Using Bovine Somatotropin (BST)
Ruminant Nutrition & Microbiology Laboratory
Bovine somatotropin has been commercially available in the U.S.
since 1994 to increase milk production and improve the efficiency of milk
production. Sales and use of
BST have steadily increased since its introduction.
With increasing use, here are some of the more common questions,
with answers, about BST use in dairy cattle.
If I stop administering BST
after several weeks or months, is there a positive or negative carry over
effect in the next several weeks or the rest of lactation?
Within 1 to 2 weeks, milk production will drop to a normal level.
If I administer BST to a cow for an entire lactation (starting at
about 60 days to drying off) will there be a positive or negative residual
effect in the next lactation if I choose not to administer BST?
Cows will milk normally based on body condition and nutrition.
When I start using BST can I feed the same diet that cows were
If cows are started on BST at
about 60 days in milk, these animals will probably be being fed an energy
and protein rich diet. Cows
may have to remain on this diet for a longer period of time if treated
with BST. If cows are started in later lactation and fed a less
nutrient dense diet, they may remain on this diet for a short period of
time. However, over the long
run, a more nutrient dense diet will probably have to fed to BST-treated
cows or body condition will suffer. Cows
that dry off in poor body condition will not milk as well in the next
Can I cheat and start administering BST to cows earlier than what
is written on the label?
Follow label restrictions because starting BST treatment at calving
has no effect on milk production. During
early lactation, the cows produces enough of her own BST to maximize
production. Administering BST
before 50 to 60 days in milk is a waste of money.
If have been using BST for several years and I don't perceive the
large increases in milk production that I saw when I first started using
the product. Why is this?
producers first start using BST, there is an obvious increase in milk in
the bulk tank if enough cows are started on the product.
After time, most herds end up with continual use of BST, which
makes it more difficult to perceive a difference.
Question: How do I know BST
is still working?
Controlled studies have shown
that cows respond similarly to BST even after four lactations. In a study at the University of Arizona, cows receiving BST
for 4 years produced on average 8.1 lbs. more milk per day and gained 114
more lbs. of body weight in a lactation than did untreated cows.
Cows responded the same to BST in the first and fourth year of