1998 Drought Information - Limit Feeding

Limit Feeding Concentrate Diets To Cows

David Lalman
OSU Animal Science



IN YEARS when hay and forage production is low due to drought, hay prices often escalate and in severe cases, forage of any kind may be hard to come by. In situations like this, some producers should consider limit feeding concentrate diets to cows. Depending on the price of grain, nutrients to maintain and grow cattle may be cheaper to purchase through concentrate feeds rather than roughage.

This nontraditional approach is often referred to as "program feeding" or "limit feeding". The basic principle is to feed corn (or some other concentrate energy source) and a supplement in just enough quantity to meet the animal's requirement for maintenance or a targeted level of weight gain. In most cases a very limited amount of roughage will be fed, but only enough to keep the animal's digestive system healthy. It is referred to as limit feeding because the diet is much more nutrient dense compared to hay or dry grass, and the amount consumed must be limited; otherwise, there is no benefit in terms of feed cost savings and the animals get too fat.

Limit feeding will not be for everyone. In fact, this technique may be limited to a small percentage of cattle producers in Oklahoma. Adoption will be limited by the additional labor requirement, management skills, feed storage capacity, and the availability of feed bunks, feed delivery equipment and a well drained dry lot or sacrifice pasture. The cost effectiveness of limit feeding will depend on each producer's price of alternative forage, the price of grain and the price of the supplement needed for the hay or the limit feeding program. This fact sheet will focus on limit feeding beef cows, and is intended to provide a few management tips to help producers evaluate the opportunity to utilize this technique.

Comparing feed energy sources

Nutrient content of corn grain is relatively consistent. According to the National Research Council (NRC), corn is approximately 88 to 90% TDN, 10% crude protein and contains 1.02 megacalories (Mcal) of net energy for maintenance (NEm) per pound of dry matter (DM). However, harvested forage is extremely variable in terms of nutrient content. Consequently, it is critical to test hay for nutrient content in order to accurately evaluate and adjust the feeding program. The value of corn versus hay as an energy source is variable, depending on hay quality as well as the price of hay and corn (Table 1).

Table 1. Cost of energy (TDN) for cattle based on hay price, corn price and hay quality.
$/Ton Corn
$/Ton of TDN
Low Quality Haya
$/Ton of TDN
Avg Quality Hayb
$/Ton of TDN
50 56 109 93
60 66 130 111
70 78 152 130
80 88 174 148
90 100 196 167
100 110 217 185
110 122 239 204
a46 percent TDN
b54 percent TDN

When low quality grass hay can be purchased for $50 per ton, the cost for energy from corn would be approximately equal when corn is priced at $100 per ton. In the case of the high quality hay example, energy from corn would cost the same at approximately $85 per ton.

Results from previous work

Results from studies conducted in Ohio are shown in table 2. After each winter feeding period, cows were turned out to pastures and monitored for grazing weight gain as well as reproductive performance. It was concluded that the limit fed diets could reduce winter feed costs by nearly one half when hay was expensive and grain was cheap, without sacrificing pasture performance or reproductive performance. It was noted that the cattle acted hungry, especially during the first few weeks of each trial. In fact, the cows consumed the bark off of trees that were located in the pens. Calf birth weights were slightly increased with the corn diet, but there was no difference in calving difficulty. Other studies conducted in Illinois and Kansas have also concluded that cow performance with limit feeding can be equal to traditional free choice hay and supplement diets.

Table 2. Animal performance and feed costs for cows limit-fed a concentrate ration or fed free choice haya
Item Limit-fed corn Free choice hay
Trial 1 Weight change, Lb.
DM intake, Lb.
Hay, Lb.
Corn, Lb.
Supplement, Lb.
Feed cost, $/dayb
4.4
15.6
2.6
10.4
2.6
$.77
-31
32.2
32.2
-
-
$1.50
Trial 2 Weight change, Lb.
DM intake, Lb.
Hay, Lb.
Corn, Lb.
Supplement, Lb.
Feed cost, $/dayb
-117.0
15.2
1.8
10.8
2.6
$.75
-51.7
29.1
29.1
-
-
$1.36
Trial 3 Weight change, Lb.
DM intake, Lb.
Hay, Lb.
Corn, Lb.
Supplement, Lb.
Feed cost, $/dayb
-48.5
17.0
2.2
12.6
2.2
$.81
-136.6
29.5
29.5
-
-
$1.37
aFrom Loerch, 1996, Journal of Animal Science, 74:1211. All studies were conducted from November through early April using spring calving beef cows with average initial weight of 1340 pounds.
bAll costs calculated using the following values: corn = $2.00 per bushel, hay (9.5% CP and 72% NDF) = $80 per ton, supplement = $150 per ton.

