Concentrations Of Cell Wall Constituents Research Articles

Feed Intake of Small Ruminants on Spring and Summer Pastures in the Mongolian Altai Mountains

Climate variability, rising livestock numbers, decreasing herd mobility, and clustered grazing patterns have incited concern about the sustainable use of Mongolia’s natural pastures as the nutritional backbone of the country’s livestock sector. In 2013 and 2014 we studied daily itineraries, grazing behaviour, and feed and nutrient intake of small ruminants on spring and summer pastures in the southern Mongolian Altai, a remote livestock-dependent region. Offer of herbage dry matter (DM, kg ha−1) along the daily itinerary was higher in 2014 than in 2013 (837 versus 711; p > 0.05) but was comparable to previously reported values. Concentration of cell wall constituents in herbage increased from June to August in both years, whereas crude protein and phosphorus concentrations declined (p < 0.05). Animals grazed most actively at noon and in the afternoon; their daily DM intake amounted to 1151 ± 300.8 g per head, with 60–72% of the ingested feed being digested. Feed intake enabled the animals to cover their nutritional requirements for maintenance, locomotion, and sizeable growth, rebutting the notion of unsustainable use of the regional spring and summer pastures. However, crude protein and phosphorus intake were deficient, pointing to a decline in vegetation quality that has to be counteracted with appropriate herd and pasture management strategies.

Biomass Yield and Composition of Perennial Bioenergy Grasses at Harvests following a Freeze Event

Seasonality of production limits when warm‐season grass biomass can be provided to the bio‐refinery. Delaying harvest after occurrence of a freeze extends this period, but the utility of this practice depends on its effect on biomass yield and composition. The objective was to quantify the effect of delaying harvest after first freeze on biomass dry matter (DM) harvested and composition of two perennial grasses. During a 3‐yr experiment, elephantgrass (Pennisetum purpureum Schum.) and energycane (Saccharum spp. hybrid) were harvested shortly before or immediately after first freeze plus an additional two to three times during the subsequent 50 to 60 d in northern Florida. Extending the harvest period did not affect energycane biomass yield (avg. 27.6 Mg DM ha−1) during 2 yr, but elephantgrass yield decreased on average from 30.7 to 21.5 Mg DM ha−1 as harvest was delayed. Elephantgrass biomass DM concentration was greater than energycane (377 vs. 356 g kg−1, respectively, in Year 1; 515 vs. 370 g kg−1, respectively, in Year 2). Concentrations of cell wall constituents in both grasses increased as harvest was delayed after freezing, and the increase was generally greater for elephantgrass than for energycane. Delaying harvest of energycane after a freeze is effective in increasing the period when biomass can be supplied to the bio‐refinery, but elephantgrass is less well suited for this management approach because biomass harvested declines with time after a freeze event.

Use of ethylenediurea (EDU) to ameliorate ozone effects on purple coneflower ( Echinacea purpurea)

Purple coneflower plants ( Echinacea purpurea) were placed into open-top chambers (OTCs) for 6 and 12 weeks in 2003 and 2004, respectively, and exposed to charcoal-filtered air (CF) or twice-ambient (2×) ozone (O 3) in 2003, and to CF, 2× or non-filtered (NF), ambient air in 2004. Plants were treated with ethylenediurea (EDU) weekly as a foliar spray. Foliar symptoms were observed in >95% of the plants in 2×-treated OTCs in both years. Above-ground biomass was not affected by 2× treatments in 2003, but root and total-plant biomass decreased in 2004. As a result of higher concentrations of select cell wall constituents (% ADF, NDF and lignin) nutritive quality was lower for plants exposed to 2×-O 3 in 2003 and 2004 (26% and 17%, respectively). Significant EDU × O 3 interactions for concentrations of cell wall constituents in 2003 indicated that EDU ameliorated O 3 effects on nutritive quality. Interactions observed in 2004 were inconsistent.

