Published by University Extension, University of Missouri-Columbia. Produced by the Office of Extension and Agricultural Information

Transcription

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2 Nutrition Written by: David L. Lalman, beef nutrition specialist, animal science extension John A. Paterson, Jr., beef nutrition specialist, animal science extension Homer Sewell, professor emeritus, animal science Published by University Extension, University of Missouri-Columbia Produced by the Office of Extension and Agricultural Information For information on how to order additional publications in the Beef Cow/Calf series, see MU publication M147, University Extension and Your Beef Cow/Calf Operation, or contact your local extension center. On the cover: Cows have the ability to convert forages into beef. During much of the year, they can get by on low-quality grazing. But, during some parts of their reproduction cycle, when they are nursing calves and preparing to be rebred, extra attention must be given to their nutrition. ~

3 MU Beef Cow/Calf Series r Contents Topic Page Finding balanced, economical herd rations 1 Production goals, Stress points Feeding Feeding the developing breeding heifers, stock Feeding at different pregnant ages heifers, Feeding pregnant cows Feeding lactating cows, Feeding bulls Winter Wintering rations with for hays cows and crop residues, Wintering on fescue pasture Protein Figuring supplements protein requirements, Nonprotein : nitrogen (urea), Bypass protein, Urea verses plant protein, Use of salt to restrict consumption of protein and energy supplements, Feeding protein at intervals Buying protein supplements 1 Supplementing Protein, Wheat crop straw residues r Creep feeding beef calves Vitamins Vitamin A, Vitamins D and E Minerals Calcium and phosphorus, Sodium and chlorine (salt), Potassium, Trace minerals Mineral mixtures for feeding free-choice, Magnesium, Magnesium and grass tetany Occurrence of grass tetany, Supplements to prevent grass tetany Tables ,

4 r A nutritionally balanced feed ration helps cattle producers achieve production goals faster and more efficiently. Eed rations for beef herds must be economical yet meet the nutritional requirements of the various classes of cattle. T wo essentials for the herd manager to know are the daily nutrients required by each class of cattle in the herd and the nutrient composition of the feeds. With this knowledge, formulating rations is simply a matter of combining feeds to meet the herd's nutrient needs. These nutrient needs are influenced by age, sex, rate-of-gain, point in the reproduction cycle, animal weight and amount of milk produced. Daily nutrient requirements of bull, heifer and steer calves are given in Table 6. Requirements for beef breeding cattle are given in Table 7. The average nutrient composition of feeds often used for beef cattle is shown in Tabl~ 8. For a more accurate ration formulation, you need a laboratory analysis. Area extension livestock specialists can provide an up-to-date list of laboratories offering feed-testing services. When cattle graze or have free access to harvested forage, the amount eaten daily is difficult to predict. Uncertain consumption combined with nutrient variability of roughages means that beef cows may be getting insufficient nutrients even though the ration would be adequate under most situations. Therefore, the appearance and perforr economical herd rations Nutrition 1

5 fiance of the herd should be monitored closely at all times to see if the cattle ar~ getting a balanced diet. ~ Production goals Stress points Feeding the breeding stock at different ages Feeding developing heifers When developing a feeding program, consider these production goals for your beef herd:.90 to 95 percent calf crop born within a 60~day calving period..a calf from each cow every 12 months..heavy weaning weights (500 pounds plus). To reach these goals, feeds must meet the nutritional needs of the herd throughout the breeding season. Be aware of the following stress times when heifers and cows are most likely to have nutrient deficiencies:.heifers -when they are being developed to breed at 13 to 15 months in order to calve at 22 to 24 months of age and when they are being prepared to rebreed after a first calf..cows -in the last 90 days of pregnancy and first 90 days of lactation. Heifers nursing their first calves often have low pregnancy rates. Inadequate nutrient intake after calving is often at fault. First'calf heifers need nutrients for their own growth in addition to those needed for milk and reproduction. First-calf heifers take longer to rebreed for their second calf, so breed them 30 days sooner than the rest of the herd. Heifer calves must come into heat at 12 to 14 months of age if they are to calve at 23 months of age. The weight at which a heifer reaches puberty and comes into heat is influenced by breed and projected mature size. The ideal weight to breed most British breeds is at 600 to 700 pounds, compared to 725 to 775 pounds for Simmental, Charolais and similar'size breeds. If a heifer weighs 400 to 500 pounds when weaned at seven months (210 days), she must have an average daily gain of 1 to 1.25 pounds for the next seven months to reach puberty and settle at 14 months of age. ) Rations for bred heifers should have a higher nutrient content than those fed to cows. A heifer's feed must keep both her and her unborn calf growing..~ 2 - Beef Cow/Calf Series

