Cereal Silage Research Articles

Fermentation Properties and Nutritive Value of Sunflower Ensiled With Different Mixing Ratios of Silage Maize, Sweet Corn and Sweet Sorghum

In recent years, with the effect of global warming, researches on the potential of plants that are more resistant to drought as forage crops and their ensiling properties have become increasingly widespread. Current study aimed to investigate the ability of ensiling, fermentation quality and nutritive value of a sunflower variety, which is more drought resistant than many forage crops, with silage corn, sweet corn and sweet sorghum at different mixing ratios. Plant species used as silage material in present study were grown simultaneously in separate plots. All plants were harvested by hand in the range of about 25-32% dry matter and these harvested crops were theoretically chopped with 2-3 cm electric shredding machine for silage. In addition to pure silages of all crop materials, mixed silages of 25%+75%, 50%+50% and 75%+25% were made in 3 replications. Besides some properties of silage beginning materials, some fermentation properties and feed quality parameters of resulted silages were investigated. As a result of this study, 50%+50% mixed silage of the sunflower variety used as silage material with maize, sweet corn and sweet sorghum increased the silage fermentation quality compared to the pure sunflower silages and improved the silage feed quality compared to the pure cereal (corn, sweet corn and sweet sorghum) silages.

ENSILADOS MIXTOS DE CEREALES DE GRANO PEQUEÑO EN LA ALIMENTACIÓN DE VACAS EN SISTEMAS DE PRODUCCIÓN DE LECHE EN PEQUEÑA ESCALA

<p><strong>Background: </strong>In small-scale dairy systems (SPLPE), multi-species pastures and small grain cereal silages have proven to be an option in the face of potential climate change effects and provide quality forage at low costs in periods of forage shortages. <strong>Objective:</strong> To evaluate the inclusion of a binary silage of barley and rye, compared to a ternary silage of barley, rye and triticale, in the feeding of dairy cows in small-scale dairy systems, in terms of productive and economic performance. <strong>Methodology</strong>: In the central Highlands of Mexico and with the participation of a small-scale dairy farmer, the inclusion of these silages in the feed of 6 dairy cows was evaluated under a cross-over design. The treatments included 40% silage (T1, binary; T2, ternary), 36% of conventional feeds (cut pasture, maize straw and alfalfa hay) offered by the participating farmer, and 24% of commercial compound concentrate. The variables evaluated were diet composition, feed intake, yield and milk composition, and an economic analysis made considering feed costs. <strong>Results</strong>: The neutral detergent fiber content was 4.8% lower in T2 (<em>p</em><0.05), a treatment that also presented a 3% higher digestibility and a higher metabolizable energy and crude protein content (<em>p</em><0.05). This was due to the incorporation of the ternary silage, a higher quality silage compared to the binary silage. Energy corrected milk production was higher in T2 (<em>p</em>=0.05), in response to the higher intake and higher digestibility of this treatment. Feeding costs were similar for the inclusion of the two silages and the implementation of the ternary treatment represented an increase of 0.8% in margins over feed costs with compared to the use of the binary silage. <strong>Implications.</strong> The use of small grain cereal mixtures silages are feasible in small-scale dairy systems to ensure a constant supply of medium quality forage, which together with moderate supplementation can generate high yields and economic income. <strong>Conclusions</strong><strong>:</strong> The inclusion of ternary silage of small grain cereals of barley, rye and triticale, and moderate supplementation with commercial concentrate (24%) and other conventional feeds (36%), is a viable alternative as a feeding strategy in small-scale dairy systems during the dry season maintaining high milk yields and a high profit margin for these systems.</p>

Management factors affecting the environmental impact of cereal-based dairy farms