Non-traditional Straws: Alternate Feedstuffs for Ruminants

The nutritive value of 4 straws, obtained after thrashing of seeds from fodder crops, was assessed as complete feed for ruminants. Sixteen male Murrah buffaloes (liveweight 365.8±19.5 kg), were divided into 4 equal groups and offered ad lib. straw of either Trifolium resupinatum, Trifolium alexandrium, Medicago saliva or Lolium perenne, supplemented with minerals and vitamin A, for 40 days in a completely randomized design. Simultaneously, each straw was offered to 3 rumen fistulated male buffaloes in order to assess the biochemical changes in the rumen. Compared to other straws M. sativa straw had higher (p<0.05) organic matter (OM), crude protein (CP), acid-detergent fiber (ADF) and cellulose content. L.perenne had the highest (p<0.05) hemicellulose and lowest (p<0.05) CP and acid-detergent lignin (ADL) content. T. resupinatum had the lowest concentration of cell wall constituents (CWC). The digestibility of nutrients of T. resupinatum and L. perenne straw was similar, but higher (p<0.05) than that of other straws. Msativa straw showed highest (p<0.05) digestibility of CP. The highest OM digestibility of T. resupinatum and CP digestibility of M. saliva were responsible for highest (p<0.05) total volatile fatty acids and trichloroacetic acid precipitable nitrogen in the strained rumen liquor. The digestible crude protein (DCP) was highest (p<0.05) in M. sativa followed by that in T. alexandrium. The total purine derivatives excreted in urine varied from 0.22-0.32 mmol/kg W 75 /d. The efficiency of microbial protein synthesis indicated that OM of straws of M. sativa and that of T. alexandrium was used more (p<0.05) efficiently. The microbial protein synthesized was highest in T. resupinatum, but statistically similar to other groups. The values for N-retention and apparent biological value were highest for L. perenne, though comparable with that of M. sativa and T. alexandrium. The available metabolizable energy (ME) was highest (p<0.05) in T. resupinatum followed by that in L. perenne and lowest in M. sativa. It was concluded that all the straws, supplemented with minerals and vitamin A, could be fed exclusively to adult ruminants with no adverse affect, as animals were able to maintain body weight (372±20.1 kg).

Nutritive Quality of Big Bluestem (Andropogon gerardii) and Eastern Gamagrass (Tripsacum dactyloides) Exposed to Tropospheric Ozone

Tropospheric ozone (O 3 ) is a phytotoxic air pollutant widespread in industrialized nations of the world. Ozone is produced by the photo-oxidation of hydrocarbons released into the atmosphere by combustion of fossil fuels. Studies demonstrate O 3 can be transported from metropolitan areas to rural areas important to agricultural and forestry practices. Reports regarding O 3 effects have focused on vegetation important to food production or agronomic crops of economic importance. However, relatively little is known about O 3 effects on native plant species . The effects of tropospheric O 3 on two warm-season grasses, eastern gamagrass ( Tripsacum dactyloides L.) and big bluestem ( Andropogon gerardii Vitman), were examined during June–September of 2003. Plants were fumigated with three levels of O 3 in a randomized-block experiment with three replicates of each treatment. Grasses were grown in open-top chambers with introduced carbon-filtered (CF) air, characteristic of clean air quality; non-filtered (NF) air, representative of quality in Auburn, AL; and air with double (2×) the ambient concentration of O 3 . Because forage quality can be as important as quantity, we determined various effects on nutritive quality characteristics in addition to biomass yield. Big bluestem exhibited little response to O 3 exposure. For eastern gamagrass, we generally found decreased nutritive quality with increasing O 3 exposure as evidenced by increased concentrations of cell wall constituents and decreased concentrations of N. Regrowth of both species exhibited little treatment effect which emphasizes the importance of timing and duration of O 3 exposures in relation to physiological stage of plant development. Decreased nutritive quality parameters observed for eastern gamagrass may have implications to diet selection and nutrient intake by ruminant herbivores. In addition, range managers can use species-specific information regarding O 3 sensitivity to make decisions about mechanical harvesting and grazing regimes of these forages growing in areas exposed to elevated O 3 concentrations. El ozono toposférico (O 3 ) es un contaminante del aire fitotóxico ampliamente diseminado en los países industrializados del mundo. El ozono se produce por la fotooxidación de los hidrocarbonos liberados en la atmósfera por la combustión de combustibles fósiles. Los estudios muestran que el O 3 puede ser transportado de las áreas metropolitanas a las áreas rurales importantes agrícola y forestalmente. Los reportes respecto al O 3 se han enfocado en la vegetación importante para la producción de alimentos o cultivos agrícolas de importancia económica. Sin embargo, poco se sabe de los efectos del O 3 en las plantas de especies nativas. De Junio a Septiembre del 2003 se examinaron los efectos del O 3 en dos especies de zacates de estación caliente “Eastern gamagrass” ( Tripsacum dactyloides L.) y “Big bluestem” ( Andropogon gerardii Vitman). Las plantas fueron fumigadas con tres niveles de O 3 en un experimento de bloques al azar con tres repeticiones por tratamiento. Los zacates crecieron en cámaras abiertas de la parte superior con aire circulado a través de un filtro de carbón (CF) aire limpio; aire no filtrado (NF), representativo de la calidad del aire de Auburn, AL y aire con el doble de la concentración ambiental de O 3 . Debido a que la calidad del forraje puede ser tan importante como la cantidad, determinamos los efectos en la calidad nutritiva, además del rendimiento de biomasa. El “Big bluestem mostró poca respuesta a la exposición de O 3 . En el “Eastern gamagrass” generalmente encontramos una disminución de la calidad nutritiva al incrementar la exposición al O 3 , evidenciado por el aumento de la concentración de los constituyentes de la pared celular y un disminución en las concentraciones de N. El rebrote de ambas especies mostró pocos efectos de los tratamientos, lo cual enfatiza la importancia de la época y duración de la exposición al O 3 en relación al estado fisiológico de desarrollo de la planta. La disminución observada en los parámetros de calidad del “Eastern gamagrass” puede tener implicaciones en la selección de la dieta y consumo de nutrientes de los rumiantes. Además, los manejadores de pastizales pueden usar información especifica de especies en relación a su sensitividad al O 3 para tomar decisiones respecto regimenes de cosecha mecánica y apacentamiento de estos forrajes creciendo en áreas con altas concentraciones de O 3 .

