Appendix 1—table 2. Rates of sperm-ZP binding, pronuclear formation, and cleavage after homologous (bovine sperm) and heterologous (murine sperm) co-incubation with bovine ovarian oocytes at different times post-insemination.

Semen group (N)	Sperm binding	Pronuclear formation	Cleavage rate
	2.5 hpi, n	18 hpi, n (%)	20 hpi, n (%)	26 hpi, n (%)	48 hpi, n (%)
Ho (231)	46 (0.6±1.0)	86 (75.8±10.21)a			99 (81.8±1.9)a
He (436)	47 (0.6±1.0)	86 (44.3±6.7)b	87 (44.9±8.8)	85 (44.7±3.6)	131 (52.6±3.1)b
Parth (43)					43 (4.4±8.7)c

Ho = homologous IVF with bovine sperm; He = heterologous IVF with murine sperm. Parth = parthenogenic non-fertilized oocytes. Sperm binding was expressed as the average number of spermatozoa that remained bound to the ZP. ‘N’ refers to the total number of oocytes fertilized per treatment or non-fertilized oocytes (Parth); ‘n’ refers to the total number of fertilized oocytes/presumptive zygotes or non-fertilized oocytes (Parth) recorded at each time point to determine rates of sperm binding, pronuclear formation, and embryo cleavage. Pronuclear formation was expressed as the percentage of oocytes with two pronuclei at each time point over the number (n) of oocytes examined. Cleavage rate was expressed as the percentage of two- cell embryos over the number (n) of fertilized or non-fertilized (Parth) oocytes. Analysis was conducted by using a one-way ANOVA, followed by Tukey´s post hoc test. Significance level was set at p<0.05. Different superscripts (a, b, c) in the same column indicate significant differences (p<0.05; n=3); Values are expressed as the mean ± SD.