Rotational Stocking Research Articles

A new perennial forage module coupled with the ECOSMOS terrestrial ecosystem model: Calibration and evaluation for Urochloa (syn. Brachiaria) brizantha

Pastures represent the main land use type in Brazil and are used for livestock production and maintenance of land ownership. Most pasture areas exhibit signs of degradation related to inadequate management, which affects pasture biomass production. Terrestrial ecosystem models are effective tools for evaluating the economic and ecological returns associated with distinct management scenarios. In this paper, a new forage module implemented in the ECOSystem MOdel Simulator (ECOSMOS) is formulated, and ECOSMOS-Forage model calibration and evaluation results were obtained for estimating tropical forage growth under continuous and rotational stocking methods subject to grazing or cutting regimes. A set of equations to simulate the daily carbon allocation, growth, senescence, and morphological characteristics of Urochloa (syn. Brachiaria) brizantha cvs. Marandu and Piatã were proposed. Biophysical and physiological parameters, including the solar radiation balance, soil water content, evapotranspiration and carbon assimilation, were calibrated and evaluated with one micrometeorological experiment. Additionally, two sets of parameters were calibrated for Marandu grass growth under continuous and rotational stocking. Based on the Marandu parameterization, a third set of parameters, thereby adjusting a few parameters, was derived for the Piatã grass under rotational stocking. The ECOSMOS-Forage model could successfully capture the energy, carbon and water fluxes and biomass dynamics during growth cycles. The net radiation, evapotranspiration and gross primary production were simulated with agreement index (d) values of 0.97, 0.89, and 0.95, respectively, during the calibration phase and 0.98, 0.90, and 0.93, respectively, during the evaluation phase. Regarding model application to simulate forage growth under rotational stocking, the model could estimate aboveground, leaf and stem dry matter accumulation levels with d values ranging from 0.91 to 0.98. Although forage growth is relatively difficult to simulate, compared with annual crops, the results suggested that the model could provide high potential for simulating tropical perennial forage grasses.

Potential of integrated trees-pasture-based systems for GHG emission mitigation and improving soil carbon dynamics in the Atlantic forest biome, Southeastern of Brazil

Brazilian cattle production is mainly carried out in pastures, and mitigating the livestock's greenhouse gas (GHG) emissions has become an essential prerequisite. The importance of planted forests in beef cattle pasture-based integrated systems has been widely recognized in the context of GHG emission mitigation. Adopting the intensification and integration with forest and crops of pasture-based livestock production systems are alternatives to optimizing the soil and tree carbon (C) sequestration; however, research on tropical conditions is still necessary. This long-term trial evaluated the potential of C sequestration (soil + trees) of the forest and the grazing systems with two replicate areas of 3 ha each: 1. continuous stocking rate (CLS) – pasture under continuous stocking; 2. agropastoral or crop-livestock system (AGROP) – pasture under rotational stocking in rotation with corn; 3. agrosilvipastoral or crop-livestock-forestry system (AGROSIL) - similar to AGROP but including eucalyptus; 4. silvipastoral or livestock-forestry system (SIL) - pasture under rotational stocking + eucalyptus and 5. Atlantic Forest (FOR). Soil samples were analysed for texture, C and bulk density in eight soil layers from three to eight trenches for each treatment, then C stock and C accumulation rates were calculated. Data from Eucalyptus urograndis of the SIL and AGROSIL systems with 333 trees. ha−1 during five first years and 166 trees. ha−1 in subsequent years were collected (five- and eight-years old trees) and used to define the wood volume and acquire wood rings. Elemental analyzer CHN performed soil and trees C content. Equations for determining stem volume and tree biomass and, afterward, the C pools of the tree trunks were proposed. The potential of GHG emission mitigation (t CO2 e.. ha−1. year−1) by annual C sequestration (soil or soil + trees) was calculated, including the wood used for the lumber-mill scenario. The participation of the C stock from the 0–30 cm soil layer was between 45 % and 53 % of the total C stock in the 0–100 cm soil layer. Regardless of the elevated C soil accumulation rates, 0.88, 2.54, and 1.74 t C. ha-1. year−1 in the conversion stages CLS → AGROP; AGROP → SIL; AGROP → AGROSIL, respectively, it was not possible to compensate for the negative result of the Forest → CLS conversion (-2.55 t C. ha-1. year−1) because this stage lasted 12 years, while the implementation of AGROSIL and SIL systems had only six years. However, when C tree accumulation rates were considered, the potential of GHG emission mitigation (t CO2 e. ha−1. year−1) by annual C sequestration (soil +trees) was 19.89 to AGROSIL and 18.97 to SIL, including the wood used for the lumber-mill scenario. Based on these results, it can be concluded that C sequestration in trees-pasture integrated systems occurs in layers deeper, with the diverse species contributing in different soil layers; there is a positive effect of improved land-use management, with the use of integrated systems on annual C soil sequestration and the trees consists of an important strategy to improve the GHG mitigation.

