LEAFLET 60 SEPTEMBER 1958 A COMPARISON of Starr Millet, Sweet Sudangrass, Johnsongrass As Dairy Forages GEORGE E. HAWKINS, Associate Dairy 14usbandman L. A. SMITH, Superintendent, Black Belt Substation W. B. KELLEY, Former Superintendent, Black Belt Substation * STARR MILLET and sweet Sudangrass are widely used for temporary summer pasture by Alabama dairymen. In some sections of the State, Johnsongrass is important as a summer grazing crop. Each of the three grasses has advantages. Although Starr millet is not as palatable as sweet Sudan, it is bothered less by diseases. Sudan grows off faster and provides earlier grazing, but the millet makes more growth after being grazed. A big advantage of Johnsongrass is that it does not require annual land preparation and seeding as do the two annuals. And, it has been well liked by cows at the Black Belt Substation during several years' use. EXPERIMENTAL PROCEDURE Three tests were made to compare the grasses: (1) Johnsongrass, Sudan, and millet were grazed continuously at the Black Belt Substation, Marion Junction, in1956; (2) all three of the forages were cut and fed to cows at the Main Station, Auburn, in 1956-57; and (8) * Deceased sweet Sudangrass and Starr millet were used in rotation grazing at the Main Station in 1956-57. Five cows were fed each forage in each test. These studies were made to compare the forages under identical management, not to compare the different methods of use. Records were kept on bodyweight changes, amounts of milk produced, and amounts of concentrate fed. Continuous Grazing Test. Johnsongrass, Starr millet, and sweet Sudangrass top-dressed with 50 pounds of nitrogen per acre were grazed continuously. Samples of each grass were analyzed for chemical composition each week of the 28-day test. Cows were fed concentrates at the rate of 1 pound for each 5 pounds of 4 per cent milk produced, Table 1. Forage Cut and Fed Green. In this 15-day test, five cows were fed Johnsongrass, five Starr millet, and five sweet Sudangrass. The grasses were cut and fed fresh each day. Each cow was fed 50 pounds per day for the first 4 days and 60 pounds per day n, r II STATION EXPERIMENT AGRICULTURAL INSTITUTE POLYTECHNIC ALABAMA qdw E. V. Smith, Director Auburn, Alabama TABLE 1. DESCRIPTION OF EXPERIMENTAL PASTURES USED IN TEST, BLACK BELT SUBSTATION, 1956 CONTINUOUS GRAZING Item Pasture size, acres Date seeded Seeding rate per acre, pounds . Start of test, date . Forage height at start, inches Johnsongrass 4.25 19551 25 7-18-56 --------------------- 8-10 Sudweetass Starr millet 4.25 29 7-18-56 15-20 6-19-56' 4.25 6-19-56' 17 7-18-56 10-15 'A cutting of 1/2 ton of hay was removed July 8. ' Seeded June 19 except for 8/10 acre that was seeded June 25. ' One acre with a poor stand was reseeded July 12. during the last 11 days. In addition to the green feed, cows were given enough concentrate to meet nutrient needs. All three grasses had some seed heads when the test was begun. Because of dry weather, the grasses matured fast. At the end of the test, most of the seed were in the late milk to dough stage. Samples of each grass were analyzed for chemical composition, and digestibility of each was determined. Rotation Grazing. Two sweet Sudangrass and two Starr millet pastures were used in this 35-day test. During the first, second, and fifth weeks of the test, the cows grazed pasture No. 1 of each grass. Pasture No. 2 of each was grazed during the third and fourth DESCRIPTION AND TREATMENT TABLE 2. OF ROTATION GRAZED PASTURES, MAIN STATION, 1957 weeks. Information about the pastures is given in Table 2. In addition to grazing, the cows were fed 1 pound of concentrate for each 3 pounds of 4 per cent milk produced. RESULTS and DISCUSSION Composition and Digestibility. Average chemical analyses of the grasses grazed and fed green are given in Table 3. Grasses grazed during the continuous grazing test were high in protein. However, protein content dropped during every week of the test. Trends in cellulose contents were: Johnsongrass - dropped each week; sweet Sudangrass - no major change; and Starr millet- increased. The trends in cellulose content were related to quality of the grasses. At the end of the test, the Johnsongrass pasture was short and mostly new growth; the sweet Sudangrass had new leaves on the old stems; and the Starr millet was mostly old growth about 15 inches high. The main difference among the grasses was in their nitrogen-free extract (mostly sugar and starch) content, which indicated that the sugar content of Johnsongrass and sweet Sudangrass was higher than that of Starr millet. Digestibility of the forages cut and fed green was measured with six steers. Johnsongrass was more digestible than sweet Sudangrass or Starr millet. In another study, however, the digestibility of Johnsongrass ranged from 53 to 64 per cent, which is lower than Item Starr millet Sweet Sudangrass 4-23-57 25 250 early bloom 1.73 full bloom 1.15 Pasture 1 4-23-57 Date seeded Seeding rate per 20 acre, poundsia Ammonium nitrate 250 per acre, pounds preStage of maturity-bloom 1.57 Pasture size, acresPasture 21 half Stage of maturity-bloom Pasture size, acres 0.90 ' Date and rate of seeding and fertilization same as for Pasture 1. TABLE 3. DIGESTIBLE NUTRIENTS AND AVERAGE COMPOSITION' FORAGES, DRY MATTER BASIS 1 OF EXPERIMENTAL Forage Digestion Total coeffi- nutrients cient of digestible Protein protein Pct. Pct. 78 58 63 Pct. 16 17 24 Fat Pct. 3 2 4 Average composition Fiber Cellulose Nitrogen- Meral Nitfrogen extract Pct. 28 28 28 Pct. 32 Pct. 45 44 86 Pct. 9 9 9 Johnsongrass-----Sweet Sudangrass Starr millet 76 65 59 82 33 1Determined only on forages cut and fed green. 