Agronomy and Crop Sciences Commons^™

Forage Analysis With Near-Infrared Reflectance Spectroscopy: Status And Outline Of National Research Project, W C. Templeton Jr, J S. Shenk, K H. Norris, K H. Norris, G W. Fissel, G C. Marten, J H. Elgin Jr, M O. Westerhaus

IGC Proceedings (1977-2023)

Objectives of this paper are to review the status of near-infrared reflectance spectroscopy (NIRS) in forage-quality evaluation and to indicate the approach being used in a national research effort to further test, validate, and develop the technology for use in forage breeding, production, and utilization programs. Use of NIRS assay of forage quality was first reported 5 years ago. Research has now been initiated at many locations.

A national research project, involving personnel at six widely dispersed locations in the U.S., was established in 1978. Com­puterized, high-precision near-infrared reflectance spectrophotometers are employed. A set of 30 forage samples provided ex­perimental …

Influence Of Sward Structure Upon Herbage Intake Of Cattle Grazing A Perennial Ryegrass Sward, M H. Wade, Y.L P. Le Du

IGC Proceedings (1977-2023)

To examine the influence of structural distribution of herbage within a sward on intake by grazing animals, two swards of contrasting structure were established at two periods in the grazing season by either infrequent mowing (C) or hard sheep graz­ing (G) of a perennial ryegrass (Lolium perenne) pasture. The plots were then allowed to grow undisturbed for about 5 weeks before being grazed by young cattle for periods of 2 weeks at two levels of herbage allowance, 30 and 60 g dry matter/kg live weight/day, in July (1) and in September (2). Detailed measurements of sward structure were …

A Mathematically And Conceptually Unified Approach To Grazing-Management Terminology, D L. Scarnecchia, M M. Kothmann

IGC Proceedings (1977-2023)

Expressions such as "stocking density," "stocking rate," "grazing pressure," "herbage allowance," "grazing intensity," "stock­ing intensity," and "stocking pressure" have long been used to describe animal-pasture systems. In general, these expressions describe relationships among the basic variables of animal demand, forage quantity, pasture area, and grazing duration. Our objective was to develop a conceptually dynamic mathematical framework of expressions summarizing all of the meaningful relationships among these variables. Elementary differential and integral calculus were used to develop this dynamic approach. The resulting expressions are dimensionally valid and are capable of accurately describing dynamic animal-pasture systems. Adoption of this system would standardize …

Regeneration Of Windmill Grass Pastures Following Severe Grazing In Semiarid Southeastern Australia, D L. Michalk, G E. Robards

IGC Proceedings (1977-2023)

Stability of windmill grass pastures in west central New South Wales was examined by measuring regeneration of two impor­tant grasses (Enteropogon acicularis and Chloris truncata) on two range sites grazed at three stocking rates (2.5, 3.7, and 4.9 sheep/ha) following 5 months of abusive grazing at 25 sheep/ha. Severe grazing reduced density and size of mature E. acicularis plants on both sites, particularly when heavy grazing (4.9 sheep/ha) was reintroduced during the period of pasture recovery. However, during the study E. acicularis density remained relatively stable because seedling cohorts compensated for plant losses in all treatments. Moderately grazed plots were …

Screening Perennial Forages By Mob-Grazing Technique, P Mislevy, G O. Mott, F G. Martin

IGC Proceedings (1977-2023)

Mob-grazing allows the study of forage response to severe defoliation by grazing animals on a limited land area. This tech­nique was used to evaluate two Digi,taria spp., one Paspalum sp., and 13 Cynodon spp. at grazing frequencies of 2, 3, 4, 5, and 7 weeks. Average dry-matter (DM) yield generally increased as grazing frequency decreased from 2 to 7 weeks. Decreasing the grazing frequency from 4 to 7 weeks resulted in a DM yield increase of 50% to 75% for most entries. Grazing at 4-and 5-week intervals resulted in the highest (42%) and lowest (22%) weed contamination, respectively, when compared …

