In Vitro Dry Matter Disappearance Research Articles

Steer Performance on Hardie and Midland Bermudagrass

Summary Hardie bermudagrass [ Cynodon dactylon (L.) Pers.] was selected and released on the basis of laboratory tests which indicated that Hardie was superior in forage quality to Midland bermudagrass, and that Hardie produced somewhat greater forage yieids from clipping studies. These two bermudagrasses have now been evaluated in a 5-year grazing trial with yearling steers. Stocking rates were adjusted to utilize available forage with season long tester steers for animal growth measurement and put and take steers for the adjustment. Length of the grazing season averaged 155 days for three years and 112 days for the two drier years. Average daily gain (ADG) was 0.85 kg for Hardie and 0.71 kg for Midland. Total gain/ha was 714 kg for Hardie and 549 kg for Midland. Carrying capacity averaged 836 and 776 steer days/ha for Hardie and Midland, respectively. These results confirm that Hardie bermudagrass, which was selected on the basis of higher in vitro dry matter disappearance (IVDMD) than Midland, can produce higher ADG and greater beef gain/ha.

Relative Winter Forage Quality of Selected Bermudagrass Cultivars1

Bermudagrass [Cynodon dactylon (L.) Pers.] forage is often stockpiled or accumulated in situ for use during winter. Very little information is available on the quality of such forage as affected by cultivar or age. This study reports results of two experiments conducted to: (i) determine relative quality of stockpiled forage of selected bermudagrass cultivars as indicated by in vitro dry matter disappearance (IVDMD) and crude protein (CP) concentrations, and (ii) monitor dormant season patterns of change in IVDMD and CP. Three cultivars (Alicia, Hardie, and Midland), two locations, and four sampling dates in the winter of 1975–1976 were included in Experiment 1. In Experiment 2, three cultivars (Hardie, Midland, and Tifton 44) were evaluated at six locations on four sampling dates in the winter of 1981–1982. Sampling in each experiment began in mid November and continued at 30‐day intervals through mid‐February. Hardie usually had higher IVDMD than the other cultivars throughout the sampling period in both experiments. There was no difference among cultivars in CP concentration in either experiment. The trend in change of both the IVDMD and CP concentrations through the winter was a decrease, but the changes were not linear, generally being best described by cubic equations. No consistent differences among cultivars in rate of change in either IVDMD or CP were found. None of the cultivars maintained high enough IVDMD levels through winter to supply minimum energy requirements for dry pregnant mature cows. Except at Mangum in Experiment 1, all cultivars maintained high enough CP levels to meet the minimum requirements of dry pregnant beef cows.

Ploidy Effects on Protein, in Vitro Dry Matter Disappearance, and Potassium/(Calcium + Magnesium) Equivalent Ratio in Tall Fescue Forage1

Use of higher ploidy levels to improve concentrations of protein and digestible matter in forage grass might adversely affect other plant characteristics. Tall fescue (Festuca arundinacea Schreb.) lines with 21, 42, or 84 chromosomes were used in a greenhouse study to evaluate the effects of pioidy level on forage in vitro dry matter disappearance (IVDMD), crude protein, K, Ca, and Mg concentrations, and the K/(Ca + Mg) ratio (calculated on equivalent bas is). Protein and IVDMD increased with higher ploidy. The K/(Ca Mg) equivalent ratios were 1.35, 1.48, and 1.61 for the 21‐, 42‐, and 84‐chromosome lines, respectively. This increase in ratio with increase in ploidy occurred because K concentrations (primarily in cell contents) increased more than Ca and Mg concentrations. Although all ratios obtained in the 25°C greenhouse were below the critical value of 2.2 that is associated with increased occurrence of grass tetany, the study suggests that increasing the pioidy level of forage grass may increase its protein and IVDMD concentrations, but may also increase its K/(Ca + Mg) ratio and the potential to induce grass tetany under some field environments.