6 r- Fall-weaned calves should gain 1 to 1.25 pounds daily during the winter to reach breeding weight at 14 months of age. Table 1 lists rations to give about 1 to 1.5 pounds daily gain on 500-pound calves. Pay attention to the energy and protein in a heifer's ration the following winter while she is carrying a calf. Heifers that are thin and undernourished at calving will have poor settling rates. The percent protein and energy needed by heifers in late pregnancy are similar to the requirements for mature cows in early lactation that have average milking ability. Therefore, the rations listed in Table 3 are adequate for yearling heifers in the last third of pregnancy. Feeding pregnant heifers r- Watch the body condition of pregnant cows. Cows in average flesh in the fall can lose 10 to 25 percent of their weight during pregnancy and still be in proper condition to nurse a calf and rebreed. Cows will lose about 100 to 130 pounds at calving. This weight loss represents the birth weight of the calf, fluid and fetal membranes. About one-half of the fetal weight develops the last 60 days of pregnancy. A practical way to condition cows for calving is to feed them so they will gain about 100 pounds the last three or four months of pregnancy (see Tables 2 and 3). At this rate, they neither lose nor gain body weight. Instead, the extra nutrients are used to add weight to the developing fetus. After calving, the cow would weigh about the same as she did three or four months before calving. Ration I Rations for 11b. daily gain: (Ibs Alfalfa hay Grass hay Forage sorghum silage Corn silage Milo or corn grain Protein suppl. (40%) Dicalcium phosphate * Vitamin A ~ :io Feeding pregnant cows Table 1. Winter rations for SOO-lb. calves. Rations for 1.5 Ibs. daily gain: (Ibs.) Alfalfa hay Grass hay Forage sorghum silage Corn silage Milo or corn grain Protein suppl. (40%) Dicalcium phosphate * Vitamin A ,... 'Supply 15,000 to 20,000 I vitamin A per head daily Nutrition 3

7 Feeding lactating cows Cows fed energy~deficient rations before calving are slower to come in heat. One sign of energy shortages during pregnancy is when cows fail to rebreed in time to calve every 12 months. Don't overfeed. Calving problems may be related to overconditioning of the cow and to calf size. But don't starve cows in the last one~third of pregnancy in an attempt to produce a smaller calf and decrease calving difficulties. Starvation makes the pregnant mother draw nutrients from her body tissue and skeleton to develop the fetus. In many cases, such cows have trouble rebreeding. In severe cases, it leads to calving problems. The daily protein and energy (total digestible nutrients, or TON) needed by a cow increases in late pregnancy and increases again after she starts lactating. A cow with average milking ability needs about 50 percent more daily protein and 30 percent more energy after she calves and starts lactating than she needs when dry and in mid-pregnancy. Cows that are heavy milkers need even greater amounts of nutrients during lactation to produce the extra milk..energy has a big effect on a cow's milk production in early lactation. Phosphorus and protein also may need to be added to cow rations. Many roughages have inadequate levels of phosphorus for cattle. Protein is often deficient in winter rations of lactating cows unless some legume forage is fed. A cow must come in heat and conceive by 85 days after she calves in order to produce a calf every 12 months. Nutrient intake after calving influences the pregnancy rate in a herd for the next year. After calving, a cow must have extra energy, protein and other nutrients, not only for milk but also to prepare her reproductive organs for pregnancy. Studies show that when cows lose weight after calving, fewer of them conceive at first service and somewhat fewer cows show heat early in the breeding season. Unless they are fleshy, cows should gain one-quarter pound to onehalf pound a day for the first 90 days after calving to have good reproductive performance. Some scientists think this Qain is so important for ~ ~ A cow needs about 50 percent more daily protein and 30 percent more energy after she calves and begins lactating. ~ 4 Beef Cow/Calf Series

8 Daily feeding of young bulls helps them stay in top condition. reproduction purposes that they recommend checking the weight gain of a sampling of cow every two weeks for the first 60 days to be sure rations are adequate. r Rations for bulls should not differ greatly from those used for cows. Because mature bulls are larger than cows, they should receive a correspondingly larger amount of feed. Rations used for pregnant replacement heifers will be suitable for young bulls except that more grain will be needed to get the growth usually desired on maturing bulls. Young bulls weighing 700 to 900 pounds should gain 2.2 to 2.7 pounds daily to express their growth potential. They should be fed a ration containing from 9.5 to 10.5 percent crude protein on a dry matter basis. One pound to 1.25 pounds of grain per 100 pounds of body weight and free-choice hay should achieve this rate of gain. One pound of 40 percent protein supplement per head daily will be needed if the hay contains less than 50 percent high-quality legume. If good-quality corn silage is full-fed, the grain allowance should be reduced to about three-quarters of a pound of grain for each loo pounds of body weight. A similar amount of grain will be needed with goodquality pasture to get maximum growth on young bulls. Watch the condition on young bulls. Keep them growing, but don't get them overly fat. Check the adequacy of your rations by weighing young bulls every month. Mineral and vitamin requirements for bulls are similar to those for heifers. Bulls used for breeding should be kept in medium flesh. Bulls that are too thin or fat will not have the best sexual activity. Don't let overly fat bulls down during the breeding season. A mature bull often loses 200 to 300 pounds during the breeding season. This means he will need to gain 1 to 1.25 pounds daily during the rest of the year to be back in condition for the next season. A small amount of grain or other extra feed may be needed 60 days before the breeding season to get mature bulls in proper condition. Body condition of the bull is an indication of whether Feeding bulls Nutrition 5