Forage accumulation, nutritive value, and grazing efficiency on rotationally stocked ‘Zuri’ guineagrass pastures as affected by pre‐graze canopy height and N rate

AbstractGrazing management and nitrogen fertilisation may affect forage accumulation (FA), nutritive value, and grazing efficiency (GE) of the highly productive ‘Zuri’ guineagrass [Megathyrsus maximus (Jacq.) B.K.Simon & S.W.L. Jacobs syn. Panicum maximum Jacq.]. The objective of this study was to assess the effects of pre‐graze canopy heights [55 and 75 cm (H55 and H75, respectively)] and N fertilisation rates [150 and 300 kg N ha−1 year−1 (N150 and N300, respectively)] on FA, GE, grazing losses (GL), and nutritive value of Zuri under rotational stocking. The stubble height was 50% of the pre‐graze canopy height. The total FA was 20% greater under H75 than H55 (22,120 vs. 18,370 kg DM ha−1 year−1), as well as the GL was greater under H75 (85%) than under H55 (79%). Regardless of pre‐graze height, the upper stratum of the canopy was composed mostly of leaves contributing to similar crude protein (CP) (142 g kg−1) and in vitro digestible organic matter (IVDOM) (559 g kg−1) concentrations. Greater N rate (N300) increased FA (23,500 vs. 16,980 kg DM ha−1 year−1) and resulted in greater GE (84% vs. 80%) compared to N150. The CP and IVDOM concentrations under N300 (157 and 571 g kg−1, respectively) were greater than under N150 (128 and 547 g kg−1). Zuri guineagrass grazed at H75 has great FA and GE, maintaining a similar forage nutritive value compared to H55.

Native forbs interseeded into native grass pastures persist under grazing

AbstractIncorporating native forbs within native warm‐season grass (NWSG) pastures has the potential to benefit cattle, pollinators, and wildlife beyond that of NWSG monocultures. However, when grazing NWSG pastures, rotational stocking is recommended as opposed to continuous stocking. Therefore, to evaluate whether within‐season rest is needed for native pasture sustainability, two NWSG grazing experiments were conducted near Greeneville, TN, 2017–2020, to assess the persistence of native forbs when an 11‐species native forb blend was interseeded into established switchgrass (SG; Panicum virgatum L.) and big bluestem/indiangrass (BBIG; Andropogon gerardii Vitman and Sorghastrum nutans (L.) Nash) pastures. Each experiment was a completely randomized design with four replicates of each within‐season rest grazing treatment (no rest, early rest, middle rest, late rest, and no graze). Within‐season rest was not influential for NWSG tiller density or total forb plant density thus indicating persistence of forbs may not require rotational stocking. Purple prairie clover (Dalea purpurea Vent.) did not establish while Illinois bundleflower (Desmanthus illinoensis (Michx.) MacMill. ex B.L. Rob. & Fernald) was only observed flowering once despite having the greatest seeding rate among forbs. Based on establishment and flowering of the 11 species in the current mixture, interseeding a 6‐species polyculture of black‐eyed Susan (Rudbeckia hirta L.), dixie ticktrefoil (Desmodium tortuosum (Sw.) DC.), eastern purple coneflower (Echinacea purpurea (L.) Moench), lanceleaf coreopsis (Coreopsis lanceolata L.), Maximilian sunflower (Helianthus maximiliani Schrad.), and oxeye sunflower (Heliopsis helianthoides (L.) Sweet) could allow for plant biodiversity while offering floral resources for pollinators during the NWSG grazing season.

Eco‐efficiency of leys—The trigger for sustainable integrated crop‐dairy farming systems

