Forage Accumulation Research Articles

Forage Accumulation and Nutritional Characteristics of Brachiaria Cultivars Grown in a Semi-arid Environment

The evaluation of the nutritional value and parameters of ruminal fermentation of tropical forages is important, aiming at its efficient use in ruminant feeding. This study was developed to evaluate the forage accumulation, chemical composition, protodioscin content, digestibility, and in vitro degradation kinetics of different Brachiaria spp. cultivars in different evaluation periods. The research was carried out in the semi-arid region of Brazil, from April 2016 to April 2017. The experiment was laid out as a split-plot arrangement in a randomized block design in which five cultivars ( B. decumbens cv. Basilisk, and B. brizantha cvs. Marandu, Paiaguás, Piatã, and Xaraés) represented the plot and four evaluation periods (establishment, transition, dry, and rainy) the subplot. There was a cultivar × period interaction effect for forage accumulation rate (FAR), for which cv. Xaraés showed the highest mean (54.1 kg/ha.day DM) in the rainy season. The lowest yield was found in cv. Paiaguás in the dry season (24.1 kg/ha.day DM). Cultivars Basilisk, Marandu, and Paiaguás had the highest crude protein content. The highest in vitro dry matter digestibility values were found in cv. Basilisk in the dry, transition, and rainy periods; cv. Marandu in the transition period, and cvs. Paiaguás and Piatã in their establishment. A correlation was found between the parameters of in vitro degradation kinetics and chemical composition. The protodioscin content was highest in cv. Basilisk, during its establishment (5.5 g/kg DM). Cultivars Paiaguás, Piatã, and Xaraés showed low protodioscin values (<1.0 g/kg DM). Cultivars Basilisk, Marandu, Paiaguás, Piatã, and Xaraés can be used as forage options in the semi-arid environment, as their forage accumulation potential and nutritional value are suitable for animal production even in periods of lower water availability.

Grazing intensity and nitrogen fertilization effects on biomass and morphology of black oat roots in an integrated crop–livestock system

AbstractGrazing stimulates root and forage mass of perennial pastures, but few studies have addressed the effects of grazing on annual pastures which are often grown in short periods within integrated crop–livestock systems (ICLS). In these pastures, N fertilization is a common practice to increase forage mass, but its effects on root morphology are unclear. In a field experiment, we evaluated how grazing intensities (ungrazed, moderate, and heavy grazing) and N fertilization rates (0, 75, and 150 kg N ha−1) affected morphological attributes of oat (Avena strigosa Schreb.) roots and forage accumulation in ICLS in Brazilian subtropics. Forage mass was evaluated in each grazing cycle and roots were sampled to a 30‐cm depth at the end of the grazing season in 2 years. Heavy and moderate grazing reduced (p &lt; 0.05) forage accumulation by 15%–37% compared to ungrazed (4867 kg DM ha−1) in the first year, characterized by extended periods of water deficit, but in the second year forage accumulation from grazed and ungrazed was similar (p &gt; 0.05), averaging 4273 kg ha−1. N fertilization increased forage accumulation in both the years, without differences between 75 and 150 kg N ha−1 in grazed treatments. Grazing and N rates mainly reduced root diameter and increased root N concentration. Increasing N fertilization rates increased root length but it was more expressive in the first year. Nitrogen fertilization with 75 or 150 kg N ha−1 on moderately grazed oat is an alternative to increase forage accumulation as it stimulates fine root development and increase N uptake, mainly when adverse climatic conditions can affect pasture growth.

