In Vitro Dry Matter Disappearance Research Articles

In Vitro Digestibilities of Summer Forages Utilized by the Rivière George Caribou Herd

The Riviere George caribou herd (northern Quebec-Labrador, Canada) is thought to be regulated by forage limitations in its summer range. In such a situation, digestibilities of plants may strongly affect the diet choice and physical condition of animals. In vitro dry matter disappearance (IVDMD) of the most important summer forages of the Riviere George caribou herd was determined during fermentation periods of 12, 24, and 48 h using rumen fluid collected from a Holstein cow. IVDMD values for Cyperaceae (Eriophorum angustifolium and Carex rariflora), and shrubs (Betula glandulosa and Vaccinium uliginosum) collected in July and August were higher for long fermentation periods (48 h) than for shorter ones (12 and 24 h). Plants collected in early summer were also more digestible than those collected in late summer. Contrary to my prediction, both Cyperaceae were more digestible than the two shrubs in mid-July. However, no difference occurred in early August. The fermentation period did not affect the IVDMD of lichens; maximum digestibility was attained after 12 h. Alectoria ochroleuca and Cetraria spp. were more digestible than Cladina rangiferina, Cladina stellaris, and Stereocaulon paschale, likely because of their lower fibre content. These results suggest that the preference of caribou for Cladina spp. is not based on digestibility, but probably on the fact that these species are abundant in the Riviere George area. Variations in IVDMD seem to be explained by plant phenology, because longer fermentation periods were necessary to attain a high level of digestibility as summer progressed. Plant digestibility alone cannot explain caribou summer diet. Other variables such as plant constituents (e.g. protein) and relative abundance must also be considered.

Nitrogen and Defoliation Management: Effects on Yield and Nutritive Value of Flaccidgrass

Abstract‘Carostan’ flaccidgrass (Pennisetum flaccidum Griseb.), a C4 perennial grass, has shown high quality potential in animal trials. Its yield response to defoliation frequency and N fertilization, however, has not been reported. We examined the influence of stubble height and of a range of N applications in two defoliation experiments over 4 yr. Experiment 1 (Raleigh, NC) combined two harvest heights, 76 and 38 cm, with two stubble heights, 25 and 15 cm (76–25, 76–15, 38–25, 38–15); all treatments received 380 kg N ha−1 yr−1. After Year 1, the 76–15 defoliation produced higher yields than 76–25 (Year 2: 11 330 vs. 7930 kg ha−1, P < 0.001; Year 3:8950 vs. 6270 g kg−1, P < 0.001), while in vitro dry matter disappearance (IVDMD) was similar (Year 3) (mean = 582 g kg−1). Compared with 38–15, the 38–8 defoliation resulted in lower yields (Year 2: 8638 vs. 9344 kg ha−1, P = 0.001; Year 3, 6173 vs. 8090 kg ha−1, P = 0.07) but higher IVDMD (Year 3, 651 vs. 635 g kg−1, P < 0.01). Experiment 2 (Raleigh, NC, and Watkinsville, GA) had four defoliations: clipping to 5 cm at 20 and 51 cm (vegetative) and to 8 cm at boot and anthesis stages (20–5, 51–5, Boot—8, Anthesis—8). All defoliation treatments were topdressed with 291 kg N ha−1, and 51–5 and Boot—8 were also evaluated with 179 and 403 kg N ha−1 (eight N—defoliation treatments in all). At both locations, highest yields were obtained with Anthesis—8, averaging 19 010 kg ha−1 at Raleigh and 12 390 kg ha−1 at Watkinsville. The 20–5 defoliation resulted in lowest yields at both locations, averaging 7648 kg ha−1 at Raleigh and 5100 kg ha−1 at Watkinsville. Defoliation frequency altered IVDMD (range = 550 to 789 g kg−1), but N application did not; however, increasing N application increased N concentrations linearly (P = 0.05). Flaccidgrass had high yield potential and high nutritive value at the Raleigh location, and warrants further evaluation in the upper South.