9 an extra feed allowance is needed as the breeding season approaches. Mature bulls can be maintained largely on pasture and other roughage. Bulls should be conditioned to pasture and not turned out with cows directly from a dry lot. They need rations with approximately 7.5 percent protein (dry matter). No extra protein will be needed ifgood-quality grass hay is fed or if 25 percent or more of the hay is composed of legumes. Vitamin and mineral supplements used for cows will be satisfactory for mature bulls. It will take 14 to 16 pounds of TDN and 2.2 pounds of crude protein daily to maintain a 1,800- to 2,000-pound mature bull. This amount of TON is contained in 25 to 30 pounds of hay or 60 to 75 pounds of corn silage. ~ Winter for rations cows Wintering with hays and crop residues. Rations for pregnant and lactating cows during the winter are shown in Table 2 and Table 3. Modifications in these rations will be necessary because feedstuffs will vary in energy and nutrient content. More grain may be needed than is given here if your feeds are lower in quality and energy. Also, cows weighing more than 1,000 pounds will need more daily feed than shown in these rations. Rations consisting totally of grass or legume roughages for lactating cows are borderline in energy even when the roughages are of the best quality. Table 2. Winter rations for 1,OOO-lb. pregnant cows during the last third of pregnancy. Good-quality roughage Constituents Legume hay, good Grass hay, good 21 Corn silage, good 67 Forage sorghum silage 70 Grass or grass-iegume haylage 62 Protein supplement (40%) Mineral mix** Rations (Ibs Moisture % , Other Constituents roughage Moisture % 7 Rations (Ibs.) Corn cobs, cottonseed hulls, wheat straw, or cornstalks Corn silage Forage sorghum silage Alfalfa meal, dehydrated Legume hay, good Grass hay, good Protein supplement (40%) Molasses (wet) Ground shelled corn Vitamin A * Mineral mix** ? , *Supply 15,000 to 20,000 I.U. vitamin A per head daily. **Include minerals to meet cows daily needs. See Tables on pp Beef Cow/Calf Series

10 ,-, Reproductive performance should be watched closely on lactating cows, especially when they are fed only roughage rations. You may need to add 3 to 5 pounds of grain per head daily to all-roughage rations to ensure rebreeding. A free-choice mineral supplement containing 8 to 12 percent phosphorus should be fed with these rations. Fescue pastures provide much of the winter feed for many Missouri beef herds. The protein, energy and other nutrients in winter grasses decline after Jan. 1. If plenty of forage is available, dry, mature, pregnant cows should receive enough protein and energy throughout the winter from fescue pasture. Some good-quality grass hay or mixture hay will be needed when snow covers the fields or in late pregnancy if cows become too thin. Cows should also have a phosphorus mineral supplement containing vitamin A. Weaned calves and cows in the first 90 days of lactation usually need about 1 pound of a 40-percent p!otein supplement and 3 to 4 Wintering on fescue pasture 1,OOO-lb. cows with average milking ability* Rations (Ibs.) Moisture % Table 3. Winter rations for cows in first four months of lactation. r- Legume hay, good Grass hay. good Corn silage 67 Forage sorghum silage 70 Grass or grass-iegume haylage 62 Ground shelled corn Protein supplement (40%) Vitamin A ** Mineral mix " Also appropriate for yearling heifers in the last third of pregnancy ** 36,000 I.U. per cow daily ,1 OO-lb. cows with superior milking ability Rations (Ibs.) Moisture % ~ Legume hay, good Grass hay, good Corn silage 67 Forage sorghum silage 70 Grass or grass-iegume haylage 62 Ground shelled corn Protein suppl. (40%) Vitamin A... Mineral mix 37,000 I.U. per cow daily Nutrition 7

11 Protein is often deficient in winter rations of lactating cows unless some legume forage is fed. pounds of grain or its equivalent in molasses or other feeds for satisfactory nutrition when they graze winter fescue pasture. This is especially true after Jan. 1. Trials at the University of Missouri Agricultural Experiment Station and stations at other universities indicate that fescue pastures, which have high levels of endophyte fungus and lack legumes, are inadequate in energy for lactating cows many months of the year. In one study, flushing cows with grain increased the settling rates of spring-calving cows bred after June 1 and fall-calving cows bred after Oec. 15, when they grazed pure stands of fescue. Feeding 4 to 6 pounds of corn per head daily, starting 15 days before breeding and continuing until the cows were bred (40 to 60 days), increased conception. A more economical approach may be to maintain legumes in the fescue stands and establish fescue stands free of endophyte fungus (see MU publication M152, Forage Management aria Hay HanAling). Cows will eat a maximum of about 2.1 pounds of dry matter for each 100 pounds of body weight. Rate of passage through the digestive tract and daily intake will be less for poor-quality, low-protein feeds. Adjust rations for moisture differences in silage and other high-moisture feeds. It takes one-third more pounds of silage with 70 percent moisture to supply the same dry matter contained in silage with 60 percent moisture. One pound of corn has total digestible nutrients (TON) equivalent to 1.6 pounds of good-quality hay or 2 pounds of poor-quality hay. Ten pounds of alfalfa hay have similar total protein and TON as 2.5 pounds of soybean meal and 4.3 pounds of corn. One pound of good grass hay equals about 2.5 pounds of corn silage and 3 pounds of sorghum silage (30 percent dry matter) in TON and crude protein. Remember, grain may be a cheaper source of nutrients than hay when hay is scarce. Feed your best roughage to calves, first-calf heifers and lactating cows. 8 Beef Cow/Calf Series

