Field Wilting Research Articles

Co-ensiling and field wilting investigated as preparation methods for the ensiling of a wet harvested catch crop for biomethane production

Early harvested cover crops usually present a high moisture content that makes them difficult to store by ensiling because of effluent production and undesirable butyric fermentation. In order to increase the solid content of ryegrass, field wilting (29.0 %TS) and co-ensiling with wheat straw (27.4% TS) were performed and compared with a direct storage of the crop (18.4% TS). The storage experiments were conducted at lab scale and monitored during 180 days to evaluate the fermentation pathways and changes in microbial community structure and methane potential. The addition of straw did not change the fermentation pathway during the ryegrass silage, while field wilting slowed down and decreased the occurrence of secondary fermentations. Despite the presence of secondary fermentations and VS losses up to 11%, the methane potential was efficiently preserved in all conditions. Wheat straw addition should be considered as an alternative to field wilting when unfavorable weather conditions are met.

Co-Ensiling and Field Wilting Investigated as Preparation Methods for the Ensiling of a Wet Harvested Catch Crop for Biomethane Production

Co-Ensiling and Field Wilting Investigated as Preparation Methods for the Ensiling of a Wet Harvested Catch Crop for Biomethane Production

Nonstructural Carbohydrate Concentration during Field Wilting of PM‐ and AM‐Cut Alfalfa

Alfalfa (Medicago sativa L.) cut in the late afternoon has a greater nonstructural carbohydrate (NSC) concentration than AM‐cut alfalfa but this difference might not be maintained during wilting. We monitored NSC concentration of PM‐ and AM‐cut alfalfa during wilting in narrow and wide swaths. Field‐grown alfalfa was cut either at 1800 h (PM) on days without rain (Day 0) or at 0800 h (AM) the following morning (Day 1) in seven growth cycles over 3 yr. Samples taken during wilting were analyzed for NSC (soluble carbohydrates + starch). At cutting, PM‐cut alfalfa had consistently greater NSC concentration [+6 to 54 g kg−1 of dry matter (DM)] than AM‐cut alfalfa. The NSC concentration decreased during wilting at rates that depended on growth cycles (0.2–3.5 g kg−1 DM h−1 on Day 1) but this decline was similar for AM‐ and PM‐cut alfalfa. When cut alfalfa reached 350 g DM kg−1 fresh matter (FM) on Day 1, NSC concentration was greater for PM‐ than for AM‐cut alfalfa (average of 15 with a range of 4–37 g kg−1 DM) and greater for the wide than narrow swaths (average of 7 with a range of 1–11 g kg−1 DM). Photosynthesis continued for 3 h on the morning of AM cutting for both PM‐ and AM‐cut alfalfa until DM concentration reached approximately 350 g DM kg−1 FM. The combination of late PM‐cutting and wilting in wide swaths can be used to increase the NSC concentration of wilted alfalfa.

Stability of fatty acids during wilting of perennial ryegrass (Lolium perenne L.): effect of bruising and environmental conditions

Oxidation of fatty acids (FA) during field wilting of herbage could cause extensive losses of polyunsaturated FA. Recent studies showed a variable effect of wilting on the losses of FA. This suggests that environment and management conditions influence the loss of FA during wilting. The present study investigated the stability of FA in untreated and mechanically bruised perennial ryegrass, wilted under field conditions for 0, 12, 24, 36 and 48 h, or wilted under controlled climate conditions at three temperatures (15, 25 or 35 °C) and two light (dark or light) regimes to dry matter (DM) contents of 425, 525 or 625 g kg(-1). During 48 h of field wilting, the total FA content declined (15.2 to 11.9 g kg(-1) DM) consistently, despite an increase in herbage DM content (197 to 676 g kg(-1)). Under controlled climate conditions, the herbage total FA content declined (15.1 to 11.7 g kg(-1) DM) mainly during the prolonged (56 to 62 h) initial drying to a DM content of 425 g kg(-1) and did not decline with further drying to DM contents of 525 and 625 g kg(-1). The decline in total FA was associated with a parallel decline in C18:3 content under field (9.15 to 6.36 g kg(-1) DM) and controlled (9.12 to 6.15 g kg(-1) DM) conditions. Concomitantly, the proportion of C18:3 in total FA decreased, whilst the proportion of C16:0 and C18:0 increased. Lower losses of FA (P<0.05) were observed at 15 °C compared to 25 and 35 °C. Light did not affect the losses of FA during wilting. The duration of the wilting period mainly affected the changes in FA content and composition. Stability of FA in herbage could be increased by minimising the duration of wilting.