AbstractThe specialisation of agricultural systems in Western Europe and the intensification of livestock and cropping production are intrinsically linked to substantial resource inputs. This intensified approach frequently leads to nutrient surpluses and biodiversity loss, resulting in detrimental environmental impacts. A transformative agricultural shift is imperative in light of climate and environmental protection objectives. Addressing this need, the Lindhof eco‐efficient pasture‐based milk production initiative, initiated in 2016, is a tangible manifestation of a productive and profitable dairy system integrated within a ley‐based Integrated Crop‐Livestock System (ICLS). Operational at the organically managed Lindhof farm, this approach involves a rotational stocking system of spring‐calving Jersey cows stocked on grass‐clover‐herb leys embedded within a cash crop rotation. The dairy cows benefit from these highly productive swards, rich in nutritive value comparable to concentrate feeding. At the same time, the cultivated crops derive advantages from the legacy effect of leys due to nutrient exchange facilitated by grazing excreta and residual crop matter. Compared to specialised systems, the ley‐based ICLS emerges as an alternative dairy production paradigm that supports many ecosystem services – including minimised nutrient losses, a lower carbon footprint and positive contributions to agro‐biodiversity. These outcomes are realised without compromising overall land‐use efficiency while reducing environmental and social costs of 20–30 Eurocent per kg of milk produced compared to specialised systems. Thus, the ley‐based ICLS conforms to the principles of ecological intensification, enhancing functional diversity within the agricultural landscape. Essentially, the Lindhof initiative represents a holistic and environmentally responsible approach to farming that could contribute to realising the EU Farm to Fork Strategy.

Effects of grazing management and concentrate supplementation on intake and milk production of dairy cows grazing orchardgrass

In pasture-based dairy systems, grazing management strategies have focused mainly on achieving a high herbage harvest per hectare, whereas strategies oriented to maximizing the intake rate of herbage have been recently explored. The objectives of the study were (i) to evaluate the herbage nutritional value, intake and milk production per animal and per hectare of mid-lactation Holstein dairy cows grazing orchardgrass (Dactylis glomerata) in response to grazing management strategies that prioritize either herbage harvest per hectare or herbage intake rate, and (ii) to assess whether concentrate supplementation affects this response. The experiment was conducted in Uruguay using twenty-four mid-lactation Holstein dairy cows grazing orchardgrass under rotational stocking over an 81-day period. The experimental design was a randomized complete block with a 2 × 2 factorial arrangement consisting of two grazing management strategies [i.e. “high intake rate” (HIR) with pre- and post-grazing sward target heights of 21 and 13 cm, respectively, vs. “high herbage harvest per hectare” (HHH) with a pre-grazing target of 3.5–4 leaves per tiller and a post-grazing target of minimum leaf area corresponding to sward heights between 7 and 11 cm] in combination with concentrate supplementation levels of 0 (CS0) or 4 (CS4) kg of dry matter/cow per day. Sward height, number of leaves, herbage morphological and chemical composition, body weight (BW), body condition score (BCS), feed intake, and milk production per cow and per hectare were measured. Statistical analyses were performed using linear mixed models. Compared to cows under HHH, cows under HIR grazed herbage with greater nutritional value and achieved a greater feed intake and greater milk production per cow (P < 0.05), regardless of concentrate supplementation level. Conversely, under HHH milk production per hectare was marginally greater (P < 0.10) and milk solids production per hectare was greater (P < 0.05). Yet, cows under HHH lost BCS when were managed without supplementation (P < 0.05). In conclusion, HIR grazing management is an effective option for grazing dairy production systems that seek to maximize individual productivity of high-producing cows. On the other hand, HHH grazing strategies remain relevant to dairy farm businesses in which profit is driven by production per hectare. Yet, high producing dairy cows under this strategy are likely to lose BCS if not supplemented.

114 Evaluation of Assertions from Educational, Outreach and Engagement Programs in Pasture-Based Livestock Systems

Abstract Assertions about grazing management and grazing systems should be evaluated based on the scientific literature. Prior assumptions can limit our ability to achieve constructive dialogue regarding the merits of various stocking methods. These include the assumption that rotational stocking is inherently superior to continuous stocking, regardless of the nature of the overall grazing system, and the presumption that continuous stocking implies overgrazing. We revisited assertions about grazing management in general, but more specifically the choice of the stocking method, and considered their merit in the context of evidence from the literature, including a chapter titled Prescribed Grazing on Pasturelands from a National Resource Conservation Service (NRCS) literature synthesis published in 2012. We framed those assertions in the form of questions. The questions were: a) Does choice of rotational stocking ensure well-managed pastures?, b) Does rotational stocking result in greater accumulation of soil carbon than continuous stocking?, c) Does rotational stocking increase pasture productivity and optimal stocking rate compared with continuous stocking?, d) Does forage nutritive value and individual animal performance increase in rotational versus continuous stocking?, and e) Do pastures “look better” in rotational versus continuous stocking?. The objectives were to consider whether these often-stated assertions about grazing management were supported, refuted, or simply not adequately assessed by the body of scientific evidence. It is important to recognize that choice of stocking method is only one element of grazing management and grazing management is only one element of a grazing system. Thus, stocking method is “one piece of a very large pie”. Additionally, stocking rate (grazing intensity) is a separate and independent grazing management choice from stocking method, such that both rotationally and continuously stocked pastures can be understocked, overstocked, or optimally stocked. It is unfortunate that choice of stocking method dominates discussions of improving grazing management to the expense of other issues, when in fact intensity of grazing has been shown conclusively to be the most important determinant of a wide array of soil, plant, animal, and ecosystem responses. We have observed that terminology such us regenerative grazing, holistic planned grazing, adaptative multipaddock grazing, management intensive grazing, high intensity low frequency grazing, and others, arise frequently and can dominate discussions in the realm of education, outreach and engagement programs in pasture-based livestock systems. These words/themes lack clear definition, and this lack of specificity may promote misconceptions, thus hindering the opportunity for critical thinking and ultimately the advancement and improvement of grazing systems. Educational efforts in pasture management should strive to remain relevant by focusing on experimental evidence. Local (i.e., state or county level) outreach and engagement programs are challenged with providing timely and specific information with implementable guidelines based on frequent observations at the landscape and farm levels.