12 An indication of whether a feed is adequate in protein for a particular class of beef cattle can be obtained by matching the protein needs in Tables 6 and 7 with the protein concentration given for the feed in Table 8. The principal way protein is added to rations that are low in protein is by supplying legumes and oil meals. A dry, mature beef cow in mid-pregnancy needs 7 percent protein in ration dry matter, whereas a cow in early lactation needs about 9.5 percent. A dry, mature cow will not need protein supplements unless most of her ration is made up of low-quality roughages such as cereal straw, corn cobs, stalks and over-mature grasses. On the other hand, a roughage ration for a cow in the first four months of lactation must consist of high-quality grasses or have some legume composition to be adequate in protein. Superior milking cows usually need energy supplements with forages. Thanks to the bacteria and protozoa in the rumen, cattle, sheep and other ruminants use urea to replace part of the protein in their diet. The rumen microorganisms use the urea "to produce microbial protein. Therefore, the protein needs of cattle are met in two ways: by microbial protein produced in the rumen and by dietary protein that escapes ruminal degradation and bypasses to the small intestine for digestion and absorption. Before a cow's body can use urea, the microorganisms in her rumen must convert urea to protein for their multiplication and growth. To do the converting, they must also have energy, carbohydrates and minerals along with the urea. Most roughages are too low in energy for this process to take place. Therefore, cattle on high-roughage rations cannot use urea as efficiently to meet their protein needs as can cattle on high-grain rations. The amount of natural protein in a feed and the extent to which this protein is broken down in the rumen determine the amount of ammonia that is derived from the feed itself. Therefore, less urea can be used with roughages of similar energy concentration that have higher levels of highly soluble protein. This means that cattle would get little use from urea added to a grass hay that had 10 percent total protein. However, urea could be used to increase the protein equivalent of a hay with similar energy concentration and 5 percent total protein. However, urea probably would not be used to the extent that the protein value in the low-protein hay would be increased from 5 to 10 percent. Therefore, urea fed with a low-protein roughage may be converted to enough microbial protein for a dry pregnant cow that needs 7 percent protein in her diet but would not furnish enough protein for lactating cows or young growing animals that need 10 to 12 percent protein in their diets. Figuring protein requirements Nonprotein nitrogen (urea) ~ Soybean meal is a low-bypass protein feed because an estimated 70 to 75 percent degrades to ammonia in the rumen. Protein sources that have low degradability and supply a large portion of bypass protein are distiller dried grains, corn gluten meal, meat scraps and blood meal. A Bypass protein Nutrition 9

13 combination of urea and a high~bypass protein feed should provide better protein nutrition with many rations than does soybean meal. The urea would ensure adequate ammonia levels in the rumen for microbial growth. Urea verses plant protein Use of salt to restrict consumption of protein and energy supplements Urea supplements have been popular for beef cows because liquid urea supplements can be self-fed to grazing cows. Also, urea can often cheapen the cost of protein. It takes about two-thirds of a pound of urea (281 percent CP) and 4.5 pounds of corn to supply the same total protein equivalent and energy contained in five pounds of soybean meal. The relative price of these three feeds largely determines whether urea or an oil meal supplement is a cheaper source of nutrients. In experiments in Missouri and other stations, urea supplements have compared favorably with oil meals as a supplement to corn silage and sorghum silage for lactating cows. Research indicates that urea supplements are 50 to 65 percent as.efficient as plant protein supplements for cows on winter-range grasses. In other words, one-half to two-thirds as much supplemental plant protein as protein equivalent from urea would be needed for equal performance on winter range. Cows with larger weight loss were compensated with more gain in the summer. The weaning weight of calves was slightly less in some trials where urea was compared with plant protein in winter supplements. Otherwise, reproductive efficiency appears similar for cows receiving plant or urea supplements. Cows wintered on range grass supplemented with products like Starea and biuret, which delay the release of ammonia in the rumen, apparently had less weight loss than cows supplemented with urea. However, plant protein supplements gave best results. Slow-release products lessen the danger of toxicity when cattle over-consume urea. Rates of gain for 400- to 600-pound calves on range pastures or grass hay are usually less when urea is substituted for natural protein supplements. A period of adaptation to urea improves performance. Feeding natural protein supplements for the first 30 to 45 days has enabled calves fed urea with corn silage or grain-roughage rations to have similar gains to those fed soybean meal. This adaptation period has improved the performance of calves fed urea with hay rations in some studies. When a protein or an energy supplement, such as grain, is fed free choice, salt can be used to limit the amount animals consume. The percent salt needed in the mixture will vary with the palatability of the supplement and other characteristics. An elevated level of salt intake is not harmful to the animals if they drink plenty of water. The kidneys cannot tolerate more than 2.4 percent salt in the urine. About 5 gallons of urine are necessary to eliminate one pound of salt. Therefore, cattle on high-salt rations must increase their water intake to eliminate the excess salt. This is the reason that water supplies must be kept from running out or icing over when salt is used to control supplement intake. One rule of thumb is that cattle eat about one-tenth of a pound of salt per 100 pounds of body weight when it is mixed with grains or oil