Yield and Quality of Forage from Orchardgrass selected for Resistance to Purple Leaf Spot1

The development of forage species with resistance to leaf diseases appears to be the only feasible method of limiting yield and quality losses. Our goal in this study was to determine if forage yield and quality were inadvertently changed during three cycles of recurrent phenotypic selection in orchardgrass (Dactylis glomerata L.) for resistance to purple leaf spot (caused by Stagonospora arenaria Sacc.), and to determine if variability existed within the third cycle for yield and quality traits. Twelve disease resistant half‐sib families from Cycle 3 were compared with a composite of the original entries (Cycle 0), with a composite of Cycle 3, and with two commercial cultivars in broadcast seeded plots harvested three times in 1982 and twice in 1983. Very little purple leaf spot occurred in the plots. Averaged over 2 yr, Cycle 3 was later in maturity than Cycle 0 (P<0.01), and Cycle 3 had slightly lower protein content (P<0.05) at first harvest than Cycle 0. Although ranges were usually small, significant differences were found among half‐sib families for crude protein (CP), in vitro dry matter disappearance (IVDMD), acid detergent fiber (ADF) at first and second harvests, and neutral detergent fiber (NDF) at first harvest (averaged over years). Significant differences were found among half‐sib families at the third harvest in 1983 for CP, IVDMD, ADF, and NDF. Half‐sib families varied in dry matter yield only for the first harvest. When entries differed significantly, the yield, CP, or IVDMD of one to several resistant half‐sib families equalled or exceeded that of Cycle 0, Cycle 3, or the cultivars. Breeding for resistance to purple leaf spot did not result in appreciable changes in the traits measured. However, the selected population contained some genetic variability for each quality trait.

Quality Analysis of Summer‐Annual Forages. III. Prediction of Wet Silage In Vitro Dry Matter Disappearance from Chemical Constituents1

AbstractSamples for the determination of silage quality are generally dried prior to analysis even though some silage constituents are lost during drying. The objectives of this study were to examine the prediction of wet silage in vitro dry matter disappearance (IVDMD) from analysis of dried samples using both oven‐dried and freeze‐dried fodder and silage. Frozen, wet silage was ground to pass a 1‐mm screen using liquid N as a cryostat. The IVDMD of ground, frozen silage (GFS) was found to be most closely related to the IVDMD of freeze‐dried fodder (FD), with GFS IVDMD = 24.7 + 0.99 (FD IVDMD) and r2 = 0.76**. Weaker relationships were found with freeze‐dried silage (FDS) (r2=0.46**), oven‐dried silage (ODS) (r2=0.35**), and oven‐dried fodder (OD) (r2=0.34**). The relationships between the IVDMD of GFS and fiber fractions of neutral detergent fiber (NDF), acid detergent fiber (ADF), permanganate lignin, apparent cellulose, apparent hemicellulose (NDF—ADF), and the ADF/lignin ratio as independent variables were examined using stepwise regression. Freeze‐dried fodder lignin (r2=0.44) and OD ADF (r2=0.37) were the two single fractions most closely related to wet silage IVDMD. Correlations from the Van Soest fractions alone in single variable regressions were not improved when using stepwise multiple regression analysis.

Selection for in Vitro Dry Matter Disappearance in Switchgrass Regrowth1

The potential for genetic progress from selection for in vitro dry matter disappearance (IVDMD) of switchgrass (Panicum virgahm L.) regrowth forage has not been determined by breeders. Improved regrowth quality is needed to increase average daily gain of ruminants in mid‐ to late‐summer. In this study, 33 half‐sib families of switchgrass were evaluated over 2 yr for initial growth dry weight, IVDMD, and N concentration, and for regrowth IVDMD. The regrowth IVDMD was measured from plant samples taken in July (IVDMDl) and August (IVDMD2). Genetic variance estimates were obtained to predict direct selection responses and correlated responses using the modified ear‐to‐row procedure. Selection indices were also constructed to predict responses to multiple‐trait selection. Expected gains from direct selection for dry weight (1.19 kg plant−1), IVDMDl (666 g kg−1), and IVDMD2 (498 g kg−1) were 0.24 kg plant−1, and 50 and 35 g kg−1, respectively, while maximum gains from correlated responses were 0.02 kg plant−1, and 40 and 36 g kg−1, for the respective traits. An estimated index consisting of initial growth dry weight, IVDMD, N, and regrowth IVDMD2 provided simultaneous expected gains of 0.04 kg plant−1 for dry weight and 42 g kg−1 for IVDMD2. Switchgrass regrowth IVDMD may be improved without greatly altering dry matter yield per plant and should receive greater priority in cultivar development.

