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Publication #AN117

Florida Cow-Calf Management, 2nd Edition - Feeding the Cow Herd1

Bill Kunkle, Jim Fletcher and Doug Mayo2

The keys to profitability in a commercial cow-calf operation include percentage of cows weaning a calf, calf weaning weight, and the annual cost of maintaining the brood cow. Nutrition is the most significant influence on these. You must meet the nutritional needs of your herd if you want a high calf crop percentage, heavy weaning weights, and short calving intervals.

Cattle are classified as ruminants; this group of animals is named for its characteristic four-compartment stomach, the major part of which is the “rumen.” Functioning like a large fermentation vat, the rumen houses a population of microorganisms (bacteria and protozoa) that digest forages. Cows derive energy from the volatile fatty acids produced by this microbial fermentation process, and they obtain microbial protein through digestion of the microorganisms. To function properly, the digestive system of the cow requires a balance of essential nutrients.

Essential Nutrients

Nutrients are essential for maintenance, growth, reproduction, fattening, and milk production. Nutrients fall into five classes: energy, protein, minerals, vitamins, and water.

Energy

The major nutrient required by beef cattle is energy, conventionally expressed in units of TDN (total digestible nutrients) or NE (net energy). Cattle obtain energy from both carbohydrates and fats. Energy is like a fuel that the cow uses to maintain itself—for grazing, maintaining body temperature, digestion, voiding body wastes, growth, reproduction, and milk production. Most of this “fuel” is made available through digestion of forages and roughage products. In fact, provided a diet that is balanced with proper amounts of protein, minerals and vitamins, the ruminant animal has the ability to obtain energy from feeds that are useless to nonruminants.

TDN is the unit of energy most commonly applied to grazing beef cattle because TDN values can be easily determined for most forages. Net energy (NE) is the unit most widely applied in the growing and finishing of cattle. This method of measuring energy is more precise, but only when the net energy concentrations of feeds have been accurately determined; accurate NE values are not available for most forages. However, good TDN values can be estimated through forage testing programs. Therefore, this publication uses TDN as the standard measure of energy for discussing nutritional requirements and formulating rations.

Protein

Protein is composed of various amino acids, which the body uses as “building blocks” for muscle, enzymes, and body tissues. These amino acids contain both nitrogen and sulfur, along with other elements. The microorganisms that populate the rumen allow cattle to utilize nonprotein nitrogen (NPN) compounds, such as urea and biuret, in order to meet protein requirements. These microorganisms break down NPN as well as much of the natural protein consumed by the cow; from it they synthesize microbial protein, which is then utilized by the cow to meet its own protein requirements.

However, in most cases, lightweight growing cattle (such as young calves) cannot adequately utilize NPN; their performance is improved by feeding on natural protein sources (such as soybean meal). Additionally, many low quality forages contain insufficient energy to permit ruminal microorganisms to synthesize enough microbial protein from NPN. Provided forages or diets with a TDN-to-crude-protein ratio above 7, animals usually respond to NPN supplementation with improved performance; in such situations, the less expensive NPN can provide an economical alternative to natural protein supplementation. However, performance of lightweight calves is almost always further improved by supplementation with natural protein; the protein requirement of these animals is seldom met by the microbial protein synthesized from NPN alone.

Minerals

Minerals are an essential part of the beef cow's nutritional requirement. Although forages in Florida provide adequate concentrations of some minerals, deficiencies in phosphorus, salt, copper, cobalt, and selenium have affected beef cattle throughout Florida. Such mineral deficiencies can be prevented by offering a good mineral supplement free choice to cattle at all times.

Phosphorus is a mineral commonly found deficient in Florida's grazing cattle. Basic phosphorus requirements increase during lactation (milk production) and growth. Generally, forages are low in phosphorus and grains are high in phosphorus. Stored in the bone, phosphorus has various functions in the body. Deficiencies can cause reduced appetite, poor digestion of feedstuffs, poor growth rate and body condition, and low reproductive rate.

Calcium deficiency is an unlikely problem because most forages, especially legumes, are high in calcium, and mineral supplements generally contain calcium in considerable amounts. The caution here is to prevent the calcium-to-phosphorus ratio of the total diet from becoming too wide; a ratio of about 2 to 1 is ideal. The ratio should not be wider than about 5 to 1. Low calcium is most often seen in cattle fed high-grain diets with little roughage.

Cattle may need supplemental magnesium under certain conditions. Grass tetany (low blood magnesium) can cause acute tetany and death in lactating brood cows grazing cool season pasture, such as rye-ryegrass. Grass tetany is discussed in greater detail in http://edis.ifas.ufl.edu/an120.

Salt (sodium and chlorine) intake is insufficient with a forage diet, so this mineral generally composes 20% to 30% of a mineral supplement. In selected situations where the water supply contains significant concentrations of sodium, cattle may decline to consume a mineral supplement that contains salt. In such cases, feed a supplement containing little or no salt so cattle will consume their mineral supplement.

Copper deficiency in Florida is common in grazing cattle that do not receive mineral supplementation. Signs of copper deficiency include dull hair coat, changes in hair color, low pregnancy rates caused by delayed estrus or embryo death, scouring, long bone fractures, lameness, reduced immunity to disease, poor body condition, and sudden death. Copper deficiency is particularly common in cattle grazing forages grown on organic soils. Such forages usually have a higher concentration of molybdenum, which reduces availability of copper to the animal.

Florida's forages are also low in cobalt. Cattle deficient in cobalt exhibit reduced appetite, and, in acute cases, they experience rapid weight loss (referred to as “wasting away disease”). Cobalt deficiency usually affects a few cattle at a time and can be treated by injecting cattle with vitamin B12. Deficiency can be prevented by providing cobalt in the mineral supplement.

Only in recent years has selenium deficiency been recognized in Florida's cattle. In most situations, signs are not very specific, but they may include buckling or weakness in the rear legs of excited calves; these calves may die if stressed. White muscle disease found at necropsy is characteristic of selenium deficiency. Other selenium-responsive conditions include Heinz-body anemia, retained placenta, and reduced immune function.

Recent research and experiences with cattle indicate that deficiencies in copper, selenium, or zinc can compromise the immune system. Marginally deficient cattle neither exhibit reduced growth rates nor have other indications of a problem; but they can fail to develop immunity following vaccination, and can also suffer higher mortality rates when exposed to diseases. Often signs are not evident until after calves are sold. Once exposed to new diseases, deficient calves may exhibit high rates of sickness and mortality.

A complete mineral supplement containing salt, calcium, phosphorus, and trace minerals offered free choice (Figure 1) is recommended to avoid mineral deficiencies. Mineral consumption varies across pastures, seasons, and individual cattle. But for a supplement with the composition shown in Table 1, average consumption of 2 oz per cow-calf per day has proved sufficient in most situations.

Figure 1. 

A complete mineral should be provided to cattle free-choice.


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A mineral's availability varies with its different chemical forms (sulfate, oxide, etc.). Since a mineral can take several different forms, the cow's ability to absorb and utilize that mineral (i.e., the mineral's availability to the animal) is determined by whatever chemical form it takes. This affects the level of mineral needed in the supplement: higher concentrations are needed for chemical forms with lower availability. Usually, supplements contain minerals in chemical forms that are highly available to the animal. But because copper is one of the critical minerals in an animal's diet, copper sulfate (high availability) is recommended over copper oxide (low availability) in a mineral supplement.