This study aimed to assess the environmental impact (cradle-to-farm gate LCA) of milk production of cereal-based dairy farms in northern Italy and to analyse which traits related to farm management (MAN_F), lactating cows’ ration composition (DIET_F), and animal responses (ANI_F) could be identified as main determinants to address specific mitigation strategies. Data originated from 28 dairy farms. The functional unit was 1 kg of fat- and protein-corrected milk (FPCM). Impact categories were global warming (GWP), acidification (AP) and eutrophication (EP) potentials and land occupation (LO). Impact values were analysed with a linear model to test separately the effects of MAN_F, DIET_F and ANI_F variables. One kg FPCM was associated with an average impact of 1.10 kg CO2-eq (GWP), 17.1 g SO2-eq (AP), 6.0 g PO4-eq (EP), and 1.3 m2/y (LO). Regarding MAN_F, GWP and LO linearly decreased with increasing values of stocking rate and feed self-sufficiency (FSS), whereas minimum EP was found for intermediate FSS values (50% DM). Regarding DIET_F, GWP linearly decreased at increasing levels of dietary inclusion of cereal silages, whereas AP and EP linearly decreased at decreasing dietary crude protein (CP) content values. Among ANI_F, GWP and EP were quadratically associated with milk yield (MY), evidencing the lowest values at intermediate MY (9100 ± 477 kg FPCM/cow per 305d-lactation). The GWP, AP and EP decreased with decreasing age at first calving. These results can contribute at drawing good practices for farmers and consultants to promote more environmentally sustainable dairy production while supporting farm functioning and farmers’ income. HIGHLIGHTS Farm and animal determinants of Life Cycle Assessment of cereal-based dairy farms were studied. Mitigation effects can be achieved by operating on farm organisation, cow’s diet, and animal responses. Good practices for farmers and consultants can be proposed for a better dairy production sustainability.

Effect of Inoculants and Sealing Delay on the Fermentation Quality of Early Harvested Wheat Forage

Winter cereal silages can suffer from an inadequate fermentative path which can lead to aerobic instability. We evaluate the pre-ensiled conditions influencing the final fermentative quality and its aerobic stability. We studied the use of hetero/homofermentative inoculants on two early-harvest wheat samples (312 and 348 g/kg of dry matter—DM levels) undergoing three ensiling delays. The fermentative profiles were evaluated during the first ten d of ensiling, at 60 d and after 7 and 14 d of aerobic exposure. Aerobic stability was recorded during fourteen d after the silo opening. Significant (p < 0.05) differences of the final fermentative profile were related mainly to DM levels at harvest, while the use of the inoculant affected only the acetic acid significantly. Finally, the sealing delay did not significantly affect the silage fermentative profile. The overall aerobic stability was 59.2 ± 23.6 h, and cumulative temperatures were lower than 438 for seven d of aerobic exposure and higher than 1526 for 14 d. Although the homofermentative inoculants reduced the counts of yeasts in the final silage for the earlier harvested wheat, the other samples showed yeasts counts of ~4.9 Log10 colony-forming units/g, with the presence of spoilage fungi (Pichia and Geotricum).

Small-grain forage mixtures for silage: Yield and botanical, morphological and chemical composition

In small-scale dairy systems (SSDS), multispecies pastures and small-grain cereal silages have been shown to be a feasible option to cope with the possible effects of climate change, such as erratic rainfall patterns and temperature extremes. The objective of this study was to evaluate the agronomic variables and green forage and silage quality of a binary mixture of barley (Hordeum vulgare) and rye (Secale cereale) compared to a ternary mixture of barley, rye, and triticale (X Triticosecale Wittmack) in two zones (San Joaquín and Tixhiñú) in the Mexican central highlands. A complete randomized design with factorial arrangement was used with the two mixtures and two locations as factors. The binary crop showed a 13.3 cm greater height (P<0.05), and forage production was similar between mixtures (P>0.05). The ternary silage had 57.6 g kg-1 DM less neutral detergent fiber, 68.1 g kg-1 DM higher digestibility and higher metabolizable energy content and crude protein (P<0.05). The binary mixture was dominated by rye, a species with a high proportion of stem (74.4%), which influenced the quality parameters. The inclusion of triticale favored the quality of the ternary mixture, and in general, barley performed poorly. The ternary mixture of small-grain cereals did not show major agronomic benefits but did show quality benefits, making silage from this mixture a viable option for use in SSDS.

Rapid identification of new isolates of Acidipropionibacterium acidipropionici by fluorescence in situ hybridization (FISH)

Acidipropionibacterium acidipropionici is widely used for many applications, such as propionic acid production, cereal silage, and also as probiotic. Due to this plethora of applications, new isolates of A. acidipropionici with improved features are being searched for. These new isolates must be accurately identified, however, most approaches become expensive and time-consuming when the number of isolates is high. On the contrary, fluorescence in situ hybridization allows the affordable, reliable, and rapid identification of microorganisms in pure cultures and environmental and medical samples. Therefore, the aim of this work was to apply a fluorescent in situ hybridization probe for the reliable identification of new A. acidipropionici isolates. To this end, probe Pap446, specific for A. acidipropionici, was validated by hybridization assays with strains of this species from different origins, other species of the same genus or family, and unrelated genera. Eight isolates with propionibacterium characteristics were obtained from milk and feces of cows. Probe Pap446, hybridized only with isolates III and VI. The identity of these isolates was further confirmed by PCR using group and species-specific primers for propionibacteria and 16S rDNA sequencing.