Relationships among Grain Quality Indicators in Oats1

Breeding efforts to improve whole grain quality of oats (Avena sativa L. and A. byzantina K. Koch) have been limited by difficulties in measuring the trait. In vitro chemical and biological tests have been used to predict grain digestibility, but laboratory facilities are required, and the procedures are time and labor intensive. Consequently, breeders primarily have used grain test weight as a crude measure of grain quality. Our objectives were to determine the relationships among indicators of grain quality, environmental effects, and practical utility of the measurement techniques. Sixteen oat cultivars were grown at two locations during each of 2 yrs on either Typic or Ultic Hapludalf soils. Traits measured were grain yield, test weight, groat fraction, acid detergent fiber (ADF), permanganate lignin, in vitro dry matter disappearance (IVDMD), groat protein, and whole grain protein. Cultivar means for IVDMD ranged from 600 to 758 g kg−1. There were consistent negative correlations and linear relationships between IVDMD and both ADF and lignin. The relationship between IVDMD and groat fraction was linear and r2 values ranged from 0.61 to 0.81, so groat fraction should be a useful indicator of the digestible energy of whole grain oats. Test weight and IVDMD were not correlated when test weights were near normal, but they were correlated when test weights were light. Test weight was not a reliable indicator of genetic variability for whole grain quality. Groat and whole grain protein concentrations are not associated with IVDMD. Whole grain protein concentration was consistently correlated with groat protein, but only 37 to 69% of the variation in whole grain protein was associated with variation in groat protein concentration. Among the indicators of digestible energy, the least amount of labor was required to determine groat fraction, and no special laboratory facilities were needed. The trait should be especially useful in breeding programs where in vitro determinations are not possible or practical.

Relationship of Morphological Characteristics to Forage Quality in Quackgrass1

The excellent adaptation of quackgrass [Elytrigia repens (L.) Nevski] in the North Central region of the USA suggests that this species may have potential as a cultivated forage. The objectives of this experiment were to characterize variation among quackgrass genotypes for in vitro dry matter disappearance (IVDMD), neutral detergent fiber (NDF), N, and several morphological characters and to determine whether quality and morphological characters were correlated. Thirty‐four genotypes of quackgrass, randomly collected in Wisconsin, were planted in four replicates on a Pillot silt loam soil (Typic Argiudoll). Vegetative growth was sampled from each genotype at the early heading stage of development in 1980, 1981, and 1982 and analyzed for IVDMD, NDF, and N. Genotypic variation averaged over years was significant for leafiness, leaf angle, leaf width, culm diameter, rhizome spreading vigor, growth habit, and all quality measurements except NDF. Genotype ✕ year interactions were significant for all characters except culm diameter and spreading vigor. Genotypic variation within years was significant for all characters in all years except for spreading vigor in 1980 and 1982, and IVDMD in 1982. Three‐year genotype means ranged from 645 to 731 g kg 1 for IVDMD, 555 to 609 g kg−1 for NDF, and 24.6 to 33.5 g kg−1 for N, and were significant except for NDF. Only growth habit was correlated with any quality character. The more prostrate plants were higher in N and IVDMD. It appears that sufficient genotypic variation exists within this population to improve IVDMD and N, and perhaps NDF. Morphology was not correlated well enough with quality in this study to be used in selection. Genotypes should be evaluated for quality for a minimum of 2 yr. Total N would be the best selection criterion among those investigated, due to its larger repeatability and lower genotype ✕ year interaction.

Forage Quality of Winterhardy Lovegrasses

Forage Quality of Winterhardy Lovegrasses

Kleingrass Yield and Quality under Three Irrigation Regimes when Harvested at Anthesis1

