In Vitro Dry Matter Disappearance Research Articles

Tall Fescue and Smooth Bromegrass. II. Effects of Nitrogen Fertilization and Irrigation Regimes on Quality1

AbstractBoth quantity and quality must be considered in selecting forages for livestock. This study was conducted to determine effects of N and irrigation treatments on the quality of tall fescue (Festuca arundinacea Schreb.) and smooth bromegrass (Bromus inermis Leyss.) forage in the Southern High Plains. ‘Fawn’ tall fescue and ‘Southland’ smooth bromegrass were grown on Pullman clay loam (fine, mixed thermic, Torrertic Paleustoll) under N rates of 0, 168, 336, 504, and 672 kg ha‐1 year‐1 on three water regimes: W‐l, a moderate (about 50‐cm) and W‐2, an adequate (about 100‐cm) irrigation water level, both distributed for season‐long production, and W‐3, a moderate (about 60‐cm) irrigation level distributed for cool‐season forage production. Forage was harvested and analyzed for N, P, K, Ca, Mg, NO3‐ and in vitro dry matter disappearance (IVDMD). Nitrogen fertilization increased N, K, and NO3‐‐N in both forages. The increased K levels increased the K/(Ca + Mg) ratios. Less marked effects of N included slight increases in IVDMD in both grasses, increases in Ca and Mg, and decreases in P in tall fescue but not in smooth bromegrass forage. The total N and NO3‐‐N were lower and the Ca and Mg were higher in forage from W‐2 than in that from W‐l and W‐3. With N rates through 336 kg/ha, NO3‐‐N remained below the 2,000‐ppm level considered harmful to livestock. Forage P and IVDMD were not affected by differences in irrigation. Although smooth bromegrass was superior to tall fescue in N, K, and Ca concentrations and in IVDMD, N fertilization at levels high enough to produce satisfactory yields increased the K/(Ca + Mg) ratios to levels considered critical for induction of grass tetany. With pure stands of smooth bromegrass, supplemental feeding of Mg would be necessary. Tall fescue contained more Mg than did smooth bromegrass, and its K/(Ca + Mg) ratios were favorable. Without P fertilization, feeding supplemental P would be necessary with both forages. Surface‐applied feedlot waste, at N rates equivalent to those applied as NH4NO3, was less than one‐half as efficient as NH4NO3 in increasing N to forage, but it increased P to levels satisfactory for nutrition of mature cows. Both irrigation adequacy and grass species must be considered in fertilizing for maximum production of high quality forage.

Sod‐Seeded Soybeans for Forage1

AbstractThe availability of quality forage in the mid‐summer often limits livestock production in the southern U.S. Corn Belt. Soybeans [Glycine max (L.) Merr.] sod‐seeded into grass pastures may give farmers a chance to improve the quantity and quality of forage available for grazing. The objectives of this study were to examine the growth and development patterns of four soybean cultivars grown in grass sod and to determine the potential of sod‐seeded soybeans for forage. The cultivars PI 89003‐1 (Group II), ‘Williams’ (Group III), ‘Bobwhite’ (Group V), and ‘Hill’ (Group V) were seeded on 18 June into a tall fescue (Festuca arundinacea Schreb.) sod with and without paraquat (1,1'‐dimethyl‐4,4'‐bipyridinium ion) at 0.57 kg(ai)/ha. Paraquat was used in this research to suppress the tall fescue sod.Total forage (soybeans plus grass) yields ranged from 6,700 kg/ha for Hill, sprayed with paraquat, to 4,500 kg/ha for Williams unsprayed. The crude protein (CP) content at frost ranged from 15 to 18%, and the in vitro dry matter disappearance (IVDMD) averaged about 60%. Tall fescue grown alone produced 2,800 kg/ha dry matter with 50% IVDMD and 8 to 10% CP.Dry matter accumulation of soybeans was affected by paraquat and the duration of constant growth rate. During the constant growth rate phase, plots sprayed with paraquat produced about 75 kg/ha·day of dry matter, whereas unsprayed plots produced about 50 kg/ha·day. Duration of constant growth rate increased with time to maturity except for the viney‐type Bobwhite, which had a shorter constant growth rate phase than expected.Late‐maturing soybean cultivars appear better for use as a forage because they offer greater flexibility as to time of harvest, maintain higher forage quality, and generally produce more forage than early‐maturing soybeans. These results, based on a single season, indicate that soybeans can add to the quantity and quality of the forage available in tall fescue pastures.

