PRACTICAL USE OF BOVINE EMBRYO SEXING (BY PCR) IN FIELD CONDITIONS IN THE CZECH
AND SLOVAK REPUBLIC
M. Jindra, M. Lopatarova, P. Krontorad, M. Fiala, R. Holasek
BOVET a.s. Sloupnice, PS 12, 565 53 Sloupnice, Czech Republic
The aim of this study is to analyse the results and to determine the practical benefits of bovine embryo sexing
performed under field conditions during a period of 3 years.
Sex determination was achieved by the detection of male-specific, Y-chromosomal DNA sequences using the
polymerase chain reaction (PCR). The assay was conducted according to the standart manual of the Bovine
embryo sexing complete reaction mix (A.B. Technology, USA). For analysis of DNA approximately 5 to 8 cells from
embryoblast or trofoblast were removed by means of razor-blade microsection. In some cases the cells
sequestered in the perivitelline space were used successfully. By means of micromanipulator majority of embryos
were split. Biopsied embryos were stored in Holding medium (AB) at room temperature till transfer (from 3 to 6
hours). Morulae, Early Blastocysts , Blastocysts and expanded Blastocysts of 1 or 2 Quality code were used for
analysis. Embryos of required sex were transfered fresh the same day by these ways:
1st group
Whole (biopsied only) embryos
2nd group
Half-embryos
3rd group
Two half-embryos into one recipient (either unilateral or bilateral)
Synchronized heifers of Czech and Slovak Red and white (Simmental) or Holstein breed were employed as
recipients. Pregnancy was determinated at 60 days by rectal palpation, sex was determinated after calving.
During 3 years 450 day 7 embryos were employed for determination of sex. 356 of embryos were successfully
determinated (79,1%), in 10 cases so called “questionable results” were observed (slight ignition in male bands
(Tab. 1). From that number 196 (55%) were designated as males and 160 (45%) as females (Tab. 2). The best
pregnancy rate 55,3% was achieved with transfer of whole embryos (1st group), the lowest 41,5% with halfembryos (2nd group), the result with transfer of two half-embryos (3rd group) was 47,8% and pregnancy rate in
total was 45,1% (Tab.3). From a total number of 46 calves sex determination was false in 3 cases (sexing
accuracy 93,5%) (Tab.4). 304 embryos were split. By means of splitting 257 embryos were transfered from 160
original female embryos (160,6%) and it ensued in pregnancy of 116 recipients (72,5%).
Tab.1 Results of sex determination
No.of biopsied embryos
Sex determinated
450
356 (79,1%)
Tab. 2 Rate of males and females
No.of successfully determinated
6
questionable
10 (2,2%)
No.designated as male
196 (55%)
not determinated
84 (18,7%)
No.designated as female
160 (45%)
Tab. 3 Pregnancy rate according to ways of transfer
1st group
2nd group
3rd group
total
No.of transfer
47
164
46
257
No.of pregnant
26(55,3%)
68(41,5%)
22(47,8%)
116(45,1%)
In the 3rd group 4 twins were born, which gives approximately the same result (in a number of calves) as in the
1st group
Tab. 4 Sexing accuracy rate
No.designated as females
46
Female calves born
43
Male calves born
3
sexing accuracy rate
93,5 %
Practical use of bovine embryo sexing in field conditions is mastered in the Czech Republic. Splitting of
determinated embryos is a good way to increase a limited number of transferable embryos.