Multi-species Pasture Research Articles

Multispecies pasture diet and cow breed impacts on milk composition and quality in a seasonal spring-calving dairy production system

In recent years, there has been significant emphasis on the composition of pasture-based cow feed and the potential benefits of incorporating multispecies swards to improve sustainability and biodiversity. This study compared the effects of a conventional perennial ryegrass (PRG) monoculture supported by high chemical nitrogen (N) usage with a low chemical N application multispecies sward system (MSS) on the composition and quality of milk across lactation using spring-calving Holstein-Friesian (HF) and Jersey Holstein-Friesian (JFX) cows. Bulk milk samples (n = 144) were collected from each group at morning and evening milking on a weekly basis (n = 36) throughout lactation and analyzed for gross composition and physico-chemical properties. Cow breed had a significant impact on milk profile, with milk from HF cows having significantly smaller milk fat globule (MFG) size, higher instability index values, higher yield, and lower total solids levels, compared with JFX cows. Notably, HF cows had increased milk total solids and fat levels when fed on MSS, as opposed to the PRG-fed HF cows. Feeding MSS pasture increased creaming velocity values in mid and late lactation, and resulted in similar milk gross composition to PRG. In comparison to PRG, MSS-fed groups showed significantly increased total solids yield, including higher levels of protein and fat yield. In late lactation, MSS feeding was associated with reduced MFG size. All physicochemical properties studied (MFG size, creaming velocity, instability index) showed decreasing values from early to late lactation stage. Overall, these findings demonstrate the significant effects of cow diet, breed and stage of lactation on compositional and physico-chemical characteristics of milk, with important implications for milk processing and dairy product quality.

A short-term effect of multi-species pastures and the plant’s physiological response on pasture growth

Multi-species pastures that include species with dissimilar physiological responses to water restriction (i.e., dehydration avoidance) and species that have a greater soil water access (i.e., deep-rooted species), can buffer the reduction in summer growth experienced by more shallow-rooted species and can out-yield pastures with less capacity to access soil water. The aim of the present study was to evaluate the performance of multi-species pastures comprising both deep-rooted and shallow-rooted species, under grazing by sheep, in relation to pasture growth, the seasonal changes in pasture botanical composition, and the plants’ physiological responses to field conditions across the year. The evaluated pastures were: Bromus valdivianus (Bv); Lolium perenne + Trifolium repens (Lp); Plantago lanceolata (Pl); B. valdivianus + L. perenne + T. repens (grass mixture pasture, GM); and B. valdivianus + L. perenne + T. repens + P. lanceolata (complex mixture pasture, CM). Herbage mass, net photosynthesis, leaf water relations and soil water content (SWC) at 10, 40 and 70 cm soil depths were evaluated. The SWC fluctuation through the year was related to rainfall within each season, and differences between the treatments were taken as an indirect indicator of soil water access and soil water uptake by the roots. During the soil water restriction period, mixed pastures based on species that differed in their soil water access buffered the reduced growth rate of the sensitive species, due to a decrease in competition for water uptake within the deeper soil layer (CM pasture). A shift of dominance between species, as measured in the CM pasture, buffered the reduction in pasture growth rate seen in the monocultures. The Bv pasture, which is tolerant of water restriction, had a similar annual yield to the multi-species pastures (both GM and CM). The present study highlighted the capacity of the deep-rooted species (B. valdivianus and P. lanceolata) to avoid periods of soil water restriction by extracting water from deeper soil layers.

Impacts of grazing management strategies on forage canopy structure in multi-species pastures during the wet-dry transition period