Digestibility of Plants in Ruminal Fluids of Barren-Ground Caribou

The comparative digestibilities of plants and their rates of digestion in vitro were assessed by fermentation with ruminal fluids obtained from barren-ground caribou ( Rangifer tarandus groenlandicus ) shot on their winter range in the southern Northwest Territories. There was a near-linear increase in the in vitro, dry-matter disappearance (IVDMD) with fermentation time (30-120 h) for all eight lichen species that we tested. In contrast, IVDMD was essentially maximal after 60 h fermentation for 10 of 11 non-lichen species. The green leaves of Carex rostrata and Equisetum variegatum were the only species with IVDMDs higher than 50% after a 60-63 h fermentation period. The two species of mosses and a liverwort were poorly digested (15-27%). The addition of 63 mg of urea to each tube markedly increased the digestibilities of both species of lichens tested, and that of Vaccinium vitis-idaea , but it lowered the IVDMD of Salix and Betula stems and the green and cured parts of Carex rostrata . The IVDMDs of four lichen species collected on the Canadian Arctic Islands were higher than those of eight terricolous species obtained from the mainland winter range of R. t. groenlandicus. Key words: Rangifer , caribou, in vitro , digestibility, forages, lichens, rates, Canada

Laboratory Analyses for Predicting Digestibility and Intake of Corn Silage1

AbstractHigh starch samples are difficult to filter using the neutral detergent fiber (NDF) method. Additional research is also required to identify the best in vitro dry matter disappearance (IVDMD) technique for prediction of in vivo digestibility of whole‐plant corn (Zea mays L.) forage. We designed experiments to compare methods of NDF and IVDMD determination for predicting in vivo intake and digestibility, respectively. In Experiment I, normal corn (105‐day maturity) harvested at five maturity stages (75% silk and 12, 24, 36, and 48 days later) was analyzed for NDF with and without amylase addition during refluxing. The standard deviation among triplicate samples was ±1.08 and ±0.56 for the unmodified and modified procedures, respectively. In Experiment II, normal and brown midrib corn of three maturity stages (75% silk and 24 and 60 days later) and mature (60 days) waxy and male sterile corn were analyzed using the treatments outlined above. In vivo digestibility was regressed on IVDMD dtermined by four methods (IVDMD, IVDMD + amylase, IVDMD + nitrogen, and IVDMD + NDF) and in vivo intake on NDF and NDF + amylase values. A greater percentage of variation in in vivo dry matter intake was explained when amylase was added (R2 = 96.0%) than when not (R2 = 52.0%). The addition of amylase to the in vitro fermentation vessel improved the prediction of in vivo dry matter digestibility (R3 = 67.2%) compared with the unmodified procedure (R2 = 53.3%).

Yield and Quality of Alfalfa Harvested During Autumn and Winter and Harvest Effects on the Spring Crop1

AbstractThe production of pasturage is insufficient to meet the needs of grazing animals during autumn in mid‐latitude states of the eastern U.S. The possibility for use of perennial forage legumes after frost has not been studied.The object of this experiment was to gain information concerning the yield and quality during autumn and winter of alfalfa (Medicago sativa L.) produced during late summer and early autumn and to determine the effects of such harvests on spring growth and yield.In replicated field plot experiments, we measured alfalfa yield, forage quality, root reserves and spring growth for two seasons. Stockpiling periods started in early August and early September with an array of harvests during autumn and winter.Two‐year average yields were 1,520 and 892 kg/ha on 1 November for growth made from early August and early September, respectively. The loss of a potential hay harvest must be considered when August stockpiling is contemplated. Forage quality declined during autumn due largely to leaf drop and stem death. On 1 November, alfalfa stockpiled from early August was significantly lower in leaf percentage, N and P concentration, and in vitro dry matter disappearance (IVDMD) than that stockpiled from early September. Forage IVDMD decreased from 59.1% to 45.4% between 15 October and 15 November for alfalfa stockpiled from early August but remained about the same, 69.9 to 70.0 for alfalfa stockpiled from early September. Crude protein (CP) generally and Ca always exceeded beef cow requirements while P and Mg concentrations declined below requirements regardless of stockpiling period. Supplementation of energy, P, and Mg would be necessary during late autumn and winter. Harvests on or after 1 November generally did not reduce root carbohydrate reserves and, with one exception, did not reduce first harvest yield in the following year, indicating that grazing or clipping could occur after that date at this location.Acceptable yields of quality forage were produced during a 6 week or longer period in late summer and autumn. This forage could be utilized by mid‐November with little reduction of the following spring crop.