2 Averages of forages continuously grazed and those cut and fed green. Sudan and millet (dry matter basis). Therefore, the average digestibility of Johnsongrass probably is similar to that of sweet Sudangrass and Starr millet. Milk Production. The average daily milk production of cows on the three forages are given in Tables 4, 5, and 6. Results of the three experiments are summarized in Table 7. Production is given as 4 per cent fat corrected milk. Milk production of cows on sweet Sudangrass increased during the first week, Table 4. Otherwise, the trend in milk production, persistency of proTABLE 4. DAILY MILK PRODUCTION AND PERSISTENCY OF PRODUCTION, CONTINUOUS GRAZING TEST, BLACK BELT SUBSTATION, 1956 duction, and average production for the test were similar for all three grasses. During the test in which the grasses were cut and fed green, average daily milk production of cows fed the three grasses was: (a) Johnsongrass, 26.0 pounds; (b) sweet Sudangrass, 26.3; and (c) Starr millet, 24.0, Table 5. With the exception of a 2.9-pound drop in milk during the first 5 days by cows on Starr millet, the trends in milk production from all three grasses were similar. The early production decrease by cows on Starr millet resulted from cows eating less of this grass than did those on sweet Sudangrass and John- songrass. TABLE 5. DAILY MILK PRODUCTION AND PERSISTENCY OF PRODUCTION, GREEN FEEDING TEST, MAIN STATION, 1956 Average production of of Period test cows on each forage Johnson- Sweet Starr Average production of grass sudan- millet grass grass Pounds Pounds Pounds 24 25 26 Before test------25 25 25 1st week 24 2nd week ----------------23 24 Period of test cows on each forage Johnson- S weet grass grass arr millet 3rd week--------4th week--------1 22 21 20 19 21 19 Average 22.0 23.0 21.9 Persistency of production, 80 76 per cent'-------- 79 1 Average production is adjusted for differences between groups before test. 2 Before test 1st 5 days-------2nd 5 days----3rd 5 days ........ Test average1 -.... Persistency of production, Pounds Pounds Pounds 25 27 25 23 27 24 24 26 28 24 28 26 24.0 26.8 26.0 Production of the last week as a percentage of that during the week before the test. The lateness in gestation of cows in the test accounts for the low persistency. 95 103 102 per cent1 Adjusted for differences in production before test. SMilk production during third 5-day period divided by production before test. DAILY MILK PRODUCTION AND TABLE 6. PERSISTENCY OF PRODUCTION, ROTATION GRAZING TEST, MAIN STATION, 1957 Average production of cows on each forage Sweet Starr Sudangrass millet Pounds Pounds 23 20 Before test--------25 23 1st week 23 21 2nd week 24 19 3rd week 23 17 4th week 26 20 5th week 21.0 22.4 Test averagePersistency of pro113 101 Sgrass duction, per cent . for differe nces in production 1 Adjusted before test. 2 Average production for fifth week divided by average prodi uction before test. Period of test TABLE 7. DAILY MteLK PRODUCTION OF ESTED, SUMMARY Cows ON FORAGES TrS, 1956-57 OFTHREETES , 1956-57Under milk, respectively, than during the fourth week. Average daily milk production for the test was 21.0 pounds for sweet Sudangrass and 22.4 pounds for Starr millet. A summary of milk production on Johnsongrass, sweet Sudangrass, and Starr millet for all tests, Table 7, shows that the three grasses are about equal as feed for dairy cows. SUMMARY Chemical composition of the Johnsongrass, Starr millet, and sweet Sudangrazed at the Black Belt Substation and fed green at the Main Station was determined. Composition of all three was similar except that Starr millet was highest in fat and lowest in nitrogen-free extract (sugar and starch) content Average Forage production' Pounds 28.02 Johnsongrass ncrea -------24.1 Sweet Sudangrasse 283.5 Starr milletlet. nto account differqAdjusted to take ences in average daily production of cows at start of tests. 2 Average for two tesSts. Results of the rot ation grazing test, Table 6, show the iin nportance of high quality pasture. Dur ing the first week astures were high of this test, both pc in quality and milk p roduction of cows 2 on both increased ]L to 13 per cent. Both of the grasses grazed during the second week were similar in quality and the changes inSmilk production were about the same .However, sweet lring the third and Sudangrass grazed du fourth weeks was nnore mature than the Starr millet. 1 his difference in quality during the third and fourth weeks resulted in a change in milkproduction. Cows graziing Starr millet increased in producti on, whereas production of cows on sweet Sudangrass pastures dropped. During the fifth week, cows grazing millet and Sudangrass produced 13 an d 17 per cent more proper management, Johnsongrass, sweet Sudangrass, and Starr millet are high quality forages for dairy cows. Proper management means keeping the pastures about 15 inches high and leafy. This can be done by: (1) Waiting until the pastures are 15 to 18 inches high before turning the cows onto them; (2) adding dry cows when the pastures are making fast growth; (3) having two or three pastures and changing at,10-day to 2-week intervals when growth is slow and (4) by staggering the planting dates of the two annuals - sweet Sudangrass and Starr millet. The acreage needed to supply good grazing throughout the summer months will vary from farm to farm. Natural fertility of the soil, amount of fertilizer applied, and amount of rainfall determine acreage needed. At similar stages of growth, Johnsongrass, sweet Sudangrass, and Starr millet were about equal as feed for milking cows. The stage of maturity at which these three grasses were grazed was more important than the grass species. For this reason, any one or a combination of these three grasses that is best suited to a farm can be used to provide forage for milking cows during the summer months in Alabama.