14 r Cattle eat about one-tenth of a pound of salt per 100 pounds of body weight when mixed with grains or oil meals. ~ meals. A cow eats 1 to 1.5 pounds of salt daily in these mixtures. Try mixing this amount with the daily allowance of feed as a starting point. Lesser amounts of salt will be eaten at first. Watch consumption of the supplement, and adjust salt levels to regulate intake of supplement to the desired amount. Cows on poor-quality roughage or winter pasture will eat about 5 pounds daily of the following two mixtures:.loo lbs. salt, 300 lbs. grain, 100 lbs. meal..100 lbs. salt, 200 lbs. grain, 200 lbs. meal. It usually takes 25 to 35 percent salt in a mixture to limit intake of soybean meal or cottonseed meal to 1.5 to 2 pounds daily for cows (see MU publication 02070, Salt to Limit Intake of Protein and Grain Supplements). Feeding a protein supplement to beef cows and heifers on winter range at two- to five-day intervals is about as effective as feeding it daily. Oil meals and legume hays have been fed successfully this way. Do not feed urea supplements in this fashion; urea can be toxic when cattle consume too much. Feeding protein at intervals,- Whether you mix your protein supplements or buy them commercially, a number of things should be considered. The cost of a pound of protein is one major consideration. But you need to look further to see how much of the protein in the supplement is derived from urea. A urea supplement mayor may not be suitable for your situation. Check the crude fiber level in the supplements. Those with high crude fiber tend to have lower energy and may have some of the protein supplied by protein products that have low digestibility. A feed tag lists the percent of crude protein in the supplement and the percent of crude protein equivalent that is derived from non-protein nitrogen. For example, a tag may state: crude protein 50 percent Buying supplements protein

15 (includes not more than 30 percent equivalent protein from non,pro, tein nitrogen). This means 30 of the 50 pounds -60 percent -of the protein in 100 pounds of supplement is supplied by non,protein nitro, gen (60 percent). Protein supplements are often relied upon to supply vitamins, min' erals and medication. Consider the kinds and amounts of these nutri, ents needed when purchasing supplements. Cornstalks, milo stalks and soybean residue can provide economical winter feed for beef cows (see Tables 2 and 4 ). Cornstalks and other crop residues are valuable sources of roughage for beef cows. They should be properly supplemented. Carrying capacity for stalk fields varies with grain yields. Two acres of cornstalks that yielded 100 bushels of grain an acre will carry a cow for 80 to 100 days. To get the most efficient use of dropped corn and stalks, an electric fence should be used. Allow one,half an acre of stalks per cow for 25 days with one,half acre added each 25 days thereafter. This prevents ~attle from gleaning all the better feed first, which often occurs when cows are allowed to range over the total 2,acre allotment. Mature beef cows in mid,gestation and medium flesh have held their weight when controlled grazing was used with this stocking rate and only minerals Table 4. Supplemental feed recommended with cornstalks. Type of Product Daily Ration Plus 32% Protein ~ Supplement Energy 1. Grazing stalk fields Dry cow -first)rj of grazing period -last % of grazing period Lactating cow -first )!3 of grazing period -last % of grazing period None 11b. Ib. Ib. None Hay or corn amount depending on condition of cow None 4-lbs. corn or full feed good quality hay. 2. Harvested and ensiled stalks Dry cow -50 Ibs. stalklage O.51b None Lactating cow -60 Ibs. (full-feed) stalklage 2 Ibs. 2-3 Ibs. corn 3. Dry stalk stalks This is not a dependable energy source. It should be considered a "supplement" energy source fed in combination with hay, silage or dryaftermath hay. Use protein and corn supplement given above as a guide. 12 Beef Cow/Calf Series