Chemical Treatment of Wheat Straw

Summary An in vitro digestion study, a lamb growth trial and a lamb digestion trial were conducted to evaluate the effect of different NaOH and Ca(OH)2 treatments on the energy availability of wheat straw. In vitro dry matter disappearance (IVDMD) of wheat straw was increased 29% by chemical treatment with 1% NaOH plus 3% Ca(OH)2 and by as much as 86% by a 4% NaOH plus 1% Ca(OH)2 treatment. A significant amount of hemicellulose was solubilized by chemical treatment with NaOH and Ca(OH)2, but little cellulose was solubilized. Rate and extent of both hemicellulose and cellulose digestion of treated wheat straw were increased significantly in comparison to corresponding measures for untreated wheat straw. Lambs fed chemically-treated wheat straw gained significantly faster and more efficiently and consumed more dry matter per day than those fed untreated wheat straw diets. Chemical treatment of wheat straw significantly increased dry matter, organic matter cellulose and hemicellulose digestibilities in the lamb digestion trial. Organic matter digestibility was increased from 51.3% for untreated wheat straw to 65.3% for 4% NaOH-treated wheat straw.

Nonstructural Carbohydrate Residue, Neutral Detergent Fiber, and In Vitro Dry Matter Disappearance of Forages1

AbstractTotal nonstructural carbohydrate residue (TNCR) has been considercd “structural carbohydrates” and assumed to be mainly cell wall constituents. Consequently, TNCR should have composition similar to other fiber residues, as neutral detergent fiber (NDF), and could be similarly correlated with dry matter digestibility. Such a relationship would permit the determination of the total non‐structural carbohydrate (TNC) status and the nutritive value of forages in the same analysis. The objective of this study was to determine the relationship between TNCR and NDF and to test the use of each to predict in vitro dry matter disappearance (IVDMD).Forages evaluated were timothy (Phleum pratense L.), tall fescue (Festuca arundinacea Schreb.), alfalfa (Medicago sativa L.), forage sorghum [Sorghum bicolor (L.) Moench] and Coastal bermudagrass [Cynodon dactylon (L.) Pers.]. Samples were analyzed for IVDMD, TNC, TNCR, total N, several fiber fractions, and water soluble carbohydrates (WSCHO).The TNCR was significantly (*, 0.05 and **, 0.01 levels) correlated with NDF in timothy (r = 0.98**), tall fescue (r = 0.98**), and sorghum (r = 0.86*), but not in alfalfa (r = 0.30) or Coastal bermudagrass (r = 0.51). The level of TNCR was similar to that of NDF in timothy, but averaged 7.7 to 15.3 percentage units higher in the other forages. TNCR was more closely correlated with IVDMD for sorghum (r = −0.94** vs. −0.75*) and for bermudagrass (r = −0.79∗ vs. −0.43) than was NDF. The IVDMD was best predicted for four of the five forages and for all five forages (in a combined analyses) when TNCR plus N composed the model compared with NDF + N. Coastal bermudagrass IVDMD was equally well predicted by a model containing TNC + N and not considering either NDF or TNCR. The TNCR was apparently as accurate as NDF for predicting IVDMD of the cool season grasses and possibly more accurate for the warm season grasses.