The condition of pastures during the wet-dry transition period reduces livestock production since there is an increase in dead material and a reduction in green tissues. This study evaluated the influence of grazing management strategies on the structure of the forage canopy during the wet-dry transition period. The pastures were composed of Aruana guineagrass (Megathyrsus maximum Syn. Panicum maximum cv. Aruana) and three legumes: Macrotyloma (Macrotyloma axillare), Calopo (Calopogoinum mucunoides), and Stylo (Stylosanthes macrocephala + Stylosanthes capitata). The treatments corresponded to four forage canopy heights (15, 30, 45, and 60 cm), and the grazing management strategies involved steady or variable stocking rates with sheep. The experiment was conducted in a randomized complete block design with four replications totaling 16 experimental units (paddocks). The masses of grass leaf blades and stems were higher at heights of 45 and 60 cm (P = 0.002), while the proportion of dead material was smaller in these than in the short pastures (15 and 30 cm) (P = 0.0497). There was an increase in the proportion of dead material over the dry-water transition period. The presence of grass and legume leaves was higher in the upper stratum of tall pastures (45 and 60 cm) and the proportion of legumes did not differ between grazing management strategies (P > 0.05). These strategies were represented by canopy heights of 45 to 60 cm and showed more leaf mass, less dead material, and better pasture structure, so these parameters can be used during the wet-dry transition period.

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>

Canopy height impact on legume mass and Megathyrsus maximus tiller dynamics in mixed pastures

ABSTRACT The use of grazing management strategies can influence canopy structure and the permanence of legumes. The objective of this work was to evaluate the determination of forage canopy heights as a grazing management strategy regarding herbage mass composition and tiller population dynamics in multispecies pastures comprising Megathyrsus maximus cv. Aruana and the legumes Macrotyloma axillare, Calopogonium mucunoides and Stylosanthes spp. Four treatments, defined by canopy heights of 15, 30, 45 and 60 cm, were evaluated in a randomised block design with four replications. The evaluations were performed under continuous stocking with sheep. Taller pastures (45 and 60 cm) contained greater (P < 0.05) total herbage mass of Aruana leaves and stems and also higher mass of legumes than smaller pastures (15 and 30 cm). The grass tiller population density was different between heights (P < 0.05) of 2.71, 2.02, 1.97 and 1.47 tillers/m2 for heights of 15, 30, 45 and 60 cm, respectively. The tiller appearance rate was highest in tall pastures (P < 0.05) and the lowest rate and stability index were found in 15 cm pastures. Aruana guineagrass and forage legumes can be managed in the height range of 30–60 cm under continuous stocking.

Fatty Acid, Carotenoid and Fat-Soluble Vitamin Composition of Multispecies Swards Grown in Ireland—Implications for a Sustainable Feed in Dairy Farming

Although traditional ryegrass pastures are still commonly used, they require intense management and input and do not perform well during the summer months. Multispecies systems have been recognised as more sustainable, needing less fertiliser and being tolerant to drought and heat. While data on monoculture system fat composition exist, information for multispecies is scarce. The present study compared the fatty acid (FA), carotenoid and fat-soluble composition of a multispecies system (consisting of perennial ryegrass, timothy, white clover, red clover, chicory and plantain) (MULTI) with two other conventional grazing systems (monoculture perennial ryegrass (PRG) and a binary mixture of perennial ryegrass and white clover (PRG+WC)) over the Irish late-summer grazing season of dairy cattle (July–September). The results showed that the three systems had similar levels of FAs (p &gt; 0.05), with mean α-linolenic acid values of 20.00 mg/g in PRG, 18.51 mg/g in PRG+WC, and 17.90 mg/g in MULTI and mean linoleic acid values of 3.84 mg/g in PRG, 4.16 mg/g in PRG+WC, and 4.39 mg/g in MULTI. Fourfold and twofold increases in the concentrations of α-linolenic acid and linoleic acid, respectively, were observed throughout July–September. Variations in stearic acid concentrations were not significant (p &gt; 0.05), and palmitic acid concentrations increased over time (p &lt; 0.05). The average values of lutein (36.68 mg/kg in PRG, 31.26 mg/kg in PRG+WC, and 35.75 mg/kg in MULTI) and α-tocopherol (2.28 mg/kg in PRG, 1.49 mg/kg in PRG+WC, and 1.83 mg/kg in MULTI) were similar among the grazing systems (p &gt; 0.05), and the average β-carotene value was 25% higher in monoculture ryegrass (140.74 mg/kg) than in the multispecies (102.51 mg/kg) (p &lt; 0.05). Nonetheless, the levels of β-carotene found in the multispecies were still above the recommended intake required for ruminants. In conclusion, multispecies pastures could be included in dairy cattle production systems as a sustainable alternative to traditional pastures while also providing typically adequate sources of fats for animal diets.