Grazing Techniques For Evaluating Quality Of Forage Cultivars In Small Pastures, A G. Matches, F A. Martz, D A. Sleeper, R L. Belyea

IGC Proceedings (1977-2023)

Because plant beeders have few laboratory analyses of forage quality that are good predictors of animal performance when grazing pasture, • we studied the feasibility of grazing small pastures with cattle in order to detect possible forage-quality dif­ferences among cultivars of tall fescue (Festuca anmdinacea Schreb). Kentucky 31, Kenmont, Fawn, and Missouri 96 tall fescue cultivars and Kenhy, a Lolium-Festuca derivative, were grown in 0.47-ha pastures and grazed in separate periods ranging from 35 to 68 days during the spring, summer, and autumn of 1974-1976. Between grazing periods, cattle grazed a reserve pasture of the same cultivar. All test pastures …

Structural Characteristics Limiting Digestion Of Forage Fiber, D E. Akin

IGC Proceedings (1977-2023)

Cell walls of forage were studied for structural and chemical factors that limit digestion by rumen microorganisms. Tech­niques used to investigate digestion were histochemistry, electron microscopy, and anaerobic culturing of rumen populations on specific substrates. Certain tissues, such as the xylem cells, totally resisted degradation by rumen microorganisms; these tissues stained positive for lignin with acid phloroglucinol (Weisner test). Other supportive tissues, such as the sclerenchyma in blades, stained positive for lignin with chlorine-sulfite (and also the Maule test) and were also generally resistant to microbial digestion. Microscopic studies revealed that certain living tissues (i.e., those having cytoplasm and organelles …

Relationship Of Forage-Evaluation Techniques To The Intake And Digestibility Of Tropical Grasses, S M. Abrams, H Hartadi, C M. Chaves, J E. Moore, W R. Ocumpaugh

IGC Proceedings (1977-2023)

Seventy-six grass hays, harvested at 2, 4, 6, and 8 weeks of regrowth, were fed ad libitum to wethers in a digestibility and in­take trial. Range of organic-matter digestibility (OMD) was 54.l % to 72.3% and that of organic-matter intake (OMI) 17.3 to 27.4 g/kg. Lignin was the chemical component most highly related to OMD (r = - 0.72). Neutral detergent fiber (NDF) was bet­ter than acid detergent fiber (ADF) as a predictor of OMD (r = - 0.66 vs. - 0.45). In-vitro NDF digestibility (IVNDFD) was superior to in-vitro organic-matter digestibility (IVOMD) and all other analyses as a predictor …

Using A Dynamic Model Of Fiber Digestion And Passage To Evaluate Forage Quality, D R. Mertens, L O. Ely

IGC Proceedings (1977-2023)

Assessing forage quality depends not only upon the characteristics of the plant and animal, but also upon the dynamic interac­tion of the forage, rumen microorganisms, and animal. Although static variables, such as composition or 48-hour in-vitro fermentation, are important for characterizing feeds and predicting in-vivo responses under standard conditions, they provide little information that can be used to assess forage quality in dynamic situations. Dynamic properties, such as rates of digestion and passage, can be used to predict digestion under varied circumstances but require an appropriate mathematical model. Our objectives were to describe a dynamic model of fiber digestion and …

Bulk Volume: A Parameter For Measuring Forage Quality And Its Influence On Voluntary Intake, P J. Van Der Aar, H Boer, G Hof

IGC Proceedings (1977-2023)

The experiment evaluated bulk volume (ml/g meal) as a method of estimating forage quality. Samples of Lolium perenne (Lp) and Festuca arundinaea, and hay samples of Lp were collected at different stages of growth. Voluntary intakes of these forages by dairy cattle had been measured previously. Volumes of samples and volumes of cell-wall residues after 0, 6, 12, 24, and 48 hours in vitro digestion were determined.