Yield and Quality of Two Cool-Season Grasses as Affected by Selected Herbicides

Several herbicides applied either in the fall or spring at rates used for musk thistle (Carduus nutansL.) control had no deleterious effects on two cool-season grasses, smooth brome (Bromus inermisLeyss.) and intermediate wheatgrass [Agropyron intermedium(Host) Beauv.]. Herbicides used were 2,4-D [(2,4-dichlorophenoxy)acetic acid], 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid], dicamba (3,6-dichloro-o-anisic acid), picloram (4-amino-3,5,6-trichloropicolinic acid), triclopyr {[(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid}, and Dowco 290 (3,6-dichloropicolinic acid). Atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] was included for comparative purposes because it is known to affect the protein content of some forage grasses. Effects on the quality of the forages were measured by in vitro dry matter disappearance (IVDMD), protein and KNO3determinations. Intermediate wheatgrass was less susceptible to damage from the highest rates of picloram and atrazine than smooth brome.

Genetic Variation and Interrelationships of In Vitro Dry Matter Disappearance and Fiber Content in Orchardgrass Herbage1

Forage digestibility, fiber content, and their relationship to animal performance are important aspects of improving forage quality through plant breeding. The objectives of this study were to determine the genetic variation and heritability of in vitro dry matter disappearance(IVDMD), acid detergent fiber (ADF), neutral tergent fiber (NDF), and to examine the interrelationships among these quality factors in orchardgrass (Dactylis glomerata L.) herbage. Fourteen selected orchardgrass parents and their open‐pollinated progenies were transplanted and planted, respectively, into a randomized, complete block experiment at Mt. Vernon, Mo. The forage was analyzed for IVDMD, ADF, and NDF at each of three harvest dates in 1976 and 1977. Parents differed significantly for all of these quality traits. There was less variation among the progenies. Years and harvests within years were significantly different. Narrow‐sense heritabilities ranged from 49 to 91, 21 to 126, and 0 to 110% for IVDMD, ADF, and NDF respectively, suggesting improvement of these traits in the populations studied may be possible through breedingCorrelations of IVDMD, ADF, and NDF with yield were low at the first harvest, but significant in the re‐growth. Maturity was negatively associated with these quality factors at the first harvest date. Stability for these traits between years was favorable

Leaf and Stem Yields and Forage Quality of Three N‐fertilized Warm‐Season Grasses1

AbstractNitrogen fertilization of warm‐season tall grasses may increase dry matter yields, percentage crude protein, and in vitro dry matter disappearance (IVDMD). Leaf and stem portions of total dry matter may vary among grasses, years, and fertility levels and during the growing season. Established pure field stands of switchgrass (Panicum virgatum L.), indiangrass [Sorghastrum nutans (L.) Nash], and big bluestem (Andropogon gerardi Vitman) were fertilized annually with 0, 45, and 90 kg N/ha and harvested at six biweekly dates beginning in mid‐June during 1973 and 1974 to determine leaf and stem yields and forage quality of these warm‐season grasses as influenced by N‐rate and plant maturity. Leaf and total dry matter yields decline 50% following the 1st year of clipping due to below average precipitation of 1974 as compared with 1973. Leaf yields increased with N fertilization more at the later harvests. Big bluestem responded with more than double the dry matter (leaf and total) production per kg of N and showed less decline the 2nd year than the other grasses. Leaf material of all grasses comprised approximately 85% of the total forage yield at most N levels both years. Leaf crude protein percentages were increased with N fertilization during the first three harvests; whereas, leaf IVDMD ercentages were increased with N fertilizer during the first five harvests. Leaf IVDMD was highest in indian. grass followed by big bluestem and switchgrass. Rapid declines occurred in leaf crude protein and IVDMD throughout the growing season, indicating that leaf maturation primarily is responsible for declining forage quality rather than increasing plant development, i.e., increasing stem growth, in these grasses.