Understanding Animal-Plant-Parasite Interactions to Improve the Management of Gastrointestinal Nematodes in Grazing Ruminants.

Grazing systems have great potential to promote animal welfare by allowing animals to express natural behaviours, but they also present risks to the animals. Diseases caused by gastrointestinal nematodes are some of the most important causes of poor ruminant health and welfare in grazing systems and cause important economic losses. Reduced growth, health, reproduction and fitness, and negative affective states that indicate suffering are some of the negative effects on welfare in animals infected by gastrointestinal nematode parasitism. Conventional forms of control are based on anthelmintics, but their growing inefficiency due to resistance to many drugs, their potential for contamination of soil and products, and negative public opinion indicate an urgency to seek alternatives. We can learn to deal with these challenges by observing biological aspects of the parasite and the host's behaviour to develop managements that have a multidimensional view that vary in time and space. Improving animal welfare in the context of the parasitic challenge in grazing systems should be seen as a priority to ensure the sustainability of livestock production. Among the measures to control gastrointestinal nematodes and increase animal welfare in grazing systems are the management and decontamination of pastures, offering multispecies pastures, and grazing strategies such as co-grazing with other species that have different grazing behaviours, rotational grazing with short grazing periods, and improved nutrition. Genetic selection to improve herd or flock parasite resistance to gastrointestinal nematode infection may also be incorporated into a holistic control plan, aiming at a substantial reduction in the use of anthelmintics and endectocides to make grazing systems more sustainable.

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&lt;0.05), and forage production was similar between mixtures (P&gt;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&lt;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.

Fate of fertiliser nitrogen in a ryegrass–kikuyu dairy pasture system

Context Dairy pasture production is reliant on fertiliser to supply nitrogen (N); however, fertiliser N-use efficiency (FNUE) is low and N can be lost to the environment. Aims The aim of this study was to track the fate of N fertiliser applied in a pasture system of ryegrass (Lolium multiflorum, temperate grass) oversown into kikuyu (Pennisetum clandestinum, tropical grass). Methods We used 15N-labelled urea to track the residual plant uptake of a one-off application of 15N over three pasture cuts subsequent to the first cut in the kikuyu growing season from February 2018 to April 2018 (Experiment 1), followed by total soil and plant recoveries of 15N over a 12-month period (Experiment 2). Total N treatment rates were 0, 120, 240 and 480 kg N ha−1 year−1, consisting of application events of 40 kg N ha−1. In Experiment 1, 15N was applied only at the first fertilisation, whereas in Experiment 2, 15N-labelled urea was applied at each fertilisation event. Key results In Experiment 1, uptake of residual 15N fertiliser in the pasture biomass was &lt;6%. In Experiment 2, FNUE was 29–32% and unaccounted 15N fertiliser was 22–142 kg N ha−1, across the 120, 240 and 480 kg N ha−1 year−1 treatments. Conclusions Recovery of 15N residual fertiliser did not increase with N rate and was attributed to the mass increase in soil 15N recovery. FNUE in the pasture did not decrease with N rate. Unaccounted 15N increased with N rate. Implications Existing and alternative N and pasture management strategies such as clover and multi-species pasture need to be implemented and explored to reduce the amount of unaccounted N in dairy pasture production.

Seasonal effects reveal potential mitigation strategies to reduce N2O emission and N leaching from grassland swards of differing composition (grass monoculture, grass/clover and multispecies)

