DM Ha-1 Research Articles

Morphology and forage quality in buffel, rhodes, and blue grama grasses in Valle del Mezquital

This study aims to evaluate the production and quality of buffel (Pennisetum ciliare), rhodes (Chloris gayana), and blue grama (Bouteloua gracilis) forage with three defoliation dates —at 50, 80, and 110 days after regrowth (dar)— in Valle del Mezquital. Crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), total digestible nutrients (TDN), relative feed value (RFV), and metabolizable energy (ME) were determined. A completely randomized design with three repetitions, a Tukey test for mean separation (α 0.05), and SAS Proc GLM for data analysis were used. The highest forage production occurs in the rhodes forage at 110 dar (12,936 kg DM ha-1). The highest CP (10.6%) was found in the buffel forage at 50 dar; in the rhodes forage, both values (80 and 110) were lower than 7%. The highest RFV was obtained by exotic grasses; however, higher TDN was recorded for the blue grama grass. Rhodes grass obtained the lowest ME at 80 dar (1.76), while the highest ME was obtained by buffel at 50 dar (1.91). The three varieties can be defoliated when the plants show intermediate yield and nutritional value, i.e., 80 days after the regrowth begins; nevertheless, buffel and rhodes should be defoliated at 50 dar.

Analysing potato response to subsurface drip irrigation and nitrogen fertigation regimes in a temperate environment using the Daisy model

Growing potatoes in temperate regions often leads to nitrogen (N) leaching, however this could be significantly reduced with drip irrigation and nitrogen fertigation if the timing and amounts of the applications matched the crop demand. Determination of when and how much to apply is not straightforward, particularly because the N mineralisation during the potato-growing season is unknown. The present study aimed at providing a solution by the means of a well-calibrated crop model. A comprehensive dataset from a two year experiment on subsurface drip irrigated and N-fertigated potato was used to calibrate and validate the Daisy model with focus on potato crop parameters. The experiment included two irrigation regimes combined with five different N fertigation levels. The calibrated model simulated LAI evolution, crop growth, N uptake and final tuber dry matter and N yield satisfactorily with discrepancies between the simulated and measured variables when simulations were evaluated treatment by treatment. The root mean squared error (RMSE) of the simulated tuber dry matter yield were 0.57 and 0.69 t DM ha-1 for the Folva cultivar in 2013 and Sava cultivar in 2014, respectively. For tuber nitrogen yield, RMSE of the model simulations were 9.7 and 12.8 kg N ha-1 in 2013 and 2014, respectively. Results demonstrated that the calibrated Daisy model could be used as a DSS tool for the optimal irrigation and fertigation of Folva and Sava potato cultivars. Compared to the experimental data the same tuber dry matter yield was simulated with substantial savings 30–55% and 35–50% of irrigation water and N fertiliser, respectively. Results indicated an overestimation of bare soil evaporation, and inconsistences in the simulated effects of water and N stresses on the crop.

Production Characteristics of Ryegrass Pasture under Different Intensities of Grazing and Nitrogen Fertilization in Integrated Crop-livestock Systems

Background: There is little information on the effect of interaction between grazing intensity and nitrogen fertilization on the productive characteristics of ryegrass (Lolium multiflorum Lam). The objective of this work was to evaluate the effect of grazing intensity and nitrogen fertilization on the productive characteristics of ryegrass pasture in a crop-livestock integration system. Methods: A randomized complete block experimental design with a 2 × 2 × 5 factorial arrangement was used, with three replications. The study factors were two management grass heights, low height (LH = 10 cm) and high height (HH = 25 cm), two different nitrogen fertilization times (NP = nitrogen applied to pasture and NG = nitrogen applied to grains crop) and five evaluation periods. Result: The forage mass was higher at higher handling heights and with lower stocking rate (HH = 3995 kg DM ha-1). The forage density tended to be higher in the plots with lower grass height and nitrogen fertilization (LH = 193.5 and NP = 184.7 kg DM ha-1 cm-1). The highest accumulation rate (AR) and forage production (FP) was observed in managed pastures with HHNP (AR = 120.4 kg DM ha-1 day-1; FP = 18471 kg DM ha-1). The management of grass with HHNP provided higher forage mass, higher accumulation rate and higher dry matter production in ryegrass pasture, due to an adequate stocking rate.