Forage Yield, Quality, and Fertility of Sorghum × Sudan Grass Hybrids in A1 and A3 Cytoplasm

Currently, no information is available comparing the agronomic performance of A1 and A3 cytoplasms in sorghum × sudangrass [Sorghum bicolor (L.) Moench] hybrids. The objectives of this study were to compare the effects of A1 and A3 cytoplasm on the maturity, fertility, height, forage yield, and forage quality of sorghum × sudangrass hybrids. In 1989, pollen from a bulk of eight sudangrass populations was used to pollinate four sorghum lines that had been male‐sterilized in both A1 and A3 cytoplasm. Hybrids were grown at the Univ. of Nebraska Field Laboratory, Ithaca, NE, in 1990 and 1991, in a split‐plot design with inbreds (females) treated as whole plots and cytoplasms treated as subplots. The soil was a Sharpsburg silty clay loam (fine montmorillonitic, mesic Typic Agriudoll). Cytoplasm had no effect on days to 50% anthesis, height, forage yield, in vitro dry matter disappearance (IVDMD), or crude protein. Seed set under selfing bags (fertility restoration) in A3 hybrids was observed, with interaction among A3 cytoplasm sources and lines.

Forage Quality Variation in the U.S. Alfalfa Core Collection

Alfalfa (Medicago sp.) is the most important perennial forage crop in the USA. The cultivars currently grown commercially are based on a limited and intermixed set of germplasm. Our objective was to survey the genetic variation in leaf and stem quality in the crop by analyzing the core collection of the U.S. alfalfa plant introductions. The 200 plant introductions of the core were planted at Rosemount, MN, in 1991 and 190 entries were sampled at flowering in 1992. Sixtyone entries were re‐sampled in 1993. Leaf and stem tissues were analyzed separately for crude protein, neutral and acid detergent fiber (NDF and ADF, respectively), acid detergent lignin, in vitro dry matter disappearance (IVDMD), and ficin degradable CP (FDCP). Additionally, stems were analyzed for cellulose concentration and enzymatic degradability, 24‐ and 96‐h in vitro NDF digestibility (IVNDFD),and lignin composition. For all forage quality traits, significant variation was found among the plant introductions. Concentration of NDF varied widely for leaves among entries, but relatively little variation occurred in stem NDF. The opposite trend occurred for IVDMD which varied more in stem material than leaves. This result was attributed to the high degree of variation in stem IVNDFD among the plant introductions. Stem FDCP was among the more variable traits measured. Quality traits of four contemporary check cultivars included in the trial were never as high or low as the extremes observed among the plant introductions. Significant sampling year effects were observed for most quality traits, but year × entry interactions were minimal. Concentration of NDF and IVDMD had significant negative correlations between leaf and stem values. In general, if leaf or stem quality was high, then the quality of the other plant part was low although this correlation was not large. Significant variation in forage quality traits exists in the U.S. alfalfa germplasm collection that could be used to improve the quality of commercial cultivars.

Rotational vs. Continuous Stocking of Beef Cows and Calves on Mixed Endophyte-Free Tall Fescue-Bermudagrass Pasture

Endophyte-free tall fescue (Festuca arundinacea Schreb.) furnishes better animal performance than endophyte- infected grass but is less persistent under grazing, especially in mixture with common bermudagrass [Cynodon dactylon (L.) Pers]. Rotational (RS), compared with continuous (CS), stocking of endophyte-free tall fescue may improve persistence when grown with an aggressive warm season perennial grass. Four 40-acre bermudagrass pastures no-till seeded witb endophyte-free 'AU Triumph' tall fescue were used, allowing two replications to compare CS and RS methods. Rotationally stocked pastures were divided into 12 paddocks to allow 2 d of grazing and 22 d of rest. Twenty Hereford (Bos taurus)x Brangus (B. indicus x B. taurus) beef cows/40-acre pasture were maintained year around for 3 yr with additional cows added in spring and summer to maintain similar forage availability. Grazing method had no effect on cow weight change, pregnancy rate, or calf weaning weight. Pasture stocking rate and calf weaning weight per acre were 38 and 37% higher (P < 0.10), respectively, and winter hay consumption was 31% lower from rotationally stocked pastures because of better tall fescue persistence and forage availability. Crude protein (CP) and in vitro dry matter digestibility of available forage generally exceeded 8 and 50%, respectively, throughout the year. Rotational stocking appears to be useful in maintaining stands of endophyte-free tall fescue in bermudagrass pastures.

