the embryo pre-implantation period in Vicugna pacos

More than 98% of the pregnancies in South American camelids is carried out in the left uterine horn (LUH). Hence, embryos originated from right-ovary ovulations have to migrate to the contralateral or left uterine horn (LUH) to implant and survive. A reason for this unique pattern of embryo implantation has not been elucidated yet. In general, embryo implantation involves an extensive extracellular matrix (ECM) remodeling within the endometrium, in which collagen and matrix metalloproteinases (MMPs) play an essential role. Deregulation of collagen and MMPs has been related to embryo implantation failure, miscarriage, and infertility. Therefore, we hypothesized that ECM components in camelids could be involved in differential embryo implantation and consequently the high incidence of left horn gestations. The aim of this study was to describe and compare changes in ECM components in the left and right uterine horn of non-pregnant and 15 days pregnant alpacas. To test this hypothesis, the collagen content was evaluated by specific staining with Picrosirius Red and using ImageJ 1.42q software. Subsequently, gene expression of the following components of the MMP pathway was determined: MMP-2, -3, -7, -9, and -14, MMP substrates (COL1A2 and COL3A1), MMP inhibitors (TIMP1 and TIMP2), LGMN, an MMP activator, and EMMPRIN, an extracellular matrix metalloproteinase inducer. Uterine horns of pregnant alpacas exhibited a marked decrease in collagen content. In contrast, transcript expression of COL1A2 and COL3A1 was higher in the LUH of pregnant alpacas. Gene expression of MMP-3, -7, -9, -14, LGMN, and EMMPRIN were also higher in the LUH of pregnant animals, whereas MMP-2 gene expression was higher in the LUH of both pregnant and non-pregnant alpacas. Expression of TIMP1 and TIMP2 increased during pregnancy, with higher values in the LUH. In conclusion, expression of ECM components displayed a specific pattern depending on the uterine side and the physiological status (pregnant vs non-pregnant) of the animal. The increased expression of ECM transcripts in the left uterine horn during early pregnancy in alpacas suggests the involvement of these molecules in a highly regulated process leading to the implantation process.

Factors affecting pregnancy rates and pregnancy losses after embryo transfer in dromedary camels

The present study was conducted to estimate incidence of late embryonic and early fetal mortalities (LEM/EFM) after embryo transfer (ET) and to investigate factors that could affect proportions of LEM/EFM in dromedary camels. The uteri of 180 donors were flushed at Day 9 post-mating and 1309 ETs were conducted in 886 recipient females in two breeding seasons (2014-2015 and 2015-2016). Pregnancy diagnosis was conducted at Day 10 after ET (Day 19 of gestation) by using the progesterone-ELISA test and by transrectal ultrasonography at Day 60 of gestation. Pregnancy rates at Days 19 and 60 and proportions of LEM/EFM were 54.5%, 34.1%, and 37.5%, respectively. Using logistic regression analysis for evaluations, shape of embryos had an effect (P < 0.01) on pregnancy rates at Days 19 and 60. Also, number of recovered embryos per uterine flushing and breeding season (year) had an effect (P < 0.05) on pregnancy rates at Day 19 and 60, respectively. Regarding rate of LEM and EFM, size of embryos and year of ET had effects (P < 0.01 and P < 0.05, respectively) on the values for these variables. In conclusion, there is a marked occurrence of LEM/EFM in recipient females between Days 20 and 60 of gestation in dromedary camels. The pregnancy rate after ET might be affected by the shape and number of recovered embryos and the year. In addition, the rate of LEM/EFM after ET might be affected by the year and size of the embryos.

