Livestock Management RANCHING
says that since their mechanisms are different, the ef- fects are additive. In a cow-calf operation, an ionophore such as Rumensin works by reducing the amount of feed that the animal consumes. Ionophores alter the population of ruminal micro-
organisms, resulting in more effi cient ruminal fer- mentation. They reduce feed requirements by 5 to 10 percent, with no effect on cow reproductive effi ciency, milk yield, or weaning weight. They also reduce time to the heifer’s fi rst estrus by 10 to 35 days. However, because it must be included in feed, correct dosing can be diffi cult and will be most effective when stored feeds are used. Ionophores can be fed at all stages of the animal’s
life without withdrawal. In a cow-calf operation, they are primarily fed to cows in order to reduce feed intake and thereby improve feed effi ciency. In a stocker operation, they can be delivered via
supplement, and can increase ADG in the neigh- borhood of 15 percent. In a lot of cases that is 0.15 pounds per day, but with high quality feeds such as small grain pastures, as much as a 0.45 pound per day increase in ADG through use of an ionophore has been documented. Another advantage to ionophores on wheat pas-
ture is that they help control bloat. They can also be delivered free choice in the appropriate minerals, but ionophores are toxic to horses so producers should be careful to restrict the access of horses to treated feed.
48 The Cattleman May 2015
Holland says the only reason to limit either implant
or ionophore use in cattle would be as the usage is dic- tated by market conditions. “All natural or non-hormone treated cattle (NHTC) market channels do exist, which can reward limiting implant and additive use,” he explains. Cattle producers who want to explore these programs need to understand what the requirements are for each program, and they also need to make sure a program will be available to them. Holland says, “If there is a premium out there for
raising an all-natural calf, I want to make sure that the premium will exist and be high enough when I market the calves, and that my cattle can qualify for the program if I forego an implant,” and lose the 23 pounds of weaning weight, or the 0.24 pounds per day ADG achieved in stocker operations. While the biggest decision is whether to use implants
and feed additives, with several products available it is important to select the correct tool for the production setting. Holland notes that many of these products have been around for a long time. The fi rst implant was ap- proved in the mid-1950s, and it is still available today. Holland says, “It’s easy for those of us out in the
country to forget what the real value of these technolo- gies is, so we get into a rut where we’ve used them for a while and wonder if they really still have value. It’s clear that they do, and there are many resources out there to help producers better understand how to apply these technologies in appropriate situations.”
thecattlemanmagazine.com
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