Pasture systems in the northeastern United States are primarily comprised of cool‐season perennial grasses. However, these systems are subject to a lag in forage production during the hot summer months. Incorporating warm‐season annual grasses (WSA) into these forage systems may improve overall forage productivity, especially for producers with a limited land base. Therefore, the objective of this study was to compare the agronomic effect of WSA interseeded into orchardgrass ( Dactylus glomerata L.; OG) and harvested at two different intervals. This study compared monocultures of OG to OG interseeded with sorghum‐sudangrass ( Sorghum bicolor × S. bicolor var. sudanense; SSG), pearl millet ( Pennisetum glaucum L.; PM) or teff grass ( Eragrostis tef L.; TEFF), harvested on either a 6‐ or 12‐week interval. Results indicated that inclusion of WSA into OG did not improve total herbage accumulation or nutritive value beyond the OG monoculture at either harvest interval ( p > 0.42). However, inclusion of WSA into OG did affect the proportion of OG in the stand at both harvest intervals ( p < 0.01). The greatest effect was observed in plots interseeded with SSG, in which there was a ∼14% and ∼25% decrease in OG compared to OG monoculture plots when harvested on a 6‐ and 12‐week interval, respectively. This study concluded that interseeding WSA into OG did not improve agronomic parameters of the stand compared to OG despite implementing different harvest frequencies. Future research is warranted evaluating the effect of warm‐season annual legumes under similar conditions on the forage production of cool‐season perennial grass pastures.

Interseeding annual forages into growing corn may be an alternative for both cover and grazing in temperate regions of the United States. A 4‐year experiment evaluated the effect of interseeding cereal rye ( Secale cereale ) into corn for grazing after harvest on corn grain, forage biomass yield and quality, soil health, and estimated spatial biomass yields using vegetation indices (VIs) from multispectral imagery collected from an unmanned aircraft system platform. Corn was planted (79,074 plants ha −1 ) each spring on two 4.8‐ha sites in central Pennsylvania. Cereal rye was interseeded (135 kg ha −1 ) into corn at the V4–V6 stage. Corn was harvested as grain in November, and each site was subdivided and randomly assigned to grazed or non‐grazed treatments. Biomass yield and quality, soil samples, and estimates of biomass yield using VIs from multispectral imagery monitoring occurred in fall and spring. Results indicated that cereal rye plus corn stover provided enough forage for an additional 105–130 animal unit days ha −1 with minimal impact on soil health indicators. Vegetative indices varied in the ability to predict biomass yield; all VIs except normalized difference red edge saturated at ∼2 Mg ha −1 . Spring growth of cereal rye was much less dependable than fall. Corn grain yields did not decrease (averaging 9.9 tonnes of dry matter ha −1 ) as a result of grazing or due to continuous corn planting except in 2019 (dry year) when corn grain yields were reduced by 35%–40%. Interseeding cereal rye into corn that is harvested as grain can be a viable method to establish a cover crop to extend the grazing season without impairing cash crop yield.

Sorghum-sudangrass hybrids (Sorghum. bicolor x Sorghum. bicolor var. sudanense; SSG) are common warm-season annual forages utilized in forage systems in the northeastern United States. However, weed control can be an issue, particularly in low-input forage systems. Interseeding annual forages, such as crabgrass (Digitaria sanguinalis L.; CG) and berseem clover (Trifolium alexandrinum L.; BC), is of interest to aid in weed control due to their rapid growth and desirable nutritive value. A 2-year small plot evaluation was conducted to determine the agronomic benefits of interseeding CG and BC via no-till drill or broadcast seeding into SSG established on different row spacings. Total herbage accumulation (HA) did not differ by year for any of the treatments evaluated (p > 0.13), despite having different row spacing and companion crop establishment methods. Botanical composition (BOT) varied among treatments (p < 0.01) for all forage components in both years. In 2022, treatments containing CG had lower percentage of SSG, BC, and weeds (other undesirable plant species), but in 2023 only the weeds percentage was lower in treatments with CG. Crude protein did not differ in either year (p > 0.55) across treatments; however, treatments containing high amounts of CG had the lowest (p = 0.03) total digestible nutrients in 2022 only. This study concluded that while row spacing and the interseeding of annual forage species did not affect the overall HA of SSG, they did affect the BOT and nutritive value of the stand. Future research is warranted for evaluating other compatible forages and contrasting defoliation methods to determine their impact on the agronomic production of these types of mixtures, such as grazing or stored forage production.