Serological evidence of Toxoplasma gondii and Chlamydia infection in alpacas (Vicugna pacos) in Shanxi Province, northern China

Toxoplasma gondii, Neospora caninum, Chlamydia and bluetongue virus (BTV) are four important pathogens which can cause reproductive loss. The present study was conducted to estimate the seroprevalence of T. gondii, N. caninum, Chlamydia and BTV in alpacas in Shanxi Province, northern China. A total of 251 serum samples were collected from alpacas, and antibodies against T. gondii and Chlamydia were examined by the modified agglutination test (MAT) and indirect hemagglutination assay (IHA), respectively. Antibodies to N. caninum and BTV were determined by using the commercially available competitive enzyme-linked immunosorbent assay (cELISA) kits, respectively. The overall seroprevalence of T. gondii was 9.16% (95% CI 5.59-12.73) in the three sampled counties, of which, no T. gondii-seropositive samples were detected in alpacas in Fanshi County. Gender differences in the T. gondii seroprevalence were observed. The overall Chlamydia seroprevalence was 13.94% (95% CI: 9.66-18.22), and there was a statistically significant difference in Chlamydia seroprevalence in alpacas between the two counties, Jiexiu and Fanshi. All serum samples tested negative for N. caninum and BTV antibodies, respectively. To our knowledge, this is the first report of T. gondii and Chlamydia seroprevalence in alpacas in China, which provides baseline information for controlling T. gondii and Chlamydia infection in alpacas in China.

Plasma steroid profiles and ovarian response in llamas treated with eCG for superovulation combined with exogenous progesterone during early luteal phase

The objective of this study was to evaluate the effects of plasma progesterone (P₄) concentrations during eCG-ovarian follicular superstimulatory treatment performed in early luteal phase and estradiol concentrations during peri-ovulatory period on ovarian response, number and embryo quality. On Day -2, females (n = 75) having a follicle ≥7 mm were treated with GnRH to induce ovulation. On Day 0, females that had ovulations (n = 54) were treated with 1000 IU eCG and were assigned to one of two treatments: (1) intravaginal device (ID) containing 0.5 g P₄ (P₄ group) and (2) no ID (Control group). On Day 5, females were administered PGF_2α and the ID was removed. On Day 7 and 8, females were mated and embryo recovery was performed 7 or 8 days later. Blood samples were collected from Day 0 to 9. Number (± SD) of follicles ≥7 mm on day of mating was greater (P =  0.04) in the control (9.7 ± 4.2) than P₄-treated (6.7 ± 4.9) group; number of corpora lutea did not differ (5.5 ± 3.1 and 5.2 ± 3.4 respectively). Ovulation rate was greater (P <  0.01) in the P₄-group (77.4%; 130/168) than control group (53.3%; 135/253). Number of embryos with an excellent grade (grade 1) tended to be greater (P =  0.07) in the P₄-group (82.4%; 42/51) than control group (65.4%; 36/55). It was concluded that supplementation with exogenous P₄ during eCG treatment in early luteal phase inhibits excessive follicular growth, increases ovulation rate and improves embryo quality.

Pregnancy and parturition in dromedary camels I. Factors affecting gestation length, calf birth weight and timing of delivery

In the present study, we evaluated the role of genetic, physiologic and environmental factors in affecting gestation length, calf birth weight and time of parturition in dromedary camels. Reproductive data were collected over a 10-year period at the world's first intensively managed, large-scale camel dairy farm. We hypothesized that environmental conditions (i.e. photoperiod) have a decisive effect on these reproductive parameters. The effect of various factors was tested with linear mixed models and variance component analysis. A total of 557 (13.1%) primiparous and 3691 (86.9%) multiparous parturitions were observed in 2,123 dromedaries. Parturitions had a pronounced seasonal distribution. The mean (±SE) length of gestation and mean (±SE) birth weight were 384.5 ± 0.17 days (n = 4,093, CV = 2.88%) and 34.5 ± 0.09 kg (n = 3,909, CV = 16.8%), respectively. All but one fixed factors (type of breeding) affected length of gestation and calf birth weight. Month of conception (27.1%), female camel (11.2%) and live-dead status of the calf (10.6%) were responsible for close to 50% of the variation in gestation length. At the same time, female camel (30.3%), parity (11.3%), year (6.9%) and month of parturition (6.2%) had the strongest relative influence on the variation in calf birth weight. Both reproductive traits showed a pronounced circannual variation. Mean length of gestation was longer by app. 18 days in dromedaries conceiving in November compared to those becoming pregnant in May. Average new-born weight was 4.4-4.9 kg higher in December compared to that in September and April. Dromedaries gave birth throughout the 24 h period, but most of the deliveries (n = 3,117, 74.1%) occurred from sunrise to sunset. The peak of deliveries was between 2 and 3 pm. Month of the year has a strong effect on the timing of deliveries. In contrast, the time from sunrise to parturition did not differ among the months. Peak of deliveries occurred 7-9 h after sunrise and the median of time from sunrise to parturition was 8 h and 24 min. These results give strong support to the original hypothesis. Seasonal changes were independent of nutritional factors, were associated with climatic conditions (i.e. photoperiod) and may reflect an endogenous circannual rhythm in foetal development. The dromedary camel could be a useful in vivo model to study the effect of the environment on feto-maternal communication, fetal development and timing of parturition.