16 Wheat straw and other crop residues, when properly supplemented, are valuable winter roughages. and vitamin A were furnished. A protein supplement usually improves cow performance, especially when the residue quality was reduced after 30 days of grazing., About 0.35 pounds per head daily of supplemental crude protein is needed with crop-residue rations. Protein supplements based completely on urea may not give optimum performance. Crop residues are low in phosphorus, so mineral supplements that have 1:2 or 1:1 ratios of calcium to phosphorus and that supply a minimum of one-half ounce of phosphorus daily per cow should be furnished. A minimum of 25,000 I.U. vitamin A should be supplied to a cow daily because crop residues have little vitamin A activity. Adding 25 I.U. of vitamin E per head daily is advised. The fleshing of cows in stalk fields should be watched closely. Supplemental feed will be needed when snow covers the feed and may be needed during wet, cold weather periods. Similar recommendations apply to the use of milo residues. Table 4 gives Purdue University scientists' recommendations for supplements to feed cows grazing cornstalk fields or being fed harvested residues. Wheat straw can make up one~third to one~half of the ration of dry, mature cows that start the winter in good condition. Half wheat straw and half good~quality grass or mixed hay is a suitable combination. One~ third hay and two~thirds wheat straw with 1 pound of 40 percent pro~ tein supplement added per cow is another possibility. Both rations may need to have 2 or 4 pounds of grain added daily starting 60 days before cows calve. Supply vitamin A and free~choice minerals. These rations are suitable for dry, mature cows, not for preg~ nant heifers. Soybean straw that has lost most of its leaves is poor feed. It is diffi~ cult to save the leaves when soybean straw is harvested. Pregnant cows grazing soybean fields should have about 1 pound of a 32 or 40 percent Protein Wheat straw Nutrition 13

17 Creep feeding beef calves Vitamins Vitamin A protein supplement a head daily. Once most of the leaves and pods are consumed, the soybean straw must be supplemented with hay or grain. When feeding harvested soybean straw to dry cows, supplement it with 1 pound of a 40 percent protein supplement, 5 to 10 pounds of grass hay or 2 to 4 pounds of grain per cow daily. Protein supplements would not be needed if legume hay replaced the grass hay. After a beef calf is 90 days old, its mother's milk will usually supply about one-half of the nutrients it needs for maximum growth. Whether the calf will gain extra weight from creep rations depends on the mother's milking ability and the abundance and quality of the pasture or other feed that is available to the cow and calf. Creep-fed calves usually weigh 30 to 60 pounds more at weaning than calves that are not creep fed. It often takes 7 to 12 pounds of a creep ration to produce an extra pound of weaning weight. Creep feeding gives bigger and more efficient weight gains when the cows' feed supplies are scanty and they are milking poorly. Creep feeds give better ~esults with first-calf heifers, old cows and herds that are made up of inherently poor milkers. Fall calving and drought also increase the value of creep feeding suckling calves. In some years, it is questionable whether it pays to creep feed when commercial calves are dropped in late winter and spring. This evaluation assumes that 8 to 10 pounds of concentrate are required to produce an extra pound of weaning weight and that the extra weight will sell for what it costs a feeder to put on this gain. Read MU publication M153, Marketing and Finance, for examples of how to determine if creep feeding will be economical for your herd. Guard against getting heifer calves too fat with creep feeds. Fat accumulation in their udders can reduce their milking ability as cows. A creep ration that has given good results is one composed of:.cracked, shelled corn -60 percent..whole oats -30 percent..soybean meal-10 percent. Milo can be substituted for the corn, wheat bran for the oats and cottonseed meal for the soybean meal. Replacing 10 percent of the corn with molasses may increase consumption. T wo parts of whole, shelled corn and one part oats, or oats alone, have been used successfully to creep feed calves (see MU publication G2060, Creep Feeding Beef Calves.) Another creep-feeding method is to allow calves to graze ahead of cows or give calves sole access to a plot of high-quality forage such as alfalfa or other legume-grass mixes. The practice is often called creep grazing. The vitamin most likely to be deficient in beef cow rations is vitamin A. Vitamins D and E may be needed in special situations. Green and yellow plants contain carotene, a pigment that animals convert to vitamin A. Cattle consuming feeds high in vitamin A actively store the surplus, primarily in the liver. This reserve is used when feed is deficient in vitamin A. Cows are most likely to need vitamin A supplementation after lengthy grazing of drought-stricken pastures or when, ~