109 Invited Talk: Grazing Management and Stocking Strategy Decisions for Pasture-Beef Systems: Experimental Confirmation vs Testimonials and Perceptions

Abstract The primary objectives of forage-based livestock grazing systems are to enhance sustainability of pastures and cattle production, and to maintain economic stability in the presence of changes in input costs and returns. Grazing management strategies and implementation vary for adapted forages according to vegetational-hardiness zones, livestock production objectives, and manager preferences for grazing systems, stocking rates, and stocking methods. Stocking methods are strategies or techniques to manipulate grazing animals in space and time and may be considered as variations of continuous or rotational stocking. In many stocking method discussions, the debates are often focused on experimental confirmational data vs testimonials and perceptions. Acceptable methodology and statistical analyses of grazing experimentation on continuous vs rotational stocking provides repeated measures of forage nutritive value, forage mass, grazing intensity, and stocking rate on gain per animal, gain per unit land area. Additional measurements may include effects on forage stand maintenance and soil nutrient analyses-status. Recent adaptations of mob stocking and intensive rotational grazing via popular press and consultants have received acclaims for methods to enhance ecosystem services, soil health, and other non-experimentally documented attributes. Managers may adopt these testimonials of stocking methods of 60 days or more deferment based on their perception of protecting and enhancing the environment rather than logic of seeking experimental evidence. However, when given a choice of forage available for consumption, cattle select more than 80% of their diet as leaves. Thus, with respect to average daily gain per animal (ADG), only a small percentage of pasture studies have shown an advantage for rotational stocking. The lack of ADG was attributed to reduced nutritive value of forage available for selection during the residence time. Selecting management and stocking strategies for optimum utilization for forage produced, individual animal performance, and overall gain per unit land area has led to flexible grazing systems. These grazing systems may not be “hardcore rotationally, time-scheduled stocked,” but they do involve multiple pastures with strategies to incorporate movement of cattle based on current paddock forage status and forage mass estimates for desired animal performance. Grazing management strategies control the degree of intensity of beef cattle production based on level of economic risk and desired-expected environmental stewardship goals. Of all the strategies that management may adopt for grazing, the primary factor that controls resultant sustainability of pastures is that of grazing intensity as measured by stocking rate or forage height-density. Implementing revised or new management strategies requires attention to detail and the use of data-results-recommendations from comparative experiments conducted by a recognized source without conflict of interest in the method promoted.

Anatomical, morphogenic and structural characteristics of Xaraés palisade grass under grazing

This study evaluated under grazing intensities and periods of the year: leaf anatomy of Urochloa brizantha cv. Xaraés and its correlation with morphogenetic and structural characteristics, and leaves degradation after in situ incubation. Treatments were four grazing intensities (GI) defined by the pasture residuals leaf area index (rLAI 0.8, 1.3, 1.8, and 2.3) with three replications in a completely randomized design. Cows grazed in a rotational stocking with pastures regrowth period determined by 95% light interception. Leaves showed a higher proportion of sclerenchyma (2.64%) in pastures under lower GI and in the dry season (2.42%). Pastures managed under higher GI showed lower number of expanded leaves (2.58), lower number of lives leaves (3.45), and lower leaf senescence rate (0.05 cm tiller−1 d−1). Positive correlation was observed between leaf elongation rate and adaxial epidermis and vascular tissues. rLAI 1.8 and 2.3 provided greater residues after in situ leaf incubation at times 12, 48, 72, and 96 h compared to rLAI 0.8 and 1.3. rLAI and period of the year had little influence on leaf anatomy of the Xaraés managed under 95% LI, and leaf anatomy is correlated with the morphogenetic and structural pasture characteristics. Pastures managed under lower GI show more residues after leaves incubation in rumen.