Production and quality of tropical grasses at different regrowth intervals in the Brazilian semiarid

The objective of this study was to evaluate the production and chemical composition of three forage species at different regrowth intervals. A 3 x 4 randomized-block factorial design with three forage species (Andropogon, Buffel, and Massai) and four regrowth intervals (21, 35, 49, and 63 days) was used. There was no interaction (p > 0.05) between forage species and regrowth interval on any of the chemical components evaluated. The crude protein content decreased but the contents of neutral detergent fiber, acid detergent fiber and hemicellulose increased with increasing regrowth interval (p > 0.05). Only the contents of crude protein and ether extract were similar (p > 0.05) among grasses. A significant interaction was observed (p < 0.05) between forage species and regrowth interval on forage mass. Andropogon grass had the highest forage mass at 63 days (3,270.1 kg ha-1 DM cut-1) and the highest productivity regardless of the regrowth interval (19.1 t ha-1 DM year-1). Therefore, Andropogon grass was the most productive forage among the tested species. Pastures should be managed with shorter growth intervals due to the highest crude protein level and the lowest contents of neutral detergent fiber and acid detergent fiber.

174 Forage Production and Nutritive Value of Alfalfa-bermudagrass Mixtures Managed Under Contrasting Defoliation Strategies in the Southeast US

Abstract Incorporation of alfalfa (Medicago sativa) into bermudagrass pastures improves forage quality and decreases the reliance on synthetic nitrogen fertilizer. The objective of this study was to determine forage mass (FM), nutritive value (NV), and botanical composition of ‘Bulldog 805’ alfalfa and ‘Tifton 85’ bermudagrass (T85; Cynodon dactylon) mixtures managed under three defoliation strategies: 1) hay production (H), 2) grazing (G) or 3) dual-purpose (DP) use. The study was conducted in two locations (Headland, AL and Tifton, GA) using a randomized complete block design with two replicates. In spring 2020, grazed plots were divided in four strips and every 7-d, animals were rotated to a new strip and stocking rate was adjusted. Under DP, plots were grazed until mid-July, then forage was harvested in late August. For H plots, forage was harvested every 28 to 35-d. Forage samples were collected prior defoliation to determine FM and on grazed periods, pre- and post-grazing samples and disk meter measurements were collected. Nutritive value responses were determined using near-infrared spectroscopy. There was no effect of defoliation strategy on FM (P = 0.604; mean 3471 kg DM/ha). Greater FM (P = 0.002) was observed in July and August than June (3531 and 3976 vs 2905 kg DM ha-1, SE= 263). This response was associated with an up to 40% increase of T85 proportion in the mixture (P = 0.001). Alfalfa percentage was 78% greater for DP than G (P = 0.029). There were no differences among treatments for NV responses (P > 0.05). Among defoliation periods, crude protein, neutral detergent fiber and acid detergent fiber concentrations ranged from 14 to 22%, 45 to 58% and 28 to 35%, respectively. These preliminary results demonstrate multi-use options for this mixture in the region while aiming for increased forage nutritive value, and extended growing season, and sustainability of forage-livestock systems.

Uso de sensores remotos en la determinación del forraje disponible de <i>Urochloa humidicola</i> cv. Llanero bajo pastoreo en la Altillanura colombiana

Modernization of pastoral systems based on the use of Urochloa species in the Colombian Eastern Llanos need the use of remote sensing techniques from satellite platforms to estimate amount of offered forage. In the Carimagua Research Centre of the Colombian Corporation for Agricultural Research (Agrosavia), an Urochloa humidicola cv. Llanero pasture was evaluated using Landsat 8 and Sentinel 2A images. The NDVI, SAVI, EVI y GNDVI vegetation indexes determined by using the blue, green, red and near infrared bands; and the results analyzed with the R free software, to relate those indexes with forage availability field measures taken during the dry season. Forage availability ranged between 290 and 656 kg DM ha-1 and the vegetation indexes for the Landsat 8 and Sentinel 2A sensors were: NDVI = 0.67 (±0.037) and 0.69 (±0.061); SAVI = 0.48 (±0.048) and 0.41 (±0.046); EVI = 0.70 (±0.052) and 0.41 (±0.047); y GNDVI = 0.60 (±0.028) and 0.70 (±0.034), respectively. The relationships between vegetation indexes and forage availability were linear. The Coefficient of Determination (R2= 0.56‒0.72) and the Mean Square Error (MSR =63.95‒80.16) of the prediction equations were used. In conclusion, under the conditions of the study, the EVI for Landsat 8 and NDVI for Sentinel 2A were considered adequate for estimating forage availability of Urochloa humidicola cv. Llanero.