Unraveling phenotypic diversity in Cynodon spp. germplasm for forage accumulation and nutritive value in the transition zone

AbstractCharacterizing phenotypic variation in germplasm collections is crucial for plant breeding. Cynodon spp. accessions maintained at the USDA National Plant Germplasm System (NPGS), and the core forage collection were screened in a replicated trial under two nitrogen rates (0 and 150 kg ha−1 per harvest) in Ardmore, OK. The goals for this study were to: (a) estimate genetic parameters for forage accumulation (FA) and nutritive value (NV), (b) estimate genotype × harvest (rgh) and genotype × environment (rge) interaction for all traits, (c) quantify FA and NV for commercial cultivars and selected accessions. The experiment was setup as a row‐column design with two replicates and augmented representation of controls: Tifton 85, Wrangler, Midland, and Cheyenne. The trial was harvested five times (twice in 2016 and three times in 2017) and data were analyzed using linear mixed models. Genetic parameters revealed the presence of significant phenotypic variation for FA and NV. Low genotype × harvest and genotype × environment interactions indicated genotypic stability and potential for selecting improved accessions for FA and NV. Several plant introductions (PIs) were identified for their improved FA and NV. The application of N increased FA and CP concentration in all harvests but did not significantly impact phenotypic variation in other NV traits. Phenotypic data will be deposited in the Germplasm Resource Information Network (GRIN)‐Global database.

Defoliation management and nitrogen fertiliser rate affect canopy structural traits of grazed guineagrass (Megathyrsus maximus) cv. Zuri under rotational stocking

Context Defoliation management by grazing or clipping, combined with nitrogen (N) fertilisation, can increase forage production in tropical grasses. Use of pasture canopy height as a practical tool for monitoring forage mass and accumulation has been proposed because of the relationship between height and canopy light interception. However, this relationship can vary due to variations in canopy structural changes and N supply. Aims Our objectives were to study canopy structural responses and forage accumulation of grazed Zuri guineagrass (Megathyrsus maximus) under rotational stocking. Methods Combinations of two pre-graze canopy heights (55 and 75 cm) and two N fertilisation rates (150 and 300 kg N ha−1 year−1) were used during two consecutive years. Cattle grazed the pastures to 50% of pre-graze height. Key results Regardless of N rate, pastures managed at 75 cm always reached 95% light interception at pre-graze. The 55 cm/300 kg N pastures underwent structural changes such as greater leaf proportion, tiller population density and specific leaf area, and smaller mean foliage angle, which resulted in 95% light interception at pre-graze. Forage accumulation was 20% greater for 75 cm pastures (22 120 kg DM ha−1 year−1) than 55 cm pastures. Pastures receiving 300 kg N ha−1 year−1 had 38% greater forage accumulation than those receiving 150 kg N ha−1 year−1. Conclusion Zuri guineagrass pastures should be defoliated when canopy height reaches 75 cm owing to greater forage accumulation, but can be grazed at 55 cm when N is applied at 300 kg ha−1 year−1. Implications Zuri guineagrass can be managed with shorter pre-graze canopy height; when grazed at 55 cm and with 300 kg N ha−1 year−1, there is no negative effect on forage accumulation, allowing for shorter rest periods.

Diferenças estruturais e produtivas entre os capins braúna, cayana e sabiá diferidos

ABSTRACT The aim of this study was to identify differences in morphogenesis, structure, and forage accumulation rate of Urochloa brizantha cv. MG13 Braúna, from Urochloa cv. Cayana and Urochloa cv. Convert 330 (sabiá grass) during the deferment period. The experimental design was completely randomized, with four replications in experimental plots of 12.25m2. The evaluations took place for two years, 2021 and 2022. The deferment period was 90 days. Phyllochron (PHY) and leaf senescence rate (LSR) were lower at the beginning of deferred, contrary to leaf elongation rate (LER) and population density tillers (PDT). Stem growth rate (SGR) was higher in 2021 and at the beginning of deferment. Leaf growth rate (LGR) and total growth rate (TGR) were higher at the beginning of deferment. The braúna grass presented higher PDT. The SGR and the TGR of cayana grass are superior to those of braúna grass. The braúna grass produces a canopy consisting of lighter and denser byts, compared to other weeds. In Uberlândia, MG, braúna grass with an initial height of 30cm produces less stem, while cayana grass produces more forage during deferral.