Vitamins

Vitamins comprise two groups: fat soluble (vitamins A, D, E, and K) and water soluble (the B vitamins and vitamin C). Bacteria in the rumen and intestines will usually synthesize the water soluble vitamins, as well as vitamin K. Vitamin D can be synthesized in the skin during exposure to sunlight, and vitamin E is found in most green forages.

Vitamin A can be synthesized in the body from carotene, which is found in forages. When good quality forages are fed to beef cattle, vitamin A deficiency is rare. But when the ration consists of weathered or low-quality hay and concentrates low in carotene content (such as old corn, small grains, or sorghum grain), vitamin A deficiency can occur.

Supplemental vitamin A can be added to the ration or mineral supplement as a dry, stabilized vitamin A premix, or it can be given as an injection. An injection containing 1,000,000 IU vitamin A will usually prevent signs of deficiency in an animal for 2 to 4 months.

Water

Water is a nutrient vital to all animal life. Because of its abundance, it is often overlooked. Clean water is most important for young, growing calves. Stagnant, dirty water can retard performance and often serves as breeding ground for disease. Generally, cattle drink about 1/2 gal water per lb dry matter intake, but this varies considerably with temperature. Water requirements increase both with temperature and dry matter intake (Table 2).

Sometimes water sources can contain high levels of salt or other harmful chemicals. Water containing dissolved solids up to 1,000 parts per million (ppm) of minerals is usually safe for consumption; concentrations of 1,000 to 10,000 ppm can be harmful; and levels above 10,000 ppm are considered unsatisfactory for cattle. Nitrate concentrations below 100 ppm are considered safe, and levels over 300 ppm are unsatisfactory. When water contains significant concentrations of dissolved minerals, consumption of free-choice mineral could be reduced.

Classification of Feeds

Feedstuffs are generally divided into two broad categories: forages and/or roughages, and concentrates. Forages and/or roughages are usually high in fiber and somewhat low in digestible energy. Concentrates, on the other hand, are low in fiber and high in digestible energy.

The two broad categories are sometimes subdivided to further classify feeds as “high energy” or “high protein.” Feedstuffs often require mineral and vitamin supplementation. (Figure 2 shows common feedstuffs classified according to use.)

Figure 2. 

Classification of feeds for beef cattle.


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Nutritional Requirements

When building a nutritional program for your cow herd, keep three points in mind. First, you must understand the nutritional requirements of the cow. Second, you must know the “stress points” that can cause nutrient deficiencies. And, finally, you should plan to make maximum use of forage supplies, filling any nutritional gaps with supplemental feed.

The nutritional requirement of the cow varies according to her size, whether she is lactating or dry, her level of milk production, and stage of pregnancy. Figure 3 divides the beef cow's production year into the various phases of production, and likewise into periods of differing nutritional requirements. Table 3 shows the nutrient requirements of a 1,100 lb beef cow during each of the production phases illustrated in Figure 3.

Figure 3. 

Beef cow's annual phases of production (calf weaned at 220 days of age).


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Period 1, the interval between calving and rebreeding, is when nutrient requirements are greatest. It is at this time that “nutritional stress” is most likely to occur. First-calf heifers that are nursing and preparing to rebreed have even higher nutrient requirements than mature cows under the same circumstances. Another critical group is yearling heifers; they must make adequate gains to reach target weights and become pregnant by 15 months of age if they are to calve at 24 months.

In addition to the period 80 days after calving, the 50 days prior to calving (Period 4) is another critical period for the cow herd. Although nutritional needs are not at their absolute highest, precalving usually coincides with a nutritionally limiting time of year. When forage quality is too low to provide adequate nutrition, it is up to the producer to ensure that cows are well nourished enough to produce a good calf crop.

As forages grow, yield increases but quality decreases. The effect of maturity on crude protein concentration for warm season perennial grasses is shown in Figure 4, and Figure 5 shows the effect on TDN concentration. Lower-quality forages have lower digestibility (TDN); also, cattle eat less of these forages, resulting in a significant reduction of TDN intake.

Figure 4. 

Effect of maturity on forage protein.


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Figure 5. 

Effect of maturity on forage TDN.


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Since forages can vary widely in quality, testing forages for their nutrient content will help determine the quantity and type of supplement needed. Forages can be evaluated using the Florida Forage Testing Program or a commercial laboratory. Contact your county Extension agent for suggestions and details on forage testing. Table 4 gives examples of rations for various classes of cattle. These rations can serve as a guide when planning a feeding program for the beef herd, or you can use them when forage analyses are not available.

Evaluating Nutritional Status with Body Condition Scoring

Adequate nutrition during the intervals 50 days prior to and 90 days following calving is critical to the cow's ability to rebreed and maintain a 365-day calving interval. If the cow receives inadequate nutrition or is in poor body condition at calving and breeding, she will take longer to come into heat and could require more services per conception.

For rebreeding, it is not economical to maintain cows that are too thin or too fat. Cows need appropriate fat reserves during calving and rebreeding to help ensure satisfactory breeding performance. However, cows that are too fat will also demonstrate reduced performance and have a higher incidence of calving difficulty.

Body condition scoring allows you to gauge the effectiveness of your feeding program, based on the condition of your cows. Such evaluation can help you plan supplemental feeding programs to maintain adequate productivity. Body condition scores (BCS) are numbers used to indicate the fatness of cows. Most research suggests using a scale from 1 to 9, with BCS 1 defined as extremely thin and BCS 9 extremely fat.

How is body condition determined? Table 5 provides descriptions of the body condition scores. Figure 6 indicates which areas of the body are best to use for scoring body condition.

Figure 6. 

Body condition score can be evaluated visually by determining fat cover in the areas labeled (Oklahoma State University).


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Research and field observations confirm the importance of adequate body condition for cows at calving through rebreeding. A summary of 12 trials conducted in Florida, Texas, and Oklahoma, using over 4,000 cows, shows pregnancy rates for beef cows improved as BCS increased from 3 to 6 (Figure 7). Not only do these data indicate a dramatic increase in pregnancy rate, they show that a BCS of 5 or 6 was necessary to achieve pregnancy rates of 90% or higher. (Scores above 6, however, have not resulted in additional increase in pregnancy rate and are usually not desirable.)

Figure 7. 

Body condition related to pregnancy rate.


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If your herd has some thin cows, it is a good practice to separate these thinner cows at weaning, and manage them to improve BCS prior to calving. Your goal for the herd should be BCS 5 or 6 at calving. Table 6 provides some guidelines for maintaining BCS 5 or 6 (optimum condition) in a 1,000 lb cow.

Winter Feeding the Cow Herd

The cost of winter feeding the cow herd accounts for 40% to 50% of the total variable cost of producing weaned calves. Because winter nutrition is vital to both the calf's health and the cow's reproductive process, adequate nutrition is essential. Wasting feed should also be avoided.

As previously illustrated, cattle in different developmental stages have different nutritional needs. Separating the herd into production groups with similar nutrient requirements will better enable you to meet those requirements; it also enables the most efficient use of feed resources.