Intake, digestion, and nitrogen balance of sheep fed shrub foliage and medic pods as a supplement to wheat straw

Low animal performance in arid and semi-arid areas of Morocco is mainly due to protein and energy deficiencies of available forages. A metabolism trial was conducted to evaluate the influence of supplementation with shrub foliage and medic (Medicago sp.) pods on nitrogen (N) utilization by sheep fed low-quality roughage. Diets were wheat (Triticum aestivum L.) straw (WS), WS plus alfalfa (Medicago sativa L.) hay (AH), WS plus oldman saltbush (Atriplex nummularia Lindl.) foliage (AN), WS plus blue wattle (Acacia cyanophylla Lindl.) foliage (AC), and WS plus medic pods (MP). Alfalfa feeding level was set to provide a crude protein (CP) concentration of 90 g kg−1 dry matter (DM) in the diet. Shrub foliage and medic pods were offered ad libitum. Average intake levels for AN, AC, and MP were 37.2, 32.4, and 47.2% DM, respectively. Chemical composition and in vitro dry matter disappearance (IVDMD) were measured. Digestible dry matter intake (DDMI) was greatest (P < 0.05) for saltbush diet (36.3 g kg−0.75), followed by the alfalfa diet (30.0 g kg−0.75). Unsupplemented wheat straw and blue wattle diets had the lowest DDMI (21.3 g kg−0.75). The daily N balance for the supplemented diets was greatest (P < 0.001) for alfalfa and saltbush diets with +6.7 g and least for the blue wattle diet (+ 3.0 g). Feeding the unsupplemented wheat straw diet resulted in the lowest N retention (+ 0.6 g day−1). A degradability trial was then conducted to investigate the rate and extent of DM and CP digestion of the same forages in the rumen. Forage samples were incubated for 0, 2, 4, 8, 12, 24, 48, and 72 h. Rate and extent of DM digestion were highest (P < 0.05) for saltbush foliage. Rate of CP degradation was fastest (P < 0.05) for alfalfa hay (0.151 h−1). Extent of CP degradation was greatest (P < 0.05) for saltbush foliage (74.4%), followed by MP (69.0%), AH (63.9%), and BW (6.8%). Inclusion of saltbush foliage, and to some extent medic pods, with low-quality forage diet was comparable to inclusion of alfalfa hay. These results indicated that improving degraded rangelands by planting palatable shrubs, and managing medic pastures to produce enough pods to be grazed in the summer should reduce the need to supply sheep with costly protein-rich supplements during periods of feed shortage.

Nutrient composition, in vitro gas production and digestibility of fenugreek (Trigonella foenum-graecum) and alfalfa forages

Nutritive value of forage from the annual legume fenugreek (Trigonella foenum-graecum L.) was evaluated by comparing its chemical composition, in vitro dry matter disappearance (IVDMD) and in vitro gas production with that of alfalfa. Samples of forage grown in a greenhouse or in field plots under irrigation were collected 9, 15, and 19 wk postseeding and nutritive quality was compared with alfalfa harvested at early-bloom. Greenhouse grown fenugreek-9 contained more ash than alfalfa cut at early-bloom, yet the IVDMD of fenugreek-9 was greater than that of the alfalfa. Total in vitro gas production was generally greater for alfalfa than fenugreek; however, lag time prior to initiation of gas production was shorter for alfalfa than fenugreek. Greenhouse grown fenugreek-15 or -19 contained less CP than alfalfa, while the NDF content of fenugreek-19 was highest. The IVDMD of fenugreek-15 and -19 were greater (P &lt; 0.05) than for alfalfa. Total in vitro gas production was similar for all forages. The rate of gas production was slower (P &lt; 0.05) for fenugreek-19 than for alfalfa. Fenugreek-9 harvested from field plots contained higher (P &lt; 0.05) CP than fenugreek-15 and -19 and alfalfa. Protein content of fenugreek-19 was similar to that of early-bloom alfalfa (P &gt; 0.05), while NDF and ADF contents of fenugreek-9 and -15 were lower (P &lt; 0.05) than alfalfa. Total in vitro gas production of fenugreek-19 was similar to that of alfalfa even though the rate of gas production was slower for fenugreek-19 than for alfalfa. Volatile fatty acids production and composition were generally similar for fenugreek-15 or -19 and early-bloom alfalfa. The estimated DM yield of fenugreek-19 from plots was approximately 10.4 t ha−1. These results suggest that the nutritive value of fenugreek biomass regardless of its stage of growth, is at least comparable to that of early-bloom alfalfa and so it has potential as a forage crop. Feeding trials with cattle are still required to determine intake and utilization potential of this crop. Key words: Alfalfa, fenugreek, IVDMD, in vitro gas production