Highlighting the benefits of biological nitrogen fixation on agronomic, physiological, and nutritive value traits of brachiariagrass

The search for efficiency in forage-based systems has intensified in recent years, increasing the need to reduce environmental impacts of animal agriculture. Reducing the dependence on fossil fuels for nitrogen (N) input with the use of microorganisms (e.g., biological nitrogen fixation, BNF) and grass-legume mixed stands has become an important practice. The objective of this study was to evaluate N input strategies that affect the agronomic, physiological, and nutritive value traits of Ipyporã brachiariagrass (Brachiaria hybrid ‘BRS RB331 Ipyporã’) based on the use of mineral N fertilization (ammonium sulfate), bacterial inoculation (Azospirillum brasilense strains Ab-V5 and Ab-V6; CNPSo), and mixed stands with forage peanut (Arachis pintoi Krapov. & W.C. Greg. cv. BRS Mandobi) in the Amazon biome. The treatments were six N-input strategies: 1. pastures with no nitrogen fertilization (control); 2. fertilized with 80 kg N ha-1 season-1 (N); 3. inoculated with A. brasilense (Az); 4. fertilized with 80 kg N ha-1 season-1 + A. brasilense (N + Az); 5. mixed stand of Ipyporã brachiariagrass and forage peanut (Mix) and 6. mixed stand + A. brasilense (Mix+Az). The experimental period was from 20 January 2015–21 March 2017, covering three summer growing seasons. Forage was cut to a 12-cm stubble when average canopy height reached 25 cm. Annual forage accumulation (FA) was greater in N, Az, N + Az, and Mix+Az (averaged 7760 kg DM ha-1) than in Control and Mix (averaged 6485 kg DM ha-1). The FA measured in Az and Mix+Az was equivalent to applying 58 and 86 kg of N ha-1, respectively when compared with Control. The greatest leaf mass was measured in N, Az, N + Az, and Mix+Az (averaged 1475 kg DM ha-1). The Az and Mix+Az can be options to improve the sustainability of forage systems and maintain forage production while using renewable sources for nitrogen.

Prescribed burning of endophyte-infected tall fescue plots: Effects on forage production, ergot-like alkaloid concentrations, and botanical composition

Our objective was to evaluate the effects of early-spring prescribed fire on forage production and botanical composition in Kentucky 31 tall fescue plots. Treatments were applied in a completely randomized design with 10 plots per treatment. Treatments were (1) no burn (CON), (2) March mowed (MWD), (3) March burn (EBRN, early burn), and (4) April burn (LBRN, late burn). Beginning in May and repeated monthly until October, tall fescue tillers were hand clipped at ground level while walking an “X” pattern. In May of each year, tall fescue seedheads were counted in twelve 0.09-m2 quadrats per plot, and species frequencies were recorded. Species frequency was collected again in October. Tall fescue seedheads were reduced by 72% (P < 0.01) for LBRN. Spring forage accumulation was reduced (P < 0.01) by MWD, EBRN, and LBRN treatments, with EBRN and LBRN having a greater reduction (P = 0.03) than MWD. Nonfescue forage species frequency increased (P ≤ 0.01) in October for LBRN. Ergovaline concentration did not differ (P = 0.57) among treatments but differed (P = 0.01) by month, with a substantial increase in June compared with other months. Early-spring prescribed fire reduced tall fescue seedhead production; however, fire also reduced forage production. Removal of a portion of seedheads from tall fescue plots did not affect ergovaline concentration in plant samples. Thus, future research should evaluate ergot-like alkaloid concentrations in various plant parts from tall fescue subjected to seedhead control measures.

Regrowth of brachiariagrasses as related to stubble characteristics under N fertilization and irrigation