Objectives: The objective of this study was to evaluate the accuracy of Brix in predicting sugar concentrations in fresh alfalfa (ALF; Medicago sativa L.) and orchardgrass (OG; Dactylis glomerata L.) forages to be used as an inexpensive and rapid field-level assessment of relative energy in forages. Materials and Methods: In a 2-yr study, fresh forages samples from ALF and OG monoculture pastures in from May to September. Samples were immediately evaluated for Brix values with a hand-held digital refractometer, and the remaining biomass was frozen immediately with liquid N to halt cellular respiration. Samples were lyophilized and analyzed for individual sugars and wet Results and Discussion: Brix was positively correlated with total and individual sugars in ALF during late spring and late summer (0.53-0.93), but correlations were nonexistent or negative in mid-summer. However, Brix values did not correlate with any notable sugar parameters in OG beyond the first sampling date. These findings were attributed to greater fibrous fraction contamination, compared with horticultural crops, and changes in seasonal growth of ALF and OG. Implications and Applications: Brix values did not and nutritive values of fresh forages.

Our goal was to investigate the effect of diets containing baleages harvested from alfalfa-grass or red clover-grass mixture on production performance, ruminal fermentation and microbiota taxa relative abundance, milk fatty acid profile, and nutrient utilization in dairy cows. Twenty Jersey cows (18 multiparous and 2 primiparous) averaging (mean ± SD) 148 ± 45.2 d in milk and 483 ± 65.4 kg of body weight in the beginning of the study were used in a randomized complete block design with repeated measures over time. The experiment lasted 9 wk, with a 2 wk covariate period followed by 7 wk of data and sample collection (wk 4 and 7 used in the statistical analyses). Cows were fed diets containing (dry matter basis) 35% of a concentrate mash and the following forage sources: (1) 65% second and third cut (32.5% each) alfalfa-grass mixture baleages (ALF) or (2) 65% second and third cut (32.5% each) red clover-grass mixture baleages (RC). Diets did not affect dry matter intake, milk yield, and concentrations of milk fat and true protein. In contrast, milk fat yield tended to decrease and energy-corrected milk yield decreased with feeding RC versus ALF. The apparent total-tract digestibilities of dry matter, organic matter, and ash-free neutral detergent fiber, milk proportions of trans-10 18:1, cis-9, cis-12, cis-15 18:3, and total n-3 fatty acids, ruminal molar proportion of acetate, and plasma concentrations of Leu, Phe, and Val all increased in RC versus ALF. Diet × week interactions were found for several parameters, most notably ruminal molar proportions of propionate and butyrate, ruminal NH3-N, milk urea N, plasma urea N, and plasma His concentrations, urinary N excretion, enteric CH4 production, and all energy efficiency variables. Specifically, ruminal NH3-N and plasma urea N concentrations, urinary excretion of N, and CH4 production decreased in cows fed RC in wk 4 but not in wk 7. Milk urea N concentration decreased and that of plasma His increased with feeding RC during wk 4 and 7, although the magnitude of treatments difference varied between the sampling periods. Efficiency of energy utilization calculated as milk energy/metabolizable energy decreased and that of tissue energy/ME increased in RC versus ALF cows in wk 4, suggesting that ME was portioned toward tissue and not milk yield in the RC diet. Interactions were also observed for the relative abundance of the rumen bacterial phyla Verrucomicrobiota and Fibrobacterota, with cows offered RC showing greater values than those receiving ALF in wk 4 but no differences in wk 7. Several diet × week interactions were detected in the present implying short-term treatment responses and warranting further investigations.