Development of a modified method of handmade cloning in dromedary camel

In this study, a modified method of handmade cloning (m-HMC), which had been originally developed in sheep, was used for somatic cell nuclear transfer (SCNT) in the dromedary camel. The unique feature of m-HMC over current SCNT methods lies in the use of a simple device (a finely drawn micropipette made of Pasteur pipette) for chemically-assisted enucleation of oocytes under a stereomicroscope with improved efficiency and ease of operation. Using this system, the throughput of cloned embryo reconstitution was increased over 2-fold compared to the control SCNT method (c-NT). Stepwise measurement of reactive oxygen species (ROS) revealed that method, steps, and duration of SCNT all influenced oxidative activity of oocytes, but their impact were not similar. Specifically, UV-assisted oocyte enucleation was identified as the major source of ROS production, which explained significantly higher total ROS of reconstituted embryos in c-NT compared to m-HMC. Fusion efficiency (95.3±3.3 vs. 75.4±7.6%) and total efficiency of blastocyst development (22.5±3.0 vs. 14.1±4.3%) were significantly higher in m-HMC compared to c-NT, respectively, and blastocysts of transferable quality were obtained in similar rates (41.9±8.2 vs. 48.0±15.2%, respectively). Significance differences were observed in total cell number (155.3±13.6 vs. 123.6±19.5) and trophectoderm (145±9.5 vs. 114.3±15.2), but not inner cell mass (10.3±4.1 vs. 9.3±5.3) counts between blastocysts developed in c-NT compared to m-HMC, respectively. However, expression of key developmental genes (POU5F1, KLF4, SOX2, MYC, and CDX2) was comparable between blastocysts of both groups. The introduced m-HMC method might be a viable approach for efficient production of dromedary camel clones for research and commercial utilization.

Effect of exogenous progesterone treatment on ovarian steroid hormones and oxidant and antioxidant biomarkers during peak and low breeding seasons in dromedary she-camel

Background:

Research about the effects of progesterone (P₄) and the relationship of P₄ to oxidative stress has been achieved in ruminants but not enough in camels.

Aim:

This study evaluated the effect of exogenous P₄ hormone using CIDR for 7 days on blood concentrations of steroid hormones and oxidative status of dromedary she-camels during peak and low breeding seasons.

Materials and Methods:

The present work was conducted on ten dark dromedary she-camels which were synchronized using a controlled internal drug release (CIDR) for 7 days as a reproductive management tool during peak breeding (November-April) and low breeding season (May-October). The blood samples were collected each other day from CIDR insertion until the end of experiment 5 days after the removal of CIDR. Camels were examined for P₄, estradiol (E₂), and testosterone (T) as well as malondialdehyde (MDA) as indicator of lipid peroxidation and nitric oxide, superoxide dismutase (SOD), and glutathione-S-transferase as antioxidant markers.

Results:

Results revealed that P₄ was higher during peak breeding season than low breeding season. While the levels of P₄ increased during CIDR insertion and declined at CIDR removal and thereafter during breeding season, its concentrations declined after CIDR application during the non-breeding season. On the other hand, blood E₂ and testosterone levels decreased after CIDR insertion in both high and low breeding seasons with higher serum E₂ concentrations during the peak than the low breeding season. MDA concentrations and SOD activities were significantly (p<0.05) high on day 3 after CIDR insertion during the breeding and non-breeding seasons. During both the seasons, GSH levels decreased after CIDR removal in camels. However, MDA was lower during non-breeding season than high breeding season with no seasonal effect on SOD activity.

