Category Archives: Livestock

We are pretty much past the point of being able to establish winter forages with our drought persisting. We generally don’t feed hay until Thanksgiving, but our cattlemen have been feeding hay for a while now. Here is a great article by Glenn Selk, Oklahoma State University Emeritus Extension Animal Scientist.
Estimating forage usage by cows is an important part of the task of calculating winter feed needs.  Hay or standing forage intake must be estimated in order to make the calculations.  Forage quality will be a determining factor in the amount of forage consumed.  Higher quality forages contain larger concentrations of important nutrients so animals consuming these forages should be more likely to meet their nutrient needs from the forages.  Also cows can consume a larger quantity of higher quality forages.

Higher quality forages are fermented more rapidly in the rumen leaving a void that the animal can re-fill with additional forage.  Consequently, forage intake increases.  For example, low quality forages (below about 6% crude protein) will be consumed at about 1.5% of body weight (on a dry matter basis) per day.  Higher quality grass hays (above 8% crude protein) may be consumed at about 2.0% of body weight.  Excellent forages, such as good silages, or green pasture may be consumed at the rate of 2.5% dry matter of body weight per day.  The combination of increased nutrient content AND increased forage intake makes high quality forage very valuable to the animal and the producer.  With these intake estimates, now producers can calculate the estimated amounts of hay that need to be available.

Using an example of 1200 pound pregnant spring-calving cows, let’s assume that the grass hay quality is good and tested 8% crude protein.  Cows will voluntarily consume 2.0% of body weight or 24 pounds per day.  The 24 pounds is based on 100% dry matter.  Grass hays will often be 7 to 10% moisture.  If we assume that the hay is 92% dry matter or 8% moisture, then the cows will consume about 26 pounds per day on an “as-fed basis”.  Unfortunately we also have to consider hay wastage when feeding big round bales.  Hay wastage is difficult to estimate, but generally has been found to be from 6% to 20% (or more).  For this example, let’s assume 15% hay wastage.  This means that approximately 30 pounds of grass hay must be hauled to the pasture for each cow each day that hay is expected to be the primary ingredient in the diet.

After calving and during early lactation, the cow may weigh 100 pounds less, but will be able to consume about 2.6% of her body weight (100% dry matter) in hay.  This would translate into 36 pounds of “as-fed” hay per cow per day necessary to be hauled to the pasture.  This again assumes 15% hay wastage. Accurate knowledge of average cow size in your herd as well as the average weight of your big round bales becomes necessary to predict hay needs and hay feeding strategies.

Big round hay bales will vary in weight. Weighing a pickup or trailer with and without a bale may be the best method to estimate bale weights. There are other calculations that can be helpful in estimating hay bale weights as seen in the chart below. Visit What Does A Round Bale Weigh to read more information from UGA Forage Specialist Dr. Dennis Hancock.

With warm weather back, UGA Extension Beef Scientist Dr. Lawton Stewart warns us about potential for grass tetany. Here is an article by Dr. Deidre Harmon and Dr. Stewart:

I’m putting out High-Mag mineral, but cows are still going down?

What is grass tetany and why is magnesium important?

Grass tetany, also known as grass staggers, magnesium (Mg) tetany, hypomagnesemia, and wheat pasture poisoning, is a nutritional disorder caused by either 1) an inadequate amount of dietary Mg, or, 2) other mineral related factor that is preventing (antagonizing) dietary Mg from being properly absorbed or utilized.  Magnesium is considered a macro mineral and is needed in beef cattle diets to insure proper growth, reproduction, and metabolic function.  When dietary Mg is low or utilization is inhibited, neuromuscular function becomes impaired and leads to the clinical symptoms of staggering, muscle twitching, convulsions, and in severe cases, can lead to death.  This disorder is most common during cool, cloudy, and rainy weather, and frequently occurs when cool weather is followed by a warm period.

Why is magnesium an issue during this time of year?

• Mg is essential, especially during lactation – Spring calving cows are highly susceptible to grass tetany because they reach peak lactation (require increased amounts of Mg) during the same time as the spring green. This onset of abundant lush forage is associated with decreased amounts of forage Mg. Older cows are more susceptible because they cannot mobilize Mg from reserves in the bone as quickly as younger cows.
• High potassium (K) content is also associated with lush, growing forages. Although K is essential, in large amounts, it can work as an antagonist to reduce Mg uptake from the soil and Mg absorption in the rumen.

I’m putting out High-Mag mineral, but I am still losing cows?