AbstractKleingrass (Panicum coloratumL.) is a promising forage species for irrigated areas in the southwestern USA. However, the effect of different irrigation regimes on dry forage yield and forage quality has not yet been extensively investigated under field conditions. Accordingly, ‘Kleingrass‐75’ kleingrass was irrigated at intervals of 2, 3, and 5 weeks during the 1981 and 1982 growing seasons near Las Cruces, NM on a fine‐loamy, mixed, calcareous, thermic Typic Torrifluvent soil. Dry forage yields, in vitro dry matter disappearance (IVDMD), and Ca, Mg, N, and P concentrations were measured for forage harvested at anthesis. Significant (P≤0.01) negative relationships were found between amount of irrigation water applied and Ca concentration, Mg concentration, and IVDMD, respectively. In addition, there were significant (P≤0.01) negative relationships between dry forage yield and Ca concentration, Mg concentration, and IVDMD, respectively. No relationships between amount of irrigation water applied or dry forage yield and N or P concentration were found. It was concluded that Ca and Mg concentrations and IVDMD were higher with lower soil moisture contents, possibly due to higher leaf weight to stem weight ratios in the lower‐yielding, water‐stressed kleingrass.

Forage Dry Matter Accumulation and Quality of Turnip, Swede, Rape, Chinese Cabbage Hybrids, and Kale in the Eastern USA1

AbstractProduction of cool‐season (C3) herbage generally is low in summer and fall in the humid eastern USA. This study was conducted to determine the yields and pest problems of spring‐sown turnip, Brassica rapaL.; swede, B. napusL.; rape, B. napusL.; interspecific crosses between Chinese cabbage, B. campestris sensufaioL., and turnip or rape; or kale, B. oleraceaL., that were stockpiled. The crops were no‐till seeded (turnip and swede at 1.4 kg ha−1, rape, the hybrids, and kale at 4.2 kg ha−1) into mature alfalfa (Medicago sativaL.)‐grass stands. Prior to seeding, the sod was treated with isopropylamine salt of N‐(phosphonomethyl) glycine at 1.1 kg a.i. ha−1. The study was made in central Pennsylvania on Hagerstown silt loam (fine, mixed, mesic Typic Hapludalfs) soil in 1979 and 1980 and on Hublersburg silt loam (clayey, illitic, mesic Typic Hapludults) soil in 1981. Dry matter yield determinations were made sequentially at 30‐day intervals from 60 to 150 days post‐seeding. Fertilizer (P and K) was applied according to soil test results and 80 kg N ha−1was applied at seeding and 70 kg N ha−1between the 60‐ and 90‐day sampling dates. Three‐year mean dry matter yields for 13 of 19 cultivars exceeded 7.0 Mg ha−190 days post‐seeding. Yields plateaued from 80 to 160 days depending on plant species, cultivar, and year. Cultivar (across species) ✕ sampling date, turnip cultivar ✕ year, and swede, rape, and kale sampling date ✕ year interactions were significant for yield. Incidence of plant diseases was positively related to slowing of growth at physiological maturity. Some New Zealand turnip and rape cultivars were more resistant to flea beetle [Phyllotreta cruciferaeGoeze and P. striolata(Fab.)] than cultivars of European origin. Crude protein concentration of turnip and Chinese cabbage hybrid tops was higher at 120 than 90 days, but it was not for other species. Crude protein concentration ranged from 110 g kg−1in roots of certain cultivars to 270 g kg−1in turnip tops. Species ✕ sampling date and year ✕ sampling date interactions were significant for crude protein concentration and in vitro dry matter disappearance (IVDMD). The IVDMD values ranged from 800 to 930 g kg−1Kale had the lowest mean IVDMD, 840 g kg−1.

EFFECT OF DEFOLIATING TIMOTHY CULTIVARS DURING PRIMARY GROWTH ON YIELD, QUALITY AND PERSISTENCE

A forage system based on timothy (Phleum pratense L.) cultivars of different maturities is recommended in Atlantic Canada. Early and later maturing cultivars are grown to spread the harvesting of timothy, at optimal primary growth maturities, to about 3 wk. At some locations the resulting harvest period has been considerably shorter and for this reason the timothy system was examined in a 4-yr field study. Four timothies, representing very early, early, midseason, and late cultivars, were cut at five dates with primary growth stages ranging from vegetative to full heading. Regrowth was cut about 45 days after cut 1. Total dry matter yield and total N concentration of combined cuts 1 and 2 were generally influenced by cutting schedules but not by cultivars. The in vitro dry matter disappearance (IVDMD) was dependent on both cutting schedule and cultivar. The early-maturing cultivar Clair reached its peak IVDMD earlier than later maturing Champ, Itasca, or Bounty. At termination of the field study, there were fewer timothy tillers per square metre and ground cover by timothy was slightly less for those cuts taken during stem elongation. The results suggest that three out of four cultivars were of similar maturity and had similar total N and IVDMD. We conclude that the currently recommended timothy cultivars in Atlantic Canada do not provide a sufficient range in maturity for the average growing season in the region to warrant multiple cultivars on individual farms. At present, timothy stands may be cut prior to and during stem elongation to lengthen the harvest period.Key words: Timothy, in vitro dry matter digestibility, total nitrogen

