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The science of feeding cattle basically boils down to feeding the microbes in their rumen.
“Consistency is a big key in ruminant digestibility and health,” Wolf says. To ensure that everything is performing optimally in the rumen, he looks for visible signs.
“I’m a big believer in walking the bunk line, and looking in the bunks to determine what cattle are eating. You can see if those calves are sorting their feed. You can also tell a lot by looking at the consistency and color of manure.
“If all the cattle in the pen are rushing the bunk when the farmer starts the tractor, they’re definitely too hungry. I like to see about a quarter of the pen standing at the bunk, with the balance slowly making their way to the bunks as they’re fed,” Wolf says.
Ration ingredient selection and degree of processing are other areas of consideration when working to maximize ruminant digestion. Tim McAllister, a principal researcher at Lethbridge Research Centre in Alberta, Canada, says understanding the impact of various levels of processing for different grain crops, and the economic impacts related to grain processing, are critical when striving to maximize performance and return.
“We have to consider surface area related to particle size. A smaller particle has a larger surface area, which more microbes can attack and more rapidly digest. This can lead to the production of too much acid in too short a time, and possibly acidosis. But, if the hull isn’t cracked or broken, and we’re essentially feeding whole grains, their shells are very resistant to microbial digestion, and we end up with more grain going out in the feces, which we also want to avoid,” he explains.
Much of McAllister’s research focuses on the ability of rumen microbes to digest various grains at different degrees of processing. He says wheat and barley are much more rapidly fermented in the rumen compared to corn and sorghum. But if you process corn to a fine particle size, it will surpass moderately processed barley in the time it takes to be fermented.
“You need to process grains to some degree to maximize utilization and, with the price of grain crops today, it pays to process them for the increased digestibility. What will work best in a particular situation depends heavily on availability and price of a given grain crop,” he adds.
Relatively new feedstuffs are also a viable option for increasing rumen efficiency. Wolf says when used correctly in rations, distillers grains can help enhance feed efficiency.