Longevity of chilled canine semen comparing different extenders

The use of chilled semen has raised increased interest due to several reasons. The present study compares 3 extenders for chilling of canine semen over a 10 days storage period. Sperm rich fractions (n = 30) were divided into three aliquots and diluted with (a) a self-made tris-egg yolk extender (TEY), (b) the commercial CaniPRO™Chill 10 (CP, Minitüb, Germany) and (c) the Uppsala Equex-2 system (UpA+B): UpA+B (n = 12) or UpA (n = 18). % of totally and progressively motile sperm using computer-assisted sperm analysis (CASA, TM, PM), % live, membrane intact spermatozoa (SYBR-14/propidium iodide), % morphologically abnormal sperm, % acrosomal changes (Spermac(®)) and % membrane intact sperm (HOS test) were examined on days 0, 1, 2, 3, 5, 7 and 10. Semen quality significantly decreased during storage with significantly lower motility and lower % of live, membrane intact spermatozoa in UpA+B diluted samples. Although quality of samples chilled with TEY, CP and UpA was similar within the first 3 days, only TEY and CP revealed good results in preserving semen quality over 10 days with significantly higher PM, CASA motility parameters and % morphologically normal sperm in CP-chilled samples (each p<0.05).