Canopy Architecture and Morphology of Switchgrass Populations Differing in Forage Yield

AbstractPhenotypic selection has been used to improve forage yield and in vitro dry matter disappearance (IVDMD), but the effects on canopy architecture and morphology are not understood. Our objectives were to determine if canopy architecture and morphology can explain genotype × environment (G ✕ E) yield differences in switchgrass (Panicum virgatum L.) and to evaluate canopy architecture and morphology as selection criteria for increasing yield. This study was conducted in 1993 near Mead, NE, and near Ames, IA. The experimental design was a randomized complete block experiment with a split‐plot arrangement of four replicates at each location. Whole plots were tiller population and subplots were sward maturity. Tiller populations were harvested on 9 June, 19 July, and 27 August at Ames and on 10 June, 27 July, and 26 August at Mead and were classified morphologically. Tillers were separated into primary yield components and dried at 55°C to determine total forage yield and dry matter contribution of morphological components. Genotype × environment interactions occurred for total forage yield and tiller density. Previous phenotypic selection for increased forage yield and IVDMD apparently altered morphological changes within the canopy of selected switchgrass populations. The most apparent changes were development of additional collared leaves and internodes in some populations across locations. Although canopy architecture may not be a useful selection criterion because of variability associated with individual canopy traits, indirect measurements showed that leaf area index (LAI) has some potential as a selection criterion for increasing total forage yield. However, selection for individual canopy traits may be most effective for modifying sward growth habits.

Amount and Quality of Chicory Herbage Ingested by Grazing Cattle

Ingestive behavior of cattle (Bos taurus L.) grazing chicory (Cichorium intybus L.) has not been elucidated. Adult Angus cows were utilized to measure ingestive behavior over a range of allowances (2.53–5.17 kg cow−1 h−1) on vegetative chicory (cv. Grasslands Puna) growing on a Maury silt loam (fine, mixed, mesic, Typic Paleudalf) soil. A change‐over design employing difference procedures was used with tethered animals to evaluate allowance effects on forage quality of available, consumed and residual herbage as well as rate of biting and dry matter intake. Pre‐ and post‐grazing herbage mass and quality were determined in three 10‐cm strata above a 5‐cm stubble. Cattle consumed about 66% of the available herbage at each allowance level during a 1‐h grazing meal. In vitro dry matter disappearance (IVDMD) ranged from 719 to 746 g kg−1 across the three canopy strata prior to and after grazing. Nitrogen concentration increased from 26 to 47 g kg−1 from the lower to upper canopy stratum. Herbage intake rate increased from 1.7 kg h−1 at the lowest allowance to 3.6 kg h‐~ at the highest, in response to a linear increase in intake per bite. Biting rate was unaffected by herbage allowance. High dry matter intake per feeding station and a relatively low number of feeding stations visited per meal suggest that chicory was not grazed in distinct horizons. Together with high intake rates, the high and uniform quality of chicory canopies indicate that this species could be useful for livestock having high nutrient and dry matter intake requirements.

Endophyte‐Free Tall Fescue Cultivars Grazed by Sheep: Forage Quality and Sward Characteristics

AbstractAlthough much work has focused on the performance of endophyteinfected (E+), Acremonium coenophialum Morgan‐Jones and Gams, tall fescue, Festuca arundinacea Schreb.; little information is available comparing performance attributes of endophyte‐free (E−) cultivars in the northeastern USA. Five paddocks of four cultivars [‘Festorina’, ‘Johnstone’, ‘Roa’, and ‘Kentucky 31’ (KY 31)] of E− tall fescue were rotationally stocked with ewes (Ovis aries) for 2 yr. Tall fescue and weed dry matter (DM) mass, leaf‐to‐stem ratio, and tiller density were determined both pre‐and post‐grazing and sward height was measured pro‐grazing. Forage crude protein (CP), acid‐detergent fiber (ADF), neutral‐detergent fiber (NDF), and in vitro dry matter disappearance (IVDMD) were determined by near infrared reflectance spectroscopy (NIRS). Total dry mass was higher for Festorina and KY 31 than for the other cultivars. Leaf‐to‐stem ratios were similar among cultivars. Forage height was greatest for Festorina and least for Johnstone. Fescue proportion of herbage biomass was greater and weed biomass lower for Festorina and KY 31 than for Roa and Johnstone. Tall fescue proportion of herbage biomass at the end of the trial was lowest for Johnstone. Mean tiller densities were similar for all cultivars and ranged from 2060 m−2 in spring to 1260 m−2 under stockpiling in fall. Pre‐grazed herbage CP of 204 g kg−1 was similar among cultivars. Roa tended to be low and Festorina high in both ADF and NDF, and IVDMD of Johnstone was higher than Festorina. Across seasons and years, ewe liveweight gain was higher for Johnstone than for the remaining cultivars, which were similar. Gains for Group 2 (late‐weaned) lambs were lower for KY 31 and were similar for the remaining cultivars. In light of this information, cultivar as well as endophyte status should be considered in designing experiments or planning grazing systems with tall fescue.