Following is a brief discussion of each production group to help you understand their different needs. Remember, not all groups will be represented in every herd, and your facilities might also limit the amount of grouping that can be done. If only limited grouping is possible, separate animals with the greatest difference in their nutritional requirements, and feed accordingly.

Mature, Dry, Pregnant Cows. In medium flesh, the mature, dry, pregnant cow has the lowest nutritional needs. This means she can use lower quality feed than other groups in the herd. Treat this group as an opportunity to cut feed costs by using feeds such as crop residue, mature standing grass, or mature hay. Recognize, however, that body condition score (the amount of flesh the cow is carrying) must be adequate if lower quality feeds are to be used. Lower quality feeds will not be suitable—even for the mature, dry, pregnant cow—if she is thin initially.

Nutritional needs begin to increase during the last third of pregnancy, then increase dramatically after calving when the cow is nursing her calf. Therefore, cows dropping calves should be moved to a separate pasture, and the quantity and/or quality of feed should be increased. This ensures the best feed for those cows that need it most, yet prevents overfeeding cows that are calving later in the season.

First- and Second-Calf Heifers. This group should be fed differently from the mature, lactating cow. Unlike the mature cow, these heifers are still growing, which means their nutritional requirements are greater. The very highest quality feed should be provided to young cows nursing calves. Calving heifers in BCS 5 to 7 and supplementing to limit flesh loss to one body condition score are essential for timely rebreeding and good calf performance.

Replacement Heifers. Both bred and open replacement heifers constitute a separate management group within the herd. Heifers going into their first winter are at the lowest level of the herd's social order and often they are “bossed” by older cows, especially at the feedbunk. At the same time, their nutritional requirements for growth demand a much higher quality feed than what is needed by the mature cow.

The bred heifer entering her second winter must be fed sufficiently to continue her own growth while nourishing a developing fetus. Higher quality feed than the so-called “dry cow hay” is required. But be careful not to get her too fat, or calving difficulties can result. If forage quality is high and enough feeding space is available that competition does not occur, then bred heifers need not be fed separately from mature, dry, pregnant cows. Calving in BCS 5 to 7 is essential for good rebreeding.

Bulls. The bull is often the “forgotten” animal during winter feeding, but he should not be. If the bull is mature and in adequate condition, nutritional requirements are not high. Feed so that the bull maintains his body condition; fattening the mature bull is a waste of feed and money.

Young Bulls. Bulls that are still growing must be fed accordingly; a high-quality forage and usually some concentrate are required. If possible, maintain younger bulls in lots separate from mature bulls, for reasons of feeding and safety.

Separate Herd into Two or More Groups. For a small herd (less than 50 cows), division into at least two separate production groups is essential— from fall weaning until spring, when perennial grass pastures can provide adequate forage growth (4 to 6 months). The two groups can be viewed as high-nutrition and low-nutrition herds.

The high-nutrition herd should include weaned calves, thin pregnant heifers, and thin pregnant cows. This high-nutrition herd can then be grazed on the best fall pasture and/or winter annual pasture, fed the best hay, given additional supplemental feeds, etc. The low-nutrition herd should include heifers and cows in good body condition (BCS 5 or higher); this group can be grazed on field-accumulated pastures, supplemented with protein, and fed the lower-quality hays. During fall and winter, the heifers and cows that calve early or have poor body condition (BCS 4 or lower) should be moved to the high-nutrition herd.

Winter Weather

Special problems accompany cold winter weather. Cold increases the rate at which feed passes through the digestive tract. Less time in the digestive tract means fewer nutrients are released during digestion of feed. In other words, a high-fiber, low-digestibility feed provides even fewer nutrients during cold winter weather.

Cold weather or cool, rainy, windy weather also increases nutrient requirements for cattle, especially energy requirements. As the temperature (wind chill factor included) drops below the critical low for an animal, the amount of energy the animal requires to maintain itself increases. Thus, prolonged cold periods not only decrease the level of nutrients obtained during digestion of feed, they also increase an animal's energy requirements. Producers can compensate for long periods of cold by increasing the quality of the forage fed, or substituting concentrate for a portion of the forage.

Certain nutrients, such as water, require specific attention in winter. If water intake is limited by freezing or cold weather, intake of feed (especially hay) will decrease. Producers must keep water sources open in the winter and, if possible, above 40°F for maximum feed consumption.

Vitamin A is especially critical in winter. Cows consuming high-fiber, low-quality hay and coming out of a hard winter will have used up most of the vitamin A stored in their bodies. This vitamin should be supplemented in winter, either by feeding or by injection.

The greatest “out-of-pocket” expense during winter feeding is generally protein supplementation. Test your forage for protein content first to determine whether you need a protein supplement. If supplementation is indicated, do not make your selection solely on price; purchase a supplement that will be useful (i.e., one that is high in natural protein). High NPN supplements have limited usefulness for young cows wintered on low-quality hays or field-accumulated forages.

Plan ahead. Before winter sets in, estimate whether the quantity of feed available will be adequate to meet your animals' needs. Table 4 shows sample rations for various classes of beef cattle. The appropriate ration can be multiplied by approximately 120 (days) times the number of cattle to estimate the amount of winter feed needed.

If forage supplies are inadequate for the entire feeding period, concentrates can be substituted for forages. A pound of corn contains the same amount of energy (TDN) as 1.4 lb excellent hay or 1.8 lb average hay. When hay is in short supply, grains often provide a cheaper source of nutrients.

Feed costs represent the greatest single expense in cow-calf production. Managing the herd to keep feed costs low and production levels high improves the profitability of your operation.

Creep Feeding Beef Calves

Creep feeding is the practice of supplying supplemental feed to a nursing calf without allowing its dam access to the feed (Figure 8). Once a calf is 90 to 120 days of age, its mother's milk supplies only about 50% of the nutrients it needs for maximum growth. The calf must obtain the remaining nutrients elsewhere in order to realize its genetic potential for growth. High-quality pasture is the best source of nutrients, but if this is unavailable or inadequate, creep feeding is an option.

Figure 8. 

Creep feeding areas can be constructed within a building or enclosed feeding area in the pasture.


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Creep feeding the nursing calf will increase both rate of gain and weaning weight. You can expect a .1 to .5 lb increase in daily gain. To determine whether the increased rate of gain will offset the added cost, evaluate the feed's conversion rate— the amount of creep feed (lb) needed to produce 1 lb of gain. Conversion rates can range from 3:1 to 18:1. For high-energy creep feeds, a 10:1 conversion rate provides a good rule of thumb. Table 7 shows the cost of additional gain evaluated for different conversion rates and feed costs.

Necessarily, your decision must be based on your particular operation, but you will generally find creep feeding profitable under the following circumstances:

  • Long periods of dry weather or drought

  • Poor-milking cows

  • Large numbers of first-calf heifers and/or very old cows

  • Late calvers (midsummer)

  • Fall-born calves

  • Only low-quality pasture available

  • Low feed costs, combined with high calf prices

On the other hand, creep feeding usually is not profitable under the following circumstances:

  • Heavy-milking cows

  • Abundant, high-quality pasture

  • High feed costs and/or low calf prices

  • Weaned calves kept to yearling weights

  • Heifers kept as replacement females

Be especially aware that creep feeding can be detrimental to replacement females. Extra fat can be deposited in the mammary gland, permanently reducing a heifer's ability to produce milk.