Conclusion:

Exogenous P₄ treatment through CIDR in dromedary camels could be more efficient during breeding season than non-breeding season, and effects on circulating oxidant/antioxidant biomarkers and their return to normal levels might refer to the adaptation of camels to CIDR by modulating their oxidant and antioxidant levels.

Changes in mucins and matrix metalloproteases in the endometrium of early pregnant alpacas (Vicugna pacos)

South American Camelids (SAC) have unique reproductive features, one of which is that 98% of the pregnancies develop in the left uterine horn. Furthermore, early pregnancy is an uncharacterized process in these species, especially in regard to the ultrastructural, biochemical and genetic changes that the uterine epithelial surface undergoes to allow embryo implantation. The present study describes the uterine horn luminal surface and the characteristics of the mucinous glycocalyx in non-pregnant and early pregnant (15 days) female alpacas. In addition, the relative abundance of Mucin 1 and 16 genes (MUC1 and MUC16) was determined, as well as the relative mRNA abundance of matrix metalloproteinases (MMPs) that could be involved in MUC shedding during early pregnancy. Noticeable changes were detected in the uterine luminal epithelium and glycocalyx of pregnant alpacas in comparison to non-pregnant ones, as well as presence of MUCs and MMPs in the endometrial environment. The decrease in glycocalyx staining and in the relative abundance of MUC 1 and MUC 16 transcripts in pregnant females would allow embryo attachment to the luminal epithelium and its subsequent implantation, as has been described in other mammals. These results suggest a crucial role of MUC1 and MUC16 and a possible role of MMPs in successful embryo implantation and survival in alpacas.

Monitoring and controlling follicular activity in camelids

This paper reviews that state of our knowledge concerning follicular wave dynamics, monitoring and manipulation. All camelids have overlapping follicular waves in absence of ovulation which is induced by a seminal plasma factor (βNGF). The interval between follicular waves varies. The size of the ovulatory follicle varies between 11 and 25 mm in camels and between in 6 and 13 mm in South American Camelids. The interval between induction of ovulation and next ovulatory follicle is 15 ± 1 day for all camelids. Follicular activity is best monitored by transrectal ultrasonography. Progesterone therapy for 7-15 days seems to suppress follicular dominance but does not completely inhibit follicular recruitment. Combination of estradiol and progesterone seems to provide better control of follicular activity. Both methods have provided variable results in the synchronization of follicular waves. Combination of induction of ovulation with GnRH and luteolysis at predetermined times shows some promise in synchronization of follicular dominance. These synchronization protocols require further investigation in order to provide practical approaches for fixed-time breeding. Ovarian superstimulation with FSH and eCG alone or in combination is somewhat successful. The best results are obtained when treatment is initiated at the emergence of a new follicular wave after induction of ovulation or following treatment with progesterone for 7-14 days. However, response remains extremely variable particularly in terms of ovulation rate and number of recovered embryos. Sources of this variability need to be studied including the effects of season, nutrition, doses and frequency of administration of gonadotropin.

Production, Preservation, and Transfer of South American Camelid Embryos

The current review summarizes progress in the field of in vitro and in vivo production of South American Camelid embryos. Both methods require ovarian superstimulation (with FSH and eCG) to obtain multiple ovulations (in vivo embryo production) or to induce follicle growth for oocyte collection (in vitro embryo production). Moreover, superstimulation entails prior administration of hormones that inhibit follicular growth (progesterone, progestagens, and estrogens). Cumulus-oocyte complexes obtained must mature in vivo (buserelin administration) or in vitro to then be subjected to in vitro fertilization or intracytoplasmic sperm injection. All these techniques also require morphologically normal, motile spermatozoa to achieve fertilization. Methods used to decrease semen viscosity and to select the best spermatozoa (Percoll®; Androcoll-ETM) are described. Additionally, nuclear transfer or cloning has been applied in llamas. Up to now, embryo deep-freezing and vitrification have progressed slowly but are at the height of development. Embryos that are obtained by any of these techniques, either in vivo or in vitro, need to be transferred to synchronized recipient females. The best results are achieved after transfer to the left uterine horn with an ipsilateral ovulation. No live offspring have been obtained after the transfer of cryopreserved embryos. Applying reproductive biotechnologies, such as those described, will permit the expansion of genetically selected animals in the population and also that of wild camelid species, vicunas, and guanacos, whose embryos could then be transferred to the uterus of domestic species.