AbstractBlack oat (Avena strigosa Schreb.) might be an attractive forage species in the northeastern United States, since it is generally more heat tolerant and disease resistant than other cool‐season grasses. Black oat is currently recommended for fall and winter production in USDA Plant Hardiness ones 8b–10a, which is beyond the northeastern United States (Zones 2a–6a). The objective was to evaluate 10 black oat breeding lines (referred to as “UF1” through “UF10”) for forage accumulation, crude protein (CP), neutral detergent fiber (aNDF), acid detergent fiber (ADF), and in vitro digestible organic matter (IVDOM) concentrations. The experiment was carried out in April–July 2022 in Pennsylvania Furnace, PA. Triticale (× Triticosecale Wittmack cv. TriCal 342) and Legend 567 oat (Avena sativa L.) were included as controls, as well as Haden oat and Gunner triticale, as regionally recommended cultivars. The forage accumulation within the black oat germplasm ranged from 364 to 864 lb dry matter (DM) acre−1, observed in UF7 and UF9, respectively, during the first harvest. During the second harvest, forage accumulation within black oat ranged from 1048 to 1408 lb DM acre−1, from UF8 and UF1, respectively. Crude protein concentrations ranged from 16% to 23% across all black oats, with no differences found within the germplasm. The IVDOM concentrations averaged 78% across all treatments during the first harvest and decreased to 66% during the second harvest. Overall, this study showed that black oat merits further evaluation as forage species in the northeastern United States, but further studies are required to address management of the species.

Corn (Zea mays) crops harvested as grain in autumn do not provide opportunity for cover crop establishment, which may be remedied by interseeding cover crops into growing corn. Grazing cover crops after corn grain harvest could provide added revenues and increase nutrient cycling in the system while providing additional ecosystem services. However, tradeoffs between cash crop productivity and cover crop inclusion, and use as grazed forage, are not fully understood. This 4-year Long-Term Agroecosystem Research Integrated Common Experiment project evaluated the effect of interseeding cereal rye (Secale cereale) into corn for grazing after corn grain harvest on corn grain yield and late-season grazing. Cereal rye was interseeded into corn in early June. After corn grain harvest, six paddocks at each location were randomly allotted to grazed (GRAZ) or not grazed (NG). The GRAZ paddocks were grazed with beef cattle in late autumn and again in early spring if regrowth allowed. Paddocks were flown with an unmanned aerial system (UAS) to characterize spatial forage yield and quality. Cereal rye provided an additional 20-30 grazing days in the autumn for 24 beef cows on 4.8 ha. Early spring growth shows potential to provide even greater forage yields than autumn, but growth is less dependable. Corn grain yields did not decrease except in 2019 (dry year) when yields were 40% lower. There were no significant differences in soil health indicators between GRAZ and NG paddocks. The UAS shows promise as a tool for monitoring forage yield and quality and optimizing grazing management.

The viability of organic dairy operations in the United States (US) relies on forage production. The objectives of this study were to (1) assess producer and farm information regarding current forage production practices and producer knowledge gaps and (2) identify forage research and educational needs of organic dairy producers across the US. A survey was distributed to 643 organic dairy producers across the US, with 165 respondents (26% response rate). A focus group consisting of extension professionals, university researchers and staff, consultants, dairy industry representatives and organic dairy producers was also consulted for forage research needs. Results showed that approximately half (51%) of surveyed producers were somewhat satisfied with their forage production systems and sometimes experienced negative weather-related impacts on forage yield and quality. A majority (64%) of producers felt their knowledge to meet farm goals was adequate but they reported a lack of resources to implement this knowledge especially for balancing high-forage diets and selecting soil amendments. This study revealed that 54% of producers rely on peer experiences as information resources to make decisions on forage programs. Producer knowledge gaps included pasture renovation with reduced or no-tillage, forage mixtures that match their needs, and forage management practices aiming for high-quality forage. Based on the survey and focus group findings, forage research and educational activities should foster climate change resilience regarding forage diversity adapted to local and regional climatic conditions, improve forage quality, enhance economic returns from soil fertility amendments and pasture renovation, and introduce new forages and forage mixtures that suit economical, agronomical, and environmental needs.