Rate And Extent Of Fermentation And Potentially Digestible Fractions Of Various Roughages, W J. Maeng, H S. Yun, I S. Yun

IGC Proceedings (1977-2023)

To determine in-vitro digestion characteristics - such as fermentation and amounts of potential digestibility of dry matter (PDDM), cell-wall constituents (PDCWC), acid detergent fiber (PDADF), and cellulose (PDC) - rice straw, barley straw, corn cobs, corn stover, orchardgrass, and alfafa were digested in vitro for 6, 12, 24, 36, 48, 72, and 144 hours.

Methodology For Determining Pasture And Animal Response Differences In Unbalanced Experiments With Intercorrelations Among Treatments, J C. Burns, R W. Harvey, F G. Giesbrecht

IGC Proceedings (1977-2023)

Conventional statistical analyses require balanced data sets. Unbalanced data can be analyzed using regression procedures, but excessive adjustments may be needed for some treatment means. The objective of this paper is to evaluate an analysis of grazing-trial data using generalized least squares. The data was obtained from a 6-year study involving 12 treatments with not all treatments being made in all years. The analyses involved estimating variance components due to years, fields, and random error and then using these estimates to obtain adjusted treatment means. Variance-component estimates for the complete data set were similar to estimates from two balanced subsets …

Use Of Principal-Component Analysis In Summarizing Nutritive And Analytical Characteristics Of Forages, O T. Stallcup, C J. Brown, Z B. Johnson, D L. Kreider, J O. York

IGC Proceedings (1977-2023)

Principal component analysis and other multivariate analyses have not been used extensively to analyze forage data. Our objective was the synthesis and summary of 98 digestion trials on forages using a principal-component analysis. The ten variables studied in all trials were dry matter (DM), crude protein (CP), digestible protein (DP), crude fiber (CF), ether extract (EE), nitrogen-free extract (NFE), ash (A), gross energy (GE), total digestible nutrients (TDN), and digestible energy (DE). Acid detergent fiber (ADF), acid detergent lignin (ADL), and cellulose (C) were summarized, in addition, for some forages. When data on thirteen variables in 24 hays were summarized, …

Yield And Forage Quality Of Panicum Virgatum, J L. Griffin, G A. Jung

IGC Proceedings (1977-2023)

In the temperate areas of the U.S.A., high temperatures and low soil moisture in summer limit the production of cool-season grasses and, consequently, the size of most beef cow-calf herds. Warm-season grasses, most productive in midsummer, may serve as a supplement to cool-season grasses for grazing and hay. Switchgrass (Panicum virgatum L. ), a warm-season species native to the Great Plains of the U.S.A., was grown on soils low in available phosphorus at two locations in Pennsylvania to determine changes in forage dry-matter yields, leaf (leaf blade): stem (sheath+ stem) ratios, and quality of leaf and stem fractions associated …

Effect Of Experimental Methods On Results Of Voluntary Intake Experiments With Grass Cultivars, U Simon, P Daniel

IGC Proceedings (1977-2023)

The amount of forage eaten by farm animals when forage is offered ad libitum is a major factor in the nutritive value of forage grasses. It is influenced by a number of internal and external factors. Experimental results of studies on the subject :reported in the literature are often contradictory, partially because, perhaps, of the methods of evaluation employed. We studied whether and to what extent different experimental procedures influenced the results of intake experiments in grass cultivars. Four cultivars of Lolium perenne differing in ploidy level and precocity were fed to sheep ad libitum, and voluntary intake was assessed …

Review Of Mechanisms Of Toxicity Of 3-Nitropropanoic Acid In Nonruminant Animals, D L. Bustine, B G. Moyer

IGC Proceedings (1977-2023)