18 r-- fed low-grade feeds in winter. Cows receiving good-quality, green hay~ lage, silage or legume hay are not likely to need vitamin supplements. A chief function of vitamin A is maintaining the epithelial tissue (skin and lining of respiratory, digestive and reproductive tracts) in a healthy condition. It is also needed for sight when an animal adapts from light to dark. Signs of vitamin A deficiency in breeding herds include lowered fer~ tility and calving percentages. Cows that are deficient in vitamin A abort, drop calves that are dead or weak, are difficult to settle and have poor vision at twilight. Pregnant cows that are fed low~carotene feeds should have 25,000 I.U. of vitamin A supplement daily; lactating cows should receive 36,000 I.U. It is advisable to supply 10,000 to 20,000 I.U. of vitamin A daily when calves are under stress, are on preconditioning rations or are being maintained on low~carotene feeds in winter. The intramuscular injec~ tion of I million to 6 million I.U. of vitamin A in cows is another method of administering vitamin A., Injections should be used when cows show deficiency, when a deficiency is likely to develop or when feeding vitamin A is not practical..r-- Vitamins D and E are usually included with vitamin A supplements or injection solutions administered to cattle. Young, growing animals have a greater vitamin D requirement than mature animals. Vitamin D aids in the metabolic use of calcium and phosphorus. It is necessary in forming sound teeth and bones. Rickets is a sign of vitamin D deficiency in young animals: Cattle exposed to direct sunlight or those consuming 3 to 4 pounds of sun-cured forage daily should not need vitamin D supplements. Most rations fed to beef cattle in Missouri are adequate in vitamin E. Alfalfa meal, green leafy forage and whole grains are sources of vitamin E. White-muscle disease in calves and lambs has been prevented and cured with vitamin E. Selenium, a trace mineral, replaces vitamin E in the prevention and curing of this disease. Vitamin E deficiency lowers reproduction in rats and other laboratory animals, but this effect has not been confirmed in farm animals. Giving 25 to 50 I.U. of vitamin E per head daily to cows grazing stalk fields or other low-quality roughages is sometimes recommended. See MU publication GlOSS, Vitamins for Beef Cattle, for more information. Vitamins D and E,.- Matching the mineral requirements of cattle given in Tables 10 and 11 with the average mineral composition of feeds listed in Table 12 gives an indication of the minerals that are most likely to be deficient in a ration. Cows fed grass and legume roughages may need extra phosphorus but little or no calcium supplementation. Both calcium and phosphorus supplements may be needed if grain, corn cobs, stalks or cottonseed hulls make up a sizable part of the cow's ration. The need for calcium and phosphorus is increased during growth, late pregnancy and lactation. T able 11 shows that a 1: 1 ratio of calcium Minerals Calcium and phosphorus Nutrition 15

19 to phosphorus is recommended in diets to maintain cows and bulls. The calcium to phosphorus ratio for young growing animals widens to as much as 2.5:1. Salt {sodium and chlorine) Potassium Trace minerals Cattle usually exceed their requirements when given free access to salt. Consumption varies, but cattle will eat more salt with high, roughage or high,moisture feeds. They will eat more loose salt, but the block form is adequate. Cattle deficient in salt eat dirt, manure and urine in an attempt to get salt. Cattle require 0.1 percent sodium dry matter or 0.25 percent salt in their ration (Table 5). Roughage rations usually have enough potassium for beef cattle. However, University of Missouri studies have shown that potassium will leach from winter fescue pasture to levels as low as 0.30 percent of the dry matter. This is much below the potassium level of 0.65 percent of ration dry matter recommended for beef cattle. Therefore, including potassium in mineral mixtures could benefit beef cattle grazing fescue pasture from J anuary through March. Cobalt, selenium, copper and zinc are the trace minerals most likely to be deficient in cow rations. Cobalt is required by rumen bacteria for synthesis of vitamin B12. There is evidence that cattle should meet their cobalt needs every day. Cobalt supplementation is advised for beef cows wintered on low~quality grass forages, cereal straws or stalks. The requirements for trace minerals in cattle rations and the levels at which some trace minerals are toxic to cattle are given in Table 5. ~ Table 5. Mineral requirements and maximum tolerable levels for beef cattle See tables 1 & to to to to to to See tables 1 & to to to to to 40 From National Research Council, Nutrient Requirements of Beef Cattle, ~

20 Free~choice mineral supplements should be formulated to supply the kinds and amounts of minerals that are deficient in feeds being con~ summed by cattle. The taste and mineral composition of free-choice mix~ tures largely deteriiiine whether cattle will eat enough of a mineral mixture to correct the deficiencies of their main diet. Trace-mineralized salt should be an adequate source of trace minerals under most conditions. Iodized salt is recommended with high~nitrate feeds. Statewide surveys have indicated cobalt and selenium are deficient in much of the fescue forage, especially in the region south of Interstate 70. Copper and zinc have been below recommended levels in several analyses of fescue pasture and hay samples submitted to the University of Missouri Forage Laboratory. A deficiency of these two minerals appears to be more of an individual farm problem than a widespread occurrence. The same free~choice mineral mixture given to a lactating cow on a legume hay diet would not be suitable if she were on a corn silage and soybean meal diet. The corn~silage ration would need both calcium and phosphorus, whereas the legume hay ~ould need only phosphorus. Table 12 gives the composition of various mineral compounds frequently used in feed formulations. Free~choice mineral supplements for cattle on grass and legume forages should have about 8 to 12 percent phosphorus. A free~choice mixture that is often recommended for cattle on grass and legume forage is composed of:.40 parts trace-mineralized salt..60 parts dicalciufi phosphate or bone meal. This mixture contains 13 percent calcium and 11 percent phospho~ rus. For more information on minerals for beef cows, see MU publica~ tions 02080, Minerals for Beef Cattle: Needs, and 02081, Minerals for Beef Cattle Supplements. Studies have indicated that a lactating beef cow needs approximate~ ly 0.7 ounces (20 grams) of dietary magnesium daily to maintain normal serum magnesium levels (2.0 mg/100 ml). A gestating beef cow requires about 0.32 ounces (9 grams). In high~risk situations (see the following section on "occurrence of grass tetany"), tests indicate cows need to be fed an average of 2 ounces (57 grams) of magnesium oxide per head daily for best prevention of grass tetany. This much magnesium oxide contains 1.3 ounces (36 grams) of magnesium, almost twice what research shows the body needs daily. Underconsumption by some animals in the herd and other factors are involved in the need for this high level of magnesium intake. Supplementing the cow with 0.6 of magnesium oxide (10 grams magne~ sium) usually is sufficient. Animals need to have a daily intake of magnesium because most of the magnesium is cleared from the blood within 20 to 30 hours after it is con~ sumed. Also, there is little or no storage of magnesium by older animals. Mineral mixtures for feeding free-choice Magnesium Grass tetany is also known as winter tetany, grass staggers, wheat poisoning tetany and hypo-magnesium. Grass tetany is caused by a physiological deficiency of magnesium, which may result from a deficiency of magnesium in the feed or factors that lower the utilization of magnesium. Magnesium and grass tetany Nutrition 17

