Estimation of seasonal effect on sperm motility in fresh semen from bulls

Estimation of seasonal effect on sperm motility in fresh semen from bulls

C Tamargo, M Carbajo, C Díez, S de la Varga and CO Hidalgo

SERIDA, Gijón, Spain, Facultad de Veterinaria, León, Spain

Seasonal changes can affect sperm motility, which is essential for fertilization. Computer-assisted semen analysis (CASA) provides more accurately values than those obtained with traditional semen analysis methods. The aim of our experiment was to investigate the possible seasonal effect on sperm motility,  assessed by a subjective measurement system complemented with a CASA system. Ejaculates (n = 373) from seven Asturiana de los Valles adult bulls were weekly collected by means of artificial vagina for one year. Immediately after collection, mass motility (MM) was evaluated and qualified from 1 (bad) to 3 (very good) by observing wave motion under a phase contrast microscope (10x). Individual (IM) and progressive motility (PM) rates were assessed by a  Sperm Class Analyzer (SCA 2002 Microptic, Spain). Semen was diluted (20 · 106 spermatozoa/ml) and loaded in warmed slides. Five fields per sample were evaluated (minimum 500 spermatozoa/sample) under a phase contrast microscope (10x). Statistical analysis was carried out by means of the GLM procedure and Duncan test for means. Values for PM were maximal during spring (72.54 ± 1.28 a,b) and winter months (69.05 ± 1.55 a), and decreased in summer (64.66 ± 1.36 c) and autumn (67.80 ± 1.18 b,c) (a,b,c: p < 0.05). Individual motility highly correlated with PM (r = +0.06, p < 0.001). We conclude that the new computer-assisted semen analysis is a useful tool for analyzing seasonal changes affecting sperm motility in our local Asturiana de los Valles breed (Performed in collaboration with ASEAVA).

Reprod Dom Anim 41, 311–377 (2006)