Nutritive Quality of Big Bluestem (Andropogon gerardii) and Eastern Gamagrass (Tripsacum dactyloides) Exposed to Tropospheric Ozone

Tropospheric ozone (O3) is a phytotoxic air pollutant widespread in industrialized nations of the world. Ozone is produced by the photo-oxidation of hydrocarbons released into the atmosphere by combustion of fossil fuels. Studies demonstrate O3 can be transported from metropolitan areas to rural areas important to agricultural and forestry practices. Reports regarding O3 effects have focused on vegetation important to food production or agronomic crops of economic importance. However, relatively little is known about O3 effects on native plant species. The effects of tropospheric O3 on two warm-season grasses, eastern gamagrass (Tripsacum dactyloides L.) and big bluestem (Andropogon gerardii Vitman), were examined during June-September of 2003. Plants were fumigated with three levels of O3 in a randomized-block experiment with three replicates of each treatment. Grasses were grown in open-top chambers with introduced carbon-filtered (CF) air, characteristic of clean air quality; non-filtered (NF) air, representative of quality in Auburn, AL; and air with double (2X) the ambient concentration of O3. Because forage quality can be as important as quantity, we determined various effects on nutritive quality characteristics in addition to biomass yield. Big bluestem exhibited little response to O3 exposure. For eastern gamagrass, we generally found decreased nutritive quality with increasing O3 exposure as evidenced by increased concentrations of cell wall constituents and decreased concentrations of N. Regrowth of both species exhibited little treatment effect which emphasizes the importance of timing and duration of O3 exposures in relation to physiological stage of plant development. Decreased nutritive quality parameters observed for eastern gamagrass may have implications to diet selection and nutrient intake by ruminant herbivores. In addition, range managers can use species-specific information regarding O3 sensitivity to make decisions about mechanical harvesting and grazing regimes of these forages growing in areas exposed to elevated O3 concentrations.

Nutritive evaluation of vegetable wastes as complete feed for goat bucks

The nutritional worth of vegetable wastes like cauliflower leaves, cabbage leaves, pea pods and pea vines was assessed in comparison to conventional green oats fodder in bucks. Each of the vegetable waste, supplemented with minerals and common salt, was fed ad lib as complete feed, to 3 bucks (Beetle × Anglo Nubian × French Alpine; 6 years old of 62.6 ± 1.1 kg BW). The leaves of cauliflower and cabbage had low ( P < 0.05) concentration of cell wall constituents, but high ( P < 0.05) concentration of CP, except that CP of pea pods was comparable with cabbage leaves. Cabbage leaves had highest (20.6%) and pea pods had lowest (4.8%) concentration of water soluble sugars. Cauliflower leaves had highest concentration of phenolics (5.9%), comparable with cabbage leaves, but lowest concentration was observed in pea pods (0.3%). The fractionation of proteins indicated that vegetable waste in general had high concentration of water soluble (54–62%) and low concentration of alcohol soluble (8–9%) fractions. Digestibility of nutrients except that of NDF was comparable in cabbage and cauliflower leaves, but higher ( P < 0.05) than in other vegetable wastes and conventional green oats fodder. The total purine derivatives excreted in urine were high ( P < 0.05) in cauliflower leaves (1.5 mmol/kg BW 0.75/day) followed by those fed pea pods, and lowest in those fed pea vines (0.29 mmol/kg BW 0.75/day). Allantoin constituted the major portion (69–91%) of purine derivatives excreted in urine. Microbial protein synthesis was high ( P < 0.05) in animals fed cauliflower leaves followed by those fed pea pods and low in bucks fed pea vines. The N-excretion as % of N-intake was lowest ( P < 0.05) in animals fed pea pods (65.1%) resulting in significantly higher N-retention (24.5 g/day) and apparent biological value (BV), which was comparable to cauliflower leaves and green oats. In spite of maximum CP digestibility, the apparent BV was lowest in cabbage leaves. The ME value of both cabbage and cauliflower leaves was significantly higher than that of pea vines. It was concluded that cabbage leaves, cauliflower leaves and pea pods could serve as excellent source of nutrients for ruminants and can economize the production of animals.

