Implants
do not cause dark cutters. Dark cutting carcasses
are caused by abnormal physiology after slaughter.
Normally, muscle contains glycogen, a type of starch
that is used by the muscle for energy. After
slaughter, glycogen is converted to lactic acid.
Because circulation has ceased, lactic acid accrues
in the muscle and the pH drops, producing normal
beef characteristics. If glycogen is absent at
slaughter, these normal changes do not occur and the
higher than normal pH results in beef that is
darker, firmer and drier than usual. This is called
a dark cutter or DFD (dark, firm and dry) beef.
Any event that causes muscle glycogen to be
abnormally low at the time of slaughter could
potentially result in a dark cutting carcass.
Usually, high incidences of dark cutters are caused
by specific stresses such as long hauls or overnight
stays before slaughter. Some cattle are more
susceptible to cutting dark than others, and there
are some times of the year that dark cutters are
predictably high. Implants can be involved, too, as
some implant programs may increase the likelihood
that some cattle will cut dark. In particular, TBA-containing
implant programs occasionally result in a higher
incidence of dark cutters than implant programs that
do not contain TBA.
