By explaining the behaviour of animals, Fred Provenza offered some
insights recently into how producers can improve the management of
their livestock.
Provenza, a professor at Utah State University’s department of forest,
range and wildlife sciences, studies the grazing behaviour of cattle
and sheep.
At the Manitoba Grazing School Dec. 3-4 in Brandon, he explained many
of the things that drive the grazing behaviour of livestock, and why
abundant, high quality feed doesn’t guarantee good herd performance.
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Provenza started by asking producers why they like a particular food.
“It tastes good,” was the immediate reply.
But according to Provenza, there is a myriad of things that influence
the palatability of livestock feed, and taste is only one.
He explained how cattle and sheep have their own way of determining
whether there is an imbalance of proteins and energy in the diet, or
whether there is too much of a particular toxin in a forage.
Subconsciously, messages are conveyed to the animals’ brains, telling
them to shift to another food source when a nutrient imbalance is
arising or if there is too much of a toxin.
Provenza gave an example of cattle eating legumes, which tend to be
higher in protein. Because an imbalance can result from too much
protein and not enough energy, cattle grazing a pasture high in legumes
such as alfalfa might seek out something like mouldy hay to restore the
balance. That’s one of the reasons farmers should include grass in the
pasture mix.
“The more adequate the food is in relation to need, the higher the
palatability,” said Provenza.
Feeding preferences are also shaped by culture and social interaction.
Calves learn at an early age from their mothers what to eat and where
to find that food.
The same goes for lambs, said Provenza. The transfer of food
preferences begins early and endures.
“These young animals learn very quickly,” Provenza said. “They learn
very quickly and they don’t forget what they learn.”
Provenza provided examples to explain the importance to livestock
producers.
There once was a trend among United States dairy producers to keep
their cattle off pasture and to feed them total mixed rations year
round. That trend is now being reversed, but not without complications.
Dairy cows confined to barns and pens throughout their lives find
pastures “scary” when first released, said Provenza. They were not
taught early that pastures are habitat and a source of food.
As a result, milk production plummets when those cows first go on
pasture. He said feeding green chop in the barn before putting the
cattle on pasture can help. The cows should then be eased onto pasture
to reduce stress and lost production.
It can also help, he said, to expose dairy calves to pasture early in
their lives so they can learn foraging skills and develop preferences
for pasture species under the tutelage of their mothers.
Provenza suggested the same approach be applied to beef cattle. Before
being shipped to a feedlot, for example, cattle should be exposed to
foods they will eat there.
That can help prevent poor performance and illness while the animals
adjust to their new setting.
That knowledge could also be relevant to producers moving cattle to
unfamiliar pastures or to producers feeding low cost feeds, such as
ammoniated straw, during the winter.
Provenza cited a study where 32 cows, between five and eight years of
age, were fed ammoniated straw from December to May. Researchers noted
some cows did poorly, while others did not.
Researchers reviewed dietary histories of the animals and discovered
half the cows had been exposed to ammoniated straw with their mothers
during the first three months of their lives, while the others had
never seen it.
Cows exposed to ammoniated straw, showed higher body weight and
condition, produced more milk and bred back sooner, even though they
had not seen straw for five years.
“The older animals get, the harder it is for them to learn these kinds
of things.”
Provenza recommended exposing replacement heifers to poor quality
forages with their mothers early in their lives so they will be better
prepared to eat those foods later.
He also noted that low quality foods such as ammoniated straw should be
incorporated into winter feeding programs gradually, allowing time to
study how well the cattle adapt.
With a better understanding of feed preferences, producers can train
livestock to make better use of pastures.
Provenza gave the example of a ranch in Montana that forced cattle to
eat some of the less preferred species during grazing.
In the first couple of years, the weaning weights of the calves dropped
dramatically, but they returned to normal after three years.
The result was better use of the pasture, especially when less
desirable plants dominate and high quality forages are grazed out.
Provenza also pointed out that livestock, like people, get bored if
forced to repeatedly eat a diet that does not offer variety. Too much
of the same thing can turn them off a particular food.
Livestock thrive on variety, he said, which helps to explain a tendency
in cattle to sometimes think the grass is greener on the other side of
the fence.