Feeding Management

The following table includes guidelines for rations based on corn grain, supplement and a minimal amount of long stemmed hay.

Table 3. Guidelines for limit fed rations based on corn grain
Amount to be fed
Stage of Production Corn 38 to 44%
Protein Supplement
Long stemmed
grass hay
Gestating .75% of body weight 2 lb per day .5% of body weight
Lactating, Avg Milk 1% of body weight 3 lb per day .5% of body weight
Lactating, High Milk 1.1% of body weight 3.5 lb per day .5% of body weight

Using these guidelines, Table 3 demonstrates examples of limit fed rations based on corn grain for a 1200-pound cow with average milk production and in average body condition.

Table 4. Limit fed corn rations for gestating and lactating cows.
Ingredient Gestation Early Lactation
-------- Lbs. Per day, as-fed basis --------
Grass Haya 6 6
Corn Grain 9.0 12
Protein supplement (38-44%) 2.0 3
Limestoneb .2 .25

aHay = 89% dry matter, 5% crude protein and 48% TDN. Quantity of hay fed daily can be gradually reduced to around 4 pounds if whole shelled corn is fed. If processed corn is fed, begin feeding .75% of body weight and gradually reduce to .5%.
bLimestone is a calcium source and is not required if protein supplement contains at least 2.5% calcium.

CAUTION: During drought years, some of the corn crop may be contaminated with aflatoxin; a toxic compound produced by molds. Make certain the grain you buy is not contaminated! See your local county extension Agriculture Educator for more details on aflatoxin contaminated grain.

Supplements for limit fed diets based on corn grain

These diets require added limestone as a source of calcium to offset the high phosphorus content of corn. Salt and Vitamin A should also be provided in the supplement or in a free choice mineral. Mineral supplements designed specifically for cattle grazing wheat pasture have high calcium, low phosphorus content, and should work well for cows receiving a limit fed corn ration.

Vitamin A supplementation must not be overlooked in years when forage quality is low, in any kind of feeding program. Conditions that lead to Vitamin-A deficiency include situations where cattle are fed

  • High concentrate diets;
  • Bleached pasture or hay grown during drought conditions;
  • Feeds that have received excess exposure to sunlight, air, and high temperature

Gestating beef cows need around 30,000 international units of Vitamin A per day while cows in early lactation need 50,000 units of Vitamin A.

Several Oklahoma feed manufacturers have supplements formulated for this purpose. The following table includes a protein supplement specifically designed for limit feeding beef cows. This supplement, or a similar one can be mixed with the corn, or top dressed over the grain. For whole shelled corn diets, the supplement should be made in a 1/4, 5/16 or 3/8 inch pellet.

Table 5. Protein supplement for limit feeding corn to beef cows
Ingredient Percent, As-fed basis Pounds per Ton
Soybean meal, 47%a
Wheat middlings
Limestone, 38%
Cane molasses
Salt
Urea
Dicalcium Phosphate
Potassium chloride
Copper sulfate
Selenium 600
Zinc oxide
Vitamin A, 30,000 units per gram
Rumensin 80®b
Total
59.00
23.06
5.00
3.75
2.50
2.25
3.00
1.00
.04
.15
.02
.15
.075
100
1180
461.3
100
75
50
45
60
20
.7
3
.4
3
1.5
2000
aCotton seed meal can be substituted for one half the soybean meal.
bTo provide 60 mg Rumensin per pound of supplement.

Additional management tips

Feeding diets high in grain to breeding females will require greater skill and discipline on the part of the herd manager. Acidosis, bloat, founder, etc. are always a risk when high-grain diets are fed to ruminants. These risks can be minimized by the following management practices:

  1. When starting the concentrate feeding program, gradually increase the amount of grain fed and reduce the amount of hay fed over a 2-week step-up period.
  2. Provide plenty of feeding space to accommodate uniform consumption. A minimum of 30 inches of linear bunk space per cow should be used, more if the cows are horned.
  3. Whole shelled corn is safer to feed compared to finely processed grain. If the grain must be processed, it should be coarsely rolled or cracked.
  4. Long stemmed hay should be fed at a minimum DM level of .25% and up to .5% of body weight for cattle receiving whole shelled corn. If cracked or rolled corn is used, provide a minimum of .5% body weight hay DM, but do not exceed .75%. Feeding less hay reduces the cost, but increases the need for greater management intensity. As the cattle and the manager adjust to the program, the amount of hay fed can be gradually reduced to the minimum value suggested above.
  5. Feeding an ionophore will help prevent acidosis and bloat as well as reduce the amount of feed needed by 7 to 10 percent. Rumensin® is currently the only ionophore cleared for feeding to beef cows, and should be fed at the rate of 100 to 200 mg per head per day.
  6. Feed cattle at the same time every day. Altering the time of feeding, especially in limit feeding programs, greatly increases the risk of digestive upset. An ideal feeding situation would be one where corn, hay and supplement could be placed in the bunk ahead of time. At the appropriate time of day, the cattle would be given access to the feed by simply opening the lot gate.
  7. Remember that the idea is to supply a ration in a very small package that is highly concentrated in energy. Consequently, the total pounds consumed per day will be less than what the cattle are accustomed to. The cattle will likely act hungry for the first few days. They will also have a gaunt appearance, compared to cattle receiving free choice hay or pasture. Resist the temptation to feed more because they act or look hungry. Otherwise the advantages of decreased cost and/or decreased hay utilization will be negated.
  8. Monitor body condition of cows closely and adjust amount of concentrate to maintain body condition score of 5 for mature cows and 6 for first calf heifers.

Alternatives to Corn in Limit Feeding Programs

Milo, wheat, soybean hulls, wheat middlings and corn gluten feed are also good candidates to be incorporated into limit feeding programs to maintain beef cows. However, be aware of the nutritional characteristics of each of these feeds and adjust the ration accordingly. Very few byproduct feeds can be fed as a single ingredient in complete cattle rations.

If wheat is used, it should be blended with other commodities to reduce the risk of acidosis. As a conservative rule of thumb, feed wheat at no more than .5% of body weight. Approximately 15 to 20% of whole grain wheat escapes digestion. Therefore, wheat should be coarsely cracked or rolled. However, if the cost (including added trucking and labor) of processing is greater than 20% of the value of the wheat, processing would not be justified.

In a programmed feeding situation, where very limited roughage will be fed, wheat middlings should be blended with another commodity to reduce the risk of founder and bloat. Soybean hulls work well in combination with wheat middlings because soybean hulls contain very little flour or starch.

Corn gluten feed must also be blended with other commodities. The potential problem with feeding this commodity as the sole concentrate source is the high sulfur content. Beef cattle can tolerate diets with a maximum sulfur concentration of around .4%. Corn gluten feed typically contains .3 to .6% sulfur. Corn grain and soybean hulls both have relatively low sulfur content and work well blended with corn gluten feed.

Soybean hulls may be the exception because as a single ingredient for a complete feed, they come close to providing adequate nutrients. However, depending on the source of hulls, this commodity would be slightly low in protein for a limit fed diet and is slightly deficient in phosphorus as well as some of the trace elements.

Many producers in Oklahoma are not set up to handle bulk grain or other commodities and may not have the equipment and/or feed bunks necessary to feed grain. In these cases, commercial feeds made in 3/8 or ¾ inch cubes should work well. Again, many feed manufacturers already have products on the shelf that will work well for this purpose. The following table is an example of a blend of byproducts and corn that can be made into a cube and fed on the ground. This formula was designed to be fed with .5% body weight of hay, much like the corn diets shown above. Because of the high level of corn and soybean hulls the pellets or cubes will be somewhat soft. Consequently, handling, auguring etc. should be minimized to reduce the amount of fines.

Table 6. Complete feed to be used for beef cows in limit feeding programa
Ingredient Percent, As-fed basis Pounds per Ton
Wheat middlings
Soybean hulls
Corn grain
Cane molasses
Cotton seed meal, 41%
Limestone, 38%
Salt
Copper sulfate
Selenium 600
Vitamin A, 30,000 units per gram
Rumensin 80®b
Total
37.87
29.0
24.0
4.75
2.85
.95
.5
.005
.03
.03
.0156
100
934.4
430.0
480.0
95.0
30.0
19.0
10.0
.1
.6
.6
.31
2000
aFeed at rate of 1.1% of body weight for gestating and 1.5% of body weight for
lactating beef cows. Also provide .5% body weight grass hay.
bTo provide 12.5 mg Rumensin per pound of feed.

Limit feeding concentrate diets to beef cows is a management technique that will need to be used in Oklahoma very infrequently. Grazing forages has always been and will continue to be the most economical and practical way to maintain beef cows. However, in unique situations limit feeding may be an economical alternative to purchasing expensive hay.



Oklahoma Cooperative Extension Service
Division of Agricultural Sciences and Natural Resources
Oklahoma State University