Does Rotational Grazing Based on Leaf Expansion Duration Modify Grazing Behavior and Feed Intake of Beef Heifers on Natural Grassland?

Grasslands develop a multifunctional role to humanity, with unique fauna and flora, besides being the primary feed source for herbivores. However, grasslands are usually considered a low-efficiency production system, often converted into other land uses such as crops and forestation (e.g., south Brazil). This study aimed to evaluate the effect of two rest intervals between grazing occupations in rotational grazing on the grazing behavior and feed intake of beef heifers. Two grazing intervals, 375 and 750 DD (degree-days) were used; based on the cumulative thermal sum necessary for the leaf expansion of native grasses of two functional groups. The experiment was conducted as a completely randomized block design, with two treatments, three replications, and repeated measures over time. The grazing behavior was evaluated continuously for 18 hours (7 a.m. to 11h59 p.m.). Herbage intake was estimated using an external marker (Cr2O3) in four periods (one for each season). The green leaf mass was similar between treatments, with a mean of 40% of the pregrazing mass (kg DM ha-1). On average grazing, time was 50% of the period, and the bite rate was 38.7 bites min-1. The number of daily meals was 6.5, with an average of 84 minutes for each meal. The number of feeding times (feeding stations by minute) visited was 6.4. On average, there was a 2.23% difference in dry matter intake (% BW) among seasons. Neither ingestive behavior or forage consumption of heifers was affected by the treatments, both maintain similar chemical composition on natural grassland.

REUTILIZAÇÃO DA ÁGUA RESIDUÁRIA DA ORDENHA NA PALMA SOB DIFERENTES FREQUÊNCIAS DE IRRIGAÇÃO E ADUBAÇÃO

Objetivou–se avaliar o desempenho da palma miúda (Nopalea cochenillifera Salm Dyck), em cultivo adensado sob diferentes frequências de fertilização e irrigação com água de reuso no semiárido sergipano. O delineamento foi em parcelas subdivididas, com três repetições de quatro parcelas de irrigação (7, 14, 21 e 28) e um controle (sem irrigação) e quatro níveis de fertilização: adubação orgânica 1 (35t esterco bovino ha-1), adubação orgânica 2 (35t esterco ovino ha-1), química (150 kg de N ha-1) e fertirrigação (água residuária). Onde as variáveis de crescimento (Altura, TCV-Taxa de Crescimento Vertical; TCH-Taxa de Crescimento Horizontal; TApC-Taxa de Aparecimento de Cladódio) não demonstraram diferenças em relação a frequencia de irrigação com o controle; os NCT-Números de Cladódios Totais, o CC-Comprimento do Cladódio, EC- Espessura do Cladódio, VT- Volume Total e a EUA- Eficiência de Uso da Água, foram semelhantes entre os tratamentos e a LC-Largura do cladódio foi inversamente proporcional; frequências de irrigação de 7 e 14 dias foram semelhantes e maiores que 21 e 28 dias. No tratamento controle (sequeiro) obteve - se produtividade de 23,84 t MS ha-1, sendo a menor obtida quando comparada a maior produtividade da frequência de irrigação de 14 dias, que foi de 30,11 t MS ha-1. A frequência de irrigação de 7 dias promoveu melhores resultados morfológicos na palma. Podendo inferir que, aos 18 meses de idade, se o fator água não for limitante, a palma miúda pode atingir o ponto máximo de crescimento, sendo este, quando atingida a 5ª ordem de aparecimento de cladódios.