Multispecies pastures containing grasses, N-fixing legumes and forage herbs can maintain high herbage dry matter (DM) yield, while reducing the need for fertiliser N inputs thus potentially reducing harmful N losses such as nitrous oxide (N2O) emission and nitrate (NO3−) leaching to the wider environment. However, our understanding of these processes in grassland swards of contrasting composition is still very limited. A lysimeter experiment was carried out over 12 months to test the hypotheses that (1) cumulative and (2) seasonal N2O emission and N leaching would be highest from the Perennial Ryegrass only (PRG, 250 kg N ha-1 yr-1) treatment compared to three other treatments; Perennial Ryegrass and Low White Clover (PRG+LWC, 90 kg N ha-1 yr-1), Perennial Ryegrass and High White Clover (PRG+HWC, 0 kg N ha-1 yr-1) and Perennial Ryegrass, White Clover and Ribwort Plantain (PRG+WC+P, 45 kg N ha-1 yr-1) and (3) that the soil N cycling pathways (nitrification/denitrification) linked to these N losses would be different between treatments. Cumulative N2O emissions (2.74–3.25 kg N2O-N ha-1), leached N (10.91–13.70 kg N ha-1), DM yields (5083–5493 kg DM ha-1 yr-1) and N uptake (122–169 kg N ha-1 yr-1) were not significantly different between treatments. Nitrogen yield scaled N2O emissions were significantly lower from all other treatments compared to the high fertiliser N input PRG monoculture. A significant interaction between treatment and season showed that in Spring, N2O emission was significantly higher from PRG (1.39 kg N2O-N ha-1) and PRG+LWC (1.19 kg N2O-N ha-1) than PRG+HWC (0.81 kg N2O-N ha-1) and PRG+WC+P (0.85 kg N2O-N ha-1). This result was linked to a numerically lower fraction of nitrification (FN) for PRG+WC+P potentially indicating that biological nitrification inhibition associated with ribwort plantain could lessen N2O emissions. This study demonstrates some of the environmental benefits of grassland management systems that require less intensive chemical fertiliser N input.

Impact of diversification and intensification of crop rotation (DICR) in soil bacterial microbiota in on-farm study after four and seven years

No-till agricultural diversification and intensification of crop rotations (DICR) effects on soil biological properties were studied in an on-farm study. DICR stands for increasing soil cultivation period and consequent reduction of fallow times by using different winter and summer crops, including cover crops, in two and three-year rotation schemes. Five different levels of DICR were tested -typical local rotation, intermediate rotation, high intensification with grasses, high intensification with legumes, and a continuous multispecies pasture-, and replicated at three different agricultural farms situated in the Argentinean Pampa. The soils were analyzed at four and seven years after DICR started. The on-farm studies were established at each site in a plot of ca. fifty hectares with a typical local rotation history and evaluated after four and seven years of changes. The impact on prokaryotic soil communities was measured by 16S rRNA gene sequencing. Overall, the sustained DICR showed a progressive effect with reduced Bray-Curtis dissimilarities at second sampling. At the phylum level, Actinobacteria, Bacteroidetes, Verrucomicrobia, BCR1, and WS3 increased with the level of DICR while Acidobacteria, Firmicutes, Gemmatimonadetes, OD1, and TM7 showed the opposite trend. Selected taxa based on LEfSe detection were associated with typical historical rotation after the four years and pasture after the seven years, expressing the cumulative effect of DICR. Bacterial communities' structures were associated with plant stubble and crop yield. Understanding how more sustainable practices such as DICR shift the soil microbiota can assist in designing agricultural systems that increase soil health, C sequestration, and crop yield.

Ecological restoration of biodiversity and forage productivity of degraded pasture ecosystems in the Central Asian Desert

The low productivity of pastures and its sharp fluctuations in the desert regions of Central Asia are due to the natural-historical factors of this natural zone. However, in recent years, these shortcomings of pastures have been further aggravated as a result of the rapid growth of the population, the continuous development of industry and transport in desert areas, and the pressure of anthropogenic and man-made factors on vegetation and soil is increasing from year to year. This caused disruption of the structure and normal functioning of pasture ecosystems, and their degradation. Mass degradation of pasture ecosystems in arid regions of Central Asia occurs in a short time, which dictates the need for environmental restoration of these destroyed pasture lands. The United Nations General Assembly, by resolution 73/284, adopted at the 69th plenary meeting on March 1, 2019, decided to proclaim 2021-2030 as the "United Nations Decade for the Restoration of Degraded Ecosystems" and called on UN member states to help strengthen political will, mobilize available resources, strengthening scientific studies on ecosystem restoration at the global, regional, national and local levels. To restore the lost biodiversity of the forage productivity of degraded pasture ecosystems in the Central Asian Karnabchul Desert, dominant species of forage plants were sown in the following ratio: Haloxylon aphyllum (15 %), Halothamnus subaphyllus (20 %), Artemisia diffusa (50 %) and Poa bulbosa (15 %). The conducted studies allow to conclude that use of zonal-typical life forms of dominant species of forage plants and sowing of their mixtures (combinations) ensures formation of multi-species multi-level pasture ecosystems with high and stable forage productivity over the years in the Central Asian desert. The restored multi-level and multi-species pasture ecosystems are endowed with the property of self-renewal and self-maintenance of the structural and functional organization. The restored multi-species shrub-semi-shrub-herbaceous pasture ecosystems with a characteristic set of species inherent in natural pasture communities are characterized by high stable forage productivity and perform a conservation function in the Central Asian desert.

