Abstract
The viscous seminal plasma (SP) is currently a major impediment to the handling of ejaculate and the development of some biotechnologies in South American camelids. The vas deferens-collected spermatozoa of alpacas is a useful technique to avoid this problem. On the other hand, SP contains a large protein component that has been implicated in the function of spermatozoa within the female reproductive tract. In this sense, the low fertility achieved using transcervical insemination with frozen-thawed spermatozoa in alpacas could be improved by adding SP. This study aimed to evaluate the effect of the whole SP on some in vitro parameters of alpaca spermatozoa after the freezing-thawing-process and the fertility after artificial insemination. It would contribute to a better understanding of the interaction between thawed sperm cells and SP. Spermatozoa were obtained by surgically diverted vas deferens. The samples were diluted with a Tris-based extender, packaged in straws, and frozen. At thawing, each straw was divided into two post-thawing conditions: with the addition of 10% of PBS (control) or with 10% SP (treatment). The sperm cells were evaluated using dynamic parameters, sperm cell morphology, and morphometry. Fertility was assessed by an artificial insemination trial. All in vitro parameters were analyzed by ANOVA. A heterogeneity test was scheduled for the fertility trial. After the freezing-thawing process, motility and plasma membrane functionality was improved when SP was added. No differences were found for post-thaw viability between the control and treatment samples. The percentage of normal cells was higher with SP at post-thawing, and a decrease of the presence of bent tailed spermatozoa with a droplet in the SP group was observed. The length of the head spermatozoa was 3.4% higher in the samples with PBS compared to those in which SP was added. Females pregnant at day 25 post-insemination were 0/12 (with SP inside the straw) and 1/10 (without SP inside the straw). In conclusion, the presence of 10% SP at post-thawing improves sperm cells' motility, functionality, and morphology, indicating that it would be beneficial to improve the frozen-thawed alpaca's physiology spermatozoa. More fertility trials must be developed to increase this knowledge.
Highlights
The most remarkable characteristics of semen in South American camelids are its high structural viscosity and thread formation [1,2,3]
This study aimed to evaluate the effect of whole SP on some in vitro parameters of alpaca sperm cells after the freezingthawing-process and the fertility rate achieved after an artificial insemination trial
This technique is described by Pérez et al [11, 13] and consists of five steps: (a) the males were fasted for 24 h before the surgery and were chemically restrained with Acepromazine maleate (0.1 mg/Kg BW); (b) the animals were placed in a supine position, and the surgical field was prepared in the inguinal region to perform local anesthesia; (c) a small incision (4 cm) was made in the skin over the penis; (d) the vas deferens of the right and left side were located and dissected in a length of 7 cm; (e) the dissected parts of vas deferens were redirected below the subcutaneous tissue and fixed to the skin of the internal face of the femoral region, and protected with a temporary patch
Summary
The most remarkable characteristics of semen in South American camelids are its high structural viscosity and thread formation [1,2,3]. Pérez et al [13] demonstrated that it is possible to obtain sperm cells from surgically diverted vas deferens in male alpacas and llamas, facilitating the evaluation of concentration, motility, abnormalities, and subsequent cryopreservation. This kind of collection may be useful for research purposes
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