Occurrence of Mycotoxins in Grass and Whole-Crop Cereal Silages—A Farm Survey

Mycotoxin incidence in forage may heavily affect the amount of toxins consumed by cattle. However, many studies have focused on mycotoxin occurrence in cereals and there are less studies of forages, particularly of grass silages. For determining the occurrence of mycotoxins in farm silages under Northern European conditions in Finland, 37 grass silage and 6 whole-crop cereal silage batches were analysed separately for surface, core and, if present, visibly mouldy spots. Mycotoxins were found in 92% of the samples. All mouldy samples contained mycotoxins. Beauvericin was the most common mycotoxin in grass silages and roquefortine C in whole-crop cereal silages. In mouldy samples, beauvericin, mycophenolic acid and roquefortine C were the most common mycotoxins in the grass silage and mycophenolic acid in the whole-crop cereal silage. Aflatoxins were not found in any of the samples. On average, all samples contained more than one type of mycotoxin. Concentrations of mycotoxins varied considerably from very low to very high values. The results of this survey indicate that silage-fed ruminants can be exposed to a broad range of mycotoxins. The absence of visible moulds does not always indicate mycotoxin-free feed. All moulded samples contained mycotoxins and some at very high concentrations, and they contained more different types of mycotoxins than samples without visible mould. Thus, feeding mouldy feeds to animals should be avoided.

In situ ruminal degradability and fermentation characteristics of novel mixtures of winter cereal and Italian ryegrass plus winter cereal silages

This study was conducted using three multiparous non-lactating rumen-cannulated Holstein-Friesian dairy cows, with the objective of evaluating the in situ ruminal degradability and fermentation characteristics of novel mixtures of winter cereal and Italian ryegrass (Lolium multiflorum Lam.) plus winter cereal silages (mixture A: triticale, oats, barley and wheat; mixture B: triticale, barley and wheat; mixture C: Italian ryegrass and oats; mixture D: Italian ryegrass, oats, triticale, barley and wheat). The rumen fermentation study was conducted replacing the ensiled mixtures (experimental diets) with vetch-triticale haylage in a total mixed ration (control diet). It was found that the effective protein degradability at 0.08 rumen outflow rates was 80.6% (mixture A), 66.2% (mixture B), 79.7% (mixture C) and 79.3% (mixture D). The effective neutral detergent fibre (NDF) and acid detergent fibre (ADF) effective degradability at 0.08 rumen outflow rates was 18.0% and 17.7% (mixture A), 19.7% and 20.5% (mixture B), 19.1% and 17.0% (mixture C), and 15.2% and 14.6% (mixture D), respectively. Different dietary treatments did not change (P > 0.05) the rumen fermentation characteristics as there was no difference (P > 0.05) between control and experimental diets, and the inclusion of 40–55% Italian ryegrass (mixture C and D) did not cause any difference. These results suggest that the mixture of winter cereals and Italian ryegrass plus winter cereal-based silages had good potentially degradable dry matter, effective dry matter and effective protein degradability at 0.01, 0.05 and 0.08 rumen outflow rates without affecting the rumen environment maintaining neutral pH. The ensiled mixtures had a moderate level of potentially degradable NDF and ADF fractions.

Aroma Profile, Microbial and Chemical Quality of Ensiled Green Forages Mixtures of Winter Cereals and Italian Ryegrass

The objective of this study was to evaluate the aroma profile, microbial and chemical quality of winter cereals (triticale, oats, barley and wheat) and Italian ryegrass (Lolium multiflorum Lam., IRG) plus winter cereal mixture silages detected with an electronic nose. Four commercial mixtures (mixture A (40% of two cultivars of winter triticale + 30% of two cultivars of winter oats + 20% of winter barley + 10% of winter wheat), mixture B (50% of two cultivars of winter triticale + 40% of winter barley + 10% of winter wheat), mixture C (55% of three types of Italian ryegrass + 45% of two cultivars of winter oat), mixture D (40% of three types of Italian ryegrass + 30% of two cultivars of winter oat + 15% of two cultivars of winter triticale + 10% of winter barley + 5% of winter wheat)) were harvested, wilted and ensiled in laboratory-scale silos (n = 80) without additives. Both the principal component analysis (PCA) score plot for aroma profile and linear discriminant analysis (LDA) classification revealed that mixture D had different aroma profile than other mixture silages. The difference was caused by the presence of high ethanol and LA in mixture D. Ethyl esters such as ethyl 3-methyl pentanoate, 2-methylpropanal, ethyl acetate, isoamyl acetate and ethyl-3-methylthiopropanoate were found at different retention indices in mixture D silage. The low LA and higher mold and yeast count in mixture C silage caused off odour due to the presence of 3-methylbutanoic acid, a simple alcohol with unpleasant camphor-like odor. At the end of 90 days fermentation winter cereal mixture silages (mixture A and B) had similar aroma pattern, and mixture C was also similar to winter cereal silages. However, mixture D had different aromatic pattern than other ensiled mixtures. Mixture C had higher (p < 0.05) mold and yeast (Log10 CFU (colony forming unit)/g) counts compared to mixture B. Mixture B and C had higher acetic acid (AA) content than mixture A and D. The lactic acid (LA) content was higher for mixture B than mixture C. In general, the electronic nose (EN) results revealed that the Italian ryegrass and winter cereal mixtures (mixture D) had better aroma profile as compared to winter cereal mixtures (mixture A and B). However, the cereal mixtures (mixture A and B) had better aroma quality than mixture C silage. Otherwise, the EN technology is suitable in finding off odor compounds of ensiled forages.