Effect of Substrate Drying Method on in vitro Dry Matter Disappearance in Moose

One identified potential source of error in nutritional evaluations using the in vitro technique is the drying method used on test substrates. This study was conducted to determine what effect, if any, different drying methods have on the dry matter disappearance of 4 browse species in moose (Alces alces L.) inoculum. Browse species were Scots pine (Pinus sylvestris L.), birch (Betula pendula Roth, Betula pubescens Ehrh.), willow (Salix spp.), and sweetgale (Myrica gale L.). In addition, we determined the effects of drying method on neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL) concentration of the browse species. Each species was either freeze-dried (-40 degrees C) or oven-dried at 35 degrees, 60 degrees and 105 degrees C, respectively. High drying temperatures significantly depressed (P <0.0001) in vitro dry matter disappearance (IVDMD) in all browse species tested except of Scots pine. High temperatures also reduced NDF (P <0.05) in all the species, while ADF and ADL were elevated (P<0.05) in all species except Scots pine. We conclude that freeze-drying is the most preferable method to be used on forage and browse samples being evaluated for nutritional quality.

Storage Method Effects on Dry Matter and Quality Losses of Tall Fescue Round Bales

Outside storage with no protection from the weather contriutes to the frequent large storage losses for round-baled hay compared with small rectangular bales stored inside. We evaluated losses in dry matter (DM) yield and forage quality of round bales bound with solid or woven-mesh plastic instead of sisal twince. Round bales of tall fescue (Festuca arundinacea Schreb.) averaging 706 ± 19 lb and 18.2 ± 1.4% moisture were wrapped with two layers of plastic mesh or solid self-adhesive plastic wrap and placed on grass sod for storage. Twine-tied bales were stored on sod or indoors for comparison. Trials were conducted in 1990 and 1991, each with four replicates of each treatment. Dry matter losses and changes in crude protein (CP), neutral detergent fiber (NDF), and in vitro dry matter disappearance (IVDMD) were measured after 1 yr of storage. Weathering affected layers 0, 0.6, 2.1, and 4.4 in. deep for indoor, solid plastic, plastic mesh, and twine-tied bales stored outside, respectively. Storage DM losses of 18.2% for twine-tied bales stored outside were reduced to 10.6% by plastic mesh wrap but were lowest for solid-plastic-wrapped (3.6%) and inside-stored bales (5.7%). Weathered hay from twine and plastic mesh-wrapped bales fell approximately 20 percentage units in IVDMD during storage. Weathering and storage treatment effects on CP and NDF were small. Using solid plastic wrap or plastic mesh wrap as binding materials for bales stored outside saved DM and solid plastic wrap improved hay quality over twine-tied bales.

Effects of adaptation to lasalocid or monensin on in vitro fermentation of prairie hay

Effects of adaptation to lasalocid (L) or monensin (M) on in vitro fermentation of prairie hay were measured in a replicated in vitro experiment with a 3 × 3 factorial arrangement of treatments. Treatments were adaptation of ruminal fluid donor steers (ADAPT; no ionophore, 200 mg steer−1 d−1 of L, or 200 mg steer−1 d−1 of M) and culture ionophores (IONO; no ionophore, 4 μg mL−1 of L, or 4 μg mL−1 of M). At 12 and 96 h of incubation, in vitro dry matter disappearance (IVDMD) was increased (P &lt; 0.10 and P &lt; 0.05, respectively) by M-ADAPT compared with L-ADAPT, and IVDMD was increased (P &lt; 0.10) by ionophore adaptation treatments compared with control at 96 h of incubation. In contrast to effects of adaptation treatments, culture ionophore treatments decreased (P &lt; 0.01) IVDMD at 12 and 96 h compared with control; furthermore, at 12 h, M in culture decreased (P &lt; 0.05) IVDMD compared with L in culture. At 24, 48, and 72 h addition of both L and M in culture to unadapted inoculum decreased (P &lt; 0.10) IVDMD compared with control. Addition of M in culture decreased (P &lt; 0.10) the rate of IVDMD when added to unadapted and L-adapted inoculum compared with C and L in culture. Acetate was decreased (P &lt; 0.10), propionate increased (P &lt; 0.10), and the acetate:propionate ratio decreased (P &lt; 0.05) by ionophore adaptation compared with control at 24 h of incubation and by culture ionophore treatments compared with control at 48 h of incubation. Results indicate that effects of ionophores on in vitro fermentation of prairie hay depended on adaptation of the donor animals to the ionophores. In addition, monensin, when added to the culture, seemed to be more detrimental to in vitro fermentation of a low-quality forage than lasalocid. Key words: In vitro, fermentation, ionophores, monensin, lasalocid