Long-term research is essential for guiding the development of agroecosystems to meet escalating production demands in a manner that is environmentally sound and socially acceptable. Research must integrate biophysical and socioeconomic factors to provide geographically scalable knowledge that involves stakeholders across the research-education-extension-policy spectrum. In response to this need, the Long-Term Agroecosystem Research (LTAR) network developed a "Common Experiment," which seeks to develop and disseminate multi-region, science-based information to enable implementation of visionary agricultural innovations while simultaneously promoting food security, well-being, environmental quality, and climate adaptation and mitigation. The core design of the Common Experiment contrasts prevailing and alternative/aspirational production systems, with the latter including novel innovations hypothesized to advance sustainable intensification in locally appropriate ways. Treatments in the Common Experiment represent a diversity of production systems under cropland, grazing land, and integrated crop/grazing land management. Where possible, treatments are evaluated at multiple spatial scales (e.g., from plot to enterprise) and are designed to evolve over the course of the experiment with stakeholder input. A common assessment framework guides data collection for the experiment and is complemented by metric-specific protocols and an emerging data management infrastructure. Currently, there are large differences among sites in the application of the experimental framework and degree of stakeholder engagement; differences largely grounded in pragmatic issues related to land access, site expertise, and resource availability. The full potential of the LTAR Common Experiment may be realized with strategic investments in network capacity.

Abstract This study investigated the effect of individual or simultaneous addition of two macroalgae species on in vitro fermentation in continuous culture. Four single-flow continuous culture fermentors were fed an orchardgrass herbage-based (orchardgrass; Dactylis glomerata L.) basal diet and randomly assigned one of four treatments: 1) control (CON), no macroalgae addition; 2) Ascophyllum nodosum dosed at 2.5% dry matter (DM; ASC); 3) Asparagopsis taxiformis dosed at 0.5% DM (ATX); and 4) A. nodosum (2.5% DM) + A. taxiformis (0.5% DM) dosed simultaneously (AS+AT). Four experimental periods were conducted in a randomized block design with 7 d of treatment adaptation and 3 d of sample collection. Fermentors were fed 82 g of DM per day in 4 equal feedings. In the last 3 d of each experimental period, daily samples of total effluent were taken for analyses of ammonia N and volatile fatty acids (VFA). Effluent was composited by fermentor and analyzed for DM, ash, neutral and acid detergent fiber, and crude protein. Purine concentrations of effluent and bacterial isolates were determined to estimate partitioning of N flow into feed, bacterial, and ammonia N fractions. Methane (CH4) emissions were measured in each fermentor every 15 min using a Fourier transform infrared gas analyzer, and pH was recorded every 2 min. Data were analyzed using the MIXED procedure of SAS v 9.4 with pre-planned contrasts comparing each individual macroalgae to CON (CON vs. ASC and CON vs. ATX) and comparing A. taxiformis with and without simultaneous addition of A. nodosum (ATX vs. AS+AT). Significance was declared at P ≤ 0.05 and tendencies at 0.05 < P ≤ 0.10. Nutrient digestibilities, CH4 emissions, pH, and N metabolism variables were not affected (P > 0.10) in ASC compared with CON, but total VFA concentration increased (P < 0.05) by 10%. Contrarily, the ATX diet tended (P = 0.61) to have reduced true organic matter digestibility, reduced (P < 0.05) total VFA concentration by 11%, and reduced (P < 0.05) CH4 production by 99.9% versus CON. Simultaneous the combination of microalgae (AS+AT) did not further reduce (P > 0.10) nutrient digestibility or total VFA concentration compared with ATX, and did not change (P > 0.10) the degree of CH4 inhibition. However, A. nodosum did not mitigate (P > 0.10) any of the negative effects on fermentation associated with A. taxiformis, as nutrient digestibilities and N metabolism variables in AS+AT were also not different (P > 0.10) from ATX. While the macroalgae species, A. nodosum and A. taxiformis, led to different fermentation patterns when added individually to continuous culture fermentors, no negative or positive interactions were observed from their simultaneous addition.