수확시기, 예건 및 싸라기 처리가 유기 청보리의 사초 생산성 및 사일리지 품질에 미치는 영향

최근에 청보리 사일리지는 국내에서 가장 많이 이용하는 조사료이지만 유기축산을 위한 유기조사료의 생산과 품질에 관한 연구는 미흡한 실정이다. 따라서 본 시험은 유기 청보리 사일리지의 적정 수확시기를 구명하고, 사일리지 품질 향상을 위하여 예건과 싸라기를 첨가하여 사일리지를 평가하였다. 시험구 배치는 12처리 3반복의 분할구 배치법으로 주구는 수확시기로 출수기, 유숙기 및 황숙기를 두었으며, 세구는 무처리, 예건, 싸라기 10%, 싸라기 15%를 두었다. 수확시 건물함량은 출수기, 유숙기 및 황숙기가 각각 12.8%, 21.9% 및 29.8%로 증가하였다. 청보리의 건물수량은 출수기, 유숙기 및 황숙기가 각각 10,346, 15,819 및 18,336 kg/ha였으며, TDN 수량은 6,288, 9,550 및 10,178 kg/ha였다. 유기 사일리지의 pH는 출수기, 유숙기 및 황숙기가 각각 4.70, 4.03 및 5.37로 유숙기가 가장 낮았다. 청보리의 수확시기가 늦어짐에 따라 조단백질, 조지방, NFC 및 TDN 함량은 감소하였으나, NDF 및 ADF 함량은 증가하였다. 그러나 조회분 함량은 유숙기가 가장 낮았다. 사일리지의 예건과 싸라기의 첨가는 조회분, NDF 및 ADF 함량을 감소시키고, NFC와 TDN 함량은 증가시켰다. 사일리지의 건물소화율은 수확시기가 늦어짐에 따라 감소하였으며, 예건과 싸라기 첨가에 의하여 건물소화율이 증가하였다. 유숙기가 다른 수확시기보다 젖산과 총유기산 함량은 높고 낙산 함량이 낮아 총유기산 중 젖산함량이 가장 높았다. 예건과 싸라기 첨가에 의한 젖산 함량 증가 효과는 출수기가 다른 수확기보다 효과가 있었다. 이상의 결과를 종합해 볼 때 유기 청보리 사일리지 제조를 위한 수확적기는 유숙기 이었으며, 예건과 싸라기 첨가에 의하여 청보리 사일리지의 품질을 향상시킬 수 있었다. Although whole crop barley (Hordeum vulgare L.) is now widely grown as a silage crop in Korea, forage production and silage quality of that for organic farm have not been published. Therefore, this experiment was conducted to evaluate the effect of harvest stage on forage production and quality of organic barley, and effect of field wilting and crushed rice for shortening of harvest date and improvement of forage quality. The experiment was split-plot design with three replications. Main plots were heading, milking and yellow stages, and sub-plot were field wilting for I day, crushed rice 10% (CR10%) and 15% (CR15%) treatments. The dry matter (DM) contents of heading, milking and yellow stages were 12.8%, 21.9% and 29.8%, respectively. The DM yields of heading, milking and yellow stages were 10,346, 15,819 and 18,336 kg/ha, respectively, and the total digestible nutrients (TDN) of these were 6,288, 9,550 and 10,178 kg/ha, respectively. The pH of milking stage showed low 4.00 pH values. The crude protein, ether extract, crude ash, non-fiber carbohydrate (NFC) and TDN contents were decreased as harvest stage progressed, while neutral detergent fiber (NDF) and acid detergent fiber (ADF) were increased. The crude ash (CA) of milking stage showed the lowest among harvest stages. Field wilting and crushed rice treatments decreased CA, NDF and ADF contents, and increased NFC and TDN contents. In vitro dry matter digestibility (IVDMD) decreased with progressed harvest stage, while field wilting and crushed rice treatments increased that of barley silage. Lactic acid and total organic acid contents of milking stage were the highest, and butyric acid of milking stage was the lowest among harvest stage. The good effect of field wilting and crushed rice was observed in heading stage. The experiment results indicate that optimum harvest stage of barley silage for organic was milking stage. The field wilting and crushed rice additive could be recommended as effective method for shortening harvest date and increasing forage quality of organic barley silage