Plant diversity with species drilled in the same or alternate rows enhanced pasture yield and quality over 4 years

This paper reports on the effects of plant species diversity and sowing method on pasture yield and quality. Nineteen seed mixtures of perennial ryegrass (PR), plantain (Pl), white clover (WC) and red clover (RC) were sown on 26 March 2015 at Lincoln University. Four mixtures of PR, Pl and WC were repeated with species separated in alternate drill rows. Plots were grazed by sheep and irrigated. After 4 years, a mixture with 25% of each species based on seed count – equivalent to 7.5 kg PR, 5.6 kg Pl, 1.9 kg WC and 4.4 kg RC (19.4 kg total seed)/ha – produced an optimal balance of increased total yield (17.44 t DM/ha/yr), weed suppression (0% of total yield), metabolisable energy (11.4 MJ/kg DM) and crude protein (19% of DM). Sowing method had no effect. Plant diversity enhanced pasture production through positive interactions and identity effects among the legumes (WC and RC) and non-legumes (PR and Pl). The strength of interactions between species depended on the identity and relative abundances of the species involved. The diversity effects occurred alongside shifts in species relative abundances over time. This study demonstrated an experimental basis for the evaluation of multi-species pasture mixtures.

The effect of feeding whole-crop barley or black oat silage in the fatty acid content of milk from cows in small-scale dairy systems in the highlands of Mexico.

Diets have an important effect on the fatty acid (FA) content in milk from dairy cows so that feeding strategies may modify the FA profile. There is little information on the fatty acid contents of whole-crop barley (BLY) and black oat (BKO) silages and on milk from cows fed these silages that are an alternative forage for small-scale dairy systems (SSDS). Given the growing interest in foods with favourable health attributes, the objective was to identify the FA content of milk from dairy cows fed whole-crop BLY and BKO silages in small-scale systems. Three inclusion levels of BLY and BKO silage were assessed in nine lactating cows at pasture for 8h/day and supplemented with 4.6kg/DM/cow/day commercial concentrate. Treatments were BLY: 10kg DM/cow/day BLY silage; BKO: 10kg DM/cow/d BKO silage; and BLY/BKO: 5kg BLY and 5kg DM/cow/d BKO silages (50:50). A 3 × 3 Latin square design repeated three times with nine cows and 14-day periods was utilised. Variables evaluated were the content of fatty acids present in feeds and milk. Contents of linoleic (C18:2n-6) and linolenic (C18:3n-3) acids, as precursors of polyunsaturated fatty acids, were 46 in BLY and 50 BKO g/100g, lower than for multispecies pasture (61g/100g). There were statistical differences in the content of short-chain fatty acids in milk (P < 0.05), being lower for BLY (18.9g/100g) compared with BKO (20.4g/100g) and BLY/BKO (20.6g/100g), the saturated fatty acids and linoleic acid (C18:2n-6c) were higher in BLY/BKO in relation to BLY and BKO. Content of health-promoting polyunsaturated fatty acids in milk was higher in BLY/BKO (P < 0.05). There were no differences (P < 0.05) in the atherogenic index, with values within reports. Small-grain cereal forages may produce milk with a favourable fatty acid content for human health.

Multi-species pastures for grazing dairy cows in small-scale dairy systems in the highlands of Mexico.