Forage Production and Quality of Synthetics Derived from Lolium ✕ Festuca Hybrids1

Nine experimental four‐parent synthetics from derivatives of Lolium ✕ Festuca hybrids and five cultivars of tall rescue (Festuca arundinacea Schreb.) were evaluated for spring growth, maturity, dry matter yield, in vitro dry matter disappearance (IVDMD), and other characters. Three synthetics were from parents that had been selected for yield and vigor in a topcross progeny test; four were from parents that were palatable in an animal acceptance trial; two were from parents that were unpalatable in an animal acceptance trial. Our objectives were to determine the effects of parental selection methods on performance of the synthetics and to compare the performance of the synthetics with that of tall rescue cultivars.Synthetics from topcross‐selected parents had greater vigor and forage yields and matured earlier than those from palatable or unpalatable parents. IVDMD of the synthetics from topcross‐selected parents was not significantly different from the average IVDMD of synthetics from palatable and unpalatable parents. The synthetics from palatable parents had significantly greater IVDMD means than those from unl~alatable parentsThe synthetics were less vigorous, matured earlier, had less first‐harvest, third‐harvest, and total season yield, and had a lower IVDMD mean than the tall rescue cultivars. Average second‐harvest yield of the synthetics significantly exceeded that of the tall rescue cultivars. Variability among the synthetics suggested that breeding could correct most of these deficiencies.

Herbage Yield and Quality of Threadleaf Sedge

Highlight: An investigation of herbage yield, crude protein, and in vitro dry matter disappearance (IVDMD) levels of ungrazed threadleaf sedge (Carex filifolia Nutt.) was conducted over a 2-year period in western Nebraska. Threadleaf sedge contributed approximately 80% of the total herbage production on the study site. Crude protein varied from over 18% in late April to 5% or less in February. Levels of IVDMD varied from 69% in May to 51% in March. Levels of these quality factors were higher than those for most grasses throughout the year.

Sorghum Stover Digestibility as Affected by Juiciness1

Most sorghum, Sorghum bicolor (L.) Moench, hybrids used for silage are juicy genetic types and, thus, are high in moisture. Contrasting dry types are available, and their merit as silage relative to juicy types needs to be ascertained. Genotypes with high and low moisture levels controlled by a single gene difference were compared to determine if their stover differed in digestibility when measured by in vitro dry matter disappearance (IVDMD). Dry matter content and IVDMD were determined for isogenic dry vs. juicy lines and hybrids produced by those lines. Samples of stover were taken at anthesis and at grain maturity and digested in vitro. Significant differences existed for stover dry matter content (62.1 to 79.8%) at both stages of development and for IVDMD at anthesis (57.7 to 63.2%). Isogenic pairs rarely differed significantly in IVDMD, indicating little, if any, advantage for juicy sorghum genotypes in this study.

Animal Preference, Nutritive Attributes, and Yield of Pennisetum flaccidum and P. orientale1

AbstractWarm‐season perennial grasses can make an important contribution to animal enterprises by providing forage for summer grazing. In the transitional belt, however, where cool and warm‐season grasses are used during the grazing season; both are hampered by periods of belownormal growth and frequently only the warm‐season species are available during midsummer. Six Pennisetum accessions initiated growth earlier in the spring in North Carolina than traditional warm‐season grasses, and continued growing through summer and into the fall until killed by frost. The objectives of this study were to evaluate these accessions for acceptance by free‐grazing animals, nutritive attributes, dry matter yield, and persistence. Plantings were made on a loam soil (Typic Hapludult, in the Clayey, Kaolinitic, Thermic family). Five accessions of Pennisetum orientale Rich (from India) and one selection of Pennisetum flaccidum Griseb. (from Afghanistan) were evaluated in one experiment (2 year study) for animal preference and associated nutritive value. Animals grazed all selections (each time forage reached 46 to 61 cm) but consistently preferred (P ≤ 0.01) P. flaccidum. In vitro dry matter disappearance (IVDMD) differed significantly among selections, but rank was not consistent from year to year. IVDMD ranged between 63.1 and 70.4%. Ranges for neutral detergent fiber (NDF) were: 55.0 to 57.9%; for acid detergent fiber (ADF), 28.5 to 34.1%; for lignin, 2.66 to 4.48%, and for N 2.95 to 3.78%. In a separate trial, dry matter yields (3‐year avg.) of the five P. orientale selections under a “short cut” regime (46 to 74 cm high cut to a 15‐cm stubble) were 7,948 kg/ha and for “tall cut” regime (76 to 102 cm tall cut to a 15‐cm stub ble) 12,393 kg/ha. P. flaccidum averaged 8,958 and 12,003 kg/ha for short cut and tall cut, respectively. Yields exceeded 15,700 kg/ha for several of the P. orientale selections managed under the tall cut regime. P. flaccidum produced more of its seasonal yield earlier (91% by 25 July) than did the P. orientale selections (only 77% by 25 July). The nutritive attributes of these forages were appreciably reduced by maturity. Mean values for the five P. orientale selections for the short and tall cut regimes and for P. flaccidum for each harvest regime respectively, were as follows: IVDMD 48.4, 44.0 and 54.7, 54.5%; NDF 61.4, 65.4 and 60.5, 61.1%; ADF 32.8, 35.8 and 33.9, 32.9%; lignin 3.07, 3.84 and 3.67, 3.30%; and N 2.39, 1.77 and 2.44, 2.13%. The Pennisetum accessions evaluated have potential as forage species in the southeastern U.S. In addition to their long growing season and high yield potential, their NDF concentrations were low compared with Coastal bermudagrass (Cynodon dactylon L.). This was especially noticeable in the more mature harvests. Such low fiber concentrations may contribute to an increased dry matter intake by grazing animals.