Effect of the stage of growth, wilting and inoculation in field pea (Pisum sativum L.) silages, III. Changes in the herbage and silage protein profiles

AbstractBACKGROUND: The effects of stage of growth, field wilting and inoculation with lactic acid bacteria (LAB) on the protein profile of herbage and silage were studied on field peas (Pisum sativum L.) harvested at four progressive morphological stages (end of flowering, I; beginning of pod filling, II; advanced pod filling, III; beginning of ripening, IV). The herbage was field wilted to a dry matter (DM) content around 330 g kg−1, for each stage of growth. The unwilted and wilted herbages were ensiled with (I) and without (C) a LAB inoculant.RESULTS: As a result of the advancing maturity of the crop, the main protein component was Rubisco in the early stages and seed storage proteins in the more advanced stages, due to the redistribution of organic nitrogen during seed filling. Extensive degradation of Rubisco occurred in all the silages, without any effect of inoculation or wilting. A good preservation of the proteins was observed in stage IV for both unwilted and wilted silages, without further protein preservation due to LAB inoculation.CONCLUSION: Protein protection observed in the more mature pea silage was due to the protein type and its localization and not to the level of DM at ensiling or to the inoculation. Copyright © 2007 Society of Chemical Industry

Taxa de desidratação e composição químico-bromatológica do feno de grama-estrela (Cynodon nlemfuensis Vanderyst) em função de níveis de adubação nitrogenada

The objective of this study was to determine the dehydratation rate of after-harvest forage in the field conditions and to evaluate the chemical composition as a function of nitrogen fertilization. It was used two fertilization levels (50 and 100 kg/N/ha) and forage was harvest with 28 days growth. During field wilting, one sample at harvest time and seven others after it were collected to determine the dehydratation rate of the whole plant and the leaf and stem fractions. A completely randomized experimental design with ten replications was used, and the chemical composition data were compared by F Test (5%). The water loss rate was higher for leaf when compared to stem fraction, showing the same pattern for both fertilization levels. In chemical composition evaluations, crude protein (CP) was different (P0.05). In vitro dry matter digestibility (INDMD) and in vitro crude protein digestibility (INCPD) were not affected (P>0.05) by the levels of nitrogen fertilization. Nitrogen fertilization increased the CP concentration in Stargrass hay, but did not affect the fiber fraction, not increasing the nutritional quality of hay.

Effect of the stage of growth, wilting and inoculation in field pea (Pisum sativum L.) silages. I. Herbage composition and silage fermentation

AbstractThe stage of growth, field wilting and inoculation with lactic acid bacteria (LAB) effects were studied by ensiling herbage of field pea (Pisum sativum L.) at four consecutive stages. Stands of semi‐leafless field pea, sown in spring, were harvested at four progressive morphological stages (end of flowering, I; beginning of pod filling, II; advanced pod filling, III; beginning of ripening, IV). For each stage of growth, the herbage was field wilted to a dry matter (DM) content of 318, 300, 348 and 360 g kg−1 for stages I, II, III and IV, respectively. The unwilted and wilted herbages were ensiled in 5‐L silos, with (I) and without (C) a LAB inoculant (Lactobacillus plantarum). High levels of ethanol, lactic acid and volatile fatty acids (VFA) were observed in all silages, facilitated by the high levels of water‐soluble carbohydrates (WSC) at ensiling (from 111 to 198 g kg−1 DM). Despite the low pH values (4.3 and 4.1 for C and I silages, respectively), all the silages showed detectable levels of butyric acid. Field peas can be successfully ensiled after a short wilting period with reduced field curing and reduce DM losses onward from advanced pod filling stage, with the aid of LAB inoculum. Copyright © 2006 Society of Chemical Industry

Forage breeding and management to increase the beneficial fatty acid content of ruminant products.