Grazing in small-scale dairy systems reduces costs and enhances sustainability. However, binary pastures (BP) have low persistency, which may be increased by including more species given their flexibility to withstand different agroecological and management situations. The objective was to assess a multi-species (MS) pasture of perennial ryegrass (RG), tall fescue (TF), bromegrass (BG), red clover (RC) and white clover (WC) in comparison to a BP of perennial ryegrass (RG) - WC grazed by six Holstein dairy cows during the dry season in an on-farm double cross-over experiment, with three 14-day each experimental periods for animal variables, and a split-plot design for pasture variables at 3 cow/ha. There were differences (P < 0.05) between pastures for sward height (MS 5.0 vs. BP 4.0 ± 0.10cm, both MS and BP) and net herbage accumulation (MS 902 vs BP 228 ± 172.4kg DM/ha, both MS and BP) and differences (P < 0.05) for chemical composition among periods. There were differences (P < 0.01) among periods for estimated DM intake, but no differences (P > 0.05) for milk yield (mean 16.8kg/cow/day), milk fat or protein content (mean 31.8 and 28.8g/kg). Multi-species pastures are a viable alternative for SSDS in the highlands of central Mexico, being more resistant to harsh environment and to weed and kikuyu grass invasion.

Ecosystem Impacts and Productive Capacity of a Multi-Species Pastured Livestock System

Regenerative agriculture is a newly codified approach to agriculture that emphasizes reducing reliance on exogeneous inputs, as well as restoring and enhancing ecosystem services such as soil carbon (C) sequestration. These regenerative agriculture principles suggest that modern livestock systems can be redesigned to better capitalize on animals' ecological niche as biological up cyclers and may be necessary to fully regenerate some landscapes. One example is a multispecies pasture rotation (MSPR) system, which symbiotically stacks multiple animal production enterprises (i.e., chickens, cattle, sheep, and pigs) on one landscape. We conducted a whole-farm life cycle assessment (LCA) of an MSPR in the southeastern United States that was originally converted from degraded cropland. We compared the production outputs, greenhouse gas (GHG) emissions, land footprints, and soil health outcomes to a conventional, commodity (COM) production system of each respective species. Our 20-year MSPR chronosequence of soil C and other soil health indicators shows dramatic improvement since establishment, sequestering an average of 2.29 Mg C ha−1 yr−1. Incorporation of soil C sequestration into the LCA reduced net GHG emissions of the MSPR by 80%, resulting in a footprint 66% lower than COM. However, when comparing required land between the two systems for food production, MSPR required 2.5 times more land when compared to COM. Thus, while our model indicates that MSPR can simultaneously produce protein while regenerating land, a considerably greater land area is needed when compared to COM. Our results present an important yet paradoxical conclusion on land and food production balance. Should society prioritize an input-intensive, COM system that produces more food from a smaller yet degrading land base? Or, alternatively, should systems such as MSPR that produce less food on a larger, but more ecologically functional landscape be more highly prioritized? These complexities must be considered in the global debate of agricultural practice and land. Our results indicate MSPRs are a useful model for alternative livestock production systems with improved environmental outcomes, but in this study may present considerable land-use tradeoffs.

Estimating pasture species biomass from canopy cover

AbstractMany tools are available to measure total aboveground plant biomass in pastures, for instance the rising plate meter, but measuring the biomass contribution of individual species requires time‐consuming clipping and sorting. Pasture composition determines forage quality, carbon storage, and other ecosystem services, so an efficient nondestructive method for estimating biomass by species would be of great value. Seasonal allometric coefficients relating canopy cover to aboveground biomass were developed for individual species and for functional groups (grass, large forb, small forb) using ordinary least squares regression on data from a grazed multi‐species experimental pasture in Pennsylvania, and tested on an independent grazed experimental study. The models performed better in autumn than in spring, although performance varied greatly among species. The functional group models were generally more accurate than species‐specific models, even for estimating single species. Total grass and forb biomasses were predicted moderately well regardless of season. Unlike many allometric models, these were developed and tested on multiple years of data from grazed multispecies pastures. Although variability was high, the results have broad applicability in highly fertile mesic pastures, at least for dominant species.