• Not consuming enough – There may be a palatability issue, especially when Mg is increased in the mineral.  However, cows typically do not voluntarily consume as much mineral this time of year.
• High-Mg mineral if fed year-round – Sometimes, the strategy is to put high-Mg mineral out all year as an “insurance policy” – High-Mg mineral is only needed during the short period of time that grass tetany may occur.  Feeding the miner year-round may condition cattle to not consume enough during the time they really need it.
• Not enough salt – Magnesium transport across the rumen wall can be reduced if 1) there is not enough salt in the diet, and, 2) if there is too much K in the diet. Collectively, too much K and too little salt can cause grass tetany, even if Mg intake is adequate.

What can I do?

• Know exactly what cattle are consuming – Do the math based on how much mineral you’re putting out, how many cows, and how fast it is being consumed. Calculate the mineral on an oz/hd/d basis and determine whether or not their consumption meets requirements. Table 1 illustrates calculated consumption based on different feeding rates and herd sizes.
• Increase intake (if need be) by mixing with feed and/or salt.  Again, do the math to ensure the correct intake.  OVER CONSUMPTION WILL NOT FIX THE PROBLEM.
• Add salt – In addition to increasing the mineral intake, additional salt will ensure that the sodium requirement is being met and thus, help to maximize absorption of Mg. DO NOT DO THIS IN PLACE OF HIGH MAG, rather in addition to. This can be as simple as putting out plain white salt blocks.

Table 1. Calculated weekly consumption amounts for different feeding rates and herd sizes.

We’re moving toward our winter season now as cattlemen have been testing forage for quality and supplemental needs. At this time, we can still make changes if needed. Here is a good article written by Effingham Ag Agent, Sam Ingram, on winter forage needs:

“It was my understanding that there would be no MATH!”

To begin the process of calculating the hay inventory needed for the winter, a producer does not need to do math! The first step is simple, send a forage sample in to a certified lab to determine the forage quality. The cost of this analysis is minimal and the lab does the math for you. The quality of the forage will determine the amount needed during the winter feeding period.

Once the producer receives and understands the forage quality analysis, they then can determine how much hay they will need to supplement. A simple example below shows how a producer can determine their hay needs:

A producer has 50 mature brood cows at 1,200 lbs., 2 bulls at 2,000 lbs and 10 weaned replacement heifers at 500 lbs. If we assume these animals must consume 2.5% of their bodyweight per day, we can say that:
Brood Cows will require 1500 lbs./day (= 1200 lbs X 2.5 lbs of DM/100lb of b.w. X 50 brood cows)
Bulls will require 100 lbs./day (= 2000 lbs X 2.5 lbs of DM/100lb of b.w. X 2 Bulls)
Yearling Heifers will require 125 lbs./day (= 500 lbs X 2.5 lbs of DM/100lb of b.w. X 10 Heifers)
So, daily hay required would be 1725 lbs. of dry hay (that is at 0% moisture or on a dry matter basis).

The calculation of 1725 lbs. of forage is on a dry matter basis. This means that if we bale the hay or receive hay at 85% Dry Matter (DM), 15 % is water and we do not account for that during feeding. So, a 1,000 lb. bale at 85% DM, would be 850 lbs. on a dry matter basis.

To continue on the calculation we need to estimate our feeding period. For this example we will say a producer needs to feed 120 days. So, if we multiply this number by our daily requirement we get an estimation of 120 days X 1725 lbs. = 207,000 lbs. of DM. If we assume the producer has 85% DM hay, then the as fed total would be approximately 244,000 lbs.

To account for storage loss and feeding loss (assuming barn stored and fed with a hay ring), we can conservatively add another 15% to the “as fed” total and get a total of 280,600 lbs. In this situation, for this moderate size herd, we need roughly 280 – 1,000 lb. round rolls of hay.

Now, depending on where the producer’s brood cows are in their calving season during the winter feeding period will determine if further supplementation is needed. A great option to decrease the need for stored forage or hay is to grow some high quality winter annual grasses. A cow is much more cost-effective at harvesting forages than we are with machinery and these annual grasses can save time producing and feeding hay.

In the end, producers need to think about their current hay inventory and start calculating for this coming winter. With current grain prices, a concentrate supplement may work to stretch hay more cost-effectively. Either way, a producer needs to plan their winter feeding program to avoid overpaying for any forage or supplement when supplies get tight.

Last year, we had many discussions and questions about supplementing minerals. Here is some information on this topic from UGA Extension Animal Scientist Dr. Lawton Stewart:

I have heard several comments that producers are cutting P out of their mineral, because they are using poultry litter as fertilizer. Although there is potential to improve the P levels in forage with little, assumptions are being made on the ability of the plant to make the P available to the animal. This is one of the examples of how we need to make sure we’re cutting cost and not cutting corners in our production system.