Phenotype, Fiber Composition, and in vitro Dry Matter Disappearance of Chemically Induced Brown Midrib (bmr) Mutants of Sorghum1

Chemically induced brown midrib (bmr) mutants sorghum (Sorghum bicolor (L.) Moench) were characterized with regard to phenotype, fiber composition, and in vitro dry matter disappearance (IVDMD). The recessive bmr genes produced brown pigmentation in the leaf midrib and stem of mature plants. Pigmentation varied among mutants in intensity, time of appearance, and degree of fading as plants matured.Stem and leaf samples of mutant and normal plants were analyzed in the laboratory to determine percent cell wall constituents (CWC), acid detergent fiber, (ADF), cellulose, hemicellulose, permanganate lignin (PL), vitro dry matter, and in vitro cell wall constituent disappearance (IVDMD and IVCWCD). Ten of the 13 mutants had significantly less stem lignin than the normal counterparts. Reductions in lignin ranged from 5 to 51% in stems and from 5 to 25% in leaves. In the case of other fiber components, only occasional differences were observed between normal and mutant plants. Increases in IVDMD and IVCWCD of as much as 33 and 43%, respectively, were associated with the presence of bmr genes.Variation among mutants in lignin concentration probably indicates that several different bmr genes were involved. Similarities between the bmr genes of sorghum and the bm genes of maize (Zea mays L.) suggest the possible existence of similar genes in other grasses, although their identification may be more complicated because of polyploidy.

もみ殼と稲わらの栄養価改善に対するアンモニア処理の条件

In search of the optimal process conditions of ammonia treatment for rice hulls and straw at the shorter duration and lower temperature possible without the use of special and expensive equipment in the field, the combined effects of ammonia concentration, temperature and duration were determined on the chemical composition and in vitro digestibility. Rice hulls were treated with 2.5, 5.0 and 10.0% of ammonia (by wt) for 15, 30 and 60 days at 25°C, or with 1.0, 2.5 and 5.0% of ammonia for 5 and 10 days at 45°C. Nitrogen contents and in vitro dry matter disappearance (IVDMD) of the ammoniated rice hulls (ARH) were increased with the increment of ammonia concentration at both the temperatures of 25 and 45°C. Duration of treatment (30 and 60 days) affected only the nitrogen content at the 5 and 10% ammonia treatment. The highest nitrogen recovery was observed in the ARH treated with 2.5% ammonia. Increased values of IVDMD in the ARH treated at 45°C for 5 days with 2.5 or 5.0% of ammonia were markedly superior to that treated at 25°C for more than 15 days with the corresponding levels of ammonia. Chemical composition and IVDMD of the rice straw (ARS) treated by more than 2.5% of ammonia at 45°C were nearly equivalent to that observed in the ARS treated for a long term at ambient temperatures. These results suggested that the ammoniated products, which was improved to have a considerable amount of the nutritive value as roughage for ruminants, are prepared by the 2.5% of ammonia concentration in only 5 days where the temperature is maintained at about 45°C in the field. fect of ammonia concentration, temperature and duration on the chemical composition and IVDMD of the rice hulls and straw, and to suggest optimal treatment conditions which are to be accepted as the short period treatment without special and expensive equipment in the field.

