Table 2.

Semen characteristics (means ± sem) of ejaculate collected approximately 10 d after harem breakup, from reindeer bulls that had prior breeding experience (E) or no prior breeding experience (IE)

	E Bulls	IE Bulls	SEM	P
BSE measures1
Ejaculate volume, mL	1.3	1.7	0.2	0.22
Sperm strength of motility rating2	2.3	2.3	0.4	1.00
Progressive motility, %	55.0	26.3	11.8	0.13
Ejaculate concentration × 106	845.8	495.8	222.2	0.31
Sperm in ejaculate × 106	1198.8	710.6	393.9	0.41
Flow cytometry measures3
Live sperm, %	42.7	31.3	5.1	0.17
Live sperm with intact acrosome, %	41.0	29.6	5.1	0.17
Sperm with polarized mitochondria, %	42.5	20.9	4.6	0.02
Live sperm with strong antioxidant capacity, %	13.3	6.4	2.3	0.08
Live sperm 3 h post-thaw, %	32.7	28.1	2.9	0.31
Morphology measures4
Normal sperm, %	57.3	24	7.4	0.22
Knobbed acrosome, %	1.5	2.8	1.2	0.47
Head defects, %	7.3	26.3	5.2	0.04
Detached heads, %	13.8	19.8	7.0	0.57
Distal midpiece reflex, %	3.80	5.8	1.3	0.31
DAG-like Defect, %	3.50	5.30	0.6	0.10
Bowed midpiece, %	1.50	1.00	0.9	0.70
Proximal droplets, %	5.3	10.5	3.6	0.34
Distal droplets, %	0.3	0.3	0.3	1.00
Coiled principal piece, %	0	1.3	0.2	0.36
Bent principal piece, %	7	4.3	3.0	0.55

Bulls were all treated with medroxyprogesterone acetate (400 mg) 60 d before semen collection.

Breeding soundness evaluations were conducted on semen immediately after collection.

Sperm motility strength was measured on a scale of 0 to 5, where 0 indicates no sperm show straight-line movement and 5 indicates most sperm show very rapid and vigorous, straight-line movement and cross the 40× microscope field of view in less than 1 s.

Flow cytometry measures were conducted on frozen-thawed semen.

Morphology measures are based on descriptions in Barth and Oko (1989).