Semen collection methods in alpacas

South American camelids, particularly alpacas, are gaining in popularity outside their native lands. Reproductive biotechnologies, such as artificial insemination or embryo transfer with cryopreserved embryos, are more complicated in these species than many others due to differences in their reproductive physiology compared to the more commonly encountered domestic livestock. This article reviews the methods currently available for obtaining semen or spermatozoa from alpacas and describes some of the problems associated with handling the viscous seminal plasma characteristic of camelids. Possibilities and limitations of reproductive biotechnologies in this species are discussed, and future developments are outlined, especially some new techniques which are currently being developed for use with camel semen and may be transferable to alpacas.

Effects of varying doses of β-nerve growth factor on the timing of ovulation, plasma progesterone concentration and corpus luteum size in female alpacas (Vicugna pacos)

Ovulation in camelids is induced by the seminal plasma protein ovulation-inducing factor (OIF), recently identified as β-nerve growth factor (β-NGF). The present study measured the total protein concentration in alpaca seminal plasma using a bicinchoninic acid (BCA) protein quantification assay and found it to be 22.2 ± 2.0 mg mL–1. To measure the effects of varying doses of β-NGF on the incidence and timing of ovulation, corpus luteum (CL) size and plasma progesterone concentration, 24 female alpacas were synchronised and treated with either: (1) 1 mL 0.9% saline (n = 5); (2) 4 µg buserelin (n = 5); (3) 1 mg β-NGF protein (n = 5); (4) 0.1 mg β-NGF (n = 5); or (5) 0.01 mg β-NGF (n = 4). Females were examined by transrectal ultrasonography at 1–2-h intervals between 20 and 45 h after treatment or until ovulation occurred, as well as on Day 8 to observe the size of the CL, at which time blood was collected to measure plasma progesterone concentrations. Ovulation was detected in 0/5, 5/5, 5/5, 3/5 and 0/4 female alpacas treated with saline, buserelin, 1, 0.1 and 0.01 mg β-NGF, respectively. Mean ovulation interval (P = 0.76), CL diameter (P = 0.96) and plasma progesterone concentration (P = 0.96) did not differ between treatments. Mean ovulation interval overall was 26.2 ± 1.0 h. In conclusion, buserelin and 1 mg β-NGF are equally effective at inducing ovulation in female alpacas, but at doses ≤0.1 mg, β-NGF is not a reliable method for the induction of ovulation.

Biochemical and protein profile of alpaca (Vicugna pacos) uterine horn fluid during early pregnancy

South American camelids show high embryo loss rate, during the first 60 days of pregnancy. One of the factors which may be related to this situation is that over 98% of the embryos implant in the left uterine horn (LUH) even though both ovaries contribute similarly to ovulation. There is scarce information about the uterine environment of female camelids at any physiological state that could explain the capability of the LUH to attract the embryo and maintain pregnancy. We describe, for the first time, the biochemical and protein profile of uterine fluid (UF), addressing the right and LUH environment in non-pregnant and pregnant alpacas. Different substrates, electrolytes and metabolites were assayed in both uterine horn fluids. Small changes were observed in glucose and total protein levels, which were more noticeable during pregnancy. In addition, 10 specific proteins were found in the left horn fluid in 5-week-pregnant alpacas, and two protein bands were identified in non-pregnant alpaca right horn fluid. These results would provide basic information for identification of possible markers for pregnancy diagnosis, reproductive diseases and hormone-treated animals evaluation and hence contributing to improve the pregnancy rate.