Genetic Variability for Chemical Composition of Alfalfa. II. Yield and Traits Associated with Digestibility1

Quantitative genetic parameters were estimated for first harvest yield, acid detergent fiber (ADF), acid detergent lignin, in vitro dry matter disappearance (IVDMD), and protein in ‘Saranac’ and ‘MSA‐C4’ alfalfa (Medicago sativa L.). Neutral detergent fiber (NDF) and in vitro cell wall digestibility (IVCWD) were determined in Saranac. Genotypic, phenotypic, and environmental correlations among each of the characters and with concentrations of 11 mineral elements were computed for Saranac. All estimates were obtained from analysis of a series of four, five‐parent diallel crosses and their parents in each cultivar.Relatively large estimates of heritability were obtained for lignin (43.8%) and protein (64.4%) in Saranac, extremely low estimates were obtained for IVDMD in both cultivars (7.9% for Saranac and 6.1% for MSA‐C4). Heritabilities for the remaining characters wcre intermediate (22.0 to 33.8%). In breeding for improved nutritive value of alfalfa, selection for greater protein content or reduced ADF, NDF, or lignin content would be recommended over selection for greater IVDMD.Estimates of genotypic, phenotypic, and environmental correlations indicated that: (1) Yield was not strongly correlated with any of the quality parameters; (2) ADF, NDF, and lignin were positively correlated with each other and negatively correlated with IVDMD and protein; and (3) IVDMD and IVCWD were positively correlated. Althongh seldom significant, most of the correlations for mineral concentration with yield, ADF, NDF, and lignin in Saranac were negative. Protein content was positively correlated with P concentration; ADF was negatively correlated with Ca, Mg, and Fe concentrations; and lignin was negatively correlated with K concentration.

Yield and Quality Trends of Tall Fescue Grazed with Different Subdivisions of Pasture1

AbstractSubsequent to a grazing experiment which showed average daily gains of growing cattle on N‐fertilized tall rescue (Festuca arundinacea, Schreb.) to be similar whether grazed continuously or in a two‐paddock grazing round baled hay aftermath system, a study was done to determine short‐term changes in the quantity and quality of herbage‐on‐offer for pastures with 0, 2, or 4 subdivisions of grazing. The objective of this experiment was to provide possible explanations for the lack of differences in rate of gain in the on‐going grazing trial. Six groups of three weaner calves grazed replicated pastures of N‐fertilized tall rescue (0.256 ha/group) for 80 days in spring‐summer and 40 days in fall. Cattle were used as defoliators, and animal performance data are not presented. During each grazing cycle, cattle were continuously grazed on pastures with no subdivisions, rotated every 20 days with 2 subdivisions and every 10 days on pastures with 4‐subdivisions. At 5‐day intervals, herbage samples (10 × 0.26 m2) were cut to ground level from each subdivision under grazing. These samples were later analyzed for in vitro dry matter disappearance (IVDMD), N, and mineral composition. Residual herbage samples were also obtained following the completion of the second and third grazing cycles.In the spring and summer (20 May to 7 August), subdivision treatments did not differ in average amount of herbage‐on‐offer/ha. On removal of cattle on 7 August when the no‐subdivision treatment was fully grazed, amount of residual herbage among treatments was nearly the same. Percent IVDMD declined curvilinearly in all treatments from an average of 64% in May to 49% in mid‐July, followed by a 2.5 percentage unit increase in August.In the fall (17 September to 27 October), average amount of herbage‐on‐offer/ha ranged from 800 to 1,000 kg/ha higher with 4 subdivisions than with the other treatments. Fall digestibilities ranged from 62 to 43% IVDMD. Low values occurred at the end of the grazing cycle, especially in the 4 subdivision treatment where the most residue (trampled herbage) was observed.Composited herbage samples from the no‐ and 4‐subdivision treatments showed little difference between the spring‐summer and fall grazing cycles in range of concentrations for N and eight minerals.The results indicate that subdividing pastures for rotational grazing did not have a marked effect on average quantity and quality of tall rescue during the spring and summer. However, pastures with 4 subdivisions did provide more herbage growth in the fall. These findings may partially explain why cattle daily gains in another on‐going grazing trial have not been different.