Effects of intercropping on temperate grasses canopy architecture and nutritive profile

This paper aimed to evaluate the impact of intercropping between oats and triticale species, over three defoliation cycles. The experiment occurred in two winters in a row, and was in split-plot randomized complete blocks design (20 plots) with five species combination, four blocks and three defoliations. The main plots were the species combination: black oat (Avena strigosa cv. IAPAR 61) – BO, white oat (Avena sativa cv. IPR Emerald) – WO, triticale (X Triticosecale Wittmack cv. Tpolo 981) – T; and the intercropping: black oat + triticale – BOT, and white oat + triticale - WOT. The sub-plots were the three defoliations cycles initially scheduled to be every 28 days. The intercropping between oats and triticale did not affect the accumulated dry matter yield (DM), but it also improved the pastures, as an increase on crude protein content (CP) (about 1.85% greater in WOT than WO; and 2.7% greater in BOT than BO). The number of leaves was also increased by the intercropping, from 4.2 (WO) and 3.7 (BO) to 7.6 (WOT) and 7.2 (BOT) leaves per main stem. Over the defoliation cycles, the maximum average of growth rate (2.72 t DM ha-1 ºCd-1), tiller per plant (10 tillers plant-1) and main tiller height (53.2 cm) were unanimously observed at third defoliation. The changes observed did not reduced the nutritional quality of the pastures, therefore both are highly indicated to these conditions.

Optimization of agricultural practices for crambe in Europe

Crambe (Crambe abyssinica Hochst R.E. Fries) has recently attracted a renewed interest by the bio-based industry due to its high seed oil content (up to 57%), particularly erucic acid (up to 65% of total fatty acids), short growing cycle, and high drought tolerance. A field trial was conducted during four consecutive growing seasons (2016−19) in Greece, Poland, and Italy. The commercial crambe variety (Galactica) was sown in early, intermediate, and late sowing dates in spring at two seeding rates (LD: 100 seeds m−2, and HD: 200 seeds m−2) in a factorial design at each test location. Mean crambe seed yields exceeded 1.5 Mg DM ha-1 across all years and locations. Italy and Greece were the most productive sites, with average seed yields of 2.11 Mg DM ha-1 and 1.97 Mg DM ha-1, respectively. Oil yield, which was only determined in Italy and Poland, was about 30% greater in the southern environment (Italy). Nevertheless, 1000-seed weight was greater in Poland (6.49 g) than Italy (6.12 g), revealing that lower temperatures during seed filling resulted in heavier seeds. In conclusion, sowing date played a key role in crambe productivity, with the earliest sowing resulting in highest yields across all locations.

Yield estimation of forage oat (Avena sativa L.) Chihuahua variety: ruler and plate methods

Objetive: To analyze forage estimations with the direct method and the plant height.
 Diseño/Metodología/Aproximación: The treatments were the plants age, assessed in a random block design, with three repetitions. Simple linear regressions were carried out and adjusted using the SPSS statistical software.
 Resultados: The highest and lowest yields occurred at 105 and 30 days after sowing (DAS), with 5,412 and 783 kg DM ha-1, respectively. Height with the rule had a significant effect on forage production, with an R2 of 0.83. For each increase per cm the plants increased 56,134 kg DM ha-1. The height with the plate had an R2 of 0.97, so that 65.032 kg DM ha-1 are produced for each cm in height.
 Limitaciones del estudio/implicaciones: None
 Hallazgos/conclusiones: The forage accumulation in Avena sativa L., var. Chihuahua varied depending on the age of the plant. The heights calculated with the plate method, had greater reliability for the forage yield estimate, compared to the graduated rule method.

Productive Performance of Alfalfa (Medicago sativa L.) at Different Age of Resprout in the Spring Season

Objective: To determine the growth and productive performance curves, to obtain the optimal cutting moment in alfalfa, depending on the age of resprouting, in the Spring season.Design/Methodology/Approach: The treatments were cuts at different age of the plant and the variables evaluated: Dry Matter Yield (DMY) Botanical and Morphological composition (BMC), Plant Height (PH), Leaf/Stem Ratio (L/SR), and Intercepted Radiation (IR). The stastical analysis was with the PROC GLM procedure, of the SAS software, and the adjustedcurves were obtained with the Curve Expert Professional 2.0 software.Results: There was an increase in the DMY, leaf, stem, PH, and IR, as the resprouting age advanced, but not, the L/SR which had an inverse behavior. The maximum DMY was obtained (4,768 kg DM ha-1) in week seven. There was a greater amount of leaf with average 52%, followed by the stem (36%), weeds (7%), detritus (4%) and inflorescence (1%). The PH washigher in week seven with 53 cm. Likewise, the highest IR in week tree with 86%. However, the L/SR was higher in week one with 2.4. The IR and L/SR presented the lowest R2 (0.90 and 0.93, respectively). In contrast, DMY and PH presented apositive relationship (R2 of 0.98 and 0.97, respectively).Study Limitations/Implications: There were no limitationsFindings/Conclusions: The productive performance of Premium variety alfalfa was variable depending on the resprouting age, in which the botanical and morphological characteristics changed, with better characteristics in the fifth week

