Ask the Vet

Grain overload

I recently had a group of large heifers break a gate and get in with my steers. They appeared normal until the next day, and then they got very sick. Why does that happen?

Answer: What you experienced was acute rumen acidosis, which is commonly referred to as grain overload. It is caused by the sudden ingestion of fermentable carbohydrates, which are usually some form of grain. The cascade of events that happen thereafter depends on the amount of grain consumed by each animal. Usually in these cases there are a couple of animals that can eat more than anyone else, and they will be the most affected.

The outcome of grain overload can range from simple indigestion to death, with many problems associated with those animals that survive. The initial signs exhibited by the animals might be very slight for the first few hours. As the grain ferments, it results in a shift of bacterial populations in the rumen and a subsequent increase of lactic acid production.

At this stage you might not notice much wrong except for the animals standing around. As time progresses, more lactic acid is produced, and it will cause fluids to be drawn into the rumen. Animals will start to exhibit distended abdomens and may act uncomfortable. Rumen contractions will usually slow down or quit altogether. Animals will start to get profuse diarrhea, which often will have large amounts of grain in it. The combination of diarrhea and rumen stoppage will lead to severe dehydration. Lactic acid entering the bloodstream through the rumen wall will cause a lowering of the blood pH. Over time the decreasing blood pH will cause a cascade of events that include muscular weakness, renal failure, shock and death. All these events will happen usually within 24 to 36 hours.

Treatments for rumen acidosis are directed at counteracting the fermenting grain. Initial assessments of the animal will determine the type of treatment needed.

Mild cases are handled with rumen buffers and diet changes. The worst cases need the rumen contents removed and replaced with rumen contents from a healthy cow. Large amounts of IV fluids are given to the worst animals to help with the dehydration and to keep renal function going. If lucky, the animal will survive the next 48 hours. Those animals that survive can later develop problems such as infected rumen walls, liver abscesses and laminitis.

Grain overload cases can be frustrating for producers and veterinarians alike because no matter how aggressive the therapy, there are still going to be animals that either die right away or must be culled early.

To achieve the best outcome, it is always best to get your veterinarian out right away and start treatment if you suspect grain overload.

Castrated bulls

Last spring I purchased 140 heifers that averaged 600 pounds and 25 bulls of the same size. I knife castrated the bulls and put them in with the heifers, upon which I saw several of the bulls breeding the heifers a few hours/days later. I have given 15 heifers lutalyse and believe they all have aborted. How long after castrating do I need to hold the bulls out before I can put them in with heifers?

Answer: Knife castration removes the testes, epididymis and part of the vas deferens. There will be some mature spermatozoa still left in the remaining vas deferens and other reproductive glands of the bull. The life span of the spermatozoa in these glands has been reported to be about seven to 10 days. That means there can be a risk of pregnancy for a short time after castration of the mature bull.

To be safe, I would wait at least three to four weeks before turning any newly castrated mature bulls in with breeding-age heifers.

Monty Belmer, DVM, is a veterinarian with the Waupun Vet Service in Waupun. To Ask the Vet, e-mail your questions to: foleary@farmprogress.com, or mail them to: Wisconsin Agriculturist, 102 E. Jefferson St., P.O. Box 236, Brandon, WI 53919.

This article published in the May, 2010 edition of WISCONSIN AGRICULTURIST.

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