The declining consumption of ruminant products has been partly associated with their high proportion (but not necessarily content) of saturated fatty acids. Recent studies have focused on the less prominent fact that they are also important sources of beneficial fatty acids, including n-3 fatty acids and conjugated linoleic acids. alpha-Linolenic acid (18 : 3n-3) is of particular interest because it also contributes to improved flavour of beef and lamb. Many recent studies showed large effects of special concentrates on levels of fatty acids in milk and meat. However, the 'rumen protection' treatments, needed to ensure a worthwhile level of fatty acid in products, are expensive. Herbage lipids are the cheapest and safest source of these fatty acids and so breeding to increase delivery of fatty acids from plants into ruminant products is an important long-term strategy. Plant lipids usually contain high levels of polyunsaturated fatty acids, particularly 18 : 2n-6 and 18 : 3n-3 which are the precursors of beneficial fatty acids. Whilst some plants are particularly rich in individual fatty acids (e.g. 18 : 3n-3 in linseed), there are also useful levels in grass and clover (Trifolium Spp.). Levels of fatty acids in forages in relation to species and varieties are considered, as well as management and conservation methods. Relationships between levels of fatty acids and existing traits and genetic markers are identified. The effects of forage treatments on the fatty acid content of ruminant products are reviewed. The higher levels of polyunsaturated fatty acids in milk from cows fed clover silages show that the level of fatty acids in herbage is not the only factor affecting levels of fatty acids in ruminant products. Further effort is needed to characterise susceptibility of unsaturated fatty acids to oxidative loss during field wilting and biohydrogenation losses in the rumen, and the relative importance of plant and microbial processes in these losses. The pathways of lipolysis and lipid oxidation are reviewed and other plant factors which offer potential to breed for reduced losses are considered.

Effect of intensity of maceration on digestibility and intake of alfalfa hay and silage fed to sheep

A study was conducted to determine the influence of intensity of mechanical conditioning on the nutritive value of alfalfa conserved as hay or silage. Fresh alfalfa was mowed and conditioned at three levels of maceration prior to field wilting during 45 h for silage (29–39% DM) or 94 h for hay (87% DM, after barn-curing), under light rain conditions during the first 2 d. The conditioning treatments were: control (conventional mowing-conditioning), light maceration (one passage through three knurled steel rolls), medium maceration (two passages), and intense maceration (three passages). Concentrations of NDF, ADF, hemicellulose, CP-NDF, and CP-ADF increased linearly (P &lt; 0.001) with the level of maceration. Silage pH, acetic acid, propionic acid, and butyric acid increased, while lactic acid decreased (P &lt; 0.001), with the level of maceration. The effective rumen degradabilities of DM, CP, and NDF, measured with fistulated cows, were not affected (P &gt; 0.10) by the level of mechanical conditioning. Forty-eight male sheep (46.8 ± 6.7 kg BW) were fed a 100% forage diet according to a completely randomized design with a 2 × 4 factorial arrangement of treatments (two storage methods and four levels of conditioning). Under restricted feeding, DM, NDF, ADF, and hemicellulose digestibilities decreased linearly (P &lt; 0.001) with the level of maceration. However, the digestibility of CP-NDF increased with the level of maceration; the effect was more important in hay than in silage (P &lt; 0.001 for the interaction). When silages were fed ad libitum to 24 sheep, daily DMI was 2.31, 2.88, 2.76, and 2.41% of BW and DM digestibility was 60.8, 60.1, 56.2, and 46.7%, for control, light, medium, and intense maceration, respectively (P &lt; 0.01). The results suggest that light maceration increases DM intake while maintaining digestibility of forages fed to sheep. Because of humid conditions and potential soil contamination due to multiple windrow pickup, intense maceration caused severe nutrient loss, which might be avoided under dry field wilting and good storage conditions. Key words: Alfalfa, hay, silage, digestion, degradability, intake