In fact, some producer may cut minerals out all together to help cut cost, because performance does not appear to change. Short term maybe, but the long term consequences may be more costly. If you look at a cow/calf annual budget, minerals represent only about 3.5%; a very small cost to insure health and performance. The greener pasture we’re seeing may reduce the feed bill, but we need to remember many forages in the Southeast are deficient in several minerals. Although minerals represent a small cost in total budget, we can cut some extra expenses by taking a second look. We can learn a lot by getting our forages tested and reading the mineral tag.

Forage Testing is the cheapest initial investment you will make. We must have a starting place if we want to know what minerals, and how much we need in our minerals.

1. Calcium and Phosphorus – These are two macro minerals that need to be addressed together due to their interaction in the biological processes. On well managed pastures, forages are typically close to meeting the requirement of brood cows, but are deficient for growing cattle. However, almost as important as the quantity of these is their ratio. The ratio of Ca to P needs to be greater than 1.5:1.
2. Sodium and Chlorine – More commonly referred to as salt, these minerals are the only ones cattle will crave and need to be offered daily.
3. Magnesium – This is a crucial mineral when cattle are transitioning into and during lactation. Generally, extra Mg is only needed during this lactation while grazing lush pastures. Often times, producer do not realize they are feeding Mg unnecessarily through the summer.
4. Sulfur – Although S is essential, it is not usually limiting in the diet. However it may be present in mineral mixes due to inclusion of other minerals as sulfates. The concern with S is its antagonism with copper, selenium, and the B vitamin thiamin. Therefore, it sometimes is necessary to feed additional copper and selenium to compensate this antagonism.
5. Micro minerals – These mineral needed in smaller amounts such as copper, zinc, and selenium. Most forages are deficient in these minerals and need to be offered as a trace mineral pack.

Read the mineral tag

• We can learn a lot by reading the mineral tag. Usually, the mineral company makes mixes to fit general needs. Some of these may fit your operation; however, there may be times your’re paying for ingredients you don’t need an/or not getting what you need.
• Check for the right mineral levels. Going back to our forage test, make sure you are getting the appropriate levels of each mineral and Ca:P ratio. If a supplement is being used, make sure you consider the mineral content. For example, if distiller’s grains or corn gluten feed is being utilized, P should be adequate, but Ca should be supplemented to maintain the proper Ca:P ratio.
• Look for additives. Often additives such as ionophores (Rumensin, Bovatec), antibiotics (chlortetracycline, GainPro), and fly control compounds (IGR) are administered through mineral mixes. Although these may improve performance, they may not be wanted in your operation and come at additional cost.

If the local feed store doesn’t provide the mineral that fits your production system, many will work with you to formulate a custom mix to provide the nutrients you need. The table below presents an example of a free choice minereal for lactating cows grazing in bermuda pastures. Remember, our goal is to cut cost and not corners to survive in the cattle business. For a complete description of both macro and micro please refer to the UGA publication Mineral Supplements for Beef Cattle.

We have run quite a few samples of hay to test forage quality these last few weeks and had many questions about supplementation. We were originally concerned about nitrate levels with end of season drought stress. However, we have not found any toxic nitrate levels, but have observed some low quality hay. Here is some information from Effingham County Ag Agent Sam Ingram:

Like many of us, annual and perennial grasses are anxiously awaiting warmer temperatures and more sunshine in the day. But as of now we  are still waiting, and this means our beef cattle producers are still feeding hay from last season which may be low in quality. This time of year there are calves on the ground nursing and bulls in the pasture breeding brood cows. With the demand set high for the brood cows, good nutrition is essential during this period. If a producer is feeding lower quality hay from last year, extra supplementation may be needed. Dr. Jacob Segers and Dr. Lawton Stewart developed a simple sheet to help producers decide if supplementation is needed in addition to their hay. A forage sample should be taken from your hay to determine the quality, a simple “estimation” is not enough to accurately supplement for the cattle.

The table above shows that majority of our cows can maintain body weight and a calf on their side with average forage. But as our quality starts to drop and our total digestible nutrients (TDN) falls below 50%, we need to look at supplementation. Those disgetible nutrients can be traced back to maturity of the grass and when it was cut. The last cutting of hay tends to be the lowest quality and that last cutting is now what most producers are feeding. If a producer wants to increase their quality, fertility is a great place to start but also cutting the forage at the right time will maintain good quality.