Acidosis in Feedlot-Bound Calves

Acidosis is a digestive upset caused by moving cattle onto grain too fast, and it can range from a mild setback to a death loss. If you background calves or finish a few head, the goal is a slow, steady step-up with professional guidance.

Key points

Acidosis happens when grain outpaces the rumen microbes' ability to adapt.
Newly weaned and stressed calves are especially vulnerable.
Follow a written step-up plan from a nutritionist without skipping ahead.
Consistent feeding times, mixing and bunk space protect the rumen.
Watch manure and intake as early warning signs.

What acidosis is

The rumen depends on a stable community of microbes that digest fiber. Grain is digested very quickly, and when a lot of it arrives before the microbes have adjusted, acid builds up faster than the animal can handle. The rumen becomes more acidic, the helpful microbes suffer and the lining of the rumen can be damaged.

Acidosis comes in forms from mild and chronic to sudden and severe. Mild cases often go unnoticed and show up as poor performance rather than obvious sickness.

Ask your nutritionist what the early warning signs look like in your own feeding system, since a bunk reader or a pen rider who knows the normal pattern can catch a change days before cattle look sick.

Why feedlot-bound calves are at risk

Calves coming off pasture or a hay diet have a rumen tuned to forage. When they get to a backgrounding yard or feedlot, they may face a sharp change in feed, new pen mates, stress from weaning and transport, and a very different eating pattern.

Those stresses can also lower feed intake at first, then lead to over-eating once appetite returns. Both swings can upset the rumen.

Signs to watch in the pen

Look at cattle at the bunk and again later in the day. A calf that stands off, kicks at its belly or looks bloated deserves attention. Some cases are found dead with no warning.

Manure often tells the story. Loose, bubbly or unusually soft manure across a pen can point to a ration or adaptation issue that your nutritionist should hear about right away.

Reduced or erratic feed intake across the group
Loose, foamy or sour-smelling manure
Dull calves standing apart, belly kicking
Visible swelling on the left side behind the ribs
Lameness showing up a few weeks later, which can be linked to rumen upset

Step-up programs and how to plan them

Most feeding programs move cattle through a series of rations, each with a bit more grain than the last. The exact steps depend on the calves, the feed ingredients and the facility. A nutritionist can write a schedule for your situation, so ask for one rather than copying a neighbor's plan.

Follow the plan day by day, and do not skip ahead because the calves look good. A good-looking pen can still have a rumen that is under strain.

Keep the plan in writing and share it with everyone who feeds. If a hired hand or a relative covers for you during a trip, a clear sheet that lists today's ration step and the next one stops well-meant mistakes.

Feeding practices that protect the rumen

Consistency does much of the work. Feed at the same times each day, mix rations evenly, and weigh or measure feed so each load matches the plan. Make sure there is enough bunk space so every calf can eat without a fight.

Weather swings can change intake sharply. After a storm or a hot spell, check with your nutritionist before returning to the usual feeding level. Feed additives such as ionophores have a place in some programs, but they work through label directions and professional guidance, and they are not a substitute for a gradual adaptation.

When to call for help

Call your veterinarian if calves look sick, if you find a death loss or if several calves are off feed together. Call your nutritionist when manure changes, intake swings or the ration schedule is not working.

Any treated animal must be held for the withdrawal time on the label or set by your vet, and the beef supply is protected by following it exactly.

After you finish a pen, review how it went with your nutritionist and vet. Note health records, sick calves pulled, any deaths and how performance compared with what you expected. Those notes are the best guide for the next group.

Common mistakes

The main error is rushing the step-up because the cattle seem healthy or because feed is on hand. Others include inconsistent feeding times, uneven mixing, letting feed sit and spoil, skipping record keeping and failing to adjust after weather. Keep a log of feed delivered, intake, manure and weather to spot problems sooner.

When to get help: Ask a nutritionist to write the step-up schedule for your calves and ingredients, and call your veterinarian when calves look sick or die. Feed additives must be used only as labeled and under professional guidance, and withdrawal times must be respected.

Sources and further reading

Organization homepages are linked so you can search them for current guidance on this topic.

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