Creep rations do not have to be complex, but they should be economical and palatable. No matter how nutritious a ration might be, if calves don't eat it, they won't gain more. Molasses or brewer's dried grains can be used to enhance palatability. For example, to formulate a creep ration that contains 12% crude protein, you could mix 68% shelled corn, 22% oats, 5% soybean meal, and 5% brewer's dried grains. If consumption of the ration then proved inadequate, you could substitute molasses for 3% to 5% of the corn to improve palatability.

Whenever possible, grains should be processed by coarse grinding or cracking. And when the creep ration comprises grain alone, it is useful to roll the grain. Other grains or grain products can be substituted for the corn and/or oats used in the preceding example ration. Since high-quality commercial creep feeds are widely available, you might find that purchasing creep feed is your best option.

Starting calves on creep rations can sometimes be a problem. One of the best starting methods is to feed their mothers small amounts of ground feed for a few days prior to the start of creep feeding. The calf learns to eat with its mother this way, and can then be switched to the creep.

Limit-fed, high-protein creep rations have drawn attention recently. Creep rations of this type could prove useful for large-framed, rapidly growing calves, which have greater-than-normal protein requirements. The possible benefit is increased gain, without excessive fattening due to surplus energy intake. But daily consumption of the creep must be carefully monitored to ensure intake does not exceed 1.5 lb. During 6 ranch trials in Florida, calves consumed .65 lb/day of protein supplement; calf gains increased .30 lb/day, so 2.2 lb protein supplement was required for each lb of additional gain. Limit-feeding a high-protein supplement was profitable in 5 of the 6 trials.

Creep grazing is basically the same as creep feeding. The calf has access to higher quality forage, while the cow does not. Access can be controlled with creep gates, constructed so that calves can pass through but cows cannot (from 15 to 18" wide, and 36 to 40" high), or an electric fence can be raised that permits calves to walk under it while restricting cows.

Feed Additives for Beef Cows

Feed additives can be either nutritive compounds that improve performance and/or feed efficiency, or nonnutritive compounds that perform as disease preventives when consumed in feed. Properly used, feed additives can greatly improve profitability of the beef cattle operation.

To use feed additives properly, it is your responsibility to:

  • Use the feed additive for its intended purpose;

  • Follow feeding guidelines and any warning statement(s) on the label;

  • Store feed properly;

  • Observe withdrawal time, when applicable.

Most feed additives fall into one of four broad classifications: fermentation modifiers, antibiotics, hormone or hormonelike products, and anthelmintics. (Other products that are approved for use in feed but do not fit these classifications will be discussed as general additives.) The following sections discuss feed additives that are applicable to beef cattle production.

Fermentation Modifiers. Sometimes called ionophores, these additives alter both the rate and end products of microbial fermentation in the rumen, allowing cattle to obtain more energy from the feed they consume. Currently, the only product approved for use in mature, reproducing beef cows is monensin (Rumensin®). This product is approved to increase feed efficiency when fed at the rate of 50 to 200 mg per head daily, and mixed with at least 1 lb feed.

Both lasalocid (Bovatec®) and monensin are approved to increase rate of gain in replacement heifers. Lasalocid should be fed at the rate of 60 to 200 mg per head daily, monensin at 50 to 200 mg per head daily. Research has shown that feeding either of these fermentation modifiers improves the reproductive efficiency of heifers.

Antibiotics. Routinely added to the feed of growing and finishing cattle, most antibiotics may also be used for beef cattle, when necessary. Usually they are fed continuously at low dosages to enhance rate of gain and feed efficiency. Antibiotics can be used at higher dosages for prevention and treatment of diseases such as bovine respiratory complex, anaplasmosis, and pinkeye.

Use caution when feeding antibiotics. Recommended dosages produce the desired results; too much can interfere with rumen function and actually decrease performance.

Hormones. Presently there are no hormone or hormonelike products that have FDA clearance for use as feed additives to regulate reproduction in beef cattle. However, considerable research has been conducted on using melengestrol acetate (MGA) for synchronization of estrus. When fed at the rate of .5 mg per head daily, MGA prevents cattle from coming into heat; heat cycles resume shortly after withdrawal. When MGA is properly used in combination with prostaglandins, the calving interval can be decreased significantly. Check label guidelines when considering the use of MGA for synchronizing estrus in heifers or cows.

Anthelmintics. Many anthelmintics (dewormers) are available in feed form. Dewormers are generally administered directly, but when handling cattle poses a problem, feeding is an acceptable method of administration. Products can be mixed into meal feed, or they are available as cubes or pellets. Some products are also available in block form or as a loose mineral. Check with a local feed or livestock supply dealer for products available in your area.

General Additives. Some products are approved as feed additives when used for specific purposes. These include products to prevent bloat when cattle are grazing lush legume pastures, and fly control products that act as growth regulators or as larvacides. These products are available in feed forms(s).

Remember, feed additives are controlled by the Food and Drug Administration; it is your responsibility to follow the FDA regulations, which are required to be listed on labels along with the directions. Use these products properly.

Feeding and Management during Drought

The effect of drought (and especially the resulting pasture shortage) on the beef herd depends largely upon the time of year that drought occurs. For example, if drought conditions occur in spring and early summer, production is decreased in both the current year and the subsequent one. Producers must not only deal with the obvious problem of decreased weaning weights, they must also understand that their herd's rebreeding schedule is in jeopardy. In such a case, managing the cows for adequate rebreeding is of primary concern. Were the same conditions to occur in late summer, on the other hand, cows should already be pregnant and calves closer to weaning age. Under these circumstances, avoiding excessive loss of condition would be the priority for the cow herd.

When deciding what to do in a drought situation, options to consider are (1) wean and market calves, (2) feed the cow herd, (3) creep feed the calves or, (4) various combinations of these.

Weaning and Marketing Calves. When forages are scarce and milk production low, weaning and marketing calves at 3 to 5 months of age can be a viable alternative to feeding the entire herd. This makes extra feed available, but too late to prepare cows for the scheduled breeding season. You should consider early weaning only when cows milk poorly, calf growth is below normal, and cows are likely to experience poor reproductive performance. Early weaning is a common practice with first-calf heifers.

Feeding the Cows. Another option to consider in a drought situation is feeding the cows, provided an economical source of feed is available. The amount of feed required varies with an animal's size, stage of production, and the amount of feed being supplied by pastures. As an example, the nutritional needs of a 1,100 lb cow during the first 3 to 4 months of lactation can be met with 20 to 25 lb high-quality hay (minimum 55% TDN, 10% protein), plus mineral and vitamin supplementation. Heavy-milking cows require another 3 to 5 lb grain or molasses, in addition to the hay and supplement. If cows are getting some portion of their requirement from pasture, then feeding can be reduced.

If the cow herd is still in its breeding season, it is preferable to supplement with good hay, rather than “saving it for winter.” Protein supplementation can help increase intake and digestion of roughage, but energy is always the highest requirement. Therefore, some grain or better quality hay might be needed for high-producing cows. Vitamin A should be supplied in the mineral and vitamin supplement since it is likely to be lacking in “dried” forage (pasture or hay).