Ruminal degradability of alfalfa and corn after processing or maceration

The effects of mechanical treatment on ruminal degradability of alfalfa and corn were determined in three experiments using nylon bags incubated in the rumen of two fistulated dry cows. The first experiment was a 2 × 2 × 2 factorial design applied to chopped alfalfa at two levels of mechanical treatment (processing with two corrugated rolls in a forage harvester or no processing), two throughput rates (medium or high) and two moisture contents (after a 4-h or a 24-h field wilting period prior to processing). The second experiment was a 2 × 2 factorial design applied to chopped corn at two levels of mechanical treatment (processed or not) and two throughput rates (medium or high). In these two experiments, forages were immediately frozen (not fermented) for later degradability measurements. In the third experiment, alfalfa was mowed either with a conventional mower-windrower or an experimental mower-macerator with three corrugated rolls. After 40 h of field wilting, alfalfa was dehydrated and processed into pellets. In the first experiment (chopped and frozen alfalfa), throughput, processing and wilting period had no effect (P &gt; 0.05) on the effective degradability of DM, CP, NDF and ADF. In the second experiment, DM degradability of chopped corn decreased with an increased throughput (46.4% vs. 43.7%) but increased with processing (43.9% vs. 46.2%). Processing also increased CP degradability of corn. In the third experiment, maceration with subsequent field wilting during 40 h and dehydration produced alfalfa pellets with a higher degradability of DM (56.0% vs. 50.4%) and of NDF (27.1% vs. 17.3%) than pellets from non-macerated alfalfa. These results suggest that the increase in ruminal degradability is greater with alfalfa macerated and wilted in the field (exp. 3) than with alfalfa frozen immediately after harvesting and processing (exp. 1). Maceration probably reduced the loss of nutrients by decreasing field respiration. Processing of corn may have increased the ruminal degradability because of increased kernel breakage that facilitated starch digestion. Key words: Maceration, crop processing, ruminal degradability, alfalfa, corn

Effect of swath treatment and duration of field wilting of grass on chemical composition and feeding value of silage in sheep

The wilting of grass prior to ensiling is an effective method of reducing the moisture content of the grass and improving the fermentation quality of the silage (Wilkinson et al., 1996). The effects of wilting grass on voluntary intake, digestibility and animal performance are variable, potentially reflecting the losses of nutrients from the crop during the wilting period. Three methods of swath treatment to accelerate the loss of water from the mown crop are currently used in northern Europe, wilting in the swath, spreading the crop to 1.0 of ground area and tedding swaths. The aim of the experiment reported here was to investigate the effect of swath treatment and duration of field wilting on the voluntary intake and digestibility of wilted silage offered to lambs.

Relationships Among Absorbents on the Reduction of Grass Silage Effluent and Silage Quality

Effluent from grass silage is a threat to water quality and a loss of valuable forage nutrients from dairy farms. Absorbents potentially reduce effluent loss when weather conditions are not ideal for field wilting. The objective was to determine the effectiveness of various absorbents at reducing silage effluent. First-harvest, direct-cut, perennial grass forage was ensiled with and without absorbents in medium-sized experimental silos for 3 consecutive yr. Silos contained 4.54kg of grass and one of the following feed quality absorbents: 10% rolled barley, 10% dried and pelleted beet pulp, or alfalfa cubes at 10, 20, or 30%. Nonfeed quality absorbents used were 1% starch grafter polymer, 1% bentonite clay, and 10% newspaper. Silage from direct-harvest control forage produced the highest effluent losses, but the wilting of grass prior to ensiling or the mixing of grass with 30% alfalfa cubes nearly eliminated effluent. Silage pH was lowest when rolled barley or beet pulp was used as the absorbent and was highest for wilted grass. Silage dry matter was increased by wilting and by the use of barley, beet pulp, newspapers, or alfalfa cubes as absorbents. The addition of 10% newspaper greatly reduced in vitro dry matter digestibility and crude protein. Increased water-soluble carbohydrate concentrations were found for silage from grass forage treated with rolled barley, beet pulp, or alfalfa cubes prior to ensiling. Although bentonite clay and newspapers reduced effluent losses, greater water-soluble carbohydrate losses were found for these treatments compared with the direct control. Alfalfa cubes were found to be effective absorbents and did not reduce grass silage quality.