Time and Rate of Fertilization on Seeded Warm‐Season and Bluegrass Pastures. II. Quality and Nutrient Content1

AbstractThere is relatively limited available information to be found which pertains to the effect of fertilizer application on the quality and nutrient concentration of seeded warm‐season as well as bluegrass pastures grown under more arid conditions. Therefore, this study was designed to measure the influence of the application of N and P fertilizers in early (mid‐April) and late (late May) spring on the quality (protein and in vitro dry matter disappearance) and nutrient (NO8−‐N, P, K, Ca, Mg) concentration of seeded warm‐season and bluegrass (Poa pratensis L.) pastures from 1971 through 1974. Applications of N (0, 45, 90, 135, and 180 kg/ha) and P (0, 8.5, 17, 25.5 and 34 kg/ha) were repeated in each of the 4 years. Whole‐plant samples were collected from each plot at harvest. These samples were analyzed for in vitro dry matter disappearance (IVDMD) and protein percentage. In addition, whole‐plant samples were collected from all plots approximately 30 days after fertilizer application in both 1973 and 1974. These samples were analyzed for NO3‐N, protein‐N, P, K, Ca, and Mg.Fertilization with both N and P had no consistent effect on the IVDMD percentage of mature forage. The protein percentage of the mature forage increased linearly with rate of fertilizer N. Kentucky bluegrass forage had a higher percentage of protein than the mixture of warm season prairie grasses which consisted of big bluestem (Andropogon gerardi Vitman.), switchgrass (Panicum virgatum L.), indiangrass (Sorghastrum nutans (L.) Nash.), and sideoats grama (Bouteloua curtipendula (Michx.) Tarr.). Protein production from the bluegrass pasture was increased eight‐fold by application of both N and P. There was a six‐fold increase in protein production from the warm‐season prairie grasses when adequate rates of both N and P were applied. The concentration of P in samples collected at harvest as well as those collected 30 days after fertilizer application increased linearly with rate of applied P in all cases.The ratio, , exceeded the critical value of 2.2 only when N and P were applied to the warm season grasses in early spring of 1974. The concentration of NO3−‐N in forage from both pastures was increased by applied N but did not approach the 2,000 ppm level generally considered to be lethal to livestock.

Grazing Pressures and Animal Performance from Pearl Millet1

AbstractIn the Gulf Costal Plain adapted summer annual forages such as pearl millet [Pennisetum typhoides (Burm.) Stapf and C. E. Hubb] are generally higher in energy content than perennial grasses and are capable of producing higher rates of gain. However, practically no data are available which define animal performance at different levels of forage utilization. The lack of definitive data on which to base a grazing program with pearl millet prompted this study which determined liveweight gains of weanling cattle grazing ]pearl millet and evaluated the relationships between gain, forage yield, forage quality, grazing pressure, and profitability.A hybrid pearl millet ‘Millex 23’ was seeded at the rate of 15 kg/ha on Thenas (Fluvaquentic Eutrochrept; coarse, loamy, mixed, thermic) soil and fertilized with 112 kg/ha each of N, P2O5, and K2O in each of 2 years. Weanling crossbred beef calves were used as tester animals and grazed at stocking rates ranging from 3.73 to 11.35 animals/ha. Liveweight average daily gains (ADG) from 0.27 to 1.01 kg were shown to be a non‐linear function of forage availability and a positive linear function of percent in vitro dry matter disappearance (IVDMD) available forage. Percent IVDMD of available forage varied from 36.29 to 63.57% and was inversely related to length of trial. Neutral detergent fiber values for available forage were negatively correlated with ADG (r= −0.84).Maximum profitability, expressed as return per ha, was found at intermediate grazing pressure and was dependent upon the magnitude of positive or negative margin between the time of purchase and the time of selling. Maximum profit occurred at greater grazing pressures as the positive margin between selling and purchase price increased.The most important factor affecting the profitability of grazing pearl millet was the differential between buying and selling price of the cattle. Aside from this factor, which the farmer seldom controls, grazing pressure is the most important determinant of profit. It was concluded that the greatest profit or least loss occurs at medium grazing pressures which, in this study, was approximately 2 kg of available forage per kg of animal liveweight.