Evaluation of Forest Tree Leaves of Semi-hilly Arid Region as Livestock Feed

Samples of 13 species of forest tree leaves fed to livestock in the semi-hilly arid zone of Punjab State in India were collected at 30 d interval for 12 months, in order to assess their nutritional worth for livestock. The ground samples were pooled for 4 different seasons viz. dry hot, hot humid, fall and winter. The chemical composition irrespective of the season revealed that CP content varied between 8.9 (Carrisa) to 22.0% (Leucaena). Globulin was the major protein fraction in most of the leaves. The lowest concentration of cell wall constituents was observed in Morus alba and Grewea. The leaves in general became fiberous and lignified during winter and fall as compared to summer season. The leaves of Grewea, Morus alba, Leucaena, Carrisa and Acacia were rich in Ca, P and most of the trace elements. The total phenolics ranged between 1.88% (Azardirachta) to 15.82% (Acacia). The leaves of Acacia had the highest concentration of hydrolysable tannins (14.6%) whereas that of Carrisa had that of condensed tannins (5.9%). The condensed tannins (more than 3%) were negatively correlated to the digestibility of dry matter (DM), neutral detergent fiber (NDF) and crude protein (CP). The digestion kinetic parameters for DM, NDF and CP revealed that leaves of Morus alba, Zizyphus and Ehretia had highest insoluble but potentially degradable fraction. The minimum rumen fill values also revealed that leaves of Grewea, Azardirachta, Morus, Ehretia and Leucaena had great potential for voluntary DM intake. The leaves of Ougeinia, Malha, Dodenia and Carrisa had significantly higher rumen fill value indicating poor potential for voluntary DM intake. Season did not have any significant impact on digestion kinetic parameters except that most of the leaves had low potentially degradable fraction, which was degraded at slow rate during winter. It was concluded that the leaves of Morus, Ehretia, Grewea and Leucaena had great potential as livestock feed, while feeding of Ougeinia, Malha and Dodonea leaves should be avoided.

Yield and nutritive quality of sericea lespedeza ( Lespedeza cuneata) and little bluestem ( Schizachyrium scoparium) exposed to ground-level ozone

Sericea lespedeza ( Lespedeza cuneata cv. Interstate 76) and little bluestem ( Schizachyrium scoparium cv. Aldous) were raised from seed in a glasshouse, transplanted into 5.7-l pots and placed into open-top chambers (OTC) on 6 June 1999. Following a 7-day adjustment period, each of six OTCs (duplicate OTCs per treatment) was ventilated with either air that had been carbon-filtered (CF) to remove ambient ozone (O 3); non-filtered (NF), representative of ambient air; or enriched to twice-ambient O 3 concentration (2X). Primary-growth forage was harvested on days 7, 32, 46, 59 and 72 following the start of fumigation, and regrowth forage from the first primary-growth harvest was harvested on days 36, 54 and 72 following the start of fumigation. Dry matter (DM) yield of either forage species did not differ among treatments except in the final regrowth period when yield of sericea lespedeza was greater for the NF than 2X O 3 treatment. In vitro DM digestibility (IVDMD) and concentrations of crude protein (CP), soluble phenolics (SP) and condensed tannins (CT) in primary-growth sericea lespedeza did not differ between treatments, but NF primary-growth forage had higher concentration of protein-precipitating tannins (PPT) than did 2X primary-growth forage. Concentrations of neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL) were higher in NF and 2X than in CF primary-growth sericea lespedeza. Similarly, concentrations of NDF and ADL were higher, and IVDMD was lower for NF and 2X than for CF regrowth sericea lespedeza. Concentrations of ADF and ADL were lower, whereas IVDMD, in vitro NDF digestibility (IVNDFD) and concentrations of CP and SP were greater, in CF than in NF and 2X primary-growth little bluestem. Percentages IVDMD and IVNDFD and concentrations of CP and SP in NF primary-growth little bluestem were greater than those in forage exposed to 2X O 3 treatment. No significant differences were observed among treatments in percentages IVDMD and IVNDFD, or concentrations of cell wall constituents or SP in little bluestem regrowth. Nutritive quality of little bluestem was decreased by <2%, and that of sericea lespedeza by ∼7% as a result of increased concentrations of cell wall constituents and decreased in vitro digestibility of NF and 2X compared with CF forages. Results indicate that existing and projected O 3 levels can drive alterations in forage quality of select warm-season forages sufficient to have nutritional and economic implications for their utilization by ruminant herbivores.