Effects of barley and corn as sources of silage and grain on dry matter intake, ruminal fermentation, and total-tract digestibility in growing beef heifers

The objective of this study was to evaluate the use of barley (BS) or corn (CS) silage when fed with dry-rolled barley grain (BG), corn grain (CG), or an equal blend (BCG) of BG and CG for backgrounding cattle. Ruminally cannulated heifers (n = 5) were assigned to an incomplete 6 × 6 Latin square design. Treatments contained either BS or CS in combination with BG, CG, or BCG. Samples were collected to determine dry matter intake, ruminal fermentation, total-tract nutrient digestibility, and nitrogen (N) balance. Interactions between cereal silage and cereal grain sources were detected for the molar proportions of propionate and butyrate where the magnitude of change with the type of cereal grain was increased in heifers fed CS relative to BS. Feeding CS increased estimated microbial N production (silage, P = 0.022) and fecal N excretion (silage, P = 0.042) over BS. Diets containing BG had greater dry matter, organic matter, starch, and gross energy digestibility values compared with CG, but values for BCG were not different (grain, P ≤ 0.043). Based on limited silage × grain interactions, use of CS in backgrounding diets may increase microbial N production relative to BS and dry-rolled CG may reduce apparent total-tract nutrient digestibility relative to dry-rolled BG.

Novel mixtures of Italian ryegrass and winter cereals: influence of ensiling on nutritional composition, fermentation characteristics, microbial counts and ruminal degradability

The study was conducted with the objective of evaluating the nutrient content, fermentation characteristics, microbial counts, and ruminal degradability of two mixtures of Italian ryegrass (Lolium multiflorum Lam.) and winter cereal silages. Two mixtures (mixture A: Italian ryegrass, triticale, oats, wheat and barley; and mixture B: Italian ryegrass and oats) were wilted and ensiled in laboratory‐scale silos without additives. At the end of 90 d fermentation mixture B silage had higher (p < .05) dry matter (DM), ether extract (EE), crude fibre (CF), neutral detergent fibre (NDF) and acid detergent fibre (ADF) contents than mixture A silage. The pH value of mixture B was higher (p < .05) than mixture A silage. Mixture A had higher lactate, acetate and ethanol contents than mixture B. However, mixture B had higher NH3-N (day 14) than mixture A silage. The mould and yeast count (Log10 CFU g−1) was higher (p < .05) for mixture A than mixture B at opening day 7. The in situ incubation revealed that potentially degradable fraction (b) of DM, CP and NDF was 39.41%, 43.59%, 80.23% (mixture A) and 39.16%, 32.39%, 94.35% (mixture B). The effective protein degradability (EPD) at 0.08 rumen outflow rates was 67.26% (mixture A) and 67.19% (mixture B). These results suggest that with the proper stage of harvesting, Italian ryegrass and winter cereal mixtures were fermented well. This kind of mixtures can be ensiled without additives in the future. The high potentially degradable NDF and effective protein degradability implies that this mixture could be included successfully in high-yielding dairy cattle diets. Highlights Italian ryegrass and winter cereal mixtures are well preserved without additives and it saves the cost of additives for dairy farmers. The ensiled mixtures have high potentially degradable NDF and effective protein degradability, which improve dry matter intake, milk production and increase the net return of farm. The mixture forage can be double-cropped with corn for silage making, which can have both environmental and economic benefits if the ensiled mixture yields are enough to cover expenses.