Seasonal and annual changes in stubble characteristics can affect the regrowth of warm-season perennial grasses. Understanding these changes and their effects on forage accumulation rate (FAR) can improve defoliation management. Our objective was to describe and relate variations in stubble characteristics with FAR during regrowth of four palisadegrasses [Brachiaria brizantha (Hochst. Ex A. Rich.) Stapf. syn. Urochloa brizantha (Hochst. ex A. Rich.) R.D. Webster], genotypes Marandu, Xaraés, Arapoty, and Capiporã, and one signalgrass [Brachiaria decumbens (Stapf.) syn. Urochloa decumbens (Stapf.) R.D. Webster] cultivar Basilisk, in southeastern Brazil. Plots were harvested at 15-cm stubble height every 28 d during the warm season and 42 d during the cool season of years 2005–2006 and 2007–2008. Stubble mass was ∼1,070 kg DM ha−1 greater in the cool than warm season, whereas FAR was less in the cool season. Arapoty and Basilisk showed generally less FAR (∼45 kg d−1) and stubble leaf, stem, dead material, and total mass during the warm season than more productive grasses Capiporã and Xaraés (∼63 kg d−1). Leaf and canopy photosynthesis varied over seasons and years, but they were similar among grasses despite differences in stubble characteristics and FAR. Marandu accumulated more leaf in the stubble than other grasses, resulting in greater residual leaf area index, but it did not increase FAR. Under less favorable growth conditions, grasses increased stubble herbage mass (SHM). More productive grasses generally present greater SHM and leaf mass, indicating that stubble characteristics play an important role in the regrowth of brachiariagrasses.

Production Potential and Quality of Panicum maximum Cultivars Established in a Semi-Arid Environment

This study was conducted to examine the forage production potential and quality of Panicum maximum cultivars in a semi-arid environment, in four different periods. Six cultivars were evaluated: Aruana, Massai, Mombasa, BRS Tamani, Tanzania, and BRS Zuri. The experiment was laid out in a randomized-block design with four replicates, and assessments took place in four different periods (establishment, dry season, transition, and rainy season). Forage accumulation rate (FAR), chemical composition, digestibility, and in vitro rumen degradation kinetics were evaluated. There was an interaction effect between cultivars and evaluation periods for all variables, except dry matter (DM) content. The highest FAR occurred in cvs. BRS Tamani (47.0 kg DM/ha/day) and BRS Zuri (86.9 kg DM/ha/day) in the establishment and rainy periods, respectively, while cv. Aruana showed the lowest FAR (14.5 kg DM/ha/day). The highest crude protein contents were found in cv. BRS Tamani in the transition period; cv. BRS Zuri in the dry season; and cv. Tanzania in the rainy season (128.2, 116.7, and 95.0 g/kg DM, respectively). Cultivar Aruana showed the highest average in vitro dry matter digestibility (810.0 g/kg DM). Cultivars Aruana and Zuri exhibited the highest means of the total in vitro gas production (23.59 and 20.24 mL/100 mg DM, respectively). Cultivars BRS Tamani and BRS Zuri had the best response in terms of forage accumulation and nutritional value. The quality of cv. Massai remained constant throughout the year. All Panicum maximum cultivars evaluated here have the potential for use in animal production systems in a semi-arid environment.

Protodioscin Content, Degradation Kinetics, and In Vitro Digestibility of Marandu Palisadegrass Hay as were Affected by Cutting Interval of the Canopy

Even though marandu palisadegrass is widely used in Brazil, the consumption of this forage may cause photosensitization in ruminants due to the protodioscin. This study aimed to recommend a harvest cutting interval for haymaking that provides a better nutritional value and lower levels of protodioscin. The experimental treatments were four cutting intervals (21 d, 35 d, 49 d, and 63 days of regrowth period up to forage harvest). The experimental design was a completely randomized block design with 4 treatments and 4 replications. We assessed the forage production, chemical composition, in vitro digestibility, in vitro degradation kinetics, and protodioscin content. The forage accumulation rate did not differ with the increased cutting interval. The crude protein contents and in vitro digestibility of dry matter decreased linearly with the increased cutting interval in fresh and hay material. The greatest gas production in hay material was occurred in 21 d cutting interval, which was 26%, 14%, and 5% greater than cutting intervals of 63, 49, and 35 d, respectively. A linear increase was observed in protodioscin concentration in hay according to the cutting interval, which in the hay with 63 d cutting interval was 7%, 29%, and 43% greater than hays with cutting interval of 49, 35, and 21 d, respectively. In addition, protodioscin contents were lower in hay compared to fresh material. The haymaking process reduced protodioscin content in relation to forage before haymaking. Our results showed that the better condition to harvest marandu palisadegrass for hay was at 21 d. The better condition to develop a productive canopy is associated with better nutritive value and lower protodioscin content.

