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Veterinarian View | November 2023

Fall Preparations for Cow Herds

contributed article by Dr. Vince Collison, Collison Embryo and Veterinary Services,

Rockwell City, Iowa

As we move into fall and winter it’s time to review and expand on a few things from prior articles.

Tracking Calving Windows

If you want to use ultrasound for pregnancy checking, the window for accurately measuring fetal age is from 30 to 120 days of pregnancy. This is probably one of the best tools available for managing calving or marketing breds. We will have producers who tag cows with a different color-coded tag for each designated time frame for calving. Usually this is just a blank feedlot tag, using three to four different colors. The intervals are broken up by two to three weeks each depending on the producer’s preference.

We have one producer who will use a different colored zip tie around the neck of the permanent numbered tag. This zip tie is cinched down tight, and the tail cut off closely so as to not catch on anything and tear out the tag. This will save putting another hole in the cow’s ear and the colored zip ties are fairly easy to see.

This program makes sorting a lot easier, but we still like to have the producer keep a record of the fetal age, so they have a precise record of when the cow is due. If you’re selling bred heifers, having this information can help you in the marketing of them.

Collecting DNA

If your herd has cows that need DNA samples collected for parentage, genomics or genetic defect testing, pregnancy checking is a great time to collect these samples. Most of these tests take some time to run and by doing it now, you will have results well in advance of any future breeding decisions that need to be made next spring.

Conducting Assessments

If you have the ability to feed cows in separate groups, body condition score cows at the time you preg check. If you feed first calf heifers separately, you can also feed the thinner cows with them so they can compete better and get access to more feed.

Administering Vitamin A

With the current drought much of the Midwest is experiencing, you can expect that the vitamin A content in harvested forages and grazed pastures may be lowered. If you feed a total mixed ration in the fall or winter, you may consider adding a vitamin A pack to the ration. This can be done very cheaply per head and works very well.

The other possibility is to use some form of injectable vitamin A product. This also works very well and will provide enough vitamin A to store in the liver for three to four months. The downside of injecting vitamin A is that reactions are fairly common, especially if given at the time other vaccinations are done.

If giving at the same time as other vaccinations, it is best to give vitamin A on one side of the neck and give other vaccinations on the opposite side. Most of these reactions are transient and not fatal, but I have talked to producers who have lost cows after using the injection. It would be prudent to keep epinephrine on hand when injecting vitamin A.

Feeding Proteins

As cows are kicked out on stalks, be sure their protein needs are being met. This can be done with protein tubs, lick tanks or other means. The main role of protein is to feed the bacteria in the rumen that break down the cellulose in forage to make it digestible.

The other role of protein is to increase intake of forages. Studies have shown that cows consuming a diet at 5 percent protein will consume about 1.6 percent of their body weight, whereas cows consuming a diet at 7 percent protein will consume 2.3 percent of their body weight.

Protein is also critical for fetal programing and restriction will adversely affect the fetus affecting its epigenome. When fetal programing is affected in a negative way, it will cause issues that will affect the calf after birth. Replacement heifers that have had optimal fetal programing will produce better and stay in the herd longer. Also, calves born to cows that are restricted on energy and protein can have increased morbidity and mortality. Some of these problems can be attributed to lower birth weights.

Another good source of protein is raw soybeans. If there are harvested soybean fields adjacent to the stalk field, cows can benefit from gleaning the soybean stubble. There are also oils in the raw soybean that will help to develop brown fat in the calf prior to birth. Brown fat is a primary energy source for newborn calves and can help to increase viability and the calf’s ability to deal with stress at birth such as inclement weather and colder temperatures.

Processing of soybeans affects the oil in a way that it will not develop brown fat in the calf in the same way that the raw soybeans will. Years ago, I actually had a client that was having issues with calf viability at birth and the next year he fed his cows 1 pound of soybeans per cow starting one month prior to calving. The results he reported were very good. Calf viability was greatly improved. He stated that if he didn’t get the calf tagged shortly after birth, he was having trouble getting the calf caught to tag.

These are just a few of the many things to think about as we get closer to winter, but we feel these topics are high on the priority list and can make a big difference when calving starts.

Dr. Vince Collison is co-owner of Collison Embryo and Veterinary Services PAC

in Rockwell City, Iowa.

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