Effect of rhizobial inoculation combined with phosphorus fertilizer on nitrogen accumulation, growth and yield of soybean in Benin

The objective of this study was to determine the amount of phosphorus application needed for the Bradyrhizobium inoculation to improve soybean N uptake and grain yield. Two factors were investigated: inoculation with Bradyrhizobium diazoefficiens strain USDA 110 and application of phosphorus fertilizer with different doses (0; 50; 100 and 150 kg ha-1 P2O5). Trials were carried out in two agro-ecological zones (ZAE) in Benin with two experimental sites namely Ketou and Ze. The experimental design was a Complete Randomized Block Design. Results showed that the highest mean height values were recorded T1+150P (42.22 cm at Ze and 43.82 cm at Ketou) while the lowest values were recorded with the treatment T0 + 0P. Treatment T0 +100P gave the highest aboveground biomass at 10 weeks after sowing at Ketou (2521.43 kg DM ha-1) while T1+150P recorded the highest aboveground biomass at Ze (3392.75 kg DM ha-1). At Ketou, the grain yield was increased under T1+100P by 98% compared with T0+0P. At Ze, the treatments T1+100P significantly increased the soybean grain yield by 147% compared with T0+0P. Likewise, T1+100P allowed to have the highest total nitrogen yields in the grain which is respectively 144.13 kg ha-1 N and 295.02 ha-1 kg N at Ketou and Ze. Overall, the inoculation with B. diazoefficiens had significantly increased the number of nodules for all of the phosphorus fertilizer amounts. The mycorhization frequency was significantly lower under the treatment T0 + 0P (41.46%) than the other treatments while that was higher under the treatment T1+50P (76.04%). Keywords: Bradyrhizobium diazoefficiens, soybean inoculation, grain yield, Benin.

Cross sectional comparison of chemical treatment on plant biodiversity at Neudamm farm, Namibia

This study determined the impact of Tebuthiuron application on plant biodiversity over a three-year period at Neudamm farm. A total of 40 (1m2) quadrats were randomly nested in three 250 m2 belt transects per each treatment to record the herbaceous plant density, species composition, dry matter and ground cover. Woody plant density, heights and canopy diameters were measured in each 250 m2 belt transects. A General Linear Model (GLM) procedure of SAS (2007) was used for analyses. The herbaceous biomass production was significantly higher (P < 0.05) in chemically treated site of 2015 (975 Kg DM ha-1) and least in the other two sites. The chemically treated site of 2016 had greater (P < 0.05) ground cover percentage than the other treatment sites. The canopy cover and woody plant densities in all woody height categories were higher (P < 0.05) in the control and chemically treated site of 2017, than the other two sites. The study concluded that the Tebuthiuron had impacted on the plant biodiversity of treated rangelands by improving the herbaceous plant species, biomass yields and reduced bush density. The study recommends that aftercare practices and application of arboricides be carried out routinely to allow herbaceous plants recovery.
 Keywords: Bush encroachment, arboricides, plant density, biomass production, canopy

5 Animal performance in grass monoculture or silvopasture systems using tree legumes

Abstract Silvopasture systems (SPS) area management option to enhance delivery of ecosystem services and diversification of income. This study evaluated productive responses of signalgrass (Urochloadecumbens Stapf.) in monoculture or in SPS in the sub-humid tropical region of Brazil during six months of the rainy season. The experimental design was randomized complete block with three replications. Treatments were signalgrass + Mimosa caesalpiniifolia Benth. (SPS-Mimosa); signalgrass + Gliricidia sepium (Jacq.) (SPS-Gliricidia); and signalgrass monoculture. Cattle were managed under continuous stocking with variable stocking rate. Response variables included herbage mass (HM), herbage accumulation (HA), stocking rate (SR), average daily gain (ADG), and gain per area (GPA). Herbage mass (HM) was greater (P < 0.0001) on signal grass monoculture (2045 kg DM/ha) than in SPS (1370 kg DM/ha, average for both SPS). Herbage accumulation rate was similar for signalgrass in monoculture and SPS-Gliricidia (avg. 61 kg DM ha-1 d-1), and both were greater than SPS-Mimosa (37 kg DM ha-1 d-1). Average daily gain was greater(P < 0.0001) for SPS-Gliricidia (1.1 kg head-1 d-1), followed by signalgrass in monoculture (0.9 kg head-1 d-1), and SPS-Mimosa (0.3 kg head-1 d-1). Stocking rate ranged from 0.6 animal units (1AU = 450-kg animal) per ha in April to 2.2 AUha-1 in June. Stocking rate and animal performance per area were similar for signalgrass in monoculture and SPS-Gliricidia, and both greater than SPS-Mimosa. Gliricidia enhanced animal performance and provided ecosystem services. Mimosa, however, reduced animal performance likely due to the competition with signalgrass. Mimosa trees, however, are an important source of income (timber used for fence posts) and that might overcome the losses in animal performance.