Crownvetch (Coronilla varia L.) now has limited use in the U.S.A. as a forage crop for ruminant animals. Even though crown vetch forage can contain high amounts of nutrients, intake by ruminants may be reduced. Toxicity problems upon feeding crownvetch to nonmminants have been traced to 3-nitropropanoic acid (NPA), which occurs esterified to glucose in the plant. Understanding mechanisms of toxicity in nonruminants will be helpful in avoiding livstock losses and in treating poisoned animals. Symptoms of NPA toxicity are similar in rats, mice, meadow voles, chickens, and rabbits and probably reflect central nervous system disorders and oxygen deprivation. …

Hydrocyanic Acid Potential In Stargrass (Cynodon Spp.), P Mislevy, E M. Hodges, F G. Martin

IGC Proceedings (1977-2023)

The acreage of stargrass and bermudagrass (Cynodon spp.) throughout tropical and subtropical regions has increased greatly. However, many Cynodons have a hydrocyanic acid potential (HCN-p) that may be toxic to livestock. The purpose of this study was to determine the HCN-p in fresh and hay samples of meristematic stem tips from nine Cynodon entries at different physiological stages of growth during the summer (19°-33°C) and autumn (11° -32°C). Two selected entries (Ona and UF-5 stargrass) were also separated into meristematic stem tips, leaves and sheaths, and nodes and internodes at different stages of maturity to monitor HCN-p, dry matter (DM), …

Effect Of Level Of Nitrogen Fertilization Of Kentucky 31 Tall Fescue (Festuca Arundinacea Schreb.) On Brood-Cow Health, J A. Stuedemann, S R. Wilinson, H Ciordia, A B. Caudle

IGC Proceedings (1977-2023)

Studies were conducted to assess the long-term effects of nitrogen (N) fertilization of tall fescue on cow-calf performance and health problems, including grass tetany, fat necrosis, gastrointestinal parasitism, and nitrate poisoning. Kentucky 31 tall fescue pastures fertilized at three levels of N were grazed with Angus cows at 0.4 ha/cow on a year-round basis. Fertilization levels in­cluded high N (667 and 0 kg N/ha/yr from broiler litter in 1968-1974 and 1975-1977, respectively); moderate N (134 and 224 kg N/ha/yr from ammonium nitrate [NH4N03] in 1969 and 1970-1977, respectively); and low N (84 and 74 kg N/ha/yr from NH4N03 in 1972 …

Beef Production From Tall Fescue Treated With Mefluidide A Chemical Plant-Growth Regulator, T W. Robb, D G. Ely, C E. Rieck, S Glenn, L Kitchen, B P. Glenn, R J. Thomas

IGC Proceedings (1977-2023)

Mefluidide treatment of Kentucky 31 tall fescue (Festuca arundinacea Schreb.) in the spring will inhibit seed-head formation, maintain the forage in an immature and vegetative stage, and increase forage N and soluble-sugar content and in-vivo nutrient utilization in the ovine. Productivity of animals grazing mefluidide-treated tall fescue, however, has not been determined. The objective of this study was to evaluate agronomic characteristics of forage and productivity of yearling beef steers and heifers grazing mefluidide-treated (T) and nontreated control (C) pastures of Kentucky 31 tall fescue. Experimental pastures of Kentucky 31 tall fescue ( 4 replications at location I and one …

Role Of Alkaloids And Toxic Compounds In The Utilization Of Tall Fescue By Ruminants, J A. Boling, R W. Hemken, L P. Bush, R C. Buckner, J A. Jackson Jr, S G. Yates

IGC Proceedings (1977-2023)

Tall fescue (Festuca arundinacea Schreb.) contains several alkaloids. Studies in our laboratory showed that perloline is a prin­cipal alkaloid in tall fescue during the summer and that concentration peaks at a time when cattle grazing tall fescue pastures fre­quently have severely reduced performance (summer syndrome or summer fescue toxicosis). The objectives of the following studies were (1) to determine the influence of perloline on in-vitro fermentation and in-vivo ruminant metabolism and (2) to determine the effects of two tall fescue strains selected for perloline concentration on performance of growing cattle and lactating dairy cows and on interrelationships with environmental …

