Experts debunk old beliefs on feeding cattle
Dairy cow health myths were busted by three experts on dairy cow nutrition in front of a packed audience of farmers in Temuka.
The DairyNZ run seminar aimed to provide farmers the opportunity to hear unbiased facts about cow nutrition, without the commercial spin.
Fronting up were Dr Jim Gibbs of Lincoln University, DairyNZ animal science principal scientist Dr John Roche and Dr Terry Hughes from Synlait.
The use of supplementary feed drew queries from the audience.
Dr Gibbs said it was "completely false" that feeding a cow straw was required for good rumen function and to regulate the rumen's pH.
"Feeding straw is a total waste of time and money," he said.
The rumen's pH of grass based pastures was fine. Moving the pH around by adding straw did not increase a cow's production, he said.
Straw was indigestible, had a metabolic energy level between 6-8 and stayed in a cow's rumen for about 72 hours.
When fed out daily, it would fill up the rumen at the expense of ryegrass.
"What you are doing is that you are diluting down your high metabolic energy (ME) diet for very low ME material for no benefit.
"Wherever straw has been put to the test it's always the same. There is no effect on the rumen pH, and production either stays identical or is reduced," Dr Gibbs said.
The exception was younger stock which needed straw for rumen development, Dr Roche added.
There was no advantage in feeding high energy supplementary feed if there were enough pasture.
The cows would simply substitute grass for the supplement with no added benefit in using the other source of feed.
Dr Roche warned farmers to be wary of dairy consultants claiming no substitution occurred when cows ate a small amount of supplement.
This would then be followed up by advice that would cost the farmer money, he said.
"There is always substitution," Dr Roche said.
There was no advantage in using a high energy dense feed when there was enough pasture. Supplements should be used to manage pasture, not to feed cows, he said.
Farmers who strategically fed grain had a higher profit than others and were better farmers.
"Because they are better farmers the strategic use of that grain, or whatever supplement they are using, is perfectly fine and they are using it at the right time."
Any new feed had to be managed correctly to avoid upsetting the rumen. It was not the amount of supplement that was important, but the rate at which it was applied, Dr Hughes said.
He urged farmers to get their feed grain tested to verify its metabolic energy levels were what was claimed.
Getting it into the cow's mouth was where it became expensive, Dr Hughes added.
Storage, wastage and how it would be fed out had to be factored into the farmer's budget.
All three warned of the dangers of feeding fodder beet to cows.
While it could be used safely and successfully, if done incorrectly it could lead to acidosis.
It was a feed that had to be used carefully and farmers could not afford to take shortcuts, Dr Gibbs said.
"It's very easy to kill cattle with it.
"It's the one feed we have in New Zealand, apart from cereal grain, that is a genuine risk for rumen acidosis if it is fed poorly. Once they're transitioned onto it, it's a healthy happy feed."
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