EVIDENCE FOR INDIVIDUAL AND BETWEEN-FAMILY VARIABILITY OF THE RECOMBINATION RATE IN CATTLE

We have conducted a study based on single sperm typing in a family des ign to assess patterns of variability of the male recombination rate i n cattle. 2214 sperm of 37 bulls were typed for 11 loci on bovine Chro mosomes (Chrs) 6, 23, and the sex chromosomes. Statistically significa nt individual variability of the recombination rate was observed for o ne interval in the pseudoautosomal region (PAR) of the bovine sex chro mosomes; one marker interval on bovine Chr 23 exhibited individual var iability that was close to significance. Thirty-five of the bulls were members of six paternal halfsib groups, and highly significant variab ility between families was found for one interval in the PAR. This var iability may be due to DNA sequence differences in the PAR or to a gen etic control of the recombination activity in this region. It is demon strated that differences in the recombination rate of the magnitude ob served in the present study may have a considerable impact on the powe r of QTL mapping experiments as well as on the sustainability of marke r-assisted selection strategies.