Two examples of application of ecological modeling to agricultural production: Extensive livestock farming and overyielding in grassland mixtures

Livestock production plays an important role in guaranteeing food security worldwide and has an important contribution to the economy of many countries. Precision livestock production (PLP), or the manipulation of livestock activity taking into account the different components of agroecosystems −pastures, cattle and pasture-cattle interactions−, has acquired growing importance in recent years to optimize productivity. Regarding the pasture component, multi-species pasture mixtures are commonly used worldwide to increase primary productivity and thereby secondary productivity.Here we present two examples of how the combination of experimental research and quantitative modelling can help to the development of protocols for food production optimization. The first example is based on a model we are currently developing for the whole agroecosystem in terms of a predator-prey dynamical system. The second example focuses on the pasture component and is based on a generalized Lotka-Volterra model we recently proposed for describing the mixture of herbaceous species in the pasture. We discuss the usefulness of both models, whose parameters were estimated from experiments or field work, as quantitative predicting tools. Population dynamic models are the common thread in this paper.

Milk yield and nitrogen excretion of dairy cows grazing binary and multispecies pastures

AbstractThree grazing experiments were carried out in late spring (early lactation), summer (mid‐lactation) and autumn (late lactation) to compare the effects of perennial ryegrass cultivar or grass species, sown in binary or multispecies mixtures, on milk yield and nitrogen excretion of dairy cows. Replicated groups of multiparous Holstein Friesian × Jersey cows were offered either a control or high‐sugar perennial ryegrass (Lolium perenne) or tall fescue (Festuca arundinacea) base grass in a binary mixture with white clover (Trifolium repens) or in a multispecies mixture with additional legumes, bromegrass (Bromus willdenowii) and forbs. During each 9‐day experiment, botanical composition, milk production and faecal and urine composition were measured. Milk solid (MS) yield for the control ryegrass, high‐sugar ryegrass and tall fescue grass types averaged, respectively, 1.53, 1.64 and 1.70 kg MS cow−1 day−1 for a binary mixture sward, compared with 1.65, 1.54 and 1.53 kg MS cow−1 day−1 for a multispecies sward. Legume content influenced milk production more than the number of species present in a mixture. There was lower urine N concentration from a multispecies sward compared with a binary mixture. Urine N concentration of cows grazing the control ryegrass, high‐sugar ryegrass and tall fescue grass types averaged, respectively, 4.6, 5.3 and 6.8 g N L−1 for a binary mixture, compared with 4.1, 3.9 and 3.9 g N L−1 for a multispecies mixture. Feeding dairy cows on multispecies swards containing forbs presents an opportunity to reduce N losses without compromising milk yield.

Intercropping black oat (Avena strigosa) and annual ryegrass (Lolium multiflorum) can increase pasture leaf production compared with their monocultures

Multi-species pastures have been viewed as a means to increase forage production relative to monocultures through enhanced three-dimensional occupation of the canopy, which will intercept and use the incident radiation more efficiently. For this to occur, increased production of photosynthetically active tissues such as leaves is required. We tested the hypothesis that intercropping of black oats (Avena strigosa Schum.) and annual ryegrass (Lolium multiflorum Lam.) can increase total and leaf forage production compared with their monocultures. Monocultures and mixed pastures of black oat and annual ryegrass were established, and their tiller morphogenetic and structural traits, as well as components of herbage production, were measured throughout the usage period of the pastures. There was no difference between treatments for total growth rate (77.1 kg dry matter (DM) ha–1 day–1), but annual ryegrass pastures presented the greatest stem growth rate (38.1 kg DM ha–1 day–1). Taking into account only the vegetative phase, the intercropped pasture produced 20% more leaf than the monocultures. There were no differences between species, either in monoculture or intercropped, for phyllochron, final leaf length, leaf elongation duration and leaf elongation rate. The most important modification in morphogenetic variables due to the inter-specific competition was an increase in senescence rate of annual ryegrass leaves. The average specific green leaf weight in the intercropping pastures corresponded to 84.6% and 137.5% of those values observed for black oat and annual ryegrass pastures, respectively. On the other hand, the intercropping pastures presented 43.5% more tillers than the black oat pastures and 17.8% fewer tillers than the annual ryegrass pastures. It is suggested that intercropping black oat and annual ryegrass does not change tiller ontogenetic processes and that the association of their different size and shape in intercropped pastures could increase pasture leaf production over their monocultures.