Managing swine on pasture is increasing in popularity for both the consumer and producer. This interest appears to be driven by an effort to create an improved perception of environmentally sustainable practices and increased animal welfare, while keeping start-up costs low. However, evidence-based guidance on pasture management practices that support quality pork production and environmentally sustainable procedures is lacking. The objective of this work was to quantify the impact of pasture rearing on pig growth efficiency and pork quality. In this pilot study, 20 pigs similar in genetics, age, weight, and sex ratio were divided across indoor (n = 10) and Outdoor (n = 10) housing environments. Pigs were weighed every 14 d and harvested upon reaching an average weight of 113 kg. Average starting body weights were similar between both groups (P = 0.98). Carcass quality was evaluated by measuring pH, loin eye area (LEA), back fat (BF) thickness, subjective color and marbling scores, and colorimetry (CIE color space [L*, a*, b*]) at the 10th rib. Final body weights at slaughter also showed no significant variation between housing groups (P = 0.98). No differences were observed in pork quality: pH 0 h (P = 0.53), 6 h (P = 0.29), 12 h (P = 0.80), and 24 h (P = 0.07) postmortem, LEA (P = 0.44), color (P = 0.73), and marbling (P = 0.40). However, hogs raised indoors had an increase in BF thickness (P = 0.04). Based on this pilot study, outdoor rearing conditions did not have significant impacts on pork quality. Further research will help to determine the impact that rearing scheme has on pH and BF. The environment in which pigs are raised, whether indoors or outdoors, is colloquially believed to impact the quality of pork. Results of this study indicate that outdoor rearing conditions do not significantly affect pork quality, challenging conventional beliefs. Raising pigs on pasture is becoming more popular due to perceived environmental sustainability and improved animal welfare. However, there is a lack of guidance on how this impacts pork quality. When pigs of similar breed, age, and weight were raised indoors and outdoors, the study found no significant difference in the starting and final weights of the pigs from both groups. Similarly, there was no difference in the quality of the pork, as measured by pH levels, loin eye area, color, and marbling scores. Pigs raised indoors had slightly thicker back fat (BF). The study concluded that outdoor rearing conditions did not significantly affect pork quality, but may impact BF thickness.

The objective of this project was to evaluate the effect of interseeding cereal rye (Secale cereale) into corn (Zea mays) for use as grazed forage after corn grain harvest on corn grain yield and additional grazing day· ha-1. In a 4-year study, corn was planted (64,246 plants· ha-1) in spring on two, 4.8-ha fields in central Pennsylvania. Cereal rye was interseeded (135 kg· ha-1) into the corn at the V4-V6 stage. Corn was harvested as grain in November and each field was divided into six, 0.8-ha paddocks and randomly assigned to either grazed (GRAZ) or ungrazed (NG) treatments. Beef cattle frontal-grazed three of the paddocks (four cows· paddock-1) in each field approximately four to five weeks after corn grain harvest and, if re-growth allowed, again in early spring before subsequent corn planting. Corn grain, corn fodder (after grain harvest), and cereal rye yields were monitored each fall. Cereal rye growth was also monitored in early spring. Statistical analyses on corn grain yield and forage biomass were conducted using the MIXED procedure in SAS 9.4 (SAS Institute, Cary, NC, USA). Least square means were separated using Fisher’s least significant difference test (α = 0.05). There were no site by treatment interactions, therefore means are presented as an average across both sites (Table 1). Corn grain, corn stover, and cereal rye yields were affected by year. Corn grain yields did not decrease as a result of grazing, or of repeated plantings of corn, ranging from 9,516-10,088 kg· ha-1 across GRAZ and NG paddocks except in 2019 (dry year) when corn grain yields averaged 6,053 kg· ha-1 across both GRAZ and NG treatments. Spring grazing only occurred in one year (2021) due to insufficient cereal rye growth in the other years. On average, the cereal rye (plus the corn stover) provided enough forage for an additional 115-130 grazing days· ha-1 in the fall. Results of this study showed that when corn is harvested too late in the year to establish a cover crop, interseeding annual forages into growing corn provides winter ground cover and an opportunity for late season grazing. Interseeding cereal rye into the corn did not negatively impact corn grain yields with repeated corn planting. While early spring growth of the cereal rye has the potential to provide even greater forage yields than fall, it is much less dependable than fall due to the potential of delayed spring growth or lack of winter precipitation under the conditions of the current study.

Approximately 80% of agricultural CH4 comes from livestock systems, with 90% of that derived from enteric CH4 production by ruminants. Grazing systems are used worldwide to feed dairy cattle. Although quantifying enteric CH4 emissions in grazing systems has unique challenges, emerging technologies have made gaseous data collection more feasible and less laborious. Nevertheless, robust data sets on enteric CH4 emissions under various grazing conditions, as well as effective and economic strategies to mitigate CH4 emissions in grazing dairy cows, are still in high demand because data collection, feeding management, and milk market regulations (e.g., organic certification, grassfed) impose more challenges to grazing than confinement dairy systems. This review will cover management strategies to mitigate enteric CH4 emissions and applicability to pastoral dairy systems. The effects of enteric CH4 in the broader context of whole-system assessments will be discussed, which are key to assess the overall environmental impact of grazing dairies.

