42 Semen Fertility of the Bull Evaluated by Second-Order Statistics

Abstract

The biospeckle (BSL) is based on the incidence of laser light upon active biological materials, followed by analysis and manipulation of secondary images, and then, application to those images of a second-order statistics technique called the inertial moment (IM) that results in information about the activity of the specimen. This technique was previously used to analyze sperm motility. A bull’s fertility could be evaluated by several semen parameters in vitro and more precisely by conception rates of AI heifers. The objective of this work was to evaluate the fertility of bull’s frozen semen showing different levels of activity in an AI program. Semen of 6 mature IA donor bulls (Bos taurus indicus) was previously divided in 2 groups (group I: motility ≥50%; group II: motility <50%), each group comprising 3 animals. Sperm concentration was 30 to 35 × 106 cells per straw. Semen was thawed at 37°C for 30 s in a water bath. Samples were illuminated by nonpolarized He-Ne laser (632 nm, 10 mW) for 40 s, the time needed to take 512 images under a time rate of 0.08 s. Images were acquired by a CCD camera and analyses were conducted by building space-time speckle matrices from center columns of 512 images of the dynamic speckle and then the IM was calculated. Beef heifers (n = 109) under the same nutrition and management conditions underwent AI with the semen samples. All inseminations were done by the same technician and donor bulls were used consecutively throughout the breeding season. Pregnancy diagnosis was done by ultrasound images (Falco 100, 6 MHz, Pie Medical, Crawley, UK) 28 days after insemination. The SISVAR software was used for variance analysis and comparison of means by Tukey test at a nominal level of 5%. The IM (194.13 ± 31.99) obtained from 10 illuminations per sample of each bull and the conception rate (CR) of group I (CR = 0.63 ± 0.49) differed (P < 0.05) compared with group II (IM = 142.03 ± 30.62; CR = 0.43 ± 0.50). Pearson correlation coefficient (P < 0.05) between IM and CR was r = 0.21, showing coherence with IM and CR, despite its low value. These data showed that second-order statistics are correlated to semen fertility and could be used to evaluate ejaculates of the bull. Financial support: FAPEMIG grant EDT 94/07 and CNPq.