Table 3. Principal component analysis of sperm cryotolerance with parameters (x) evaluated after incubation at 37°C for 240 min.

Component	Variance	Combinations of variables	aij	aij 2
1	64.11%	% Viable spermatozoa without changes in m.p. (YO-PRO-1−/PI−)	0.95	0.90
		Free cysteine radicals in sperm nucleoproteins	−0.95	0.90
		% Spermatozoa with fragmented DNA	−0.94	0.88
		% Non-viable spermatozoa (YO-PRO-1+/−/PI+)	−0.93	0.86
		% Viable spermatozoa (SYBR-14+/PI−)	0.91	0.83
		% Viable spermatozoa with low intracellular Ca2+ levels (Fluo3-AM−/PI−)	0.88	0.77
		% Viable spermatozoa with low lipid disorder (M540−/PI−)	0.86	0.74
		% TMOT	0.83	0.69
		% Non-viable spermatozoa with low intracellular Ca2+ levels (Fluo3-AM−/PI+)	−0.82	0.67
		% Viable spermatozoa with high lipid disorder (M540+/PI−)	−0.82	0.67
		% Membrane intact spermatozoa (PNA-FITC−/PI−)	0.81	0.66
		VAP	0.79	0.62
		VCL	0.77	0.59
		% Non-viable spermatozoa with high lipid disorder (M540+/PI+)	−0.76	0.58
		% Membrane damaged spermatozoa that present o.a.m. (PNA-FITC+/PI+)	−0.75	0.56
		VSL	0.75	0.56
		GMFI E+/YO-PRO-1−	0.74	0.55
		% PMOT	0.72	0.52
		% Viable spermatozoa with early changes in m.p. (YO-PRO-1+/PI−)	−0.66	0.44
		% Membrane damaged spermatozoa with lost o.a.m. (PNA-FITC−/PI+)	−0.66	0.44
		% Non-viable spermatozoa with low membrane lipid disorder (M540−/PI+)	0.63	0.40
2	11.49%	GMFI E+/Total	−0.90	0.80
		% Viable spermatozoa with high intracellular superoxide levels (E+/YO-PRO-1−)	−0.86	0.73
		% Viable spermatozoa with high intracellular peroxide levels (DCF+/PI−)	−0.75	0.56
		% Viable spermatozoa with high intracellular calcium levels (Fluo3-AM+/PI−)	0.71	0.51
3	9.70%	GMFI DCF+/PI−	0.96	0.92
		GMFI DCF+/Total	0.80	0.64
		% LIN	0.77	0.59
		% STR	0.62	0.38
4	5.24%	GMFI Fluo3-AM+	−0.91	0.83
5	3.66%	% WOB	−0.89	0.79
Total	94.20%

Each cryotolerance index was calculated as follows:.

(m.p.: membrane permeability; o.a.m.: outer acrosome membrane; GMFI: Geometric mean of fluorescence intensity; arbitrary units).