Effects of Various Additives on Fermentation, Aerobic Stability and Volatile Organic Compounds in Whole-Crop Rye Silage

Whole-crop cereal silage represents an important component of ruminant diets and is used as a substrate for biogas production. Due to the scarcity of data on whole-crop rye (Secale cereale L., WCR), our study aimed to evaluate the effects of a range of biological and chemical additives of different compositions on the fermentation and aerobic stability of silage made from this species. In addition, the production of various volatile organic compounds (VOCs), which potentially contribute to greenhouse gas emissions, was monitored. Regardless of additive treatment, all WCR silages were well fermented as reflected by the complete absence of butyric acid. Inoculants containing Lactobacillus buchneri and chemical additives reduced dry matter (DM) losses during fermentation for 53 days (p &lt; 0.001), which were closely related with the concentration of ethanol upon silo opening (R2 = 0.88, p &lt; 0.001). Silage treated with Lactobacillus buchneri, alone or in combination with a homofermentative strain, had the lowest yeast count (p &lt; 0.001) and, simultaneously, the highest aerobic stability (p &lt; 0.001). Chemical additives outperformed all other additives by largely restricting the formation of ethyl esters of lactic and acetic acids (p &lt; 0.001). The concentration of ethanol strongly correlated with those of ethyl lactate (R2 = 0.94, p &lt; 0.001), ethyl acetate (R2 = 0.85, p &lt; 0.001), and total ethyl esters (R2 = 0.94, p &lt; 0.001). The use of a simple linear regression model exclusively based on the ethanol content proved useful to predict the concentration of total ethyl esters in WCR silage (R2 = 0.93, p &lt; 0.001).

Nutrient content and fermentation characteristics of ensiled Italian ryegrass and winter cereal mixtures for dairy cows

The interest in new alternative forages in Europe has increased in recent years. The nutritional composition and fermentation characteristics during different stages of ensiling were studied with Italian ryegrass (Lolium multiflorum Lam.) and winter cereal mixtures. The trial was carried out on a large-scale farm Galgamenti Agricultural Limited Company, Tura, Hungary. Two different forage mixes were studied: Mixture A (three types of Italian ryegrass 40% + two types of triticale 20%+ two types of oats 20%+ wheat 15%+ barley 5%) and Mixture B (three types of Italian ryegrass 55% + two types of winter oats 45%). Experimental field was 30.600 m 2 by the treatments, respectively. The two different forage mixes were sown on 11th September 2017 (Mixture A: 75 kg seed/ha; Mixture B: 75 kg seed/ha) with depth of 2-5 cm. Plant protection treatment was not applied during the growing season. Cutting was carried out in heading stage of triticale by hand at 10 cm stubble height. The fresh Mixture A (dry matter 189 g/kg; crude protein: 161 g/kg DM; NDF: 485 g/kg DM) and the fresh Mixture B (dry matter 195 g/kg; crude protein: 159 g/kg DM; NDF: 519 g/kg DM) were wilted to 28-32% DM (24h) without any movement on the windrow. The wilted forage was picked up by hand and chopped by a forage harvester (John Deere 7300) on concrete surface with theoretical chop length of 9 mm (weight: 800 kg). Wilted and chopped material of 510 g were packed by hand into a glass jars (0.00072 m3 volume, n=5, total no. of minisilos = 15). Five laboratory silos per mixtures were opened on 7, 14 and 90 days after ensiling. Dry matter (DM), crude protein (CP), crude fiber (CF), neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), ether extract (EE), ash, and total sugar of all treatments were determined. Additionally, pH and the concentration of ammonia-N, volatile fatty acids were measured in the ensiled mixtures. At the end of 90 days of ensiling in both mixture silages, there were significant differences (p&amp;lt;0.05) in all nutrient contents except for ADF in Mixture A and CP, ash and CF in Mixture B which was not affected by fermentation duration. Ensiling caused a significant decrease in pH (p&amp;lt;0.05), due to the production of lactic acid and succeeded to achieve lactic acid type fermentation. Values for ammonia-N, ethanol and acetic acid, butyric acid were all low. These results indicated that the fermentation quality of Italian ryegrass and winter cereal silages underwent rapid fermentation and were well-preserved.

