Chopped hay allows more digesting bacteria

Francis Fluharty thinks chopping hay to shorter lengths is the most important innovation in cutting since sliced bread.

“I think it the biggest breakthrough in technology for cow-calf operations, nutritionally, in 50 years,” said Fluharty, an animal science professor from Ohio State University who specializes in ruminant nutrition and animal growth.

“Going from the small square bale to the round bale that saved on labour, that was the last really big thing. This (cutting forages) has the opportunity to take advantage of the efficiency of round baling and the technology of feed processing that we don’t normally think about.”

Claas introduced chopping cutters as an option for round balers several years ago. They are knives on the front of the machine to cut alfalfa and other forages into shorter pieces before the material enters the baler.

John Deere, Vermeer and New Holland have similar systems, often aimed at growers looking to produce haylage.

Fluharty said chopping hay into shorter lengths is important because it can increase digestibility by 30 to 35 percent and boost cattle gains on grass hay by 50 to 100 percent.

Fluharty said cattle thrive when hay pieces are shorter partly be-cause bacteria in the rumen have more surface area to break down forages and less energy is expended on maintaining the digestive organs in cattle.

“Unlike grain based diets, there is a time period, referred to as the lag phase, required for cellulose digesting bacteria to attach to forage particles,” he said in a document on the topic.

“The reason that ruminants chew their cud is that the chewing … physically creates more surface area for the bacteria to attach.”

As a result, chopping hay into shorter pieces increases the surface area for bacteria and reduces the amount of time that forages spend in the lag phase.

“What we’re really talking about is the rate of digestion, the percent of forage that’s digested per hour,” he said.

Fluharty said shorter lengths are also beneficial because cattle that feed solely on forage can suffer from a condition known as hay belly, in which the digestive organs expand and grow larger.

“That particle size in a round bale, or even in a big square bale, is basically as long as the grass was tall,” Fluharty said.

“When an animal eats these longer stem forages, what really happens with this hay belly is that the actual empty weight of organs — the rumen, reticulum … small intestine, large intestine — they actually can increase in physical weight by 20 percent.”

Cattle fed a diet of haylage or corn silage don’t get hay belly because the particle sizes entering the rumen are much smaller, which reduces the amount of time and energy expended to digest the material.

As well, cutting forage into smaller pieces means the indigestible component is already broken down enough so that it passes readily out of the rumen, Fluharty said.

The downside of hay belly is that the larger organs suck energy, which reduces feed efficiency.

“Those tissues take about half of the total calories that animal intakes every day, for maintenance, so half of that animal’s maintenance requirements is to maintain the digestive organs,” he said.

“If you reduce maintenance energy, you proportionally increase the amount of available for net energy for gain.”

Fluharty said chopping hay into shorter pieces boosts the intake of digestible feed by five to 10 percent. It also saves 10 percent on the energy needed to maintain digestive organs in cattle.

As well, feeding shorter pieces of hay increases the intake of digestible feed by five to 10 percent.

Dan Undersander, a University of Wisconsin forage extension specialist, estimated that feed losses associated with shorter pieces of hay are five to 10 percent less than those for standard forage lengths because less hay winds up on the ground.

Fluharty said few cow-calf producers in North America have balers with pre-cutters or chop cutters, despite data suggesting chopped hay has significant advantages over conventional hay.

The technology is available, but most producers require double-duty balers for straw production or have feeding systems that take advantage of longer forage lengths.

Producing dry hay with alfalfa also requires gentle handling to avoid leaf losses, which encourages growers to avoid hay processing at harvest. Instead, they use bale processors when feeding to obtain more efficient feed lengths.

Fluharty feels growers haven’t adopted the technology because cow-calf operators don’t track feed efficiency and digestibility.

That’s in sharp contrast to dairy producers, who pay close attention to forage particle size because they “take measurements every day in bulk tanks.”

“I think it (chop cutting) is being ignored because most people don’t measure things in grazing situations,” he said.

“If it’s a cow-calf operator, what do they measure? They measure weaning weight and they attribute everything to seasons and to genetics. We pay so much attention to genetics that we forget about nutrition … and digestibility.”

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