When pastures are short and the corn crop contains little grain due to drought, producers frequently decide to green chop the damaged corn and feed it directly. This can be extremely dangerous! Drought-stricken corn fed as green chop, whether grazed or baled, carries a high risk of nitrate toxicity. And while the nitrate level of forage can be checked, it also changes constantly. The safest use for drought-stricken corn is to ensile it, then wait 6 to 8 weeks before feeding. Although this would not help solve an immediate feed shortage, it does reduce nitrate content of the corn stalk by 40% to 60%, providing a safe feed for later use.

Sorghum and sorghum-cross plants that are used for temporary summer pasture are also potentially dangerous during drought due to increased prussic acid content. These plants should not be grazed during (or shortly after) drought periods when they are stunted or wilted.

Creep Feeding. As previously discussed in this chapter, creep feeding offers extra merit during drought. When pastures are adequate and of good quality, and cows are supplying plenty of milk for the calves, the benefits of creep feeding might not outweigh the added cost. But when pastures are very poor during drought, the increase in calf gain usually compensates for the expense of creep feeding.

Balancing Rations

Feed costs represent the greatest portion of the total cost of producing a feeder calf. Feeding cattle a balanced ration prevents wasted feed dollars and enables the most efficient level of production. A ration is the amount of feed an animal receives in a 24-hour period. Balancing a ration requires some basic information, which is defined below.

Balanced Ration - A ration that supplies the proper amounts and concentrations of nutrients required for an animal's maintenance, growth, and lactation or gestation. Table 8 lists the amounts (lb) and/or concentrations (%) of nutrients required for beef cattle.

Nutrient Concentration - The relative quantity of a specific nutrient contained in a given feed. Nutrient concentration is expressed as a percentage of the dry matter. You can look up values for nutrient concentrations in a feed composition table (see Table 9); however, feed composition tables list only average values. So, unless your feed is “average,” its particular nutrient concentrations will differ from the table values. Accurate information can be obtained by running a nutrient analysis on stored forages; such analyses are easily arranged at reasonable cost.

Dry Matter - The portion of feed that remains after all water is removed. Typical amounts of dry matter intake for cattle are given in Table 8. These amounts indicate what animals can consume under normal circumstances. Pasture and silages contain a lot of water and, therefore, have low concentrations of dry matter; hay and concentrates contain higher concentrations of dry matter. Converting quantities of feed to dry matter values eliminates differences in the water content of feeds and provides a common basis for nutritional comparison. So rations are balanced on a dry matter basis, then feed ingredients are converted back to as-fed values so the ration can actually be measured out.

Using a systematic approach simplifies the process of balancing rations. First, determine the nutritional requirements of the animal being fed; you need to know its type, size, and level of production. Next, look up the corresponding requirements in Table 8. Then determine what feeds are available for use and obtain their nutrient compositions, on a dry matter basis, from a feed composition table (such as Table 9) or feed analysis. Now you have the information necessary to calculate what proportions of feed ingredients will balance your ration.

Using the Pearson Square

A relatively simple technique for balancing rations involves use of the “Pearson Square.” This method calculates the corresponding proportions of two feed materials that will yield a ration with the desired nutrient concentration. Although this method only determines proportions for two feed ingredients, one or both of those feeds can be mixtures.

The Pearson Square method for balancing rations is easily explained by example; in the following, a ration is balanced for a 400 lb heifer calf with a desired gain of 1.5 lb per day. Daily nutrient requirements are obtained from Table 8:

Dry matter intake - 10.2 lb

Crude Protein - 11.4%

TDN - 68.5%

Table 10 lists specific feeds used in this example; feed composition values are from Table 9.

The heifer calf requires a 68.5% TDN ration. Place 68.5 in the center of a square (Figure 9). Place the TDN values for bermudagrass (48%) and corn (90%) on the left side of the square and subtract diagonally, smallest from largest:

Bermudagrass -

68.5 (center) – 48 = 20.5 (lower right)

Corn -

90 – 68.5 (center) = 21.5 (upper right)

Figure 9. 

Pearson Square showing proportions of bermudagrass and corn that yield a 68.5% TDN ration.


[Click thumbnail to enlarge.]

The numbers on the right side now show that 21.5 parts of bermudagrass (upper right) and 20.5 parts of corn (lower right) yield a 68.5% TDN ration. This makes a total of 42 parts (21.5 + 20.5) in the mixture. Divide each of the partial values (21.5 and 20.5) by the total number of parts (42) to calculate the preliminary percentages of bermudagrass and corn in the ration:

% Bermudagrass -

21.5 ÷ 42 = .512 = 51.2%

% Corn -

20.5 ÷ 42 = .488 = 48.8%

(Multiplying by 100 converts a “fractional” value to a percentage, and dividing by 100 converts a percentage to its fractional value.)

The next step is to determine the percentage of crude protein in this bermudagrass-corn mixture. Multiply the crude protein concentration of each ingredient by its fractional percentage in the mix. Bermudagrass contains 6% crude protein and constitutes 51.2% of the mixture (fraction = .512); corn contains 10% crude protein and constitutes 48.8% of the mixture (fraction = .488):

Add the two percentages to calculate the concentration of crude protein in the mix (7.95%). Since the heifer requires 11.4%, the crude protein concentration must be increased by adding a protein supplement.

Use the Pearson Square, but this time balance the bermudagrass-corn mix (B-C mix) with soybean meal (SBM) to obtain the 11.4% crude protein ration required. Place 11.4 in the center of the square, with 7.95 and 50 on the left side (Figure 10); subtract as before. Add the values that result on the right side of the square (38.6 and 3.45) to determine the total number of parts in the ration (42.05). Divide each partial value by the total number of parts to determine the fractional percentage of each ingredient in the ration:

% Bermudagrass-corn -

38.6 ÷ 42.05 = .918 = 91.8%

% Soybean meal -

3.45 ÷ 42.05 = .082 = 8.2%

Figure 10. 

Pearson Square showing proportions of bermudagrass-corn mix (B-C mix) and soybean meal (SBM) that yield an 11.4% crude protein ration.


[Click thumbnail to enlarge.]

Now that you know the percentage of each ingredient in your ration, the next step is to determine the amount of dry matter (lb) each ingredient contributes to the total ration. Multiply the amount of dry matter the heifer is expected to consume daily (10.2 lb) by the fractional percentage of soybean meal (.082) needed in the ration:

Soybean meal -

10.2 lb * .082 = 0.84 lb

Subtract the amount of soybean meal (.84 lb) from total dry matter intake (10.2 lb) to determine the amount of dry matter remaining to be supplied by the bermudagrass-corn mixture:

Bermudagrass-corn -

10.2 lb - 0.84 lb = 9.36 lb

Next, dry matter content must be determined for each component of the bermudagrass-corn mixture. Multiply the amount of dry matter in the mix (9.36 lb) by the fractional percentages of bermudagrass (.512) and corn (.488) contained in the mix, which were obtained in the first square:

Finally, amounts of dry matter contributed by each ingredient must be converted to “as-fed” values, so you can determine how much to actually feed. As-fed values are calculated by dividing dry matter values for each ingredient by the fractional percentage of dry matter contained in that particular feed (see Table 10):

Bermudagrass -

4.79 lb ÷ .85 = 5.64 lb

Corn -

4.57 lb ÷ .88 = 5.19 lb

SBM -

0.84 lb ÷ .91 = 0.92 lb

In summary, a 400 lb heifer that consumes 5.6 lb bermudagrass hay, 5.2 lb corn, and .9 lb soybean meal should meet TDN and crude protein requirements for a 1.5 lb daily gain (Figure 11).