Forage systems and sustainability of milk production: Feed efficiency, environmental impacts and soil carbon stocks

Farm sustainable intensification is an important strategy to reduce environmental impacts, which can be obtained in particular through improvements in the milk production per cow and feed efficiency, as well as by increasing the net primary production of the Utilized Agricultural Area. Farming systems that are mainly based on multi-annual/perennial forages may increase soil carbon (C) sequestration, which is a significant greenhouse gases mitigation strategy. The aim of the present study has been to identify the forage systems related to dairy farms that are able to maximize feed production and to improve feed efficiency and C sequestration, in order to achieve the best environmental sustainability result. A group of 46 dairy farms was selected to represent the most widespread forage systems in Northern Italy. The identified forage systems were: CONV, conventional corn silage system; MIXED, low intensity mixed system; HQFS, high quality forage system; WICE, winter cereal silage system; PR DRY, hay system for Parmigiano Reggiano PDO cheese production and PR-FRESH, hay and fresh forage system for Parmigiano Reggiano PDO cheese production.Primary data were collected to carry out a life cycle assessment. Soil samples of representative crops of the forage systems were collected to determine in particular the soil organic carbon density and soil organic matter. The WICE, CONV and HQFS forage systems provided the greatest amount of dry matter (DM) per hectare, whereas the PR FRESH system showed the highest soil C density. The LCA results showed that the HQFS system registered the lowest values for all the impact categories (except for land occupation and the use of non-renewable resources), probably due to the higher milk production, both in terms of individual production (fat and protein corrected milk/head) and feed efficiency (kg milk/kg DMI). More intensive systems, such as HQFS, demonstrated that the milk production per cow and feed efficiency are negatively related to the impact per kilogram of product. The HQFS system also resulted to be more sustainable, in terms of feed self-sufficiency, as a high amount of DM per hectare. However, as far as this forage system is concerned, there is still room to strengthen environmental sustainability, since HQFS also showed the lowest C soil density. Further investigations are needed to consider environmental sustainability over a wider spectrum.

Fusarium mycotoxins in total mixed rations for dairy cows.

Mycotoxins produced by certain fungal species of the Fusarium genus are frequently found as contaminants in cereals and feedstuffs. Fumonisins (FBs), deoxynivalenol (DON) and zearalenone (ZEN) are of special concern relative to animal health and productivity. The aim of this work was to analyse the levels of Fusarium mycotoxin contamination in samples of total mixed rations (TMRs) for dairy cows. To accomplish this analysis, an HPLC-MS/MS multi-mycotoxin method was developed and validated. The relation between the formulation of TMR samples and the presence of mycotoxins was also studied. From February 2016 to January 2018, a total of 193 TMR samples for dairy cows collected from farms located in different areas of Spain were analysed for the presence of FBs, ZEN, DON and their metabolites. In total, 112 samples (58%) were contaminated with at least one mycotoxin, and 38 samples (20%) presented more than one mycotoxin. FBs were the mycotoxins most frequently found (34% positive samples). DON was detected in 17% of samples, and ZEN was detected in 16% of samples. Among the metabolites analysed, only deoxynivalenol-3-glucoside (DON-3-Glc) and 15-acetyldeoxynivalenol (15-ADON) were detected. The levels of all the Fusarium mycotoxins studied were always below the values recommended by the European Commission for feedstuffs. The wide variety of ingredients used in the formulation of the analysed samples made it difficult to reach definite conclusions, although it seemed that some cereal silages and concentrates such as cereals or compound feed used as ingredients of the TMR may be related to the presence of mycotoxins.

Effect of feeding barley or corn silage with dry-rolled barley, corn, or a blend of barley and corn grain on rumen fermentation, total tract digestibility, and nitrogen balance for finishing beef heifers.