Screening methodology for post-harvest fungal resistance in alfalfa

Forage deterioration due to field and storage fungi represents a major economic loss for hay producers. A series of experiments was conducted to develop a methodology for screening alfalfa plants for resistance to post-harvest fungal colonization. Pure cultures of Aspergillus glaucus, Aspergillus repens, Aspergillus flavus, Aspergillus versicolor and Aspergillus fumigatus, isolated from alfalfa forage sampled during field wilting and storage, were established and maintained to produce a 105 spore mL−1 suspension containing an equal proportion of spores from each Aspergillus spp. Alfalfa leaves were dipped in concentrations of propionic acid solution to simulate levels of resistance to fungal activity. Fully-developed trifoliate leaves were placed adaxial side down onto petri plates containing a dichloran (2 mg mL−1) and glycerol (18% vol/vol) agar. The Aspergillus spp. spore suspension was sprayed onto each petri plate and the plates were incubated under dark conditions at 25 °C and 70% relative humidity. Plates were monitored daily for percent of leaf area colonized. The random screening of a small population of cloned alfalfa genotypes using this screening procedure indicated that variation in post-harvest resistance to fungal attack does exist for greenhouse and field-grown plants harvested at an early vegetative stage. Leaf dry matter was not related to genotype variation in post-harvest susceptibility to fungal colonization; however, leaf soluble carbohydrate level was negatively correlated (P &lt; 0.05) with leaf area colonized. The screening procedure did not detect consistent differences among genotypes when dried leaves were used. Key words: Alfalfa, genotype, post-harvest fungi, Aspergillus spp., resistance, screening

SIMULATING THE EFFECT OF CONDITIONING ON THE DRYING OF CUT GRASS

Field wilting and drying of hay is an important agricultural process upon which the quality of material subsequently conserved is dependent. The research described here aims at translating the biophysical processes that affect field drying of grass into parameters sets to be used for decision support systems that would aid effective management of field wilting for silage making. A mechanistic model of field drying of grass was implemented, largely based on Thompson's (1981) multi-layer canopy representation. Given the meteorological conditions at a 10 minutes interval, an iterative algorithm calculates the profile of evaporation within a drying swath. The time course of moisture content is calculated by integration. The model is shown to reproduce in detail changes of swath moisture content, including dew interception at night time. Three input parameters (i.e. swath resistance per unit tissue moisture content, minimum initial resistance and water content at stomatal closure) were adapted in order to simulate different conditioning treatments. Model predictions and measurements on reference plots were compared with experimental drying rates of perennial rye-grass (Lolium perenne), either lightly or heavily conditioned. The results make clear that coupling grass handling procedures to parameters of a mechanistic model of the drying process can provide tools for use in optimising such procedures.