Biodegradation of cell wall components of maize stover colonized by white‐rot fungi and resulting impact on in‐vitro digestibility

AbstractTreatment of crop residues with some species of white‐rot fungi can enhance digestibility. This study was conducted to investigate changes in in‐vitro dry matter disappearance (IVDMD) and degradation of cell wall constituents in maize (Zea maize L) stover treated with three white‐rot fungi: Cyathus stercoreus, Phlebia brevispora and Phanerochaete chrysosporium. Solid fermentation of maize stover for 28 days at 27°C improved IVDMD from 409 g kg−1 (control) to 514 g kg−1 for P brevispora and 523 g kg−1 for C stercoreus. In contrast, growth of P chrysosporium reduced IVDMD from 409 to 298 g kg−1. All fungi degraded cell wall p‐coumaric acid (PCA) and ferulic acid (FA), but P chrysosporium was the least effective in degrading PCA and FA. Conversely, P chrysosporium degraded lignin 1·6 times more effectively than C stercoreus and 1·4 times more than P brevispora, indicating that lignin degradation alone cannot account for the IVDMD enhancement and that degradation of PCA and FA may be important. Hemicelluloses were preferentially and highly utilized by all the fungi. Cellulose was extensively degraded only by P chrysosporium (69% lost after 28 days of incubation), while substrate colonized by the other two fungi retained more than 84% original cellulose. Incubation of C stercoreus and P brevispora decreased the concentrations of both xylose and arabinose, but increased glucose concentration, whereas P chrysosporium removed less xylose and decreased glucose concentration. Preferential removal of arabinose over xylose by the fungi caused an increase in the xylose to arabinose ratio of the treated residues. Enhanced digestibility may have resulted from cleavage of lignin‐carbohydrate bonds. Results of this study suggest that digestibility enhancement of maize stover colonized by white‐rot fungi is regulated by a complex combination of various factors, including the degradation of structural carbohydrates, cell wall phenolic acids and lignin.

Morphological and Climatological Predictors of Forage Quality in Tall Fescue

Forecasting quality losses of standing forage may aid producers when making harvest decisions. The objectives of this research were to compare morphological, climatological, and chronological models as predictors of forage quality in ‘Kentucky‐31’ and ‘All‐Triumph’ tall fescue (Festuca arundinacea Shreb.) receiving three N treatments; and test those models for their ability to predict forage quality. Pure stands of Kentucky‐31 and AU‐Triumph tall fescue were fertilized to meet University of Georgia (UGA) Cooperative Extension Service recommendations with all nutrients except N. Stands were divided into individual plots which received either 50, 100, or 200 kg N ha−1, and harvested weekly after initiation of spring growth. In 1990 and 1991, tillers were counted, staged for morphological development, and weighed. Samples were ground, scanned with a near infrared reflectance spectrophotometer (NIRS), and a subset was analyzed chemically to develop calibrations for forage quality. Near infrared spectrophotometric quality values were regressed with mean stage count, mean stage weight, growing degree days (MSC, MSW, and GDD, respectively) and calendar day, and regression equations were validated with samples harvested from plots in 1992 and 1993. The MSC and MSW equations had poor fit in AU‐Triumph (range of R2 from 0.28–0.35 and 0.58–0.61, respectively) and were not validated. Calendar day and GDD had predicted quality better (range of R2 from 0.76–0.90 and 0.74–0.87, respectively); validation statistics of those equations had intercepts equal to 0.0 and linear coefficients equal to 1.0 for in vitro dry matter disappearance (IVDMD) and occasionally for crude protein (CP), but not for neutral (NDF) or acid (ADF) detergent fiber.

