Untitled - Faculdade de Medicina Veterinária e Zootecnia - Unesp

Table 1. Effect of genetic group (Nelore – Bos indicus, Holstein – Bos taurus and Buffalo –
Bubalus bubalis) on OPU-IVP (Gimenes et al, 2010)
Nelore Holstein Buffalo
(Bos indicus) (Bos taurus) (Bubalus bubalis)
(n=9) (n=9) (n=9)
Mean number of visualized follicles 41.0 a 2.1 22.1 b 1.3 18.8 b 0.9
Mean number of total oocytes 37.1 a 2.5 15.4 b 1.2 14.8 b 1.0
Recovery rate (%) 89.4 a 73.3 b 82.8 ab
Mean number of viable oocytes 30.8 a 2.4 10.7 b 1.0 7.9 b 0.7
Mean number of structures in in vitro
culture
18.7 a 0.8 8.0 b 0.5 7.5 b 0.4
Mean number of cleaved structures 15.4 a 0.7 4.6 b 0.4 4.4 b 0.3
Cleavage rate (%) 81.8 a 59.1 b 62.3 b
Mean number of blastocysts on D7 5.1 a 0.6 1.0 b 0.2 0.6 b 0.1
Blastocyst rate (%) 25.8 a 13.6 b 9.1 b
Mean number of hatched blastocysts 2.6 a 0.4 0.3 b 0.1 0.3 b 0.1
Hatching rate (%) 50.6 a 23.2 b 31.9 ab
a ≠ b: superscript letters in the same row differ (P 0.05). Although
the number of viable oocytes was greater in nulliparous animals than in multiparous animals
(13.4±2.2 vs. 6.3±0.8), the percentage of viable oocytes was lower in summer than in winter
(55.5±3.6 vs. 64.4±2.6). The number of copies of mtDNA is shown in Figure 1. Although mtDNA
analyses do not suggest a negative effect of summer on oocyte viability, further conclusions on the
effect of seasonality on oocyte competence are expected from ongoing gene expression analyses.