Performance of Switchgrass and Bluestem Cultivars Mixed with Cool‐Season Species1

AbstractForage availability in summer is critical for sustaining high stocking densities of herbivores on pasture in the eastern U.S. The objective of this study was to determine forage productivity and quality of switchgrass (Panicum virgarumL.) and bluestems [Andropogon gerardiiVitman, Schizachyrium scoparium(Michx.) Nash, and Bothriochloa caucasica(Trin.) C.E. Hubb.] in summer. The experimental site was located in southwestern Pennsylvania on Guernsey silt loam (fine, mixed, mesic Aquic Hapludalf) soil. Two replicates, each containing eight warm‐season grasses with different proportions of volunteer cool‐season grasses and overseeded legumes were grazed from 1975 to 1977 and then harvested for hay in 1978 and 1979. Pastures were grazed each year in mid‐May, late July or early August, and early October. Nitrogen at 0, 45, and 90 kg ha−1and P at 0, 20,40 kg ha−1were applied to subplots. ‘Blackwell’ switchgrass and ‘Kaw’ big bluestem from the Great Plains readily established stands but did not persist as well as cultivars from the eastern USA. Total annual production from switchgrass‐dominated pastures was about 8.0 Mg ha−1and that from ‘NY 1145’ big bluestem was 6.0 Mg ha−1, Over a 4‐yr period, NY 1145 produced about 70% more forage in late July than did Kaw big bluestem. Mean yield distribution of the switchgrass and bluestem pastures was approximately 15% in May, 55% in July‐August, and 30% in October. July yield increased about 11 kg kg−1of N applied. Mean in vitro dry matter disappearance (IVDMD) values for switchgrass and bluestem ranged from 470 to 570 g kg−1,, but it was determined that IVDMD under‐estimated in vivo digestibility by 100 to 200 g kg −1, Crude protein concentration ranged from 70 to 120 g kg−1, Mean crude protein concentration of grass fertilized with 45 and 90 kg N ha−1over a 3‐yr period was 10 and 26% higher, respectively, than that for unfertilized grass. Overseeded legumes, especially red clover (Trifolium pratenseL.), established good stands in warm‐season grasses with < 75% stands. Mixed stands of warm‐ and cool‐season grasses and legumes can be maintained under grazing or hay production, with a substantial shift in seasonal yield distribution that can be very beneficial to beef (Bos taurus) producers.

Wetting Effects on the Yield and Quality of Legume and Legume‐Grass Hays1

AbstractInformation is needed on rain effects on yield and quality of legume and legume‐grass hays. A field study was conducted on a Piano silt loam soil (fine‐silty, mixed, mesic, Typic Argiudoll) to evaluate rain effects on the yield and chemical composition of hays from pure swards of alfalfa (Medicago sativaL.), red clover (Trifolium pratenseL.), and birdsfoot trefoil (Lotus corniculatusL.) and mixtures with smooth bromegrass (Bromus inermisLeyss.). Plots for the factorial experiment (each 1.1 by 7.6 m) were arranged in a split plot design with legume species and pure or mixed sward type combinations as main plots and wetting treatments as the sub plots with four replicates. Wetting treatments consisted of field drying to 750 g dry matter (DM)/kg of total mass (TM) or more without rain or exposure to rain or artificial wetting during drying. Samples were collected just after cutting and after hay curing for quality analysis. Rain reduced the proportion of leaf by 109 and 151 g/kg for alfalfa and birdsfoot trefoil, respectively, but did not affect red clover leaf content. Rain increased DM loss by as much as 154 g/kg (pure alfalfa) but did not affect DM loss for the birdsfoot trefoil‐grass mixture. Legume‐grass hays generally had more neutral detergent fiber (NDF) and lower N and in vitro dry matter disappearance (IVDMD) concentrations than pure legume hay. Rain or wetting reduced IVDMD by from 13 g/kg (birdsfoot trefoil‐grass) to 64 g/kg (alfalfa). Except for Ca, which was reduced in some cases, rain or wetting did not affect mineral concentrations in dry hay. The presence of grass in the sward provided consistent advantage in hay drying only for red clover. Rainfall increased DM losses during hay curing except for the grass‐dominated birdsfoot trefoil mixture. Rain or wetting reduced hay quality by reducing IVDMD and increasing NDF concentration. Nitrogen, P, K, and Mg concentrations were not greatly affected by rain or wetting.

