Breed influences on in vitro development of abattoir-derived bovine oocytes

Table 1 Significance of the oocyte donor’s breed on the number (mean ± SD (n)) of oocytes developed into different maturation stages, after in vitro production

Variable	Beef*	SH	SR	LRT	P
Cleavage rate % (n)	73.9 ± 0.03 (613)^a	72.5 ± 0.02 (290)^a	71.9 ± 0.03 (448)^a	Chisq = 3.77 (df = 2)	0.150
Cleaved beyond 2-cell stage at 44 hpi % (n)	44.9 ± 10.6 (613)^a	44.2 ± 6.95 (290)^b	52.1 ± 6.98 (448)^ab	Chisq = 1.008 (df = 2)	0.60
Blastocysts developed by day 7 (168 hpi) % (n)	8.8 ± 3.33 (613)^a	3.2 ± 3.19 (290)^a	5.9 ± 5.8 (448)^a	Chisq = 3.71 (df = 2)	0.156
Blastocysts developed by day 8 (192 hpi) % (n)	14 ± 7.6 (613)^a	7.4 ± 4.5 (290)^b	15.3 ± 0.6 (448)^a	Chisq = 8.13 (df = 2)	0.0156
Number of nuclei in day 8 blastocysts	101.4 ± 6.9^a	79.2 ± 8.7b	98.9 ± 7.7^ab	Chisq = 23.02 (df = 2)	<0.001
Blastocyst grades day 8 (1 – 4 where 1 = best grade)	2.1 ± 0.2^a	2.4 ± 0.1^a	2.4 ± 0.2^a	LR = 4.19 (df = 2)	0.123

Cleavage and blastocyst ratios are calculated from number of oocytes inseminated with dairy bull semen. In each row, different letters after data indicates statistically significant differences between oocyte donor’s breeds. LRT is the likelihood-ratio test (statistical values), and P are p-values that represent the significance of the effect of the independent variable oocyte donor’s breed on the dependent variable. * The beef breed oocyte donors deviated in age and carcass conformation compared to the dairy breeds (p < 0.05).

ISSN: 1751-0147