Efficacy of Pediococcus pentosaceus for alfalfa forage exposed to precipitation during field wilting

The objective of the current study was to determine the preservation potential for an inoculant containing two strains of Pediococcus pentosaceus for forage that had been exposed to precipitation during the wilting phase. Forage was exposed to 26.4 mm precipitation and moderate drying conditions prior to being baled at 20–25% moisture without (Wet) or with Pediococcus pentosaceus (Wet-PP) application at the time of baling. A third hay treatment consisted of forage exposed to 27.6 mm precipitation and baled at 15–20% moisture without inoculant application (Dry). Contrary to results from previous studies with good drying conditions, application of Pediococcus pentosaceus at a rate of 105 cfu g−1 forage did not reduce extent of fungal invasion during storage as determined by storage temperature, glucosamine change, post-storage visual scores and fungal populations. Two wilting trials were conducted to determine the effect of exposure to precipitation during the wilting phase on the indigenous microbial population on the surface of forage material. Forage that was not exposed to precipitation during drying had total bacteria, lactic acid bacteria and total fungal populations ranging from 105 to 106, from 101 to 103, and from 104 cfu g−1 forage DM, respectively, at the time of baling. Exposure to precipitation resulted in population ranges of 107–108, 103–105, and 104–105 cfu g−1 forage DM, respectively. Total bacterial populations increased significantly due to exposure to precipitation. Utilization of a bacterial inoculant at 105 cfu g−1 forage may not be an adequate application rate when the density of the indigenous population on the forage surface is 100–1000 times greater. Key words:Pediococcus pentosaceus, hay, storage, mold, bacteria

Quality of Whole Crop and Pressed Forage from Mechanically Dewatered Alfalfa, Red Clover, and Birdsfoot Trefoil

AbstractForage harvesting techniques that reduce losses in yield and quality that normally occur during field wilting of silage and curing of hay are needed. A 2‐yr field study was conducted to evaluate mechanical dewatering of first‐cutting forage of alfalfa (Medicago sativa L.), red clover (Trifolium pratense L.), and birdsfoot trefoil (Lotus corniculatus L.) harvested at four stages of maturity. Each species, grown on Plano silt loam soil (fine‐silty, mixed, mesic Typic Argiudolls), was harvested at weekly intervals beginning on 27 May 1980 and 26 May 1981, and the forage was macerated and pressed at 6.9 × 105 Pa for 2 min. Samples of the whole crop collected immediately after cutting and of the pressed forage were dried at 55°C to constant weight. Birdsfoot trefoil was the highest in N concentration of the three whole crops, and red clover was higher in N than alfalfa in 1 of the 2 yr. Pressed forage of alfalfa averaged 6.0 g kg−1 less N than the whole crop. Pressed forage averaged 106, 151, and 49 g kg−1 more neutral detergent fiber (NDF) than whole crop for alfalfa, red clover, and birdsfoot trefoil, respectively. Birdsfoot trefoil in vitro dry matter disappearance (IVDMD) was affected least by Pressing, and red clover IVDMD was affected most. Results of this 2‐yr experiment indicate that mechanical dewatering reduced IVDMD and generally N, and increased NDF concentration. Differences in legume species response to pressing were substantial and would preclude generalization of mechanical dewatering responses across species. However, whole crop dry matter, N, and IVDMD predicted 0.81 or more of the variation in pressed forage IVDMD of the three species, indicating that pressed forage IVDMD can be accurately predicted from whole crop composition.

Concentrations of Glucosinolates and S-Methylcysteine Sulfoxide in Ensiled Rape (Brassica napus L.)

Cruciferous forages (Brassica sp.) contain glucosinolates and S-methylcysteine sulfoxide, compounds that are potentially toxic to livestock, but there is little information concerning the possible effects of ensiling on these constituents. This study compared concentrations of glucosinolates and S-methylcysteine sulfoxide in rape (Brassica napus L.) forage before and postensiling after 0, 4, or 25h of field wilting. Field-grown rape was harvested 100 d after planting and immediately ensiled in laboratory scale silos or wilted for 4 or 25h prior to ensiling. After 30 d, silages were frozen and stored at −20°C. Unensiled samples also were frozen at −20°C for an estimate of glucosinolates and S-methylcysteine sulfoxide in fresh forage. In addition to analysis for glucosinolates and S-methylcysteine sulfoxide, determinations were made of DM concentration in fresh and ensiled material and pH of the silage. Ensiling reduced glucosinolate concentration from approximately .3 to .03% of DM and wilting had little additional effect. Ensiling slightly but significantly reduced S-methylcysteine sulfoxide; wilting had no significant additional effect. Results of this study indicate that ensiling can effectively reduce the potential toxicity of rape forage.