Figure 11. 

For good gains, heifers weaned in summer and fall need to be separated from the cow herd, grazed on the best pastures and fed supplements.


[Click thumbnail to enlarge.]

You might need to feed some extra hay or other feeds if part of the ration is wasted. Minerals and vitamins are generally supplied by a commercial mineral supplement, offered free-choice (Table 1).

Supplementing Cows Fed Free-Choice Hay

The following illustrates another method for balancing rations. In this example, cows are receiving free-choice hay; and quantities (lb/day)—rather than concentrations (%)—of nutrients are balanced according to daily consumption, using the “trial and error” method. Consider a 1,100 lb cow with superior milking ability nursing a calf in the first 3 to 4 months postpartum. As always, the first step is to determine the nutritional requirement of the animal to be fed (Table 8):

Dry matter intake - 22.3 lb

Crude protein - 2.6 lb

TDN - 14.5 lb

Assume bahiagrass hay is being fed, and that corn and soybean meal are available; determine the nutrient composition of each feed (from Table 9):

Since we are interested in using as much hay as possible, let us initially assume that the cow will consume her entire dry matter requirement (22.3 lb) from bahiagrass hay. (This amounts to 26.2 lb hay, as fed: 22.3 lb dry matter ÷ .85 dry matter content = 26.2 lb)

Next, calculate the nutrients supplied by 22.3 lb bahiagrass hay (dry-matter basis):

TDN -

22.3 lb * .53 = 11.8 lb

Protein -

22.3 lb * .07 = 1.56 lb

Compare the nutrients supplied by 22.3 lb hay (dry matter basis) to the cow's daily requirement:

The superior milking cow will not be able to consume enough of this bahiagrass hay to meet her TDN or protein requirement. If you do not feed supplements, she will lose weight. This might not delay rebreeding if she is in BCS 5 or higher and weight loss is moderate. If the cow does not have extra flesh to lose, you could feed either higher quality hay or concentrate supplements.

The following approach uses “trial and error” to determine how much supplement to feed. First, balance the energy, then the protein. Assuming the cow maintains her 22.3 lb dry matter intake regardless of feed-type, then 1 lb corn (containing .90 lb TDN) could replace 1 lb bahiagrass hay (containing .53 lb TDN) on a dry matter basis, for a net increase of .37 lb TDN (.90 to .53) per lb corn fed.

So if the bahiagrass hay diet leaves a deficiency of 2.7 lb TDN, and lb-per-lb (dry matter) substitution of corn yields a net increase of .37 lb TDN, calculate the amount of corn to feed in order to meet this cow's TDN requirement:

2.7 lb TDN ÷ .37 lb TDN / lb corn = 7.3 lb corn

Since dry matter consumption is assumed constant, the amount of dry matter initially obtained from hay (22.3 lb) is reduced by the amount of dry matter now obtained from corn (7.3 lb):

Bahiagrass hay -

22.3 lb – 7.3 lb = 15 lb

So now the ration consists of 15 lb bahiagrass hay and 7.3 lb corn on a dry matter basis.

Next, determine the amount of protein contained in the new ration of bahiagrass hay and corn; then substitute soybean meal for some of the corn to balance the protein:

The amount of protein supplied by each feed ingredient is determined by multiplying the amount of dry matter (lb) it contributes to the ration by its protein concentration (fractional percentage):

Bahiagrass hay -

15 lb * .07 = 1.05 lb

Corn -

7.3 lb * .10 = .73 lb

Together, the bahiagrass and corn provide 1.78 lb protein. Since the cow requires 2.6 lb, this leaves a deficiency of .82 lb protein in the ration. Substituting 1 lb soybean meal (containing .50 lb protein) for 1 lb corn (containing .10 lb protein) on a dry matter basis yields an increase of .4 lb protein per lb substituted. So, to increase protein in the ration by .82 lb requires 2.05 lb soybean meal.

.82 lb protein ÷ .4 lb protein / lb SBM = 2.05 lb SBM

This reduces the amount of corn in the ration by the amount of soybean meal substituted, as follows:

Corn -

7.3 lb – 2.05 lb = 5.25 lb

And now the ration consists of 15 lb bahiagrass hay, 5.25 lb corn, and 2.05 lb soybean meal.

Calculate the amount of TDN and crude protein supplied by the new ration:

Amounts of TDN and protein supplied by each ingredient are calculated by multiplying the amount of dry matter (lb) the ingredient contributes to the ration by its respective TDN and protein concentrations (fractional percentage), as follows:

Bahiagrass hay

TDN -

15 lb * .53 = 7.95 lb

Protein -

15 lb * .07 = 1.05 lb

On a dry matter basis, the ration of 15 lb bahiagrass hay, 5.25 lb corn, and 2.05 lb soybean meal can be expected to supply 14.4 lb TDN and 2.61 lb protein. This comes very close to meeting the nutrient requirements for the 1,100 lb cow producing 20 lb milk/day: TDN is only .1 lb below the requirements (caused by replacing corn, which contains 90% TDN, with soybean meal, which contains 84% TDN). You could adjust the ration to balance exactly, but these values are certainly close enough, considering the inherent inaccuracies in estimation of forage intake, forage quality, and the cow's nutritional requirements.

The final step is to convert the ration ingredient amounts from lb dry matter to lb as fed, so you know how much to weigh out. Divide dry matter values for each ingredient by the fractional percentage of dry matter contained in that particular feed:

Animals gain more efficiently when fed a balanced ration. Using nutritional requirements and feed compositions, you can balance rations for your own cow-calf operation. Your county Extension agent can help you obtain forage analyses, and can assist in balancing your rations.

Tables

Table 1. 

Suggested composition of free-choice mineral.

Minerala

Composition, %

Salt

20-30

Calcium

15-20

Phosphorus

8

Zinc

0.4

Iron

0.2

Manganese

0.2

Copperb

0.15

Iodine

0.016

Cobalt

0.01

Seleniumc

0.002

aMineral has been adequate in most situations in Florida when fed free choice and consumed at 2 oz per cow-calf, daily.

bCopper sulfate is recommended as the source of copper.

cLevel of selenium in mineral supplements is restricted by FDA.

Table 2. 

Total daily water intakea, as affected by temperature and feed intake.

Temperature

40° F

50° F

60° F

70° F

80° F

90° F

Gallons of water/lb of dry matterb

0.37

0.40

0.46

0.54

0.62

0.88

500 lb calf (12 lb dm)

4.4

4.8

5.5

6.5

7.4

10.6

750 lb pregnant heifer (16.6 lb dm)

6.1

6.6

7.6

9.0

10.3

14.6

1100 lb dry pregnant cow (20 lb dm)

7.4

8.0

9.2

10.8

12.4

17.6

1100 lb lactating cow (22 lb dm)

8.1

8.8

10.1

11.9

13.6

9.4

aGallons.

bDry matter abbreviation = dm.