Stocking method effects on forage accumulation, canopy attributes, and nutritive value of grazed Mulato II brachiariagrass pastures

AbstractRotational stocking (RS) is generally associated with the intensification of pasture‐based animal production systems, although many studies have shown little advantage over continuous stocking (CS). The objective of this research was to describe and explain the effects of two average canopy heights (20 and 30 cm) and three stocking methods (CS; rotational stocking with lenient defoliation, RSL; and rotational stocking with moderate defoliation, RSM) on forage accumulation (FA), vertical distribution of plant‐part components, and nutritive value of ‘Mulato II’ hybrid brachiariagrass (Brachiaria spp. syn. Urochloa spp.) during two summer rainy seasons in Piracicaba, São Paulo, Brazil. Pastures were maintained at average canopy height of 20 and 30 cm under CS, and treatments under RSL and RSM were imposed by variations of ±20 and 30% of the average canopy heights, representing defoliation intensities of 33 and 47% of the pre‐graze heights, respectively. The FA was not affected by CS, RSL, RSM stocking methods, averaging 8090 kg DM ha−1 year−1. Canopy bulk density and distribution of plant‐part components in the canopy profile were better at the average canopy height of 20 cm, accompanied by the greater nutritive value. The leaf bulk density was generally greater in RSM compared to CS. Pastures under CS had greater crude protein and in vitro digestible matter, and lesser neutral detergent fibre concentrations. Mulato II brachiariagrass should be managed at an average height of 20 cm under CS.

Vegetation dynamics in nitrogen‐fertilized versus mixed legume‐smooth bromegrass pastures interseeded with sorghum‐sudangrass

AbstractInterseeding annual warm‐season grasses may increase forage and pasture productivity. From 2017 to 2019, we conducted a grazing experiment that examined smooth bromegrass (Bromus inermis Leyss.) pasture responses to interseeding sorghum‐sudangrass [Sorghum bicolor (L.) Moench × S. bicolor (L.) Moench ssp. drummondii (Nees ex Steud.) de Wet &amp; Harlan]. The experiment had a split‐plot design with six main plots each containing two, 0.60‐ha pasture subplots (i.e., 12 total subplots). The six main plots included three replications each of two pasture types: (A) nitrogen (N)‐fertilized smooth bromegrass (FERT) and (B) mixed legume‐smooth bromegrass [LEG; alfalfa (Medicago sativa L.), red clover (Trifolium repens L.), and birdsfoot trefoil (Lotus corniculatus L.)]. The subplots included sorghum‐sudangrass interseeded and unseeded control treatments. Each pasture subplot, which supported two steers (Bos taurus) from spring through summer, contained six, 0.10‐ha sub‐subplots for rotational stocking. Sorghum‐sudangrass was interseeded after stocking cycle 2 in two of the sub‐subplots in the interseeded subplot each year. Vegetation responses were evaluated in these sub‐subplots and in two adjacent sub‐subplots in the unseeded control subplot. Across years, sampling dates, and subplot treatments, the LEG main plots supported 7% greater forage biomass (2743 ± 102 kg ha−1) and six more grazing days than the FERT main plots (2552 ± 111 kg ha−1). Sorghum‐sudangrass interseeded sub‐subplots, however, had 36% greater forage biomass than unseeded sub‐subplots pre‐grazing in stocking cycle 5. To optimize forage biomass, producers should fertilize in early spring or maintain legumes in smooth bromegrass pastures. Interseeding sorghum‐sudangrass provides an option to increase late‐summer forage biomass.

Grazing management and stocking strategy decisions for pasture-based beef systems: experimental confirmation vs. testimonials and perceptions