Cell wall composition and degradability of stem tissue from lucerne divergently selected for lignin and in vitro dry‐matter disappearance

AbstractLucerne populations that had previously been divergently selected for acid detergent lignin (ADL) concentrations of whole herbage were additionally divergently selected for in vitro dry‐matter disappearance (IVDMD) of basal stems. Parental plants of the four selected populations were intercrossed and the half‐sib progeny evaluated in a replicated field trial in 1988 over two harvests. Cell wall composition of basal stems was determined for detergent fibre components and neutral sugars, uronic acids, Klason lignin and esterified and etherified phenolic acids of the total fibre fraction. Lignin polymer composition was measured by nitrobenzene oxidation. Degradability of cell wall polysaccharide components was determined by a 48‐h in vitro ruminal fermentation. Cell wall composition was changed by both selection criteria. Klason lignin proportion of the total fibre did not differ as a result of selection, whereas the ADL concentration of neutral detergent fibre was different among selection groups. The cell wall polysaccharides of lucerne basal stems shifted towards more cellulose (glucose residues) and less hemicellulose (xylose residues) with selection for either low ADL or high IVDMD. While degradability of the cell wall polysaccharides was correlated with various measures of lignin composition and concentration, the results were variable and inconclusive. Surprisingly, Kiason lignin and ADL were positively correlated with cell wall polysaccharide degradability, and esterified ferulic acid was negatively correlated with degradation of the cell wall. Selection for herbage ADL and basal stem IVDMD of lucerne did alter cell wall degradation, but the associated changes in cell wall lignification were not consistently correlated with cell wall degradability.

Big Bluestem Production and Forage Quality Responses to Burning Date and Fertilizer in Tallgrass Prairies

Tallgrass prairies are an important source of hay and summer forage in the Great Plains. A study was conducted in 1989 and 1990 on two excellent condition tallgrass prairies in eastern Nebraska to determine if the production and forage quality of big bluestem (Andropogon gerardii var gerardii Vitman), the dominant warm-season grass, could be manipulated by burning on different dates in the spring and applying fertilizer. Vegetation was harvested at approximately 30-d intervals from mid-June to mid-August. Big bluestem was separated from the vegetation, weighed, analyzed for in vitro dry matter disappearance (IVDMD), crude protein concentration (CP), and neutral detergent fiber concentration (NDF). Early or mid-spring burning increased June forage production by at least 52%, and mid-or late-spring burning increased August forage production by at least 70% compared with no burning. In June 1989 and 1990, big bluestem IVDMD was greatest on areas burned in late spring. Late-spring burning increased CP in June by at least 15% when compared with all other burn treatments, and increased CP in July by 8% compared with early spring burning. Fertilization increased CP in June by 22% and in July by 23% and 17% in 1989 and 1990, respectively, when compared with nonfertilized big bluestem. Burning in early, mid-, or late spring 1989 decreased NDF in June and August when compared with no burning. The quantity and quality of big bluestem forage available during the summer can be improved by spring burning and fertilization. Research Question Durum wheat is a major crop in North Dakota. Farmers plant durum seed derived from widely varied sources. The primary objective of this study was to accumulate samples from farmers' drills to compare the quality of seed being planted and evaluate the field performance. Literature Summary Numerous studies have related the effect of seed viability and seed vigor to field performance. Seed size or test weight is another component of seed quality that has been studied extensively. Generally large seed with good viability has the best performance. Surveys have been conducted in several states to evaluate the quality of seed being planted. Frequently, these surveys have been used to bring attention to a continuing need for improved purity of seed being sold in commercial channels. No studies, however, have been published to associate the impact of seed quality on economic potential for durum wheat. Study Description Durum seed sources used by farmers were sampled at planting time in eight North Dakota counties during 1987 and 1988. Accumulated samples were analyzed for germination percentage and purity variables in the lab. Replicated field trials were conducted at two locations in the year following sampling to determine emergence, grain yield, and test weight performance. Applied Questions What is the quality of durum seed currently being planted? Overall quality of the seed samples from 274 drills was extremely variable. Germination tests averaged 84.5%, which is below the minimum standard for certified seed. Mean values for purity were excessive for other crops and weed seeds exceeded the maximum level for certified seed, but did not differ significantly from certified seed samples. Field emergence ranged from 26 to 100%. Stand had a significant effect on grain yield, particularly when the environment favored high yield potential (Fig. 1). How does certified seed compare with noncertified in yield performance? The survey indicated that 13.2% of the durum acreage was planted with certified seed. Grain yield from certified seed averaged 7.1070 higher than from noncertified seed. These data indicate the statewide average durum yield and economic return could be increased simply through the exclusive use of seed equivalent to certified seed. Cost inputs associated with additional weed control and possible reduced crop value due to seed impurity would add to the economic value of high quality seed. Figure 1Open in figure viewerPowerPoint Effect of plant stand on durum grain yield averaged over two locations.