Yield and quality characteristics of bahiagrass ( Paspalum notatum) exposed to ground-level ozone

Early and late season-planted bahiagrass ( Paspalum notatum Flugge, cultivar ‘Pensacola’) were grown in open-top chambers (OTC) to which added air had been carbon-filtered (CF), representative of that found at pristine air quality sites; non-filtered (NF), characteristic of ambient air in Auburn, AL and representative of that found in rural agricultural areas; or enriched with ozone (O 3) to twice-ambient O 3 concentration (2X), representative of that found in the vicinity of large metropolitan areas. Primary-growth and regrowth forages from each planting were harvested periodically throughout the experiment from each of six OTC (two OTC/air treatment). Mean daytime (09:00–21:00 h) O 3 concentrations over the entire 24-week experiment (7 May–23 October 1997) were 22, 45 and 91 ηl l −1, respectively, for CF, NF and 2X treatments. Mean daytime ambient O 3 concentrations peaked in mid-May and again in late August–late September at 50–60 ηl l −1, and highest individual ambient O 3 concentrations were recorded in late June, late July, late August and mid-September at ∼90 ηl l −1. Dry matter (DM) yield was greater for CF than for NF primary-growth forage, and concentrations of neutral detergent fiber (NDF) were higher in 2X than in NF primary-growth and regrowth forages from the early-season planting. Concentration of acid detergent fiber (ADF) tended to be higher in 2X than in NF primary-growth forage and was higher in 2X than in NF regrowth forage, whereas acid detergent lignin (ADL) concentration was higher in 2X than in NF primary-growth forage and tended to be higher in 2X than in NF regrowth forage from the early-season planting. Crude protein (CP) concentrations were lower in CF than in NF regrowth forage from the early-season planting and in CF than in NF primary-growth forage from the initial harvest of the late-season planting. No differences were observed among treatments in DM yield or concentrations of cell wall constituents in primary-growth or regrowth forages from the late-season planting, although concentrations of CP, NDF and ADF tended to be higher in 2X than in NF regrowth forage. No differences were observed among treatments in concentrations of total phenolics in primary-growth or regrowth forages from either planting, although concentrations of total phenolics tended to be higher in CF than in NF primary-growth forage from the late-season planting. Particularly in the case of early-planted bahiagrass, alterations in DM yield and quality of primary-growth and vegetative regrowth forages were of sufficient magnitude to have nutritional and possibly economic implications to their utilization for ruminant animal production under existing and projected global climate scenarios.

Mycophagy by small mammals in the coniferous forests of North America: nutritional value of sporocarps of Rhizopogon vinicolor, a common hypogeous fungus.

We evaluated the nutritional value of sporocarps of Rhizopogon vinicolor, a common hypogeous fungus in the coniferous forests of North America, for two small mammal species: the Californian red-backed vole (Clethrionomys californicus) and the northern flying squirrel (Glaucomys sabrinus). Although the nitrogen concentration of sporocarps was high, much of it was in non-protein form or associated with cell walls, suggesting that it may be of low nutritional value or protected from mammalian digestive enzymes. Sporocarps also had high concentrations of cell wall constituents, indicating low availability of digestible energy. When fed a diet of this fungus alone in a controlled feeding experiment both mammal species lost a small amount of body mass. Digestibilities of dry matter, nitrogen, cell wall constituents and energy from sporocarps by both species were lower than the digestibilities of other food types by other similarly sized small mammals. Red-backed voles digested the various components of sporocarps at least as well as the flying squirrels, even though they were almost six-fold smaller in body mass. This observation supports the notion that red-backed voles, like other microtine rodents, have morphological and physiological adaptations of the digestive system that are postulated to permit greater digestion of fibrous diets than predicted on the basis of body size. Despite this, our results re-affirm previous conclusions that hypogeous fungi are only of moderate nutritional value for most small, hindgut-fermenting mammals. Future studies should focus on the importance of mixed-species of fungi in the diet of small mammalian mycophagists.

Shearing force of alfalfa stems as affected by seeding rate

Physical properties of forages may provide a simple method of predicting animal voluntary feed intake. Physical measurements, such as shearing force, may indicate the resistance of the forage to particle breakdown during mastication. The objective of this study is to determine the effects of seeding rate on the physical characteristics and cell wall chemical constituents of alfalfa (Medicago sativa L.) stems, and to relate these characteristics to shearing strength. Stems of eight alfalfa cultivars (120, Legend, Multiking 1, OAC Minto, Saranac, Vernal, Vertus, WL320) seeded at 6, 12 and 24 kg ha−1 were harvested in the first and second production years and divided into three 16 cm segments: top, middle and bottom, and the force required to shear each segment was measured using a modified Ottawa Texture Measuring System. For both years, shearing force, segment weight and stem diameter measurements generally decreased as seeding rate increased when measured at the middle and bottom shearing segments on the stem, but this was not observed for the top shearing segment. Effect of seeding rate on differences in segment weight and stem diameter among cultivars was variable among years and stem segments. Concentrations of cell wall constituents in stems were not influenced by seeding rate, and these influenced shearing force to a lesser extent than physical characteristics. Shearing force was directly related to the diameter and weight of the stem. Because of the associations between shearing force and diameter and weight, physical characteristics of the stem may influence forage breakdown during mastication independently, and to a greater extent than cell wall chemical constituents. Key words: Alfalfa, seeding rate, shearing force, cell wall chemical constituents, diameter, weight

