Controlling Intake of Pasture Supplements to Grazing Cattle

By Wendy Flatt, Livestock Specialist, University Of Missouri Extension. Ag Connection Newsletter, Volume 13. As many producers know, salt can be added to feed to limit supplemental feed intake of grazing cattle, but how much is the question?
calendar icon 2 August 2007
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This could be especially important in dry years or late summer when the pastures decline significantly in nutritional quality and supplementing is necessary.

The Salt Institute is the world’s foremost authority on salt and its more than 14,000 uses. Salt (Sodium Chloride- NaCl) is one of the few minerals cattle crave when it is in short supply:

Larry Berger, University of Illinois Professor of Animal Science wrote the booklet entitled “Salt and Trace Minerals for Livestock, Poultry and other Animals”. He suggests that the “science” of using salt to regulate intake has been adequately researched but, the “art” of using this technology is still developing, as many producers can attest.

The proportion of white salt in a self-fed mixture can vary from 5 to 40%, which is a huge variation. Do not use trace mineralized salt at greater than 0.05% of the mixture.

Berger suggests if producers want to limit intake from 1 to 2 pounds per day of supplement, they need to add between 30 to 40% salt in the mix, especially for mature grazing cows. For yearling cattle use 5% initially to limit intake to a pound a day. As cattle grow and the grass matures and becomes limited, 20 to 30% may have to be added to the supplement to maintain desired levels of intake.

Besides desired intake, producers also should factor in age and weight of the livestock, the quality and quantity of accessible forage, the grind of the salt (the finer the grind, the less salt needed in the mix), salinity of the water source (the higher the salinity of the water source the less salt that should be added to the feed). As weather becomes more severe, more salt is required because the livestock are less prone to graze. Also consider that if your livestock are really hungry, more salt is going to be required in the mix to keep them from over-eating. The Salt Institute recommends hand-feeding for a week before allowing free choice access to the supplement.

When using salt to restrict feed intake, water requirements can easily increase by 50 to 100%, so make sure your livestock have a plentiful water supply. Livestock can tolerate high amounts of salt in their diets, but they have to have access to water. When winter arrives and the snow starts flying and the temperatures are below freezing, this becomes even more important. Livestock tend to increase their consumption of the salt mixture during these times, so producers need to be aware that placing the salt mixture right by the water supply will restrict grazing distribution.

Another option producers can use to restrict feed intake is adding ionophores such as monesin (Rumensin) or lasalocid (Bovatec) to the supplement mix. Adding an ionophore, according to research, allows the use of a salt concentration that reduces the animal to animal variation in intake, increases average daily gain of grazing cattle and decreases the number of adjustments in salt concentration by half. Muller et al, showed that self-feeding a salt-monesin-supplement gave the same improvement in daily gain (0.2 pounds per day) as hand feeding the monesin supplement without salt. Salt is already a proven intake regulator and can be made even better with the addition of ionophores. Using salt as an intake regulator of self-fed supplements on grass is one management tool that can increase the bottom line of cattle producers.

July 2007

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