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Limit-Feeding Grain: An Option to Manage Tight Forage Supplies

Greg Lardy, NDSU Animal and Range Sciences


Highlights


 

Table of Contents

 

Types of Cereal Grains

Cost per Unit of Energy

Managing Cows on High Grain Diets

Summary



Types of Cereal Grains

Almost any cereal grain can be fed to beef cows as part of a gestation or lactation ration. However, grains differ in nutrient content and rate of starch fermentation (Table 1). Corn and wheat have the greatest energy content, while oats and barley are somewhat lower. Protein content of barley and wheat is greater, and may reduce or eliminate the need for supplemental protein. Wheat and barley starch ferments very rapidly in the rumen, and as a consequence, tend to be more difficult to feed. This can result in greater problems with metabolic disorders.


Properly processed grains should be coarsely ground and should not contain fines or floury material as this increases the likelihood that metabolic disturbances will occur. In some cases, corn and oats do not need to be processed and can be fed whole. Barley should be coarsely processed due to its relatively indigestible hull.


Table 1. Nutrient content of selected cereal grains1.

Nutrient2

Barley

Corn

Wheat

Oats

CP (%) 

13.2

9.8

14.2

13.6

TDN

88

90

88

77

NEm (Mcal/kg)

2.06

2.24

2.18

1.85

NEg (Mcal/kg)

1.40

1.55

1.50

1.21

Calcium (%)

0.05

0.02

0.04

0.07

Phosphorus (%)

0.47

0.31

0.44

0.36

1Adapted from NRC, 1996, and AS-1182, Alternative Feeds for Ruminants.

2CP, crude protein; TDN, total digestible nutrients; NEm, net energy for maintenance; NEg, net energy for gain; Mcal/kg, mega calories per kilogram.


Cost Per Unit of Energy

In the past, cereal grains, and in particular, corn, have had a lower cost per unit of energy source than forages, particularly in areas affected by drought. However, the upturn in corn prices in the fall of 2006 has changed that picture somewhat. Currently, the cost per unit of total digestible nutrients (TDN) for corn is greater than hays and other forages. Because of the energy density of cereal grains (Table 2), the typical cost per unit of energy is lower than forages in most cases; so there may still be opportunities to utilize grain in rations for wintering beef cows.

 

Table 2. Effect of corn price on price of TDN.

Corn Price ($/bushel)

Corn Price ($/ton)

Price of TDN ($/ton)

1.50

53.57

59.52

1.75

62.50

69.44

2.00

71.43

79.37

2.25

80.36

89.29

2.50

89.29

99.21

2.75

98.21

109.13

3.00

107.14

119.05

3.25

116.07

128.97

3.50

125.00

138.89

3.75

133.93

148.81

4.00

142.86

158.73


Managing Cows on High Grain Diets

 

Managing beef cows on a diet consisting mainly of cereal grains requires more intensive management than wintering cows on forage diets. Cereal grains ferment rapidly in the rumen. Consequently, a high degree of management is necessary to avoid acidosis, founder, and other metabolic disorders.


Cows should be adapted to high grain diets in routine, incremental steps over the course of two to three weeks. Since grain is more energy dense than forages, cows will require less grain than the forage it replaces. As a result, cows will appear hungry and will aggressively seek out feed even though their energy needs are being met. Tight fences and adequate bunk space are necessary to manage cows fed these rations. A minimum of 30 inches of bunk space should be allowed for each cow (more for larger cows) so that every cow can get to the bunk at the same time when the ration is offered. If this is not the case, some cows will receive more of the ration than intended while others will not receive enough.


The roughage in the ration needs to be a minimum of 0.5 to 0.75 percent of body weight, which is equivalent to approximately 6 to 9 pounds of roughage for a 1,200 pound cow. This will ensure the ration contains adequate roughage to promote rumination, salivation, and normal rumen function. It also helps reduce the risk of metabolic disorders such as acidosis. Grains contain low amounts of calcium while at the same time containing greater amounts of phosphorus than typical roughages. As a result, it is necessary to provide supplemental calcium in the form of limestone or some other calcium source to maintain the proper calcium-to-phosphorus ratio (minimum of 1.5 to 1).


In order to meet the protein needs of both the ruminal microorganisms and the cow, supplemental protein is needed when corn is the primary cereal grain. Urea can be used as a portion of the supplemental protein, but other natural protein sources are also effective. Supplemental vitamin A should be provided in the ration to protect against vitamin A deficiency since it is generally low in most cereal grains.


Ionophores such as monensin or lascalocid can be used in high grain rations to improve energy efficiency and keep cows on feed. Do not attempt to self-feed supplements containing ionophores. These feed additives should be included as an ingredient in the protein supplement and mixed in the ration to ensure adequate daily intake.


Monitor cattle daily. Any animals that appear sick or uninterested in feed should be carefully evaluated and treated appropriately. Cow body condition should also be monitored periodically. If cows appear thin, adjust the amount of ration offered.

Summary

 

In an effort to reduce the cost of winter-feeding, beef cows can be limit-fed on diets consisting largely of cereal grains. However, pay careful attention to feeding management to ensure the program is successful. Take steps to ensure that cows have adequate bunk space and grains are properly processed to reduce the risk of digestive disturbances.


The dramatic upturn in corn prices experienced this fall means the use of corn in this type of feeding program is not economical at this time, but opportunities may exist for using other cereal grains, byproducts, or alternative feeds in limit-feeding programs.


NDSU Central Grasslands Research Extension Center
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