In much of the United States, wet springs often cause poor field conditions leading to harvest and/or grazing delays and subsequent reductions in forage nutritive value. The objective of this study was to compare monocultures and combinations of orchardgrass (Dactylis glomerata L.), chicory (Cichorium intybus L.), and white clover (Trifolium repens L.) to determine the effects of interspecies competition on plant maturity, nutritive value, and forage mass over two consecutive springs. It was hypothesized that shade and competition from chicory would delay orchardgrass maturity resulting in greater nutritive value and an extended harvest or grazing window for high-nutritive value forage. Mixtures containing chicory delayed orchardgrass maturity by at least 9 days in the first spring as compared to orchardgrass monocultures and orchardgrass-white clover mixtures. Even with decreased chicory mass in the second year (due to drought and winterkill), both 1:1:1 and 4:1:1 (ratio of seeds per hectare) orchardgrass-white clover-chicory mixtures provided greater forage mass and nutritive value (crude protein and net energy) yield over 2 years compared to an orchardgrass monoculture; however, only the 1:1:1 orchardgrass-white clover-chicory mixture provided greater benefits to forage mass and nutritive value yield when compared to orchardgrass-white clover mixtures that are commonly found on farms. This study showed that chicory inclusion provides benefits to orchardgrass and orchardgrass-white clover pastures when planted in appropriate seed proportions; however, increasing chicory longevity will require further investigation to provide continued benefits in perennial cool-season grass and legume pasture systems.

Introduction:There is a growing interest in utilizing seaweed in ruminant diets for mitigating enteric methane (CH4) emissions while improving animal health. Chondrus crispus is a red seaweed that grows in the Gulf of Maine (United States) and has shown to suppress CH4 production in vitro. Organic dairy producers in Maine are currently feeding seaweed due to herd health promoting benefits. However, large-scale adoption depends on technical and financial factors, as well as validation from pilot studies.Methods:A survey was developed to identify barriers and drivers towards the adoption of CH4-reducing algal-based feeds. Concurrently, a randomized complete block design study was conducted to investigate the effect of C. crispus on enteric CH4 emissions and milk production in a typical Maine organic dairy farm. Twenty-two organically certified Holstein and Jersey cows averaging 29 ± 6.8 kg of milk/d and 150 ± 69 days in milk, were blocked and randomly assigned to a control diet without C. crispus (0CC), or with 6% [dry matter (DM) basis] C. crispus (6CC). Samples were collected on the last week of the 2-wk covariate period, and wk 3, 5, 8, and 10 after initiation of treatments for a total of 12 weeks. Gaseous emissions were measured using a GreenFeed unit. Data were analyzed using the MIXED procedure of SAS with repeated measures over time.Results:All survey respondents (n = 35; 54% response rate) were familiar with seaweeds as feed, and 34% were already users. Producers who were willing to pay 0.64 USD/cow/d on average for a CH4-reducing algal-based feed, also stated the need for co-benefits in terms of cattle health and performance as a requirement for adoption. Feeding 6CC decreased enteric CH4 production by 13.9% compared with 0CC (401 vs. 466 g/d). Further, milk yield (mean = 27.1 kg/d), CH4 intensity (mean = 15.2 g of CH4/kg of energy corrected milk), and concentrations and yields of milk fat and true protein were not affected by treatments.Discussion:Producer receptiveness to CH4-reducing algal-based feeds will not only be dependent on purchase price, but also on co-benefits and simplicity of integration into existing feed practices. Feeding C. crispus at 6% of the diet DM decreased CH4 production in dairy cows by 13.9% without negative effects on milk yield and composition. Identifying the bioactive compounds in C. crispus is critical to understand the effect of this red seaweed on mitigating enteric CH4 emissions in dairy cows.