Digestion Kinetics and Composition of Normal and Brown Midrib Sorghum Morphological Components

The brown midrib (bmr) mutation has shown the potential to improve the nutritive quality of forage sorghum [Sorghum bicolor (L.) Moench]; however, no study has been conducted to directly compare the effect of the bmr gene in a sudangrass (sorghum × drummondii (Steudel) Millsp. &amp; Chase) and its hybrid with a grain sorghum. Research was conducted to evaluate the relationship between cell wall composition and digestibility within the morphological components of normal and bmr sorghum cultivars. Cell wall constituents, structural carbohydrates, alkali‐labile phenolic monomers, and in vitro digestion kinetics were determined for ‘Piper’ (normal sudangrass), ‘S407’ (Piper. bmr‐6 sudangrass), and ‘F1006‐8 × S407’ (male sterile grain type bmr‐6 sorghum × Piper bmr‐6 sudangrass). Whole plants were harvested at the boot and hard dough growth stages and separated in to leaf blade, leaf sheath, inflorescence, and stem components. Significant differences were found between cultivars in concentrations of cell wall constituents. Neutral detergent fiber (NDF) concentration was lower (P &lt; 0.05) in the bmr cultivars than in Piper due to lower concentrations of cellulose and acid detergent lignin (ADL). Concentrations of ADL averaged g kg−1 dry matter for Piper, 28 g kg−1 for S407, and 25 g kg−1 for F1006‐8 × S407. The bmr cultivars had lower (P&lt;0.05) concentrations of p‐coumaric acid and higher (P &lt; 0.05) concentrations of vanillin than Piper. There were no differences (P &gt; 0.05) among cultivars ferulic acid concentration. p‐Coumaric acid concentrations averaged 25 g kg−1 of NDF for Piper, 16 g kg−1 NDF for S407, and 14 g kg−1 NDF for F1006‐8 − S407. Rate constants for in vitro digestion of NDF were similar (P &gt; 0.05) among cultivars. The bmr sudangrass (S407) had a greater (P &lt; 0.05) extent of NDF digestion than either Piper of F1006‐8 × S407. Extent of NDF digestion averaged 0.596 for Piper, 0.623 for S407, and 0.597 for F1006‐8 × S407. Results of this study indicate that the bmr mutation can effectively be expressed in both sudangrass and sorghum × sudangrass hybrid backgrounds

Nutritional-Value of Hypogeal Fungal Sporocarps for the Long-Nosed Potoroo (Potorous-Tridactylus), a Forest-Dwelling Mycophagous Marsupial

Although mycophagy (fungus-feeding) is widespread among small ground-dwelling mammals, there has been little evaluation of the nutritional benefits of this feeding habit. In Australia, some members of the Potoroidae (or rat-kangaroo family) consume large amounts of hypogeal fungi throughout the year. Hypogeal fungi appear to be of marginal nutritional quality for small mammals with simple stomachs but potoroos have an enlarged forestomach in which microbial fermentation takes place, and this may allow more effective utilisation of protected nitrogenous components and structural carbohydrates of fungi. In a feeding experiment, we evaluated the nutritional value of sporocarps of the hypogeal fungi Mesophellia glauca (Mg) and Rhizopogon luteolus (R1), for the long-nosed potoroo (Potorous tridacytlus). Although the concentration of nitrogen was high in both fungi, much of that nitrogen was in non-protein form or associated with cell walls and may be either of low nutritional value or protected from digestive enzymes. The concentration of cell-wall constituents (fibre) was high in both fungi, suggesting low availability of digestible energy. Despite these features, the digestibilities of dry matter (Mg 86%, Rl 80%), ingested nitrogen (Mg 72%, Rl 72%) and energy (kJ kg-1) (Mg 93%, Rl 76%) of both fungi were high. Consequently, P. tridactylus maintained positive nitrogen balance and high intakes of digestible and metabolisable energy. We conclude that the sporocarps of hypogeal fungi represent a nutritionally valuable food for rat-kangaroos and suggest that lack of a foregut-fermentation strategy in other similar-sized ground-dwelling mammals in the forests of south-eastern Australia explains why they use the hypogeal fungal resource to a lesser extent than do rat-kangaroos.