Productive and nutritive traits of Piatã palisadegrass after thinning the forest component of a silvopastoral system in southeastern Brazil

AbstractSilvopastoral systems (SPSs) are sustainable alternatives for pasture intensification. Management practices such as thinning are options to diminish competition for resources between pasture and trees, ensuring appropriate forage production. The objective of this study was to evaluate the productive and nutritive traits of Piatã palisadegrass (Urochloa brizantha cv. BRS Piatã) after thinning the forest component of a SPS. Forage production and nutritive value, along with microclimate variables were assessed in a SPS and in an intensive system (INT) in São Carlos-SP, Brazil, from 2016 to 2018. The INT was a full sun pasture of Piatã palisadegrass, while the SPS was established with Piatã palisadegrass shaded by eucalyptus (Eucalyptus urograndis clone GG100) spaced 15 × 2 m but thinned to 15 × 4 m before the onset of the experiment. In the SPS, measurements were made under the tree row (SPS_1), 3.75-m (SPS_2), 7.5-m (SPS_3) and 11.25-m (SPS_4) distant from the North row. Forage accumulation in the two systems were similar, whereas the pre-grazing forage mass in most of the SPS positions were smaller than that of the INT during the autumn of 2017 and summer of 2018. Crude protein (CP) content was greater in the SPS than in the INT in most positions and seasons. Forage production was favoured by the thinning of the trees mainly in the seasons close to the event, while forage CP was consistently greater in the understory pasture. Thinning of trees in SPSs can be adopted to provide forage production similar to intensive pastures with higher protein content.

Management of dual-purpose wheat genotypes by rotatinuous stocking

The objective was to evaluate whether rotatinuous stocking management in dual-purpose wheat genotypes provides greater forage performance compared to the traditional rotational grazing management, which could become an alternative to ryegrass, once this new management strategy has been validated. Three dual-purpose wheat cultivars (BRS Pastoreio, BRS Tarumã and BRS Tarumaxi) and a black oat cultivar (Embrapa 139 Neblina) were used in the experiment, in traditional rotational and rotatinuous stocking. The experiment was carried out in a randomized complete blocks design, with treatments arranged in a 4 x 2 factorial scheme (cultivars x management strategies), with pre and post-harvest heights in traditional rotational management (RT) of 25 and 5 cm, and 25 and 15 in the rotatinuous stocking management (RN). The experiment was carried out at Embrapa Trigo, in Passo Fundo, Rio Grande do Sul state, southern Brazil. Nitrogen was applied after sowing and after cuts, according to the management strategies. Dry matter yield, percentage of leaf blades and forage accumulation per cut and total were evaluated. Wheat cultivars in rotatinuous stocking management showed higher numbers of cuts, greater cycle, percentage of leaves and average rate of forage accumulation, with smaller intervals between cycles. The total forage production showed no difference between the cultivars, however, BRS Tarumaxi was higher in the rotatinuous stocking management. Thus, responses between the genotypes in relation to the management strategies adopted are different.

Forage accumulation, morphological composition and height of Panicum maximum cv. tanzania with organic and chemical fertilization

Objective: To evaluate the dry matter accumulation, morphological composition and height in the Panicum maximum cv. Tanzania grass in order to determine the optimal cutting point under four fertilization schemes. Methodology: Tanzania grass was evaluated with fertilizations: T1) chemical (120-60-00 NPK), T2) vermicompost (10 t ha-1), T3) compost (10 t ha-1), and T4) compost + leachate. Cuts were made every 14 days where dry matter (DM), morphological composition and height were measured. A randomized complete block design was used, with an arrangement of measures repeated over time. Results: The maximum accumulation of DM in the T1, T2 and T3 treatments was at 80 days after cutting, the maximum height was with T1 at 80 days after cutting with 206.2 cm. Fertilization with biological products such as vermicompost, compost+leachate and compost presented a higher proportion and conservation of leaves over time. Study Limitations/Implications: Grasslands are not seen as a crop so in most cases they are not fertilized; when they are, it is done with chemical fertilization so there is little information about organic fertilization in tropical fodders. Conclusions: The optimal cutting point is from 50 DAC for chemical treatment, compost+leachate and vermicompost. Fertilization with vermicompost or compost+leachate can be an inexpensive and affordable option for producers to fertilize their meadows.