We evaluated the effects of incremental amounts of ground flaxseed (GFX) on diversity and relative abundance of ruminal microbiota taxa, enteric methane (CH4) emissions, and urinary excretion of purine derivatives (PD) in lactating dairy cows in a replicated 4 × 4 Latin square design. Twenty mid-lactation Jersey cows were used in the study. Of these 20 cows, 12 were used for ruminal sampling, 16 for enteric CH4 measurements, and all for spot urine collection. Each period lasted 21 d with 14 d for diet adaptation and 7 d for data and sample collection. Diets were formulated by replacing corn meal and soybean meal with 0%, 5%, 10%, and 15% of GFX in the diet's dry matter. Ruminal fluid samples obtained via stomach tubing were used for DNA extraction. Enteric CH4 production was measured using the sulfur hexafluoride tracer technique. Diets had no effect on ruminal microbiota diversity. Similarly, the relative abundance of ruminal archaea genera was not affected by diets. In contrast, GFX decreased or increased linearly the relative abundance of Firmicutes (P < 0.01) and Bacteroidetes (P < 0.01), respectively. The relative abundance of the ruminal bacteria Ruminococcus (P < 0.01) and Clostridium (P < 0.01) decreased linearly, and that of Prevotella (P < 0.01) and Pseudobutyrivibrio (P < 0.01) increased linearly with feeding GFX. A tendency for a linear reduction (P = 0.055) in enteric CH4 production (from 304 to 256 g/d) was observed in cows fed increasing amounts of GFX. However, neither CH4 yield nor CH4 intensity was affected by treatments. Diets had no effect on the urinary excretion of uric acid, allantoin, and total PD. Overall, feeding GFX decreased linearly the relative abundance of the ruminal bacterial genera Ruminococcus and Clostridium and enteric CH4 production, but no change was seen for CH4 yield and CH4 intensity, or urinary excretion of total PD, suggesting no detrimental effect of GFX on microbial protein synthesis in the rumen.

Enteric methane (CH4) emissions from ruminants are a significant contributor to total greenhouse gas emissions from the livestock sector. Previous research has demonstrated that the red seaweed Asparagopsis taxiformis strongly inhibits ruminal methanogenesis, but its effects on CH4 production, nutrient digestibility, and ruminal fermentation when added to a cool-season herbage diet have not been assessed. A 4-unit, single-flow continuous culture fermentor system fed orchardgrass (Dactylis glomerata L.) herbage was used to assess the effects of incremental addition of dietary A. taxiformis (0, 5, 10, or 15 g/kg DM) on nutrient digestibility, volatile fatty acid (VFA) concentration, pH, CH4 production, and N metabolism. Treatments were randomly assigned to fermentors in a randomized block design with 7 d of treatment adaptation and 3 d of sample collection. Fermentors were fed a total of 76 g of DM per day, split equally into 4 feedings (07:30, 10:30, 14:00, and 19:00 h). In the last 3 d of each experimental period, daily samples of total effluent were taken for analyses of ammonia N and VFA. One liter of effluent was collected daily (3 L total) for a composite sample that was blended and lyophilized for analysis of DM, ash, neutral and acid detergent fiber, crude protein, and total purines. Headspace CH4 concentration in each fermentor was measured every 15 min (192 readings/d) using a Fourier transform infrared gas analyzer, and pH was recorded every 2 min. Data were analyzed using the GLM procedure of SAS with orthogonal polynomial contrasts. Methane production in fermentors receiving all 3 levels of A. taxiformis was reduced by 99.9% within the first 24 h of each experimental period and remained predominantly below the limit of detection for the remaining 9 d. Apparent digestibility of neutral and acid detergent fiber, as well as apparent and true DM digestibilities, linearly decreased with A. taxiformis inclusion. Total VFA concentration decreased quadratically, and molar proportion of acetate decreased in a cubic manner. Overall, A. taxiformis acutely inhibited CH4 production in continuous cultures fed orchardgrass herbage, but also negatively affected fiber digestibility and total VFA concentration, especially at higher feeding rates. In vitro results indicated that A. taxiformis could be effective in reducing enteric CH4 production in grazing ruminants, but in vivo research is needed to determine how A. taxiformis may impact ruminal fermentation and milk production or average daily gain in grazing systems.

