309 MORPHOMETRICAL ANALYSIS OF THE LAMA GLAMA SPERM HEAD

Abstract

During the last decades, the interest in breeding South American Camelids has increased, not only as companion animals but also for their high- quality fiber. Although several studies have been carried out on artificial insemination in Lama glama, this technique has not been widely applied in reproductive programs, principally due to the difficulty in collecting raw semen from males and the lack of knowledge about freezing/thawing techniques and semen characteristics. The aim of the present study was to objectively characterize llama sperm morphometry by a computer-assisted system, thereby increasing the knowledge on male llama physiology, leading to further developement of reproductive biotechnologies such as artificial insemination. Five semen samples were obtained by electroejaculation from each of 8 males, 6- to 10-year-old llamas of proven fertility. Smears were prepared from each sample and stained with Tinción 15^® (Biopur S.R.L., Rosario, Argentina) and observed at x 1000 magnification. Images of sperm heads were captured by a Leica DC180 camera (Leica Microsystems Co., Wetzlar, Germany), obtaining 200 images from each sample. Binary images were obtained and area, length, width, equivalent circle diameter, curve length, curve width, perimeter, convex perimeter, roundness, and elongation were measured using QWin Plus (Leica Microsystems Co.). A total of 8005 sperm heads were measured. Descriptive statistics of the complete population was performed, with the following results obtained (mean ± SD): area (μm²) 20.09 ± 0.6, length (μm) 6.6 ± 0.3, width (μm) 4.14 ± 0.1, equivalent diameter ((μm) 5.06 ± 0.1, curve length (μm) 5.8 ± 0.3, curve width (μm) 3.48 ± 0.3, perimeter (μm) 18.54 ± 0.1, convex perimeter (μm) 17.34 ± 0.3, roundness 1.28 ± 0.04, and elongation 1.6 ± 0.01. Coefficients of variation were between 0.47 and 8.72%. A design considering the male as a fixed factor and the ejaculate as a nested factor was used for the purpose of identifying differences in morphometry between ejaculates of the same male and/or between males. Normality was tested using the Kolmogorov test. Significant differences between ejaculates of some males were found for curve length, curve width, perimeter, roundness, and elongation (P < 0.05). There were no intra-male differences for sperm head area, length, width, equivalent circle diameter, and convex perimeter. Of the parameters, there were significant differences between males for sperm area, length, equivalent circle diameter, and convex perimeter (P < 0.05). The differences found in sperm morphometry confirm the great polymorphism observed when subjectively evaluating llama semen morphology and make the establishment of a single pattern of normal llama sperm morphometry impossible.