Early‐, Mid‐, and Late‐Spring Establishment of Switchgrass at Several Seeding Rates1

AbstractConcerns of forage producers about seed cost and difficult stand establishment have limited the popularity and use of switchgrass (Panicum virgatum L.) as a summer forage alternative in the humid northern USA. ‘Cave‐in‐Rock’ switchgrass was seeded with atrazine (2‐chloro‐4‐ethylamino‐6‐isopropyl amino‐1,3,5‐triazine) for weed control in 1981 and 1982 on a Webster‐Nicollet soil complex (fine‐loamy, mixed, mesic, Typic Haplaquoll‐Aquic Hapludoll) at three seeding dates (April, May, and June) and five rates, ranging from 3.4 to 16.8 kg pure live seed (PLS) ha−1. Precipitation patterns primarily accounted for differences in mean seedling numbers of 27.8,13.0, and 28.0 seedlings m−1 of row for April, May, and June seeding dates, respectively. Mean tiller numbers of 118 m−1 in 1981 and 131 m−1 in 1982 suggest that tillering compensated for observed differences between years in initial seedling number, and producers should not hastily attempt to reestablish new seedings which initially appear to be marginal. Greater seeding rates increased seedling number, tiller number, and forage dry matter (DM) yields, but slightly decreased forage in vitro dry matter disappearance (IVDMD) and crude protein (CP). Seeding date had a greater effect than seeding rate on switchgrass forage yield and quality. Seeding‐year forage DM yields were 8.5, 6.5, and 4.5 Mg ha−1 for April, May, and June seedings, respectively. Forage IVDMD and CP concentrations were greatest for June (619 and 120 g kg−1, respectively) and least for April (524 and 84 g kg−1, respectively) seeding dates. Results suggest that highly productive switchgrass stands can be obtained during the establishment year with mid‐April to early May seeding dates at rates of only 3.4 kg PLS ha−1 when atrazine is used for weed control.

EFFECTS OF LIQUEFIED FISH, COTTONSEED MEAL AND FEATHER MEAL ON IN VIVO AND IN VITRO RUMEN CHARACTERISTICS OF SHEEP

Two rumen-fistulated wethers were utilized to study rumen fluid characteristics of wethers fed supplements containing liquefied fish (LF), cottonseed meal (CSM) or hydrolyzed feather meal (FM). These supplements provided 50% of the total dietary crude protein (CP) in each treatment. Supplements were fed twice daily along with grass hay. Each treatment consisted of a 12-day adjustment period and a 3-day collection period; rumen fluid samples were taken every hour for 4h after feeding. Treatment means were different (P < 0.05) in rumen pH, acetic:propionic acid ratio (A/P) and molar percentage of acetic (Ac), propionic (Pro), isobutyric (IB) and valeric (V) acids. Rumen pH was generally lower in the latter part of the 4-h collection period. The feeding of LF resulted in increased rumen fluid ammonia-N (NH3-N; P < 0.01) compared with CSM and FM treatments. In vitro digestibility trials were conducted in which varying levels of LF were substituted for urea-N in a liquid supplement (LS). Trials were conducted to determine the optimum level for inclusion of LF in LS based on in vitro digestibility of grass hay and cellulose (Solka floc). Treatments were formulated to contain 14% CP (dry basis) with LF added to replace 0, 2.5, 5, 7.5, 10 and 15% of urea-N in LS. Cottonseed meal and FM were used as controls. In vitro dry matter disappearance (IVDMD) was increased (P < 0.01) by increasing LF levels. The NH3-N (P < 0.01) and total volatile fatty acids (VFA) concentration (P < 0.05) were higher in the supernatant for LF-treated samples than for the FM treatment. When Solka floe was used as the substrate, there were no differences (P > 0.05) among levels of LF treatments for the various supernatant characteristics, but LF treatments increased (P < 0.05) IVDMD, NH3-N, A/P and molar percentage of Ac, Pro, and IB aids compared with the controls. Key words: Sheep, liquefied fish, liquid supplements, ammonia-nitrogen, forage digestion