Five ruminally cannulated heifers were used in an incomplete 6 × 6 Latin square design to determine the effects of cereal silage (barley vs. corn), cereal grain (barley vs. corn vs. a 50:50 blend of barley and corn), and their interaction (S × G) on dry matter intake, ruminal fermentation, total tract digestibility, nitrogen balance, and in situ degradation. Corn silage (CS) or barley silage (BS) was included at 8% of dietary dry matter (DM). Within each silage source, diets contained (DM basis) either dry-rolled barley (BG; 86%), dry-rolled corn (CG; 85%), or an equal blend of barley and corn (BLEND; 85%). Periods were 25 d, with 5 d of dietary transition, 13 d of dietary adaptation, and 7 d of data and sample collection. Samples collected included feed and refusals, total urine and feces, and ruminal fluid. All data were analyzed using the Mixed model of SAS with the fixed effects of silage, grain, and the S × G. Dry matter intake (P ≥ 0.19) and mean ruminal pH (P ≥ 0.096) were not affected by the silage, grain, or S × G. Total short-chain fatty acid concentrations were greater for BLEND than BG or CG (grain, P = 0.003) and for CS (silage, P = 0.009) relative to BS. The molar proportion of acetate was greater for BS-BG and BS-CG (S × G, P < 0.001), while molar proportion of propionate was greater for CS-BG (S × G, P < 0.001) relative to other silage and grain source combinations. Rumen ammonia-N concentration was greater for CG than BG, or BLEND (grain, P < 0.001), and greater for CS compared to BS (silage, P = 0.023). Apparent total tract digestibility of DM, organic matter, neutral detergent fiber, starch, and gross energy were greatest for BG (grain, P ≤ 0.035). Digestible energy content (Mcal/kg) was greater for BG (grain, P = 0.029) than CG and BLEND. Total nitrogen retention (g/d and % of intake) was greatest for CS-BG (S × G, P ≤ 0.033) relative to all other treatments. In situ degradation rates of DM, crude protein, and starch were greater for BG than CG (P ≤ 0.004). The potentially degradable fraction of DM, crude protein, and starch was greater for CG (P ≤ 0.031), while the undegradable fraction was greater for BG (P ≤ 0.046). For silage sources, CS had greater 24 h in situ DM digestibility (P = 0.009) and starch digestibility (24, 48, and 72 h incubations, P ≤ 0.034) relative to BS. Results suggest that while feeding a combination of CS and BG promotes propionate production and greater N retention; few other additive effects were observed.

Agricultural small anaerobic digestion plants: Combining economic and environmental assessment

In the most recent decade, anaerobic digestion (AD) has been widely studied as an interesting and profitable solution to produce renewable energy. Focusing on AD plants fed with agricultural feedstock, the most investigated ones were big plants fed with cereal silages. However, the spreading of these plants has reduced after the variation of the subsidy framework, and it has been counterbalanced by the increase of small plants (<300 kW electrical power) fed almost only with animal slurries.Therefore, in this study were analysed two small AD plants in order to evaluate their environmental and economic performances. Life Cycle Assessment is adopted to assess the environmental side, while Net Present Value, payback period and Internal Rate of Return are adopted for the economic evaluation.Of the two small plants, the one totally fed with slurries showed both the best results on all the studied environmental impact categories, and the most interesting economic results, while the plant digesting pig slurry and maize silage was less beneficial. Moreover, the cost for reducing Greenhouse Gases (GHG) emissions (expressed as tons CO2 eq) was quantified for the two small plants in comparison with two other plants of 999 kW, resulting that small plants fed with slurries allow reducing GHG with lower subsidies respect to big plants that co-digest energy crops, even if these last plants produce more electricity.

Environmental sustainability of integrating the organic Rankin cycle with anaerobic digestion and combined heat and power generation

Given the growing scarcity of primary energy resources, increasing the efficiency of energy conversion is one of the key challenges for optimising energy use. For this reason, low-grade or waste heat from various processes is becoming increasingly more attractive as an energy source. This study considers anaerobic digestion (AD) coupled with a combined heat and power plant (CHP) as a source of low-grade heat for electricity generation utilising an organic Rankine cycle (ORC) system. The aim is to evaluate the environmental sustainability of such a system relative to the AD-CHP system without heat recovery. Ten real AD-CHP plants using cereal silage and animal slurry as feedstocks are considered for these purposes and their impacts have been estimated through life cycle assessment. The results suggest that systems with the ORC have lower impacts than those without it, but the average reductions are relatively small (1.6–5.8%). However, for the smaller plants fed mainly with animal slurry, climate change increases significantly (up to 27 times). The reduction in impacts is greater for the bigger plants where the surplus heat available for the ORC is higher. The impacts from the ORC plant are insignificant, with its electrical efficiency and lifespan showing little effect on the results. Small slurry-fed plants without the ORC have lower environmental impacts than the bigger silage-fed plants fitted with an ORC system for nine out of 13 categories considered; climate change is up to 32 times lower. They are only slightly worse than the bigger plants with the ORC for ozone depletion and human toxicity due to the economies of scale. Therefore, while there are clear benefits of fitting an ORC system to an AD-CHP plant, greater benefits can still be achieved by utilising waste feedstocks, such as animal slurry, instead of fitting an ORC to a plant utilising cereal silage.