Initial Rate Of Digestion And Legume Pasture Bloat, R E. Howarth, K J. Cheng, J P. Fay, W Majak, G L. Lees, B P. Goplen, J W. Costerton

IGC Proceedings (1977-2023)

Studies were conducted to provide the basic knowledge for breeding a bloat-safe alfalfa cultivar. Two working hypotheses of pasture bloat were tested. The cell-rupture theory proposed that leaf mesophyll cell rupture is an important event in the occur­rence of pasture bloat. The initial-rate-of-digestion (IRD) theory proposed that susceptibility to rapid initial digestion by ruminal bacteria is a characteristic of bloat-causing forages. The studies involved comparisons of bloat-causing and bloat-safe legumes: alfalfa (Medicago sativa L. ), red clover (Trifolium pratense L.), arrowleaf clover (Trifolium vesiculosum Savi), birdsfoot trefoil (Lotus comiculatus L.), deer milkvetch (Astragalus cicer …

Feeding Value Of The Legume Component In Pasture And Silage, K.F M. Reed, P T. Kenny

IGC Proceedings (1977-2023)

Grazing experiments were conducted to examine the feeding value of various pastures for grazing sheep and, in some cases, as silage. Recently, the use of legumes for improving the growth of weaned lambs during the dry summer and early autumn was in­vestigated at Hamilton, Victoria. Studies in Australia showed that the fleeceweights of weaner sheep grazed on eight pasture mixtures of varying grass species increased as the amount of clover in the pasture increased (r -0.88 • *). In a separate study, young sheep grew faster on lucerne· grass pasture than on grass-subtenanean dover pasture. Most recently, live-weight gains of …

Increasing Productivity And Extending Grazing Season Of Cynodon Pastures For Steers With N And Overseedings Of Trifolium And Festuca In The Southeastern U.S.A, H A. Fribourg, J B. Mclaren, R J. Carlisle

IGC Proceedings (1977-2023)

A series of grazing experiments has been conducted 80 km east of Memphis, Tennessee, since 1969 on fine-silty, mixed, ther­ mic, Typic Hapludalfs soils to evaluate productivity and quality of Cynodon pastures grown with N fertilizer or in combination with Festuca arundinacea and/or Ladino, TnJolium repens, and sometimes with T. pmtense, for growing beef steers. Pastures were grazed by the put-and-take system, and forage growth and consumption were determined by the cage-and-strip method. These experiments have shown that bermudagrass pastures can support many young beef animals for 5 months/yr if they are fertilized with N, can produce rapid gains in …

Simulation Of Complementary Forage Cropping By Feeding Oat Grain To Ewes, J L. Wheeler, D A. Hedges, C Mulcahy

IGC Proceedings (1977-2023)

In many parts of the world where year-round grazing is feasible, complementary forages such as oats or sorghum are sown to impove the quantity and quality of the forage available at specific periods. Experiments in which these crops complement well­fertilized grassland have generally not shown an increase in animal production compared with all-grassland systems. The pres­ent experiment aimed to determine the effects of a simulated complementary forage crop on pasture yield and on the production of breeding ewes. Eight groups of 10 sheep grazed 0.6-ha plots of Phalaris aquo.tica L.-Trifolium repens L., and eight groups of 10 sheep grazed 0.8-ha …

Effect Of Feeding Level And Forage: Concentrate Ratio On The Digestibility Of Pelleted Diets By Sheep And Cattle, G.M J. Horton, M J. Farmer, B E. Melton, S Sklane

IGC Proceedings (1977-2023)

