Two studies were conducted to determine
the effect of feed additives on the transit
shrink of yearling cattle. In Trial I, 146
mixed-breed heifers were offered a mineral
mixture containing either Terramycin® or
Bovatec®, or without additive while grazing
native grass pastures. Shrinkage after 300
miles in transit was lower (P<.09) for
Bovatec-fed heifers than the other groups. In
Trial II, 60 mixed-breed heifers were offered
free choice prairie hay, plus soybean hulls
without additive or containing either Aureomycin
®, Rumensin, or Bovatec®. Both
ionophores tended to reduce live weight shrink
following a 10-hour withholding of feed and
water, but treatment differences were not
significant (P>.05). The small shrinkage
differences observed in these two trials would
not justify changes in the weighing practices of
feeder cattle.