21 Affected animals may become excitable and then show such symptoms as trembling muscles and grinding of the teeth, followed by violent convulsions, deep coma and death. Some animals remain quiet but are unable to rise. Cows often resemble those with milk fever; many of them have a low serum calcium as well as low serum magnesium. Occurrence of grass tetany Supplements to prevent grass tetany The greatest number of tetany cases usually occur in April and May, but many cases are now seen in the fall and winter. Tetany occurs most frequently in cows 6 years old and older that are nursing calves under 2 months of age. Cows grazing grass pasture or consuming grass hay account for most of the cases. Cloudy, windy, rainy weather with the daytime temperature between 40 F and 60 F seems to affect both the cow and the grass she consumes, increasing the incidence of grass tetany. Tetany seldom occurs when legumes or legume-grass mixtures are a major portion of an animal's diet. Legumes may contain more than twice the concentration of magnesium that grasses contain when grown "on the same soil. Soils that have a high level of available potassium (above 250) in the top 3 inches are more suspect than others. But tetany can also occur under other soil conditions. Keep plenty of magnesium oxide mineral available during danger periods such as early spring and after calving. Other magnesium compounds can be used, but the availability of the magnesium and palatability of the compound is a problem with some. Dolomitic limestone is not a satisfactory magnesium supplement for cattle. To be effective, a mineral mix should contain at least 10 percent magnesium. Some commercial mineral mixes marketed for the prevention of grass tetany contain less. Keep minerals in boxes located at several places in the field to give all animals ready access. Feeding some good legume or grass-iegume hay in danger periods is helpful because legumes are higher in magnesium than grasses. In Virginia Polytechnic Institute trials, cows on grass pasture ate 0.6 to 1.6 ounces of magnesium oxide daily when fed the following supplements: one part trace-mineralized salt; one part magnesium oxide; and one part of either dried molasses, ground shelled corn, cottonseed meal, dehydrated alfalfa meal, or distillers' dried grain with solubles. Other mixtures to feed include: Mineral mixtures ( figures refer to lbs. ) : a. T race-mineral salt, 30; bonemeal or dicalphosphate, 30; magnesium oxide, 30; dried molasses, 10. This mixture provides about 18 percent magnesium. b. Salt 75, magnesium oxide 25. Concentrate mixtures: a. For self-feeding with forage containing 10 percent crude protein. Ground grain, 65; magnesium oxide, 20; salt, 15. b. For self-feeding with low-protein roughages. Cottonseed meal, 65; magnesium oxide, 20; salt, 15. c. For hand-fed supplements, use (a) or (b) but omit salt. '""'"\ 18 Beef Cow/Calf Series

22 Table 6. Daily nutrient requirements for growing bull, steer and heifer calves. """' ~ '"'"" 20 Beef Cow/Calf Series

23 r Table 6. (continued) Daily nutrient requirements for growing bull, steer and heifer calves. Medium-frame heifer calves ~...,- Nutrition 21

24 Table 7. Requirements for breeding cattle. Weight (Ibs.) ADG (Ibs.) DMI (Ibs.) CP% (Ibs.) NEm (Mcal) Pregnant yearling heifers -last third of pregnancy NEg (Mcal) TDN (Ibs.) Ca (Ibs.) p (Ibs.) K (Ibs.) ~ Dry pregnant mature cows -middle third of pregnancy Dry pregnant mature cows -last third of pregnancy ~ 2-yr. heifers nursing calves -1 st 3-4 months postpartum Cows nursing calves -avg. milking ability -1st 3-4 months Cows nursing calves -Superior milking ability -1st 3-4 months """"'., 22 Beef Cow/Calf Series

25 Table 8. Feed composition r CF % CA % p % K % ~ QS ?3 0:,\4 n1q , Nutrition 23

26 ~ UNIVERSITY COLUMBIA OF MISSOURI.Issued in furtherance of Cooperative Extension Work Acts of May 8 and June 30, 1914 in cooperation with the United States Department of Agriculture. Ronald C. Powers, Interim Director, Cooperative Extension Service, University of Missouri and Lincoln University, Columbia, Missouri An equal opportunity institution. M151, New 9/93/7M Printed on recycled paper with soybean oil ink ~