Abstract Grazing management and stocking strategy decisions involve the manipulation of grazing intensity, grazing frequency, and timing of grazing to meet specific objectives for pasture sustainability and economic livestock production. Although there are numerous stocking systems used by stakeholders, these methods may be broadly categorized as either continuous or some form of rotational stocking. In approximately 30 published experiments comparing continuous vs. rotational stocking, there was no difference in liveweight gain per animal between stocking methods in 66% of studies. There was no difference in gain per hectare between methods in 69% of studies, although for gain per hectare the choice of fixed or variable stocking rate methodology affected the proportion (92% for fixed; 50% for variable). Despite these experimental results showing limited instances of difference between rotational and continuous stocking, rotational strategies (e.g., “mob stocking” or “regenerative grazing”) have received what appears to be unmerited acclaim for use for livestock production. Many proposed “mob stocking” or “regenerative grazing” systems are based on philosophies similar to high intensity-low frequency stocking, including provision for &amp;gt;60 d of rest period from grazing. In addition, grazing management practitioners and stakeholders have voiced and proposed major positive benefits from rotational stocking, “mob stocking”, or “regenerative grazing” for soil health attributes, carbon sequestration, and ecosystem services, without experimental evidence. The perceptions and testimonials supporting undefined stocking systems and methods have potential to mislead practitioners and result in economic disservices. Thus, we suggest that scientists, extension-industry professionals, and producers seek replicated experimental data as the basis for predicting outcomes of grazing decisions.

Índice de nutrição nitrogenada e morfogênese em papuã na Depressão Central do Rio Grande do Sul

ABSTRACT: This study assessed the nitrogen nutrition index, morphogenic characteristics and tiller structure of Alexandergrass (Urochloaplantaginea (LINK) Hitch) pasture submitted to different nitrogen (N) levels (zero, 150 or 300 kg ha-1 of N). The experimental design was entirely randomized with repeated measures arrangement. The experimental animals were Angus heifers under rotational stocking grazing method. The number of animals was variable to keep 30±5 cm post-grazing sward height. Nitrogen nutrition index increased linearly according N levels (Ŷ = 59.8 + 0.1216N; P &lt; 0.0001; r²=0.53). The leaf appearance rate adjusted to a positive linear regression model according the thermal sum (TS) with zero of N (Ŷ0N = 0.0077 + 0.0000087TS; P = 0.0308; r² = 0.72) and 150 kg ha-1 of N (Ŷ150N = 0.0020 + 0.000021 TS; P = 0.0022; r² = 0.92). The use of 300 kg ha-1 of N did not alter the leaf appearance rate (0.0124 leaf degree-days-1). The use of up to 300 kg ha-1 of N increases the Alexandergrass nitrogen content. The leaf appearance rate in Alexandergrass is modified using N while the morphogenic characteristics leaf expansion, stem expansion, phyllochron, leaf lifespan, leaf elongation duration and tiller structure are not altered by N utilization.

Características morfogênicas, estruturais e índice de estabilidade populacional de perfilhos de azevém submetidos a métodos de lotação

ABSTRACT This study aimed to evaluate the morphogenic and structural characteristics and the population stability index of ryegrass (Lolium multiflorum Lam.) tillers when the pasture was submitted to two stocking methods during grazing cycles. The experimental design was a complete randomized block, with repeated measurements over time (n=6 cycles), two treatments (stocking methods) and three area replicates. In the continuous stocking method, the highest population density of tillers was observed. The highest tiller weight occurred in the rotational stocking method. The morphogenic variables and the other structural variables were not altered by the stocking methods and showed differences during the grazing cycles. The tiller population stability index was similar in the two pasture management strategies, and both can be used for ryegrass management considering this parameter.

176 Costs for Supplementing Small Ruminants Under the Various Grazing-Based Production Systems

Abstract The supplementary feeding costs of small ruminants can be substantial when there is not much vegetation available for grazing or browsing. However, such costs have not been reported well and the strategies to minimize them not discussed enough. The objective of this study was to quantify the feeding costs involved in supplementing small ruminants under grazing-based production systems. Grazing studies were conducted from July to October in 2021 (88 d) in woodlands with lactating Kiko does (17) along with their young kids (33). Animals were divided into two groups (1 &amp; 2) and randomly allocated to three woodland plots each for rotational stocking. Group 1 was allowed to rotationally graze in nearby silvopasture plots for 3-4 hours daily and Group 2 was supplemented with ad lib. hay and corn (0.5% metabolic wt.). Another study was conducted from October to December 2021 (70 d) involving 56 Kiko goats and 18 Katahdin-St. Croix ewes. During this study, there was not much foliage available, and animals were supplemented with hay (ad lib.) and corn (0.5% live wt.). Cost and amount of hay and corn used for supplementation were recorded. Data were analyzed in Excel for descriptive statistics. In the woodland study, cost for supplementing animals was $0.13 per animal per day, with 86% of the cost accounted for hay and 14% for corn. In the second study, when not much vegetation was available for grazing, cost for supplementing animals was $0.43 per animal per day, with hay cost accounting for 77% and remaining for corn. Findings of this study suggest that planted forages can be used to replace the need for purchased feed during the forage-growing period. The costs of supplementation can be significantly high during the lean period of forage production.