6 Animal performance in grass monoculture or silvopasture systems using tree legumes

Abstract Silvopasture systems (SPS) area management option to enhance delivery of ecosystem services and diversification of income. This study evaluated productive responses of signalgrass (UrochloadecumbensStapf.) in monoculture or in SPS in the sub-humid tropical region of Brazil during six months of the rainy season. The experimental design was randomized complete block with three replications. Treatments were signalgrass + Mimosa caesalpiniifolia Benth. (SPS-Mimosa); signalgrass + Gliricidia sepium (Jacq.) (SPS-Gliricidia); and signalgrass monoculture. Cattle were managed under continuous stocking with variable stocking rate. Response variables included herbage mass (HM), herbage accumulation (HA), stocking rate (SR), average daily gain (ADG), and gain per area (GPA). Herbage mass (HM) was greater (P < 0.0001) on signal grass monoculture (2045 kg DM/ha) than in SPS (1370 kg DM/ha, average for both SPS). Herbage accumulation rate was similar for signalgrass in monoculture and SPS-Gliricidia (avg. 61 kg DM ha-1 d-1), and both were greater than SPS-Mimosa (37 kg DM ha-1 d-1). Average daily gain was greater(P < 0.0001) for SPS-Gliricidia (1.1 kg head-1 d-1), followed by signalgrass in monoculture (0.9 kg head-1 d-1), and SPS-Mimosa (0.3 kg head-1 d-1). Stocking rate ranged from 0.6 animal units (1AU = 450-kg animal) per ha in April to 2.2 AUha-1 in June. Stocking rate and animal performance per area were similar for signalgrass in monoculture and SPS-Gliricidia, and both greater than SPS-Mimosa. Gliricidia enhanced animal performance and provided ecosystem services. Mimosa, however, reduced animal performance likely due to the competition with signalgrass. Mimosa trees, however, are an important source of income (timber used for fence posts) and that might overcome the losses in animal performance.

Impact of pasture height and herbage mass on suppression of variegated thistle in North Island East Coast hill country

Variegated thistle in East Coast North Island hill country reduces pasture and livestock productivity. To quantify the impact of increasing amounts of pasture cover (herbage mass) on this weed, variegated thistle seeds were hand-sown in autumn into pasture swards that ranged in height from 0 cm (bare ground) to 12 cm, on an East Coast property near Gisborne. Sward height was maintained by mowing without damaging the thistle plants. Increasing pasture cover reduced thistle emergence, height, diameter, biomass, survival, and seed production. By early June, 7 weeks after sowing, thistle emergence was greatest from bare ground and from maintaining a pasture at a height of 3 cm (>1100 kg DM ha-1 in autumn) and declined with increasing pasture height. By December, thistle height, diameter, biomass, flowerhead production and survival were highest in the bare ground treatment (thistle biomass ≈760 g plant-1), much lower in the 3-cm pasture height treatment (≈20 g plant-1), negligible in the 6-cm (>1600 kg DM/ha) and nil in the 8-cm (>1800 kg DM ha-1) and 12-cm (>2700 kg DM ha-1) pasture treatments (P<0.002). Maintaining pasture height of 3 cm severely reduced variegated thistle establishment, growth and flowerhead production. Results infer that grazing management strategies, such as lengthening the interval between grazing events in autumn and early winter, will increase pasture cover and are likely to severely reduce thistle establishment, growth and seed production.