Electricity Generation from Anaerobic Digestion in Italy: Environmental Consequences Related to the Changing of Economic Subsidies

In recent years, the increasing market trend of Renewable Energy Sources (RES) in the European Union has been connected with the public subsidies guaranteed to encourage their production. In Italy, the northern regions have played a leading role and contributed deeply to increase the share of RES in the national energy mix. An increase in the number of Anaerobic Digestion (AD) plants fed with agricultural feedstock has been detected, reaching 1800 units in only 20 years. AD is considered as one of the most promising technologies for RES production, especially when wastes are used as feed. In fact, the use of wastes brings to increase the added value and reduces the economic and environmental costs related to the waste treatment as well as the energy purchase. Despite these advantages, the economic subsidy framework has encouraged entrepreneurs to increase the productivity of plants by using dedicated crops as feed, of which maize silage is the most widely used. Since the economic subsidy for bioenergy production has already been reduced, it can be expected its end in the future, thus potentially making the feeding of plants with dedicated crops uneconomic. In particular, subsidies could be essential to guarantee revenues and to cover the feeding supply costs.This study aims to evaluate the consequences of the potential deletion of the subsidy framework for AD production plants. Consequential life cycle assessment (cLCA) method was implemented in order to evaluate the environmental effects related to: (i) the substitution of dedicated crops in the feeding mix with pig and cow slurry; (ii) the end of plants fed with dedicated crops and the substitution of the related renewable energy production with non-renewable energy in the national energy mix.Results highlighted that the substitution of cereal silages with an additional share of animal slurry entails an environmental improvement respect to the BASELINE scenario. Considering the displacement of land use towards the cultivation of cereals for feeding, the contraction of import contributes to an improvement of environmental impacts. The higher nitrogen efficiency of the digestate could also reduce the volume of supplemental fertilisers for crops cultivation. Moreover, slurry storage at farm in traditional open tanks causes an increase in Greenhouse Gas Emissions (GHG) due to emissions to the atmosphere. The achieved results support the decision of policy makers to drive the future towards a more sustainable energetic production.

Production and economic responses to intensification of pasture-based dairy production systems.

Production from pasture-based dairy farms can be increased through using N fertilizer to increase pasture grown, increasing stocking rate, importing feeds from off farm (i.e., supplementary feeds, such as cereal silages, grains, or co-product feeds), or through a combination of these strategies. Increased production can improve profitability, provided the marginal cost of the additional milk produced is less than the milk price received. A multiyear production system experiment was established to investigate the biological and economic responses to intensification on pasture-based dairy farms; 7 experimental farmlets were established and managed independently for 3 yr. Paddocks and cows were randomly allocated to farmlet, such that 3 farmlets had stocking rates of 3.35 cows/ha (LSR) and 4 farmlets had stocking rates of 4.41 cows/ha (HSR). Of the LSR farmlets, 1 treatment received no N fertilizer, whereas the other 2 received either 200 or 400 kg of N/ha per year (200N and 400N, respectively). No feed was imported from off-farm for the LSR farmlets. Of the 4 HSR farmlets, 3 treatments received 200N and the fourth treatment received 400N; cows on 2 of the HSR-200N farmlet treatments also received 1.3 or 1.1 t of DM/cow per year of either cracked corn grain or corn silage, respectively. Data were analyzed for consistency of farmlet response over years using mixed models, with year and farmlet as fixed effects and the interaction of farmlet with year as a random effect. The biological data and financial data extracted from a national economic database were used to model the statement of financial performance for the farmlets and determine the economic implications of increasing milk production/cow and per ha (i.e., farm intensification). Applying 200N or 400N increased pasture grown per hectare and milk production per cow and per hectare, whereas increasing stocking rate did not affect pasture grown or milk production per hectare, but reduced milk production per cow. Importing feed in the HSR farmlets increased milk production per cow and per hectare. Marginal milk production responses to additional feed (i.e., either pasture or imported supplementary feed) were between 0.8 and 1.2 kg of milk/kg of DM offered (73 to 97 g of fat and protein/kg of feed DM) and marginal response differences between feeds were explained by metabolizable energy content differences (0.08 kg of milk/MJ of metabolizable energy offered). The marginal milk production response to additional feed was quadratic, with the greatest milk production generated from the initial investment in feed; 119, 99, and 55 g of fat and protein were produced per kilogram of feed DM by reducing the annual feed deficit from 1.6 to 1.0, 1.0 to 0.5, and 0.5 to 0 t of DM, respectively. Economic modeling indicated that the marginal cost of milk produced from pasture resulting from applied N fertilizer was less than the milk price; therefore, strategic use of N fertilizer to increase pasture grown increased farm operating profit per hectare. In comparison, operating profit declined with purchased feed, despite high marginal milk production responses. The results have implications for the strategic direction of grazing dairy farms, particularly in export-oriented industries, where the prices of milk and feed inputs are subject to the considerable volatility of commodity markets.