Effect of Ploidy on Yield and Quality of Pearl Millet × Napiergrass Hybrids1

AbstractThe highly male and female sterile triploid pearl millet [Pennisetum americanum (L.) Leeke) × napiergrass (P. purpureum Schum.) interspecific hybrids produce high yields of high quality forage. Colchicine induced hexaploids are male and female fertile and morphologically resemble the triploids. However, information concerning the effects of increased ploidy on agronomic, quality, and elemental factors of the forage is limited. In 1979 and 1980, triploid and hexaploid clones of several interspecific hybrids were established in the field on a Fuquay soil (loamy, siliceous, thermic Arenic Plinthic Paleudults) and evaluated for dry matter yield, concentrations of dry matter, in vitro dry matter disappearance (IVDMD), crude protein, total sugars, cell wall, and the elements P, K, Mg, Ca, Mn, Zn, Fe, and Cu. Triploids on the average had higher dry matter yields, and dry matter and protein concentrations than hexaploids. At anthesis, 3x plants were equal to or higher than 6x plants while at the vegetative stage 6x plants were generally higher than or equal to 3x plants in IVDMD. No differences were observed between 3x and 6x plants for total sugars and cell wall. Significant differences for elemental concentrations between ploidy levels were observed in 1980 for P (6x>3x), K (6x>3x), and Fe (3x>6x). These differences were not consistent for all clones. Increased ploidy from 3x to 6x in thisstudy generally had a neutral or negative effect on the characters studied. Triploids have the potential to produce higher yields of higher quality forage than hexaploids.

INFLUENCE OF TEMPERATURE ON CHEMICAL COMPOSITION AND IN VITRO DRY MATTER DISAPPEARANCE OF NORMAL- AND LOW-TANNIN SERICEA LESPEDEZA

A normal and a low-tannin sericea lespedeza (Lespedeza cuneata (Dumont) G. Don.) cultivar were grown in controlled environments under a warm (32/24 °C) or cool (22/17 °C) temperature regime. Both cultivars accumulated more dry matter at the higher temperature. The normal-tannin sericea contained a higher concentration of tannin, and lower concentrations of crude protein and neutral detergent fiber (NDF than the low-tannin sericea. Tannin concentration in the leaves of the normal-tannin cultivar was 10 percentage units greater and crude protein and NDF were each 3 units lower at 32/24 °C than at 22/17 °C. Tannin concentration in the leaves of the low-tannin cultivar was 2 percentage units higher, crude protein was 3 units lower, and NDF was 3 units higher at 32/24 °C than at 22/17 °C. In vitro dry matter disappearance (IVDMD) of the normal-tannin leaves was approximately 20 percentage units less than that of the low-tannin leaves, and was not influenced by temperature. Stems were more digestible than the leaves in both cultivars, but normal-tannin stems were slightly less digestible than the low-tannin stems. The IVDMD of low-tannin stems was 6 units lower at 32/24 °C than at 22/17 °C. Future breeding efforts with low-tannin sericea should place emphasis on lower tannin and NDF concentrations because both these components tend to increase with temperature and bear negative associations with IVDMD.Key words: Lespedeza cuneata, neutral detergent fiber, crude protein, forage quality

Minimum‐Tillage Forage Turnip and Rape Production on Hill Land as Influenced by Sod Suppression and Fertilizer1

