Ki Fanning, PhD, PAS, Great Plains Livestock Consulting, Inc., Eagle, Neb., offers these tips for preventing and managing acidosis.

Acidosis is one of the most costly problems in the feedlot. Acidosis is also known as bloat, founder, or sticking an animal. Acute acidosis is easily identifiable in the feedlot whereas subacute acidosis normally goes unnoticed. Hallmarks of acute acidosis are a high left side, long toes, poor doing calves, and sudden death. The immediate symptoms are watery stools with white residue after it dries, increased rate of respiration, standing in water, rocking back and forth due to sore feet, kicking the belly, going off feed, and in extreme cases, death.

Subacute acidosis is usually not penwide, so the pen of cattle will continue to eat. However, there will be individuals that are off feed or have lower intakes resulting in low pen intakes, causing gains to be less than expected. Subacute acidosis symptoms are slightly depressed pen intakes, loose stools and a tight left side. Subacute acidosis is quite common in the feedlot industry because ruminants are not adapted to consuming high-grain finishing diets. Rather, calves must learn how much, how fast, and how often to eat without becoming acidotic. The biggest challenge associated with subacute acidosis is that it is not easily detectable, yet it is quite costly due to performance losses.

There are several different causes of acidosis. The first is changing from a high roughage diet to a high concentrate diet too quickly. This is the reason why we use a series of step-up diets consisting of a Starter, Grower 1, Grower 2, Finisher 1, and Finisher 2. Each diet is to be fed three to five days at minimum. This gives the rumen bacteria (bugs) time to adapt to the higher concentrate diet and prevents the bacteria from producing too much lactic acid during fermentation (digestion) of the feed.

The amount of concentrate fed can also be a problem. A recent example would be cattle that went through the heat and humidity the last week of June. The excessive heat depressed intakes and was followed by a cool down that promoted normal intakes. The cattle may have dropped to about 30% of the previous intakes for several days (nothing anyone could do about that) and if intakes were not managed correctly, the subsequent increase in intake could have caused acidosis. The increase in intake needs to be controlled to about 1.5 lbs of dry matter or approximately 3.0 lbs of feed as fed per day.

The rate of fermentation or digestion can also be a problem. A feedstuff with a fast rate of fermentation is commonly referred to as a “hot” feed and may contribute to acidosis. A good example of this is feeding by-products, which ferment slower than rolled corn, which ferments slower than ground corn, wheat, or barley. For this reason, never feed fine ground corn to ruminants, especially not in a self-feeder. This is also the reason that we use only a limited amount of wheat in a ration.

Prevent feedlot acidosis
Acidosis, both acute and subacute, can be prevented by feeding within 15 minutes of the same time every day, by having at least 12 in. of bunk space for finishing cattle or 24 in. for cows, receiving calves, and cattle that are being limit fed. When transitioning from one ration to another make sure that the cattle have been on the previous ration for at least three days. It is also critical there is not a storm or weather change predicted for the immediate future, and that the rations are blended for one to three days.

For example, feed the new ration in the afternoon for two days when the cattle are not as aggressive and the previous ration in the morning prior to going completely to the next consecutive ration. The cattle should have feed in front of them no less than 16 hours per day and no more than 20 hours per day, unless otherwise specified. Make sure the cattle are not sorting feed. This does not mean that the bunks are slick, however; it does mean the cattle are not moving feed back and forth in the bunks, creating bare spots in the bottom of the bunk. This is one of the more common problems we see, due to the longer length of hay in the bunk.

By practicing good bunk management, observing the cattle and their stools, watching the weather, and moving the cattle through the diets according to the proper protocol then acidosis can be minimized. This will translate into improved performance and additional dollars for you and/or your customer.

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