269 EFFECT OF DIFFERENT COLLECTION FREQUENCY INTERVALS ON THE QUALITY OF SEMEN OF FRENCH BULLDOGS

Abstract

Dogs produce fewer sperm than other species. Furthermore, for French Bulldogs, anatomical peculiarities, low libido, and increased sensitivity to stress could cause further reductions in sperm count. The objective was to compare effects of semen collection at 24- versus 48-h intervals on semen quality of French Bulldogs. Five purebred French Bulldogs, 19 to 48 months old, were subjected to 5 semen collections (24 h apart). After a 30-day rest, collections were repeated, but the interval between collections was 48 h. Semen was collected (all 3 fractions) by digital manipulation without female stimuli. Volume was measured in a 20-mL syringe. Sperm concentration was determined with a Neubauer counting chamber. Motility and vigor were evaluated with a coverslipped drop of semen on a slide (preheated to 37°C). Motility was expressed as a percentage of motile sperm, and vigor was classified on a scale of 1 to 5. Morphology was evaluated by the panoptic method; 100 cells were counted and results expressed as the percentage of normal or defective cells. Effects of collection interval were analysed using PROC MIXED of SAS (animal as subject and collection as a repeated measure), with collections 2 to 5 compared with collection 1 (using the DIFF option). For collection every 24 h, the third, fourth, and fifth sperm collections were lower than the first collection for volume (10.4 ± 1.1, 8.3 ± 1.1, 5.6 ± 1.1, 3.5 ± 1.1, 2.4 ± 1.1 mL), concentration (437 ± 24, 448 ± 24, 370 ± 24, 322 ± 27, 258 ± 31 ×10⁶ sperm mL^–1), vigor (4.6 ± 0.2, 4.2 ± 0.2, 3.6 ± 0.2, 3.7 ± 0.2, 3 ± 0.2), and morphologically normal sperm (82 ± 2.2, 83 ± 2.2, 72 ± 2.2, 68 ± 2.5, 66 ± 2.9%). However, when the interval was increased to 48 h, only the fourth and fifth collections were lower (P < 0.05) than the first for volume (11.8 ± 1.1, 10.2 ± 1.1, 8.8 ± 1.1, 6.6 ± 1.1, 2.5 ± 1.1 mL), concentration (447 ± 24, 410 ± 24, 407 ± 24, 322 ± 24, 241 ± 31 ×10⁶ sperm mL^–1), vigor (5 ± 0.2, 4.8 ± 0.2, 4.4 ± 0.2, 4.2 ± 0.2, 4 ± 0.2), and sperm with normal morphology (92 ± 2.2, 90 ± 2.2, 87 ± 2.2, 80 ± 2.2, 81 ± 2.9%). Motility decreased (P < 0.05) following the fourth collection at 24-h intervals and decreased (P < 0.05) after the third collection at 48-h intervals. With a 24-h interval, 4 dogs had <60% motility lower at the fifth collection, whereas only 2 dogs had motility <60% on the fifth collection at 48-h intervals. In conclusion, semen collected at 48-h intervals was of better quality than semen collected at 24-h intervals.