Adapted from: Winchester and Morris. 1956. Water intake rates of cattle. J. Anim. Sci. 15:722.

Table 3. 

Daily nutrient requirements for a 1100 lb beef cowa.

Nutrient

Unit

Periodb

1

2

3

4

TDN

lb

13.3

11.5

9.5

11.2

Protein

lb

2.3

1.9

1.4

1.6

Calcium

g

33

27

17

25

Phosphorous

g

25

22

17

20

Vitamin A

IU

39,000

36,000

25,000

27,000

a15 lb daily milk production.

bPeriods correspond to those defined in Figure 3.

Adapted from: NRC. 1984. Nutrient Requirements of Beef Cattle (6th Ed). National Academy Press, Washington, DC.

Table 4. 

Sample daily rations for various classes of beef cattle.a,b

Weaned Heifer Calves - 500 lb - 1.25 lb gain

Bahiagrass pasture

(late summer, fall)

+ 5-6 lb grain supplementc (12% protein)

Excellent hayd

(8-10 lb)

+ 5-6 lb grain supplementc (10% protein)

Average haye

(6-8 lb)

+ 8-9 lb grain supplementc (12% protein)

Winter annual pasture

(2/3 acre/calf)

+ hay (December-March)

Bred Yearling Heifers - 850 lb - 1.0 lb gain

Bahiagrass pasture

(late summer, fall)

+ 3-4 lb grain supplementc (12% protein)

Excellent hayd

(16-18 lb)

+ 3-4 lb grain supplementc (10% protein)

Average haye

(14-16 lb)

+ 6-7 lb grain supplementc (12% protein)

Average haye

(10-12 lb)

+ 2/3 acre winter annual pasture (limit graze)

Dry Pregnant Cows - 1100 lb - Last 1/3 gestation; BCS 5+ / maintain BCS

Bahiagrass pasture

(summer)

 

Bahiagrass pasture

(fall)

+ 1.5 lb protein supplement (20% protein)

Crop residues

 

+ 1.5 lb protein supplement (20% protein)

Average haye

(22-24 lb)

 

Dry Pregnant Cows - 1000 lb - Last 1/3 gestation; BCS 4 / increase BCS

Bahiagrass pasture

(summer)

+ 1.5 lb grain supplement (20% protein)

Bahiagrass pasture

(fall)

+ 5-6 lb grain supplementc (12% protein)

Excellent hayd

(24-26 lb)

 

Average haye

(20-22 lb)

+ 5-6 lb grain supplementc (12% protein)

Lactating Cows - 1000 lb - Good milk; BCS 6 at calving / decrease BCS

Bahiagrass pasture

(fall)

+ 2 lb protein supplement (20% protein)

Excellent hayd

(30 lb)

 

Average haye

(23-25 lb)

+ 4-5 lb grain supplementc (14% protein)

Average haye

(20-22 lb)

+ 1/3 acre winter annual pasture (limit graze)

Lactating Cows - 900 lb - Good milk; BCS 4 at calving / maintain BCS

Bahiagrass pasture

(fall)

+ 8-9 lb grain supplementc (12% protein)

Excellent hayd

(28-30 lb)

+ 4-5 lb grain supplementc (12% protein)

Average haye

(18-20 lb)

+ 8-9 lb grain supplementc (12% protein)

Average haye

(18-20 lb)

+ 2/3 acre winter annual pasture (limit graze)

Young Herd Bulls - 1300 lb - 2 or 3 years old; growing /maintain BCS

Bahiagrass pasture

(spring, early summer)

 

Bahiagrass pasture

(late summer, fall)

+ 9-10 lb grain supplementc (12% protein)

Average haye

(23-25 lb)

+ 9-10 lb grain supplementc (12% protein)

Average haye

(18-20 lb)

+ 1 acre winter annual pasture

Mature Herd Bulls - BCS 5+

Bahiagrass pasture

(spring, summer)

 

Bahiagrass pasture

(fall)

+2 lb protein supplement (20% protein)

Average haye

(30-40 lb)

 

aMineral-vitamin supplement (Table 1) offered free choice to all cattle.

bSupplement level required depends upon forage quality, an animal's level of production (gain, gestation, milk), body condition score, and weather conditions.

cGrain supplement assumed to contain 70% TDN; can be replaced with 1.25 times the amount of a molasses-based supplement (16% protein or less).

dExcellent hay contains 12% crude protein and 56% TDN in the dry matter.

eAverage hay contains 7% crude protein and 48% TDN in the dry matter.

Table 5. 

Description of body condition scores (BCS).

BCS

Description of Body Condition Score

1

Emaciated - Bone structure of shoulder, ribs, back, hooks, and pins is sharp to the touch and easily visible. There is little evidence of fat deposits or muscling.

2

Very Thin - Little evidence of fat deposits, but some muscling is evident in the hindquarters. Spinous processes feel sharp to the touch and are easily seen, with space between them.

3

Thin - Beginning of fat cover over the loin, back, and foreribs. Backbone is still highly visible. Processes of the spine can be identified individually by touch and may still be visible. Spaces between the processes are less pronounced.

4

Borderline - Foreribs not noticeable; 12th and 13th ribs may still be noticeable, particularly in cattle with a big spring of rib and ribs wide apart. The transverse spinous processes can be identified only by palpation (with slight pressure), and feel rounded rather than sharp. Fullness, but straightness, of muscling in the hindquarters.

5

Moderate - 12th and 13th ribs not visible unless animal has shrunk. Transverse spinous processes are not noticeable; they can only be felt with firm pressure, and feel rounded to the touch. Spaces between the processes are not visible, and are detectable only with firm pressure. Areas on either side of the tailhead are fairly well filled, but not mounded.

6

Good - Ribs are fully covered, not visible; hindquarters are plump and full. Noticeable sponginess to covering of foreribs and on either side of the tailhead. Firm pressure now required to feel transverse processes.

7

Very Good - Ends of the spinous processes can only be felt with very firm pressure. Spaces between processes can barely be detected. Abundant fat cover on either side of tailhead, with some patchiness evident.

8

Fat - Animal taking on a smooth, blocky appearance; bone structure disappearing from sight. Fat cover thick and spongy, with patchiness likely.

9

Very Fat - Bone structure not easily seen or felt. Tailhead buried in fat. Mobility may be impaired by excess fat.

Table 6. 

Body condition score 90-100 days prior to calving.

Current Scorea

Desired Scoreb

Recommendation

3

5

Gain 200-300 lb

4

5

Gain 150-200 lb

5

5-6

Gain weight of fetus (100 lb)

6

5-6

Gain weight of fetus (100 lb)

7

5-7

No weight gain needed

aBody condition score 90-100 days prior to calving.

b Body condition score desired at calving.

Adapted from: Beverly. 1985. Reproduction in beef cattle as related to nutrition and body condition. Proceedings, Kentucky Beef Cattle Roundup. pp 1-12. University of Kentucky, Lexington.

Table 7. 