This study assessed how methods of inoculating continuous culture fermentors with rumen particulate digesta affected in vitro fermentation. A 4-unit, single-flow fermentor system was used in a 4x4 Latin Square with treatments arranged in a 2x2 factorial design. Dietary treatments were 1) a corn-silage-based total mixed ration (TMR) diet; and 2) an orchardgrass (Dactylis glomerata L.) and ground corn-based (ORG) diet balanced to support similar levels of milk production. Within each diet, two inoculation methods were used 1) direct addition of particulate digesta (32 g) into the fermentor vessel (-S); or 2) blending an equivalent quantity of particulate digesta with 0.5 L of rumen liquid for 2 minutes, straining through two layers of cheesecloth, and adding only the strained liquid to the vessel (-B). All fermentors were inoculated with identical total quantities of rumen liquid (1.5 L). This resulted in four treatments, ORG-S, ORG-B, TMR-S, and TMR-B, which were randomly assigned to fermentors with 7 d of treatment adaptation and 3 d of sample collection. Effluent samples (24-h composite) were collected on d 8-10, composited by fermentor within period, and analyzed for volatile fatty acids (VFA), and organic matter (OM) and crude protein (CP) for determination of nutrient digestibilities. Data were analyzed using a mixed model with period and treatment as fixed effects, and fermentor as a random effect. Preplanned contrasts were used to compare the effect of inoculation method within each diet, and the interaction between inoculation method and diet. Apparent OM digestibility was 16% greater in ORG-S compared with ORG-B (P < 0.01), whereas no effect of inoculation method was observed in the TMR diet (P = 0.36), which resulted in an interaction of diet and inoculation method (P < 0.01). Concentration of total VFA was greater with direct addition of particulate digesta in both diets, though there was a significant interaction of diet and inoculation method (P < 0.01) due to a greater increase in VFA in the ORG diet (34%; P < 0.01) compared with TMR (10%; P = 0.01). Crude protein digestibility tended (P = 0.06) to be greater in ORG-S vs. ORG-B, whereas inoculation method did not affect CP digestibility in the TMR diet (P = 0.58). Inoculation method affected methane production (mmol/d) only in the ORG diet; total methane production was 58% greater in ORG-S compared with ORG-B (P < 0.01), whereas methane production was not different in TMR-S vs. TMR-B (P = 0.76), leading again to an interaction of diet and inoculation method (P = 0.04). In general, adding particulate digesta directly to fermentor vessels increased feed degradation and methane production in the ORG diet, but had a lesser effect in the TMR diet.

Brassica plants play an important role in common agricultural practices, such as livestock feed or biofumigation, due to the bioactivity of the natural degradation products of glucosinolate metabolites. Therefore, the ability to survey comprehensive glucosinolate profiles for individual brassicas is essential for informing proper species selection for the intended application. Current methods for glucosinolate identification and quantification involve complex or unconventional procedures, and proper reference materials are not readily available. Therefore, researchers with limited resources that require glucosinolate profiles are at an extreme disadvantage. In this work, a simple and accurate HPLC-MS method was developed and validated to build preliminary glu-cosinolate profiles for three agriculturally relevant forage brassica varieties [turnip (B. rapa L.), canola (B. napus L.), and rapeseed (B. napus L.)]. The average glucosinolate content across three herbage collection dates for canola, rapeseed and turnip were 2.9 & PLUSMN; 0.9 mg g-1, 6.4 & PLUSMN; 1.3 mg g-1, and 14 & PLUSMN; 3.4 mg g-1, respectively. GLS concentrations are reported in milligrams of glucosinolate, calculated as sinigrin equivalents, per gram of dry plant material. This semi-quantitative approach for reporting total GLS content in brassicas is accurate within 15%. Several minor individual glucosinolates were identified that have not been previously reported in canola, rapeseed and turnip species, including glucotropaeolin and 4-hydroxyglucobrassicin (canola), glucoraphanin and glucoberteroin (rapeseed), and glucosinalbin and glucobarbarin (turnip). This non-targeted screen of several forage brassica varieties demonstrates the inherent variation in both the individual glucosinolate content and the total glucosinolate profile among brassicas, and highlights the importance of such glucosinolate characterization in agricultural practices. Additionally, the method developed in this study can be used as a tool for researchers with limited resources to build accurate glucosinolate profiles of brassica plants.