Limit-Feeding Concentrate Diets to Beef Cows
KC Olson, Ph.D., PAS, Dipl. ACAN
Beef Nutrition and Management Specialist
Commercial Agriculture Program

Alternative nutritional management of beef cows is called for when hay and pasture stocks are low. Harsh conditions are predicted for much of the Midwest during the winter of 2001 and that coming close on the heels of dry summer and fall weather. With a likely shortfall in forage availability, cow-calf operators may wish to consider limit-feeding concentrate diets to mature cows. This practice can be an economical alternative to feeding forage. When compared based on the amount of feed energy supplied per unit of weight, grains and grain-milling byproducts are often less expensive than hay.

Limit-feeding beef cows involves supplying the animal with just enough grain or grain byproducts to maintain its body condition, produce a targeted amount of milk, and, if necessary, to achieve a targeted amount of weight gain. This can be accomplished with little forage added to the diet. Compared with a standard forage diet, limit-fed diets are more energy dense. The amount of these high-energy rations made available for consumption on a daily basis must be closely controlled to prevent digestive disorders (e.g., acidosis, founder, and bloat). As a result, limit-feeding requires a fairly high degree of management skill to implement safely.

Several items must be kept in mind when considering a limit-feeding program for beef cows. Any time ruminant animals are switched from a high-forage to a high-concentrate diet, resident microorganisms in the rumen may require up to 14 days to adapt to the new feeding regime. As a result, changes in the diet must be achieved by very gradually increasing over time the amount of grain relative to hay in the ration. The preferred adaptation period is 14 days in length to accommodate the switch from a high-forage to a high-concentrate diet. Conversely, ruminant livestock can usually be switched from a high-concentrate to a high-forage diet quite rapidly.

In order for a limit-feeding program to work properly, care must be taken to ensure that feed intake patterns are consistent over time. Cattle must be fed at roughly the same time each day with very little fluctuation in the amount offered. Concentrate-based rations should be offered to livestock in bunks to prevent excessive feed wastage. Mature cows require 24 to 30" of bunk space per head in order to ensure uniform consumption. Less than adequate bunk space causes erratic, non-uniform feed consumption patterns within the herd. The results can be dire and include reproductive failure, bloat, and acidosis. Researchers at Ohio State University have noted that even properly managed limit-fed cows often appear gaunt and behave as though they were hungry. It is important to resist the temptation to provide these animals with additional feed. Doing so can eliminate any economic advantages to the limit-feeding program. Cattle should be evaluated on the basis of body condition only to determine whether adjustments in the daily feeding amounts are desirable. If such adjustments are called for, increases should be achieved gradually.

Small amounts of long-stem forage can continue to be offered to cows managed under limit-feeding programs. Forage serves to maintain ruminal health and aids in preventing potentially serious digestive disorders. Oklahoma State researchers recommend that long-stemmed hay be fed at 0.25 to 0.50% of animal body weight in addition to the grain or grain byproduct portion of the diet.

The concentrate portion of the diet should be constructed from feeds that complement the basal forage. That is, concentrate feeds should ideally be low in starch, high in fiber, and moderate to high in protein. Feeds that fit into this category are cottonseed hulls, soybean hulls, corn gluten feed, brewer's grain, distillers dried grains, and rice meal. Corn and other high-starch feeds can also be used in limit-feeding programs; however, there is a greater risk of digestive disorders involved with feeding extremely starchy grains. In the case of corn, the risk is reduced substantially by feeding the grain in whole form. Grinding or rolling serves to increase the rate of starch digestion in the rumen and, in so doing, increases the risk of acidosis and bloat.

A few specific limit-fed high-energy rations are listed below. Please keep in that nutrient content of feeds, particularly milling byproducts, can vary widely among sources. When considering a limit-feeding program, consult with your local extension professional or veterinarian for a ration formulation that is specific to your needs.

Beef producers that are not equipped to handle grain or grain byproducts in bulk may opt for commercially prepared rations for their particular limit-feeding program. Cubed or pelleted feeds are available from Missouri feed retailers that are well suited to limit-feeding. Most of these are designed to be fed with hay or pasture supplied at 0.5% of animal body weight per day.

Recently, the strategy of limit-feeding was tested at the University of Arkansas Southwest Research and Extension Center located in Hope (Prof. Anim. Sci. 16:220). A research team led by Dr. Stacey Gunter evaluated several different limit-fed diets for mature beef cows in relation to free-choice hay feeding. One-hundred-sixty cows maintained on drought-stricken pastures were stratified according age, body condition score, and body weight and randomly assigned to receive one of five diets: free-choice hay + corn gluten feed supplement (control); corn + cottonseed hulls (treatment 1); corn + rice hulls (treatment 2); corn gluten feed + cottonseed hulls (treatment 3); and corn gluten feed + rice hulls (treatment 4). All diets were formulated to meet maintenance energy requirements (NE_m) and provide similar metabolizable protein yields. Diets were fed to cows during the fall and winter for a period of 87 days.

Cows receiving the limit-fed diets weighed less than cows receiving free-choice hay at the end of the trial. This was due to the fact that limit-fed cows consumed an average of 55.2% less dry matter per day than cows fed hay free-choice. Authors speculated that this fact resulted in a much lower level of gut fill for the limit-fed cows.

In contrast, body condition score of cows was not affected by dietary treatment, indicating that all diets were supplying sufficient protein and energy to meet production goals. Cows fed hay free-choice cost approximately $1.03 per day to maintain during the study, whereas limit-fed cows cost an average $0.54 per day. After the study, all cows were returned immediately to forage-based diets. No subsequent differences between treatments were noted for body weight, body condition score, calving date, or calf performance. Moreover, cattle made the transition from a high-concentrate to a high-forage diet very smoothly. Gunter and colleagues concluded that limit-feeding of high-concentrate diets to gestating cows is a viable alternative to feeding hay during periods when hay and pasture stocks are in short supply.

Site maintained by people at AgEBB
agebb@missouri.edu

University of Missouri Extension does not discriminate on the basis of race, color, national origin, sex, religion, age, disability or status as a Vietnam-era veteran in employment or programs.