Thermal sum in the determination of the phenological stages of Chihuahua and Cuauhtémoc oats in Güémez Tamaulipas

Objective: To determine the thermal sum requirements in degrees days of development (GDD) of the varieties of Avena sativa, Cuauhtémoc and Chihuahua by phenological stage and its effect on the accumulation of total forage and by morphological component in Güémez, Tamaulipas.&#x0D; Design/methodology/approach: The sowing was carried out in plots of 6×6 m and four repetitions of the Cuauhtémoc and Chihuahua varieties through the mechanized preparation of the land, with doses of 120 kg ha-1 of seed and, subsequently, irrigation and fertilization work was carried out. The treatments were made up of the two varieties and six phenological stages (Zadoks scale: Z2, Z3, Z4, Z7, Z8, Z9) in a random complete block design.&#x0D; Results: It was found that, the months of November to March allow to obtain 1923.5 and 1831.5 GDD as a requirement of the crop to complete the biological cycle of the Chihuahua and Cuauhtémoc varieties. Yields by morphological component depended on the observed phenological stage and the highest leaf yield was obtained with 2.7 and 3.6 t ha-1 in Cuauhtémoc and Chihuahua, respectively (P&lt;0.05) in stage Z3, with an accumulation of 1032 and 980 GDD in the stem elongation stage.&#x0D; Limitations on study/implications: These results are applicable only for the evaluation area, because they are physiological responses where the environment intervenes.&#x0D; Findings/conclusions: In Güémez, Tamaulipas, the Chihuahua oat variety requires 1923.5 GDD to complete the biological cycle, while Cuauhtémoc 1831.5 GDD. The difference between the thermal accumulation of the varieties and the phenological stages has an impact on the total forage yield and by morphological component.

Agronomic performance and chemical composition of genotypes and cultivars of Megathyrsus maximus in Roraima’s savannas

The agronomic performance of 23 genotypes and six commercial cultivars of Megathyrsus maximus was evaluated under natural field conditions at the Roraima´s savannas, during the period of June 2015 to September 2019. The evaluated parameters were green dry matter (GDM) yield, leaf, stem and dead DM yields, crude protein (CP) contents, concentrations of neutral detergent fiber and acid detergent fiber. The genotypes and cultivars evaluated affected the yields and the chemical composition of the forage. The most promising genotypes showed superior agronomic performance than the commercial cultivars evaluated. The genotypes B16; PM10; PM40 and PM14 showed the highest green dry matter yields and forage with better nutritional quality, higher CP and lower fiber contents. These showed average yields of 5,103 and 3,925 kg ha-1, for green DM and leaf DM, respectively, which represented increments of 20.7 and 12.8%, compared with those registered for the commercial cultivars. The genotype PM15 evidenced the highest productive performance during the dry season, constituting an option for regions with climatic restrictions, notably reduced rainfall. All genotypes and cultivars showed seasonal growth. The genotypes that showed the best seasonal distribution of forage production were PM11, PM36, PM30 and PM33, which provided 47.9; 46.8; 41.0 and 40.7% of GDM production during the dry season. In general, higher crude protein and lower fiber contents were directly correlated with the percentage of leaves in the available forage. The evaluated genotypes presented great genetic variability for the accumulation of forage and its chemical composition that can subsidize the generation of new commercial cultivars.