Composition of Leaf Protein Concentrate and Deproteinized Juice from Alfalfa, Red Clover, and Birdsfoot Trefoil1

AbstractLosses during field wilting of silage and curing of hay reduce both yield and quality. Direct harvest and mechanical dewatering avoid these losses and produce a protein concentrate. A 2‐year field experiment was conducted to evaluate legume species and harvest date effects on the yield and composition of the protein concentrate and deproteinized juice fractions from spring growth legume herbage. The soil was a Plano silt loam (fine‐silty, mixed, mesic Typic Argiudoll). Alfalfa (Medicago sativa L.) protein concentrate averaged 201 g dry matter (DM) kg−1 total mass, slightly higher than red clover (Trifolium pratense L.) and birdsfoot trefoil (Lotus corniculatus L.). Harvest date effects on DM concentration in both the protein concentrate and the deproteinized juice were significant but showed little relationship to shoot maturation stage. Alfalfa protein concentrate averaged 102 g N kg−1 DM, which was more N than the protein concentrate from red clover and birdsfoot trefoil in 1981 but not in 1980. Harvest date effects were small for alfalfa protein concentrate N concentration but red clover and birdsfoot trefoil had less of that constituent on the last harvest date. Total nonstructural carbohydrate (TNC) was highest in the deproteinized juice from red clover, which had 327 g TNC kg−1 DM, followed by birdsfoot trefoil and alfalfa with the lowest concentrations. Harvest date effects on TNC differed among species, but these differences were not large enough to be of practical importance. Alfalfa and red clover whole crops differed in the concentrations of several amino acids, but they differed less than the whole crop differed from the pressed forage and protein concentrate fractions within each species. Red clover protein concentrate had more threonine and valine than alfalfa protein concentrate but only 85% as much methionine, 52% as much cystine and less isoleucine. Results of this 2‐yr experiment indicate that N and DM concentrations differ in protein concentrates from different perennial legumes. Amino acid concentrations in protein concentrate were generally less affected by species and maturation than the same constituents in the whole crops. Species differences in deproteinized juice TNC concentrations were substantial and should be considered in the development of mechanical dewatering systems.

The chemical composition of grass silages prepared with and without pre-treatment with inoculants containing Lactobacillus plantarum

Two experiments are described in which silage inoculants containing Lactobacillus plantarum as the active principle were applied to perennial ryegrass ( Lolium perenne), which was ensiled in 2-kg capacity silos. In the first experiment, wilted ryegrass (304 g dry matter (DM) kg −1) was ensiled without additive treatment, or with the addition of 2 × 10 4, 1 × 10 5, 1 × 10 6, or 1 × 10 7 Lactobacillus plantarum/kg ensiled grass. Increasing quantities of bacteria applied to herbage resulted in decreases in the quantities of ammonia-nitrogen (expressed as a proportion of total nitrogen), and increases in the quantities of residual water-soluble carbohydrate and lactic acid in the silages. In the second experiment, ryegrass was ensiled either without a field-wilting period (187 g DM kg −1), or after 20 h (194 g DM kg −1) or 48 h field wilting (240 g DM kg −1). At each DM level, the grass was ensiled without additive treatment, or with the addition of 6.8 × 10 4, 9.1 × 10 4 or 3.4 × 10 7 L. plantarum/kg ensiled grass. The treatment which contained 6.8 × 10 4 bacteria, also contained cellulase, hemicellulase and amylase enzymes. Irrespective of the DM at which the grass was ensiled, when compared with the untreated silages, the application of inoculants reduced silage pH and concentrations of ammonia-N (expressed as a proportion of total N), acetic and butyric acids, and increased the concentrations of residual water-soluble carbohydrate and of formic and lactic acids in silage DM. These effects were most apparent when 3.4 × 10 7 bacteria were applied/kg grass; inclusion of enzymes in the inoculant did not have any measurable effect upon silage composition.