  It is shown that the dependence of ratio $f_s/f_d$ could be understood within
the fragmentation approach. However, the validity of fragmentation model is
questionable at low $p_T$, and contributions of nonfragmentation mechanisms are
possible. It is demonstrated, that the precise measurements of $p_T$ dependence
of $f_s/f_d$, $f_{\Lambda_b}/f_{B}$ and analogous values as function of $p_T$
can essentially improve our understanding of heavy hadron production.At large
$p_T$ a plateau is expected in $f_s/f_d$ distribution. Contrary, a plateau is
not expected in $f_{B_c}/f_{B}$ distribution on $p_T$.