Supplementation of lamb ewes with different protein sources in deferred marandu palisadegrass (Brachiaria brizantha cv. marandu) pasture

ABSTRACT The objective of this study was to evaluate the effect of different protein sources on the performance of lamb ewes and their offspring supplemented in deferred pasture. The treatments were the different protein sources: soybean meal, cotton cake, babassu cake and coconut cake. The ewes were weighed and evaluated for their body condition score during the gestation, parturition and weaning phases. The lambs were weighed at birth and at weaning. The structural variables and chemical composition of the pasture were evaluated during the usage period. Grass height and forage mass were higher when the ewes were in the gestation and weaning stages. The leaf mass was not altered during the pasture usage with a mean value of 566.1kg ha-1 DM. The highest levels of crude protein in the leaf blade were observed during the parturition and weaning phases. The body weight of the ewes did not differ between the sources with averages 45.0, 39.9 and 36.6kg for the gestation, parturition and weaning phases, respectively. Weights at birth and at weaning had an effect from protein sources, with the highest values observed in the lambs of ewes who received soybean meal and babassu cake supplementation. The lambs of ewes supplemented with soybean had higher average daily gain and total gain. Babassu, coconut and cotton cakes can replace soybean meal in supplementation of ewes in deferred pasture.

Morphogenic and structural characteristics of Panicum cultivars during the establishment period in the Brazilian Northeast

This study aimed to evaluate the morphogenic and structural characteristics of six Panicum maximum cultivars during the establishment period. A completely randomized block design with four replicates and six treatments (Tamani, Mombaça, Massai, Tanzania, Aruana and Zuri cultivars) was used. Morphogenic (leaf appearance rate, leaf elongation rate e stem elongation rate), structural (final leaf length, tiller population density e number of leaves per tiller) and productive (forage mass, leaf blade mass, stem mass, senescent material mass and leaf:stem ratio) characteristics were evaluated. There was no difference (p > 0.05) between the cultivars in terms of the number of live leaves per tiller (2.95 leaves/tiller). Mombaça cultivar had (p < 0.05) higher canopy height (50.64 cm) compared with other cultivars. The highest (p < 0.05) tiller population density was observed in Tamani (235.90 tillers m-2) and Massai (201.60 tillers m-2) cultivars. Leaf lifespan (54.18 days), phyllochron (17.40 days/leaf) and leaf senescence rate (0.87 cm tiller day-1) were not different (p > 0.05) between cultivars. However, leaf appearance rate was higher (p < 0.05) in Tanzania (0.07 leaves tiller day-1) than in Aruana cultivar (0.05 leaves tiller day-1). Leaf blade mass was higher (p < 0.05) in Mombaça cultivar (1518.31 kg DM ha-1), whereas Massai showed higher (p < 0.05) leaf:stem ratio (9.25). Panicum cultivars Tamani, Tanzania and Massai establishment after 75 days, while the other cultivars establish at 105 days of sowing in the Brazilian Northeast.

Comportamiento forrajero del estrato herbáceo en diferentes densidades arbóreas de selva baja caducifolia

La sombra de los árboles proyectada sobre el estrato herbáceo que crece bajo el dosel representa para los ganaderos un efecto no deseado para la producción de forrajes en el sistema silvopastoril. Con el objetivo de determinar la producción de materia seca y la composición florística del estrato herbáceo con diferente cantidad de radiación fotosintéticamente activa, se seleccionaron tres parcelas con baja densidad arbórea (BDA; 50 a 200), moderada densidad arbórea (MDA; 201 a 350) y alta densidad arbórea (ADA; 350 a 500) árboles ha-1. En cada parcela se estimó la radiación fotosintéticamente activa (RFA) que incide en el estrato herbáceo y se determinó la producción de materia seca (MS) de las herbáceas forrajeras presentes durante 15 semanas de la estación lluviosa. La intensidad de luz bajo el dosel y la producción de biomasa forrajera herbácea en BDA, MDA y ADA fue 8 594, 6 437 y 3 801 MJ m2 año-1 y 2 859, 1 988 y 1 679 kg de MS ha-1, respectivamente. El número de especies herbáceas en BDA, MDA y ADA fue 38, 48 y 27, respectivamente, aunque las especies dominantes, con más de 80% de la composición botánica, fueron solo seis. Se concluye que la densidad arbórea modifica la cantidad de luz que incide en el estrato herbáceo, afectando la producción de biomasa y la composición florística de las herbáceas forrajeras que crecen bajo el dosel arbóreo en un sistema silvopastoril tradicional en la selva baja caducifolia.