Evaluation of an artificial intelligence system for bull sperm morphology evaluation

The morphological characteristics of bull spermatozoa are usually evaluated visually using bright-field microscopy according to the guidelines proposed by the Society for Theriogenology (SFT) for the Bull Breeding Soundness Evaluation (BBSE). However, analysis is labor consuming and requires experienced personnel to obtain reliable results. Nevertheless, the artificial insemination industry increasingly demands the implementation of genomic selection schemes for young bulls. Hence, there is a growing need for a more standardized technique to analyze semen quality, particularly for the evaluation of spermatozoa abnormalities that affect semen freezing suitability and fertilizing capacity. Therefore, an Artificial Intelligence (AI) algorithm for the automated classification of microscope-acquired images of spermatozoa was developed using neural networks, specifically YOLO networks, based on convolutional neural networks (CNNs) that were able to learn and extract relevant features from complex visual data through image segmentation. The aim was to assess the algorithm ability to identify sperm cells in microscope-acquired images, establish their viability and to classify morphology based on a simplified scheme which included only normal or major/minor defect categories. The dataset comprised 8243 images, which were labeled and annotated with bounding boxes to allow the segmentation algorithm to learn. The performance obtained by the algorithm showed an accuracy of 82 %, although it was not observed for all classes (excluding a probable case of overfitting where accuracy reached 100 %), and a precision of 85 % in the correct classification of spermatozoa morphology. Results thereby confirmed the potential applicability of the algorithm in bull semen analysis without excluding its future implementation for achieving optimal performance.