In Vitro Digestibility of Dry Matter and Cell Wall Constituents of Smooth Bromegrass Forage1

The availability of forage cell walls to ruminants is dependent on the concentration and digestibility of cell wall constituents. The objectives of this study were to quantify genotypic variation for in vitro digestibility of individual cell wall constituents and relate this variation to variation in concentration of cell wall constituents of smooth bromegrass (Bromus inermis Leyss.). Eighteen clones were grown at Arlington, WI, and sampled in 1982 and 1984. Forage samples were harvested to simulate a normal first cutting. Samples were analyzed for cell wall constituents of dried forage and forage that had been previously digested by rumen microorganisms. In vitro digestibility (IVD) of cell wall constituents was computed from differences obtained between undigested and digested forage samples. Genotypic variation was significant for IVD of neutral detergent and acid detergent fiber (NDF and ADF, respectively), cellulose, and hemicellulose, but not for acid detergent lignin (ADL). In vitro digestibilities of dry matter, NDF, ADF, cellulose, and hemicellulose were mutually correlated, with r ≥ 0.87. Concentration and IVD of cell wall constituents generally were not correlated, with ‒0.52 ≤ r ≤ 0.22. Selection for divergent IVD of dry matter (IVDMD) resulted in similar changes to IVD of NDF, ADF, cellulose, and hemicellulose; differences between high and low IVDMD clone groups ranged from 37 to 42 g kg−1 for IVD of cell wall constituents. The additional information provided by determining IVD of cell wall constituents makes these selection criteria potentially valuable. Because of their close interrelationships and similar correlated selection responses, IVD of NDF, which is the easiest and least expensive to determine, would satisfactorily represent the other IVD variables in smooth bromegrass.

Chemical and in Vitro Digestible Dry Matter Composition of Maize Stalks after Selection for Stalk Strength and Stalk‐Rot Resistance1

Although maize (Zea mays L.) is a major forage crop, little attention has been given to possible alteration of forage quality associated with breeding for increased resistance to stalk lodging. This study was designed to evaluate changes in stalk composition and digestibility resulting from three cycles of recurrent selection each for improved stalk strength (BSlMS) and stalk‐rot [Diplodia maydis (Berk.) Sacc.] resistance (BSlSR). The second elongated internmode plus half of each adjacent internode from plants of the original population (BSlCO) and from C1 to C3 for the BSlMS and BSlSR populations were sampled approximately 35 days after midsilking for chemical and in vitro digestible dry matter (IVDDM) evaluation. Major composition changes from the BSlCO to BSlMSC3 and BSlSRC3 populations, respectively, were: concentration of cell wall constituents, 616 to 520 and 542 g kg−1; concentration of acid detergent fiber, 422 to 353 and 373 g kg−1; concentration of lignin, 57 to 42 and 47 g kg−1; concentration of total nonstructural carbohydrates (TNC), 184 to 258 and 244 g kg−1; and concentration of IVDDM, 514 to 621 and 594 g kg−1. Both selection regimes increased TNC concentration, which diluted stalk fiber concentration and resulted in a net increase in IVDDM. Recurrent selection for traits associated with improved stalk lodging resistance did not have negative effects on the forage quality of maize stalks in late reproductive stages.

Effect of Sample Grinding Size on Forage Quality Estimates of Smooth Bromegrass Clones1

Particle size of ground forage influences in vitro digestibility and the concentration of cell wall constituents. Little information is available on the effect of ground forage particle size on the relative rankings of genotypic or phenotypic values for quality of ground forage. Our objective was to determine the effect of two grinder screen sizes on the relative rankings and repeatability of forage nutritive value estimates of smooth bromegrass (Bromus inermis Leyss.) clones. Dried forage of 75 smooth bromegrass clones was ground through a 2‐mm screen, from which a sample was reground through a 1‐mm screen. Neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), hemicellulose, cellulose, and ash were determined on duplicate samples of fine‐ and coarse‐ground forage. All traits except ADF and hemicellulose had average absolute values of duplicate differences reduced significantly by fine grinding. The correlation between duplicate samples was increased by fine grinding for each trait, except hemicellulose and ash. Fineness of grind severly affected the relative rankings of ADL and hemicellulose; NDF, ADF, and cellulose were also more highly correlated with one another when forage was ground finely. The interactions between particle size groups and clones raises the question of which size provides a better predictor of animal performance potential. We concluded that forage breeders should grind forage samples fine enough to obtain adequate repeatability unless it can be shown that coarser grinds give results more highly correlated with animal performance.

Wet Fractionation Process: Preservation and Utilization of Pressed Alfalfa Forage

Lactation, digestion, and laboratory silo fermentation trials compared wet fractionated alfalfa silage treated with formic acid to conventional low-moisture silage. Eight Holstein and two Ayrshire cows in mid-lactation were fed either the formic-acid treated, pressed silage, or conventional low moisture silage as the only source of forage plus grain according to milk production. Daily intake of dry matter from forage, total intake of dry matter, and 4% fat-corrected milk production were similar for treatments. Ruminal concentrations of acetic, propionic, and butyric acids (molar %) and ammonia nitrogen (mg/100ml) were 61.3, 55.3; 19.5, 21.1; 13.5, 14.8; 18.63, 32.99; for formic-acid pressed silage and conventional low-moisture silage treatments. Apparent digestion coefficients for formic-acid pressed and low-moisture silage were: dry matter 66.3, 67.1; crude protein 71.9, 76.5; and hemicellulose 69.3, 57.4. Pressed forages treated with .00, .20, .35, .50, and .65% formic acid were incubated at 37.8C for 60 days in evacuated plastic bags. As formic acid increased, ammonia nitrogen, nonprotein nitrogen, total volatile fatty acids, and acetic acid decreased while the concentration of cell wall constituents and hemicellulose increased. Lactic acid content increased by addition of .20 and .35% formic acid and decreased when .50 or .65% formic acid was added.