Pasture traits and cattle performance in silvopastoral systems with Eucalyptus and Urochloa: Systematic review and meta-analysis

This study evaluated pasture traits and cattle performance in silvopastoral systems (SPSs) with Eucalyptus spp. and Urochloa spp. through a systematic review and meta-analysis. Systematic searches of databases, scientific journals and references of selected articles found 2,639 articles, of which 29 (120 comparisons) were selected. Comparisons were classified according to the covariates of distance between tree rows, number of trees/ha, tree planting orientation, system age and forage type. Data were submitted to meta-regression followed by subgroup analysis for covariates with a significant effect (P < 0.05) on the response. Data were analyzed in random effects models using mean difference and 95% confidence interval (P < 0.05). Forage mass (FM) was greater for SPSs with up to 99 trees/ha and lower for the other groups, compared to that for grass monoculture. Forage accumulation (FA) was also greater for SPSs with up to 99 trees/ha, but lower for SPSs with more than 300 trees/ha, compared to that for grass monoculture. FM was lower for SPSs of all spacings between tree rows and planting orientations, compared to that for grass monoculture, with the lowest being with smaller spacing and with north-south planting orientation. FA was lower for SPSs with up to 28m between tree rows, compared to that for grass monoculture, while that for SPSs with more than 28m did not differ. Neutral detergent fiber concentration was lower and crude protein greater for SPSs compared to grass monoculture, while lignin was greater and in vitro dry matter digestibility did not differ, which indicated no significant improvement in nutritive value in SPSs. Average daily gain was greater in SPSs with up to 99 trees/ha, and lower in those with more than 400 trees/ha, than in grass monoculture, with other subgroups not differing. Total weight gain per area (GHA) was lower in SPSs with less than 28m between tree rows or with more than 199 trees/ha, but greater in SPSs with more than 28m or with up to 99 trees/ha, compared to grass monoculture. GHA was lower in SPSs with a north-south orientation compared to grass monoculture, but those with an east-west orientation did not differ. The use of U. brizantha cv. Marandu and an east-west planting orientation are efficient strategies in maintaining FM, FA and GHA. GHA was greater in SPSs with more than 28m between tree rows and with up to 99 trees/ha, than in grass monoculture, which may facilitate the implementation of these SPSs in commercial farms.

Assessing the freshwater fluxes related to beef cattle production: A comparison of integrated crop-livestock systems and a conventional grazing system

Beef production is one of the largest water consumers of all food production systems, but there are substantial knowledge gaps about the accounting and interpretation of its freshwater consumption. Moreover, hardly any study has assessed the freshwater fluxes related to beef cattle in integrated crop-livestock (ICL) and crop-livestock-forestry (ICLF) systems. We aimed at quantifying the freshwater fluxes related to beef cattle raised on continuous permanent Brachiaria pastures (CON) or in ICL and ICLF systems in the Brazilian Cerrado in the rainy and dry seasons. Evapotranspiration of forage grass, Eucalyptus trees in ICLF, and from drinking water troughs were calculated from meteorological data collected in the field. Forage accumulation was measured in 11 paddocks over both seasons, and forage intake, drinking water intake, and bodyweight were quantified in 12 growing Nellore heifers per system during two months per season. Freshwater fluxes related to forage production and animals were estimated. Drinking water intake and water intake via forage did not differ (P ≥ 0.073) between the systems, and were greater (P ≤ 0.035) in the rainy than the dry season. Faecal and urinary water excretions were greater in the dry than the rainy season (P ≤ 0.005). The respiratory and cutaneous water losses were greater (P < 0.001) in the rainy than the dry season. In the rainy season, evapotranspiration related to forage accumulation and freshwater consumption for raising beef cattle were greatest in CON, whereas they were greatest in ICLF in the dry season. Although ICLF appeared to be less resilient to dry periods, both integrated systems offer the potential for reduced freshwater consumption for raising beef cattle under grazing conditions, by improving the efficiency of forage use and/or decreasing evapotranspiration of forage.

Agrometeorological and Agronomic Characterization of Megathyrsus Grasses Cultivated in Tropical Humid and Semi-Arid Conditions: A Multivariate Approach.