AbstractInsufficient herbage during the fall in the temperate areas of the world has long been a serious limitation in animal production. The purpose of this research was to determine the feasibility of producing Brassicaspp. forage crops for fall grazing of sheep on hill land. The experiment was conducted near Waynesburg, Pa., in a 4‐ha hill pasture, predominantly Dormont silt loam (fine‐loamy, mixed, mesic Ultic Hapludalf) on the sideslopes and Culleoka loam (fine‐loamy, mixed, mesic Ultic Hapludalf) on the ridge. A split‐plot block arrangement was used with blocks of ‘Sirius’ turnip, (Brassica rapaL.) ‘Fora’ rape, (B. napusL.), and ‘Perko P.V.H.’ winter rape (B. rapaL.) randomized in each of six blocks. Competition from the existing species was suppressed with paraquat (l,l′‐dimethyl‐4,4′‐bipyridinium ion) or glyphosphate [isopropylamine salt of N‐(phosphonomethyl)glycine] at 1.1 kg a.i. ha−1. Nitrogen and P fertilizer treatments were assigned to subplots in a randomized complete block design. Fertilizer was applied before seeding in 1978 and 1979 to provide 0, 33, 66, 99, or 132 kg N ha−1and 0, 15, 30, 45, or 60 kg P ha−1in a 52factorial arrangement. The crops were minimumtillage (min‐till) planted on 10 Aug. 1978 and 25 July 1979. Dry matter (DM) yields were determined 60 and 90 days after planting. Select samples were taken to determine crude protein, in vitro dry matter disappearance (IVDMD), and mineral element composition. Mean crop yields were similar for the two herbicide treatments in 1978 but were−35 to 75% higher on glyphosate‐treated plots than on paraquat‐treated plots in 1979. Grass yield in the Brassicaplots in 1979 were twice as high in the paraquat‐treated plots as in the glyphosate‐treated plots. At the higher rates of applied N and P, DM yield exceeded 7000 kg ha−1in 1978 and 9000 kg ha−1in 1979. Crop yield responses were quadratic functions for N fertilizer rates and linear functions for P fertilizer rates for both harvests in 1978. In 1979, yield responses were linear functions for N fertilizer rates for both harvests and for P fertilizer rates for the 60‐day harvest; and were quadratic for P rates for the 90‐day harvest. Yield of turnip and rape was affected more by P fertilizer before the 60‐day harvest than afterwards. Crude protein concentration ranged from 60 to 250 g kg−1. Nitrogen and P fertilizers differentially affected the crude protein concentration of forage turnip and rapes. Mean IVDMD was 950 and 900 g kg−1for turnip tops and roots, respectively, 910 g kg−1for Fora rape, and 930 g kg−1for Perko rape. Yield of digestible DM of turnip was up to 67% higher than that of stockpiled orchardgrass. The Brassicaspp. had different DM mineral element compositions, and concentrations of P, K, Ca, Mg, and Zn generally were higher in Brassicaspp. than in orchardgrass checks.

Breeding Apomictic Lovegrasses: Forage Potential of Boer ✕ Weeping Hybrids1

Breeding schemes have been developed for several apomictic species. However, few assessments of the potential of hybrids developed through manipulation of apomixis have been published. Apomictic lovegrass Eragrostis curvula (Schrad.) Nees, hybrids were developed from crosses of sexual boer ✕ apomictic weeping lovegrass. The objectives of this research were to determine the forage potential of boer ✕ weeping hybrids, assess the genetic potential of the parent genotypes, and begin to evaluate the usefulness of the apomictic breeding scheme. Significant differences in forage vigor and quality were found among the hybrids. ‘Morpa’ weeping lovegrass produced hybrids that were higher in in vitro dry matter disappearance (IVDMD) than common weeping lovegrass hybrids. Boer lovegrass genotype 40‐9‐69FQ (40‐9) was inferior as a female parent because its hybrids tended to be lower in vigor than those from other boer lovegrass genotypes. Several hybrids from the cross 40‐9 ✕ Morpa were significantly higher in IVDMD than Morpa or ‘Ermelo’, the most digestible cultivars. However, IVDMD and vigor were negatively related in that cross (r = ‐0.31 to ‐0.72**, significant at the 0.01 level of probability). Two hybrids with superior IVDMD and average vigor were identified. Diplosporic apomixis can be successfully manipulated to develop higher quality lovegrass cultivars if the negative relationship between IVDMD and vigor can be broken or is found to be less important in other crosses.