The Cow/Calf Manager "Better Diets for Cows"
Livestock Update, January 2001
John Hall, Extension Animal Scientist, Beef, Virginia Tech
Last month we talked about evaluating the nutritional status of your cows (i.e. body condition scoring) and evaluating your forages through forage testing. Now, let's work on putting those two things together to decide what you need to feed your cattle at different stages of production.
Remember feed costs represent at least 60% of the total cost involved with keeping a cowherd. So we need to concentrate on supplementing just the nutrients we need. This month we will concentrate on energy and protein supplementation, and next month we will discuss minerals.
The "6 Steps to Better Cow Nutrition" are:
Some typical Virginia forages and their nutrient values compared to cow requirements are shown in Table 1. This table illustrates some important points about forages and supplementation. First, it pays to make good hay. Notice that most of the hays that were made at the right time - boot stage to early bloom- meet or exceed most of the cows' requirements. Second, that ENERGY is the nutrient that most often needs supplemented with cool-season hays like fescue and orchardgrass. Warm-season grasses and silage need protein supplementation. Since, most of the feed supply in Virginia is cool-season hays, you should think of energy first when supplementing cows. Finally, Pre-calving and Calving Through Breeding are the times when cows usually need supplementation.
Let's look at an example of deciding on supplements. The hay on hand is the mature fescue hay and the orchardgrass hay listed in Table 1. We calve in March. So we need to plan for the Pre-calving period and the early Calving Through Breeding period since that's when we will need to feed hay. Possible supplements are listed in Table 2. The rest of the year, grazing and stockpiled fescue will feed the herd.
Step 1. Compare feed to cow requirements. After looking at the chart, the best fit is to use the fescue hay for the Pre-Calving period and the orchardgrass hay for the Calving Through Breeding period.
Step 2. Decide what nutrient to supplement. The fescue hay will need ENERGY supplementation. The orchardgrass hay will need ENERGY plus a little PROTEIN.
Step 3. Identify feeds. Good choices to supplement the fescue hay are corn, cracked corn, soybean hulls, corn gluten feed, soybean meal, whole soybeans, and whole cottonseeds as they are high in energy. Notice that several of these feeds are high in protein, but this is NOT important since we don't need extra protein to match the fescue hay to feed during the pre-calving period.
On the other hand, we need a feed that is high in energy and moderate in protein to supplement the orchardgrass for use during the Calving Through Breeding period. Good supplements for the orchardgrass are corn gluten feed, whole soybeans, soybean meal, whole cottonseeds and a 80% poultry litter 20% corn mix.
Table 1. Comparison of Cow Nutrient Requirement to Forage Analysis
|Cow Nutrient Requirements by Stage of Production|
|Weaning to 60
8.6 % CP
11.5 % CP
55 % TDN
7.5 % CP
56 % TDN
9.2 % CP
68 % TDN
8.2 % CP
60 % TDN
12.9 % CP
Step 4. Decide on best cost feed. For our supplement to the fescue hay it is easy to eliminate some choices. Soybean meal, corn gluten feed and whole cottonseeds can be quickly eliminated on price. Cracked corn can be eliminated because added energy value of cracking the corn is probably not worth the cost of cracking.
But which is a better buy, whole-shelled corn at $110/ton or whole soybeans at $135/ton? To find out we need to compare them on an ENERGY basis since that is the nutrient we need. To do that we use the following formula:
In our example, the price of whole-shelled corn per ton of energy = ($ 110/.87)/.88 = $ 143.67 per ton of Energy
The price of whole soybeans per ton of energy = ($ 135/.90)/.94 = $ 159.57 per ton of energy
Therefore, whole-shelled corn is the best buy.
You can use a similar system to decide which would be the best feed to supplement the orchardgrass hay. However, corn gluten feed or whole soybeans appear to be the best option. If protein is what we needed to supplement, then simple replace % TDN with % CP in the above equation.
Table 2. Nutrient Content of Some Feeds Common to Virginia
|Nutrient content on a dry matter basis|
|Energy Feeds||% Dry|
|Bulk Price ($)
|Corn, 56 lb/bu||87||88||9.8||4.3||100.00 -130.00|
|Corn, cracked||88||90||9.8||4.06||110.00 - 150.00|
|Barley, heavy||88||74||13.20||2.2||55.00 - 70.00|
|Brewers grains, wet||21||70||26.0||6.5||25.00 - 40.00|
|Corn gluten feed||90||80||23.8||3.9||90.00 - 100.00|
|Soybean hulls||91||80||12.2||2.1||60.00 -70.00|
|Soybean meal - 44||89||84||49.90||1.6||195.00 - 198.00|
|Whole soybean, roasted||90||94||42.8||18.8||135.00 - 150.00|
|Cottonseed meal||92||75||46.1||3.15||175.00 - 190.00|
Step 5. Work with an agent or nutritionist to calculate the amount you need to feed. For most cow diets, this is rather simple, as we usually need only one ingredient. Producers can learn how to do the calculations or some computer programs are available to perform the calculations. We teach this in our VA Cow/Calf Management Course. However, many producers would rather seek the advice of their Animal Science Extension Agent or nutritionist.
In our examples, I calculated that a 1100 to 1200 lb. cow would need 7.0 pounds of corn in addition to all the fescue hay she could eat to meet her requirements during the Pre-calving period. Because of the better quality of the orchardgrass hay, the same cow would need 4.5 pounds of corn gluten feed along with all the orchardgrass hay she could eat after calving.
Step 6. Adjust feed or diet for body condition of cows. The requirements listed in Table 1 are for cows in BCS 5 or better. Usually your agent or nutritionist will consider BCS while working on Step 5. The changes in requirements will depend on the BCS of the cows and how long we have to increase body weight of the cows. Sometimes, we can just use a rule of thumb on body condition adjustments. Roughly, you will need to increase the energy in the diet by 20% for each body condition score your cows are below BCS 5. In our example, we would need to increase the corn to 10 lb. per cow per day if cows were in BCS 4, so they could gain weight before calving. If they were BCS 3, we would need to feed over 14 lb. of corn per cow per day! However for best results, a professional should calculate thin cow diets.
Remember you need to test your own forages and calculate diets for your own herd. By using the "6 Steps to Better Cow Nutrition", you will find the process is not hard and it can result in better nutrition for your cows for less money!!