Productivity of beef cattle grazing Brachiaria brizantha cv. Marandu with and without nitrogen fertilizer application or mixed pastures with the legume Desmodium ovalifolium

AbstractThe use of forage legumes to contribute biologically fixed nitrogen (N) to pastures is an alternative to increase beef cattle production in tropical regions. The objective was to compare the impact of the introduction of a legume with that of N fertilizer application on forage and animal production in Brachiaria pastures. This two‐year study assessed three pasture treatments: (1) mixed Marandu palisadegrass (Brachiaria brizantha [syn. Urochloa brizantha] cv. Marandu) and the legume “ovalifolium” (Desmodium ovalifolium) cv. Itabela (Mixed), (2) Marandu palisadegrass pastures with 150 kg N ha−1 (Fertilized), and (3) Marandu palisadegrass without N fertilizer (Unfertilized). Rotational stocking with a variable stocking rate was used with a target herbage allowance of 1.0 kg forage kg body weight−1. The pre‐grazing green herbage mass was similar for Fertilized and Mixed pastures, with 54% and 63% more mass than Unfertilized pasture, respectively (p &lt; .001). Cattle that grazed the fertilized pasture had the greatest average daily gain (ADG; p = .017). The stocking rate and liveweight gain per area were greatest for the Fertilized and Mixed pastures (p &lt; .001 and p &lt; .001, respectively). No differences between treatments were found for DM forage intake (p = .555). Organic matter digestibility was lowest (p &lt; .001) for the Mixed pasture. The inclusion of the ovalifolium legume in the Marandu pasture had the same impact on beef cattle production as annual fertilization with 150 kg N ha−1. The potential and environmental benefits of ovalifolium are discussed.

Methane emissions and milk yields from zebu cows under integrated systems

Integrated systems are technologies that potentially increase animal production and environmental preservation, but the effect of these systems on the efficiency and methane emissions of dairy cows is still unknown. This study aimed to compare enteric methane emissions, dry matter intake and performance of grazing dairy cows in integrated systems in the Brazilian Cerrado biome, i.e., crop-livestock integration (CLI) or crop-livestock-forest integration (CLFI). Eighteen Holstein-Zebu cows were randomly assigned to the two production systems (n = 9 for each system) based on Monbasa pasture (Megathyrsus maximus cv. Mombaça; Syn. Panicum maximum) under rotational stocking management. Herbage allowance ranged from 12 to 14% body weight, and cows were supplemented with concentrated feed according to milk yield. Herbage samples were collected by simulated grazing to determine nutritional value. Milk yield was determined weekly. Herbage intake was estimated from fecal output and indigestibility of the pasture dry matter. Fecal output was estimated by the external indicator LIPE®, and dry matter digestibility was estimated by the internal indicator NDFi. Enteric methane emissions were estimated by the SF6 tracer gas technique. Data were collected in three sampling periods to characterize the rainy season, the transition from the rainy season to the dry season and the dry season. Data were analyzed in split plots, with animals within the system as the plot and seasons as the subplot. Statistical significance was considered at P < 0.05. The herbage crude protein content was 35.9% higher on average in the CLFI than in the CLI. In vitro dry matter digestibility was 16.7% lower in the CLI than in the CLFI in the rainy season. Milk yield and feed efficiency were similar between systems and seasons. The total dry matter intake in the rainy season was 34.6% higher in the CLFI than in the CLI. The energy loss, production and yield of methane were 29.8%, 35.0% and 31.3%, respectively, lower in the rainy season than in the other seasons. Enteric methane emissions, milk yield and feed efficiency were similar between the integrated CLI and CLFI systems in the Brazilian Cerrado region.

Determining the pre-grazing sward height of Kikuyu grass (Cenchrus clandestinus - Hochst. ex Chiov.) for optimizing nutrient intake rate of dairy heifers.