Variability in climatic conditions of low-latitude tropical grass cultivation can affect forage production dynamics. Pasture ecosystems are complex and preferably studied from a multifactorial point of view through multivariate approaches. Therefore, in this study, we characterized different growing conditions for grasses of the Megathyrsus genus through studies conducted in tropical humid and semi-arid conditions. We applied principal component, canonical correlation, and discriminant function analyses to the measurements of agronomic and agrometeorological variables in six studies with Guinea and Massai grasses. The principal component analysis, through the climatic characterization by the first principal component, reflects the contrast between water availability and nitrogen variables and energy supply. Agronomic characterization occurred through the distinction between the density of tillers, forage accumulation, and increase in height, versus the accumulation of stems and dead material. The canonical correlation analysis generated a correlation coefficient of 0.84 between the agronomic and agrometeorological variables. There was a contrast between the dead material accumulation and the other agronomic variables, while the agrometeorological variables showed characteristics similar to the first principal component. Discriminant function 1, with 70.36% separation power, distinguished the cultivation conditions based on the study locations. Grass cultivars were differentiated by discriminant function 2, with a 19.20% separation power. From a multivariate variability analysis, despite the similarities of radiation and temperature in the regions studied, the availability of water and nutrients and measurements of agronomic variables can aid in future modeling studies on forage production.

Nitrogen fertilisation as a strategy for intensifying production and improving the quality of Massai grass grown in a humid tropical climate

The use of nitrogen fertilizers intensifies forage production, especially in tropical climates. This study aimed to evaluate the effects of nitrogen fertilization on the quantitative and qualitative characteristics of Massai grass grown in a humid tropical climate, specifically Am-type. A completely randomized design was used with six treatments and five replicates. The treatments used were a control treatment (without nitrogen application) and five doses of nitrogen fertilization (100, 200, 300, 400, and 500 kg N ha−1 year−1). Urea was used as the nitrogen fertilizer for six applications, with an interval of 30 days. The leaf elongation rate increased by 69.1% at a dose of 500 kg N ha−1 compared to that of the control. The leaf appearance rate and green leaves per tiller increased with nitrogen fertilization. Nitrogen fertilization did not affect the percentage of leaf blades and dead tissue. The average height of the canopies was 44.0 cm, regardless of fertilization. There was a quadratic response in total forage accumulation (TFA), with a maximum of 19,136 kg dry matter at a dose of 391 kg N ha−1year−1. Nitrogen utilization efficiency was the same as that of TFA. There was a reduction in the recovery of applied nitrogen and the agronomic efficiency of applied nitrogen with nitrogen fertilization. The number of cuts increased linearly with nitrogen fertilization, from 3.2 to 7.5 cuts. Crude protein content increased with nitrogen fertilization. Therefore, nitrogen fertilization favored the productivity and quality of Massai grass grown in a humid tropical climate.

La interfaz suelo-planta en Megathyrsus maximus cv. Mombasa sometida a diferentes dosis de nitrógeno en pastoreo rotacional

This work aimed to evaluate the effects of three nitrogen (N) doses on the morphogenic and structural characteristics, root mass (RM) and distribution in the soil profile, and penetration soil resistance of Mombasa guineagrass pastures managed with rotational stocking. The experimental design used randomized blocks with three N doses (100, 200, and 300 kg ha-1) and three replicates. The criterion for interrupting the pastures’ regrowth was the height of 80 to 90 cm of the canopy (90–95 % of light interception by the canopy). The animals were removed from the paddocks when the canopy reached 50 % of the pre-grazing height. Forage mass and accumulation, canopy morphogenic and structural characteristics, RM and distribution in the soil profile, and soil resistance to penetration were evaluated. In pastures fertilized with 200 and 300 kg ha-1 of N, the highest leaf appearance (0.090 and 0.081 leaves-1 tiller-1 d-1), elongation rates (2.82 and 2.61 cm tiller-1 d-1) and highest daily forage accumulation (113.8 and 106.6 kg ha-1d-1) were observed. Using 300 kg ha-1 of N promoted greater soil resistance to penetration at 10 cm of depth in the post-grazing (3.3 MPa). No effect of N doses was observed for RM (P&gt;0.05). The pre- and post-grazing height control of animals in the paddocks therefore helped to maintain the pasture structure and avoid the soil compaction process. According to the results, it is concluded that 200 and 300 kg ha-1 of N fertilization is a strategy for intensifying pastures.