In recent years, governments and the general public
have been paying ever more attention to the effect of
animal production on environmental pollution. The European
Union Environment Commission issued a final
report indicating the level of N excretion for different
livestock farming (ERM/AB-DLO 1999) among which
culled cows had relatively high excretion. In fact, due
to the high percentage of beef cows and their greater
carcass weight and meatiness compared with dairy
cows, a considerable amount of meat is produced by
this category of cattle (Fiems et al. 2004, 2005). Because
culled cows sales represent from 15 to 30% of
the gross revenue of a cow-calf enterprise, they should
be viewed as a potential source of profit. In the European
Union, half the slaughtered adult cattle are culled
females including 60% cows and 40% heifers
(Cabaraux et al. 2005) while in China even more percentage
of adult cows were slaughtered for beef
industry. However, culled cows are often in poor body
condition and culled cows have to be fattened to improve
the available cash of farmers (Little et al. 2002).