Understanding the grazing process and animal response to sward structures (e.g., sward height) is key to setting targets for efficient grazing management. We hypothesized that the short-term intake rate (STIR) of dry matter (DM) and digestible organic matter (OM) by dairy heifers is maximized with Kikuyu grass (Cenchrus clandestinus—Hochst. ex Chiov.) of intermediate sward heights. The treatments consisted of five pre-grazing sward heights (10, 15, 20, 25, and 30 cm) randomly assigned to two of ten paddocks. The experimental design included two measurements of each paddock at different periods and times of day. Three Holstein heifers (440 ± 42 kg body weight) were used to determine the STIR, which was estimated using the double-weighing technique with correction for insensible weight losses. The bite mass (BM), bite rate (BR), sward structural characteristics, and nutritional value of herbage samples were assessed. The data were analyzed using mixed models with a factorial arrangement of five sward heights, two times of day, and two evaluation periods. The sward height of Kikuyu grass that maximized both STIRs was approximately 20 cm. The STIR of the DM was 30% and 15% lower than the maximum in the shortest and tallest swards tested, respectively. In swards shorter than 20 cm, the STIR was lower because the BM decreased with sward height, whereas in those greater than 20 cm, the lower BM and STIR of DM was explained by a decrease in bulk density and bite volume. The top stratum was composed mainly of highly digestible leaf blades with similar nutrient content across sward heights; therefore the STIR of digestible OM was also maximized at 20 cm. Hence, the optimal pre-grazing sward height of Kikuyu grass should be managed at 20 cm under rotational stocking systems to maximize nutrient intake rate of dairy heifers.

Feeding Strategies to Mitigate Enteric Methane Emission from Ruminants in Grassland Systems.

Simple SummaryRuminants under grazing conditions play an important role, especially in developing countries. Enteric methane emissions from ruminants are greater with pasture-based diets; however, it is not clear which abatement practices are effective to reduce methane emissions under grazing conditions. The objective of this review was to identify and describe enteric methane abatement practices for ruminants that are applicable under grazing conditions. Decreasing the pre-grazing herbage mass reduced methane emissions per unit of product. Other grazing management practices such as increased stocking rate, decreased forage maturity, rotational stocking, and incorporating tannin-containing or non-tannin-containing legumes showed inconsistent results. Nitrogen fertilization or silvopastoral systems did not modify methane emissions, although they may alter carbon sequestration in a system. Supplementation in grazing conditions shows inconsistent responses on methane emissions. However, lipid supplementation showed promising results. Identifying and implementing grazing strategies and supplementation practices under grazing conditions is required to increase efficiency and reduce the environmental impact of these systems.Ruminants produce approximately 30% of total anthropogenic methane emissions globally. The objective of this manuscript was to review nutritional enteric methane abatement practices for ruminants that are applicable under grazing conditions. A total of 1548 peer-reviewed research articles related to the abatement of enteric methane emissions were retrieved and classified into four categories: non-experimental, in vitro, in vivo confined, and in vivo grazing. The methane abatement strategies for grazing systems were arranged into grazing management and supplementation practices. Only 9% of the retrieved papers have been conducted under grazing conditions. Eight grazing management practices have been evaluated to reduce methane emissions. Decreasing the pre-grazing herbage mass reduced the methane emission per unit of product. Other grazing management practices such as increased stocking rate, decreased forage maturity, rotational stocking, and incorporating tannin-containing or non-tannin-containing feeds showed contradictory results. Nitrogen fertilization or silvopastoral systems did not modify methane emissions. Conversely, supplementation practices in grazing conditions showed contradictory responses on methane emissions. Lipid supplementation showed promising results and suggests applicability under grazing conditions. Identifying and implementing grazing strategies and supplementation practices under grazing conditions is required to increase efficiency and reduce the environmental impact of these systems.

Stocking method and monensin supplementation effects on cow and calf performance and pasture productivity

AbstractIn the northeastern United States, pastures are predominantly cool‐season perennial grasses and legumes that are dormant in the summer resulting in a decline in forage nutritive value and availability, commonly referred to as “summer slump.” Strategies to alleviate summer slump may include stocking management or supplementation with or without an ionophore such as monensin to maximize efficiency. A 3‐yr study (n = 32 cow–calf pairs; 718.0 ± of 83.9 kg) was conducted to evaluate the effects of rotational (ROT) or continuous (CONT) stocking method with or without monensin on forage production, pasture nutritive value, and animal production. Continuous and ROT stocking treatments were assigned to eight 2.9‐ha pastures with two replicates/year for 56 grazing days during the summer. Treatments were arranged as a 2 × 2 factorial, and supplements included with or without monensin (200 mg cow−1 daily; Rumensin 90, Elanco Animal Health) delivered once daily (0.45 kg cow−1). Disk meter height was maintained using put‐and‐take animals with four tester cow–calf pairs per pasture. Carrying capacity (CC) and calf average daily gain (ADG) were not influenced by stocking management. Rotational stocking increased cow body weight (BW) change by 6.6 kg. Monensin improved CC by 9% regardless of stocking method but did not affect cow BW change or calf ADG. Based on this study, monensin can improve carrying capacity and stocking rate regardless of stocking method. Implementing rotational stocking may improve pasture health by suppressing weed growth and enhancing forage nutritive value in pastures containing cool‐season perennial forages.