Near Infrared Reflectance Spectroscopy Prediction of Quality from Masticated Temperate Forage Species

Masticated forage provides information related to the quality and fractionation characteristics of a ruminant's diet. This study reports the use of near infrared reflectance spectroscopy (NIRS) to predict the in vitro dry matter disappearance (IVDMD), in vitro organic matter disappearance (IVOMD), and ceil‐wall concentrations of particle size fractions and the whole masticate of temperate forages. Esophageal extrusa samples, with saliva retained, were obtained from fistulated steers (Bos taurus) that were intermittently grazing tall fescue (Festuca arundinacea Schreb.), orchardgrass (Dactylis glomerata L.), and ryegrass (Lolium perenne L.). Grazing was initiated at canopy heights of 100, 200, and 300 mm during spring and fall of two consecutive years. Samples were collected at the start of grazing at each canopy height and after defoliation to a 50‐ram residue. Masticates, quickfrozen in liquid N2, were subsequently lyophilized and dry sieved into seven particle size fractions and, along with a whole‐masticate subsample, were scanned for NIRS analyses. A single broad‐based calibration encompassing all experimental factors predicted quality constituents within acceptable limits of precision for this methodology. Standard errors of cross‐validation (SECV) were 6 g kg−1 for organic matter, 16.0 g kg−1 for IVDMD, 16.2 g kg−1 for IVOMD, 14.8 g kg−1 for neutral‐detergent fiber (NDF), and 14.3 g kg−1 for ash corrected NDF. Separate calibrations for each species × sample time combination resulted in little reduction in SECV. Sample numbers used in calibration could be reduced to = 7% of total samples with SECV of 16.3 g kg,−1 for IVDMD. Masticate quality constituents of temperate species were satisfactorily predicted by NIRS when obtained from a wide range of seasonal and plant variation.

Hybrid Quality and Yield Differences for Corn Silage in Pennsylvania

Differences among corn (Zea mays L.) hybrids for forage quality traits have been reported, but the stability of forage quality differences over diverse environments is not well documented. To evaluate hybrid stability for yield and forage quality, nine commercial hybrids were evaluated at two locations in Pennsylvania in 1990 and one location in 1991. All hybrids were harvested on the same day at the 2/3 milk line to black layer stage, depending on the hybrid. Whole plant and stover sub-samples were collected from each plot, chopped, dried, and ground for analysis. Forage analysis for crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), and in vitro dry matter disappearance (IVDMD) was performed using near infrared reflectance spectroscopy (NIRS) on both whole plant and stover samples [...]

Relationships between lignin content and fermentability of intact and chemically treated big bluestem fiber (1994)

An accurate assessment of forage quality is required to allow prediction of animal performance. One of the most commonly used methods of forage evaluation is to measure lignin content, with more heavily lignified materials being considered less digestible. Two measures of lignin, acid detergent lignin (ADL) and acetyl bromide lignin (ABL), were assessed with regard to their ability to predict forage digestibility. Big bluestem forage samples were collected from three ungrazed, annually burned pastures at 38, 58, and 97 days postburn. These times were selected to represent a broad range of forage quality. Cell wall material was treated chemically by: 1) partial delignification (chlorite), 2) isolation o f "- cellulose, or 3) NaOH extraction. Control and treated cell-w all material was analyzed for ABL and ADL and 24 and 72 hr in vitro dry matter disappearance (IVDMD). ABL increased with advancing maturity for intact fibers, whereas ADL was highest in the most mature forage but lowest for the intermediate maturity. Fermentability of the intact fiber decreased with maturity and was correlated highly to ABL content. ABL was a better indicator of forage degradability for intact bluestem fiber than was ADL, but neither ABL nor ADL was adequate for evaluating fermentability of treated residues.