Concentration, Composition, and in vitro Disappearance of Hemicellulose in Tall Fescue and Orchardgrass1

AbstractHemicelluloses are complex groups of cell wall polysaccharides which comprise significant proportions of the dry matter of many forages. Factors affecting hemicellulose concentration in grasses could influence efficient utilization of fibrous feeds by ruminants. The purpose of this research was to evaluate the effects of N‐fertilization, maturity, and plant tissue on the disappearance of cell wall constituents (CWC), hemicellulose, and the components of hemicellulose in two forage grasses during in vitro rumen fermentation.Tall fescue (Festuca arundinacea Schreb.) and orchardgrass (Dactylis glomerata L.) plots on a Chalmers silty clay loam (fine silty typic argiaquolls) were fertilized with either 0 or 112 kg/ha of N as urea. The grasses were labeled with 14CO2 on 21 May 1975 (heading stage) and were sampled on the 1st, 7th, and 19th days after labeling. Cell wall constituents were prepared by neutral detergent extraction of lyophilized, ground tissue before and after the tissue had been incubated in buffered rumen fluid for 48 hours. Hemicellulose was hydrolyzed in situ with 1.0 N H2SO4. Sugar residues of hemicellulose were separated and identified by paper chromatography and the radioactivity was measured by liquid scintillation counting.The concentrations of each cell wall component of tall rescue and orchardgrass generally were not significantly different (P = 0.10). Leaves of N‐fertilized grass contained 51.1% CWC and 29.5% hemicellulose compared to 58.1% CWC and 24.0% hemicellulose in leaves of non‐fertilized grass. Concentrations of CWC and hemicellulose in stems were 10 and 5 percentage units, respectively, higher than in leaves. Xylose and arabinose were the major components of hemicellulose, accounting for 37.8 and 23.6%, respectively, of the hemicellulose. Glucose, galactose, and uronic acids formed the remainder. The relative proportion of xylose in the hemicellulose of leaves declined an average of 14% during the sampling period.Disappearance of CWC and hemicellulose was 52.6 and 69.1%, respectively, during in vitro tureen fermentation. All of the hemicellulose components were not fermented equally. The ratio of xylose:arabinose increased from 1.6 in the original leaf tissue to 3.0 after rumen fermentation. Arabinose in vitro disappearance was 74.7% compared to 53.7% for xylose. 14C‐Xylose accounted for 50% of the radioactivity in hemicellulose before rumen fermentation and more than 70% of the radioactivity in hemicellulose after fermentation. Greater than 96% of 14C‐arabinose and nearly all of the radioactivity in glucose and galactose were lost during fermentation, further indicating that the constituents of hemicellulose are not equally available to rumen microorganisms. An inverse relationship between hemicellulose in vitro disappearance and the xylose: arabinose ratio suggests possible selection criteria for improving forage utilization by ruminants.

Comparative nutritive value of hay made normally and by desiccation with paraquat

In a series of five experiments, hay made by conventional methods was compared with hay made by spraying with paraquat prior to mowing. In all the experiments, chemical composition of the hays was measured and in three of them the hays were fed to sheep. In the first experiment the digestible organic matter intake (DOMI) and digestibility of oaten hay made by the two methods was similar. In the second experiment rapid desiccation was achieved using paraquat on a pasture of Wimmera ryegrass (Lolium rigidum) and subterranean clover (Trifolium subterraneum), but leaf losses during baling were higher than for turning and baling mown herbage. In the third experiment, on a densestand of Wimmera ryegrass, the stem bases were not reached by the paraquat spray and desiccation took 14 days longer than with mowing and turning. In both experiment 2 and 3 sheep consumed similar amounts of DOMIand had similar liveweight changes when fed the two types of hay, although digestibilities were lower for the hays made using paraquat. Also, in these two experiments there were higher concentrations of cell wall constituents, and in experiment 3 lower concentrations of water soluble carbohydrates (WSC), in hay made by using paraquat. In experiments 4 and 5 it was shown that large losses of WSC occurred consistently when herbage on ryegrass pastures was desiccated with paraquat. The effect was shown to occur within 24 hours of application. A further effect, that needs more research, was that the digestibility of cell wall material was lower in hay made with paraquat than in normal hay. It is concluded that the use of paraquat to provide rapid desiccation of herbage is unlikely to result in hay of higher quality than that made conventionally.