Costa of extra gain from creep feeding.

Feed, lbb

Feed Cost, $/cwt

5

6

7

8

9

6

30

36

42

48

54

8

40

48

56

64

72

10

50

60

70

80

90

12

60

72

84

96

108

aUnit = $ per cwt of extra gain.

bFeed required per lb of extra gain.

Table 8. 

Nutrient requirements for beef cattlea

Body

Weight (lb)

Daily

Gain (lb)

Dry Matter

Intake (lb)

Crude Protein

TDN

Ca (%)

P (%)

lb/day

% of DM

lb/day

% of DM

Heifer calves

400

1.5

10.2

1.17

11.4

7.0

68.5

.45

.24

500

1.5

12.1

1.25

10.3

8.3

68.5

.38

.22

600

1.5

13.8

1.32

9.5

9.4

68.5

.32

.21

Pregnant yearling heifers - last third of pregnancy

750

1.4

16.6

1.5

8.9

10.0

59.9

.32

.21

850

0.9

17.6

1.4

8.2

9.6

54.5

.26

.20

950

0.9

19.0

1.5

8.0

10.3

54.1

.27

.20

Dry pregnant mature cows - middle third of pregnancy

1000

-

18.1

1.3

7.0

8.8

48.8

.18

.18

1100

-

19.5

1.4

7.0

9.5

48.8

.19

.19

1200

-

20.8

1.4

6.9

10.1

48.8

.19

.19

Dry pregnant mature cows - last third of pregnancy

1000

0.9

19.6

1.6

7.9

10.5

53.6

.26

.21

1100

0.9

21.0

1.6

7.8

11.2

53.2

.26

.21

1200

0.9

22.3

1.7

7.8

11.8

52.9

.26

.21

Two-year-old heifers nursing calves - first 3 to 4 months postpartum; 10 lb milk per day

800

0.5

17.6

1.9

10.8

11.2

63.8

.34

.24

900

0.5

19.2

2.0

10.4

12.0

62.7

.32

.23

1000

0.5

20.8

2.1

10.0

12.9

61.9

.31

.23

Cows nursing calves - first 3 to 4 months postpartum; average milking (10 lb/day)

1000

-

20.2

2.0

9.6

11.0

56.6

.28

.22

1100

-

21.6

2.0

9.4

11.5

56.0

.27

.22

1200

-

23.0

2.1

9.3

12.1

55.5

.27

.22

Cows nursing calves - first 3 to 4 months postpartum; superior milking (20 lb/day)

1000

-

20.6

2.5

12.3

13.8

67.0

.39

.27

1100

-

22.3

2.6

11.9

14.5

65.2

.38

.27

1200

-

23.8

2.7

11.5

15.2

63.7

.36

.26

Bulls - maintenance and slow rate or growth (regain condition)

1400

2.0

27.7

2.2

8.0

17.8

64.0

.25

.20

1600

1.0

29.7

2.2

7.3

16.6

55.8

.22

.19

1800

0.5

30.9

2.2

7.0

16.1

52.0

.20

.20

aVitamin A requirement for (1) pregnant heifers and cows = 1270 IU per lb dry feed; (2) lactating cows and breeding bulls = 1770 IU per lb dry feed.

Source: NRC. 1984. Nutrition Requirements of Beef Cattle (6th Ed). National Academy Press, Washington, DC.

Table 9. 

Composition of commonly used feeds (dry matter basis)a.

Feedstuff

Dry Matter

%

Concentration in Dry Matter, %

TDN

Crude Protein

Calcium

Phosphorus

Pasture/Forage

         

Bahiagrass hay, 4-5 wk regrowth

85

60

10

.40

.32

Bahiagrass hay, 8-10 wk regrowth

85

53

7

.26

.20

Bermudagrass hay, 4-5 wk regrowth

85

58

12

.38

.22

Bermudagrass hay, 8-10 wk regrowth

85

48

6

.30

.15

Crimson clover pasture

18

63

17

1.33

.32

Corn stover

85

55

71

.40

.20

Limpograss hay, 4-5 wk regrowth

85

60

10

.35

.30

Limpograss hay, 8-10 wk regrowth

85

59

5

.28

.22

Perennial peanut hay, 6-8 wk regrowth

85

60

14

1.25

.30

Rye pasture, immature

24

69

15

.39

.33

Ryegrass pasture, immature

25

60

15

.65

.41

Sorghum stover

88

54

5

.52

.13

Stargrass hay, 4-5 wk regrowth

85

60

13

.38

.20

Stargrass hay, 8-10 wk regrowth

85

51

6

.28

.15

Wheat pasture, immature

22

73

20

.40

.38

White clover pasture

19

65

25

1.20

.35

 

 

Silage

Corn silage, few ears

29

62

8

.34

.19

Corn silage, well-eared

33

70

8

.23

.22

Sorghum silage, forage-type

30

60

6

.35

.21

 

 

Concentrate/By-product

Brewer's grains

92

84

30

.30

.60

Broiler litter

78

53

25

2.10

1.80

Citrus pulp

90

79

8

1.80

.15

Corn gluten meal

91

89

67

.05

.51

Corn grain, shelled

88

90

10

.02

.30

Corn/Distiller's grain, dehydrated

91

87

27

.30

.75

Cottonseed hulls

91

42

4

.15

.09

Cottonseed meal, 41%

91

76

47

.21

1.18

Cottonseed, whole

90

94

23

.16

.62

Feather meal

92

69

88

.40

.60

Fish meal

90

72

66

6.40

3.60

Hominy

90

92

11

.04

.45

Meat and bone meal

93

71

55

9.95

5.00

Molasses, blackstrap

78

78

9

1.10

.10

Oat grain

89

76

13

.09

.40

Peanut meal

91

77

48

.20

.52

Peanut hulls

91

22

8

.26

.07

Rye grain

89

81

12

.07

.39

Sorghum grain (milo)

89

84

10

.04

.34

Soybean meal, 44%

91

84

50

.40

.71

Soybean hulls

91

77

14

.63

.22

Soybeans, whole

88

93

40

.27

.64

Urea, 45% nitrogen

99

0

287

.00

.00

Wheat grain

89

88

12

.06

.40

Wheat middlings

89

82

18

.14

1.04

aFeed composition data compiled from several sources, including: Preston, R.L. 1993. Typical composition of feeds for cattle and sheep, 1993-94. pp 40-42. Feedstuffs, May 16, 1993.

Table 10. 

Nutrient composition of feedstuffsa used in Pearson Square example (dry matter basis).

Feed

DMb

%

TDN

%

Protein

%

Ca

%

P

%

Bermudagrassc

85

48

6

.30

.15

Shelled corn

88

90

10

.02

.30

Soybean meal

91

84

50

.40

.71

aSee Table 9 for a more comprehensive listing.

bDM = dry matter

c8-week re-growth

Footnotes

1.

This document is AN117, one of a series of the Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date October 2001. Revised September 2007. Reviewed September 2012. Visit the EDIS website at http://edis.ifas.ufl.edu.

2.

Bill Kunkle, professor and Extension beef specialist, Department of Animal Sciences; Jim Fletcher, county Extension director, Madison County; and Doug Mayo, livestock Extension agent Jackson County, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.