Sheep are frequently used to determine the nutritive value of cattle feeds. However, there is some evidence that digestion coef­ficients for cattle and sheep may differ and that digestibility may be influenced by feeding level. The purpose of this study was to investigate the effects of feeding level and animal species on the digestibility of pelleted diets containing different ratios of alfalfa hay to barley grain. Five 4O-kg yearling crossbred lambs and four 35O-kg yearling steers were used to evaluate each diet. The six diets were isonitrogenous, containing the following proportions of barley grain and alfalfa hay (percentage as fed …

Effect Of Supplements On The Live-Weight Gain Of Beef Cattle Given Forage During The Dry Season, C Thomas, P N. Mbugua

IGC Proceedings (1977-2023)

The low quality of standing pasture grasses in the dry seasons presents a major problem in the intensification of beef produc­tion in the tropics. The objective of this research was to examine the role of maize and grass silage or standing napiergrass (Pen­nisetum purpureum) as sources of forage when given alone or with supplements to beef cattle. In the first of three trials conducted at the National Agricultural Research Station, Kitale, Kenya, 36 Friesian castrates, initially 249 kg live weight (LW), were given silage of whole-crop maize either alone or supplemented with corn-and-cob meal. Each of these two basal diets …

Intake Of Grass Silage By Dairy Cows And Its Potential To Meet Requirements Of Maintenance And Milk Production, J P. Dulphy, C Demarquilly, J P. Andrieu

IGC Proceedings (1977-2023)

The main objective of our research was to measure the :intake and digestibility of grass silages in order to estimate their poten­tial for meeting requirements for maintenance and milk production. Twelve silages were prepared by the following three techniques, which considerably improve the intake compared with those used 10-20 years ago: (1) fine chopping (1-3 cm), (2) add­ing formic acid as an efficient preservative (3.5 I/ton), and (3) covering the roughages with plastic to prevent oxygen from enter­ing the silo. Three other silages were made simultaneously with 3 of the same forages, but without formic acid. All forages were directly …

Utilization Of Energy Of Fresh Pasture By Lactating Dairy Cows, T E. Trigg, C R. Parr, N R. Cox

IGC Proceedings (1977-2023)

The New Zealand dairy industry is almost totally reliant on grazed herbage for the production of milk solids, but few data ex­ist on the efficiency with which lactating cows utilize energy of fresh herbage offered as the sole diet. One hundred thirty-two energy balances have been conducted by indirect calorimetry using cows at two levels of feeding and at two stages of lactation over 3 years. Mixed pasture suitable for grazing and cut twice daily was the sole diet. Data for the utilization and partitioning of energy have been subjected to regression analysis on a within-cow basis. Efficiency of utilization …

Energy Balance Studies With Lactating Cows Fed Fresh Or Frozen Grass From Pasture Suitable For Grazing, Y Van Der Honing, A.J H. Van Es

IGC Proceedings (1977-2023)

Information on feeding value and energy utilization of grass consumed by grazing cattle, especially lactating cows, is limited. It is nearly impossible to perform calorimetric studies with grazing dairy cows. Similar studies indoors often show low intakes of fresh grass and require much labor. Still, in much of the world, cattle graze at least half the year; therefore, knowledge of the feeding value of grass is important for practice. In the Netherlands, each year (1973-1974) each of four permanent pastures in the grazing stage of maturity was cut twice daily and either fed fresh or stored at - 20°C to …

Long-Term Feeding Of Corn Silage As The Sole Forage In Diets Of Lactating Dairy Cows, C H. Noller, N J. Moeller, C L. Rhykerd

IGC Proceedings (1977-2023)

The long-term feeding of corn silage as the sole forage to lactating dairy cows has had only limited success due to problems with production, reproduction, and health after one lactation. Consequently, a long-term study was begun in August 1975 with two groups of 19 cows, 15 2-year-old heifers, and 4 3-year-old cows assigned at random to each group as they calved. One group was fed a diet with corn silage as the sole forage and the other group a diet with a 50: 50 ratio of forage as corn silage (CS) and low-moisture alfalfa-orchardgrass ( AO) silage. Both rations contained …