Regrowth Ages Research Articles

Productivity and quality of Mulato II grass (Urochloa híbrido) alone and silage with agroindustrial by-products

The use of silage is considered as a feeding strategy in animal production systems with ruminants during dry periods. The objective was to evaluate the yield and nutritive value in forage and silage of Mulato II grass (Urochloa hybrid) and two additives, at different regrowth ages. Ages of 3, 6 and 9 weeks and additives (orange peel and molasses) were evaluated in silages: 1) Mulato II (ME); 2) Mulato II + orange peel; 3) Mulato II + molasses and 4) Mulato II + orange peel + molasses. The variables were: yield (kg ha-1) of total dry matter (TDM) and by morphological component, plant height (PH, cm), leaf area index (LAI), CP, NDF, ADF and lignin in forage and silage; pH, brix degrees and DM (%) in silage. When the forage was harvested at nine weeks of regrowth, the highest DM yield was obtained (7 508 kg ha-1), while the CP content was higher in week three of regrowth (201 g kg-1), exceeding by 10 and 29% that found in the sixth and ninth weeks. The silages with additives presented the highest CP values and the lowest values of ADF, NDF and pH. The higher the age of regrowth, the higher the dry matter yields, while the nutritive value decreased; however, the use of orange peel and molasses in grass silages improved the nutritive value.

Indicators of kidney function in guinea pigs (Cavia porcellus) fed with the inclusion of pisonay (Erythrina edulis) meal of three regrowth ages

Indicators of kidney function in guinea pigs (Cavia porcellus) fed with the inclusion of pisonay (Erythrina edulis) meal of three regrowth ages

Yield and nutritive value of Urochloa hybrids at different regrowth ages

Objective: To evaluate the productive behavior of Urochloa hybrids, depending on the regrowth age.
 Design/Methodology/Approach: The study was carried out under rainfed conditions during 2018. The Cayman, Mulato II, Convert 330, Cobra, Camello I, and Camello II hybrids were evaluated based on the regrowth age (2, 4, 6, 8, and 10 weeks). The following variables were evaluated: plant height (PH), total dry matter (TDM) yield, dry matter per leaf (DMl) yield, dry matter per stem (DMs) yield, crude protein content (CP), acid detergent fiber (ADF), and neutral detergent fiber (NDF). The data obtained were evaluated by means of a randomized complete block design with three repetitions, divided into plots: a large plot for the cultivars and small plot for the regrowth ages.
 Results: The Camello II cultivar obtained the highest TDM yields during the sixth and eighth weeks (4.15 and 6.35 t DM ha-1, respectively); however, during the tenth week, the yield was equal to the yield obtained with the Mulato II and Cayman cultivars (p<0.05). The highest DMl yield was obtained by the Mulato II cultivar during the sixth, eighth, and tenth weeks (3.37, 4.56, and 3.86 t DM ha-1, respectively). The Mulato II cultivar recorded the highest CP values during the second and fourth weeks (158 and 126 g kg-1, respectively); however, the Camello II cultivar obtained the highest CP values during the sixth, eighth, and tenth weeks (99, 95, and 87 g kg-1, respectively). The NDF and ADF values increased as the regrowth age increased: in the tenth week, the Camello II and Cobra cultivars obtained the highest NDF values, while the Camello II cultivar recorded the highest ADF value during the same period.
 Study Limitations/Implications: Urochloa cultivars were developed for their establishment in humid tropical conditions, where their productive performance is greater. However, in dry tropical conditions, the Cayman, Mulato II, and Cobra cultivars have had a better performance than other grasses —such as buffel grass (Pennisetum ciliare), which is used to feed ruminants. In this sense, other Urochloa cultivars (e.g., Camello I and Camello II), which have greater tolerance to droughts, show desirable forage characteristics, such as yield and forage quality.
 Findings/Conclusions: The cultivars with the best productive performance were Camello II, Mulato II, and Cayman.

Do regrowth age and microbial inoculant usage affect the microbial diversity and fermentation characteristics of forage peanut silage?

AbstractThis study evaluated the fermentation characteristics, microbial diversity, chemical composition, and in vitro digestibility of forage peanut silage harvested at two regrowth ages and treated with microbial inoculants at different fermentation periods. A randomized block design was used, with two regrowth ages (R; 40 and 80 days), three microbial inoculants (I; control without inoculant [CTRL], strain AV14.17—Lactiplantibacillus pentosus strain AV14.17 [ISO], and commercial inoculant [CI] Sil‐All 4 × 4 (Lallemand Animal Nutrition®, Patos de Minas‐MG, Brazil), and four storage time (ST; 3, 14, 30, and 60 days after ensiling) arranged in a 2 × 3 × 4 factorial scheme, with four replications. The R × I × ST interaction had a significant effect (p ≤ .05) on the ammoniacal nitrogen content in relation to total nitrogen (NH3‐N/ total N) and on the yeast population. The I × ST interaction also had a significant effect (p ≤ .05) on pH, soluble carbohydrate, NH3‐N/total N, lactic acid bacteria, yeast, and filamentous fungi. Inoculated silages with ISO and CI showed lower pH and NH3‐N/total N values, as well as lower abundance of enterobacteria, yeast, and filamentous fungi. In silages inoculated with ISO, the relative abundance of genus Lactiplantibacillus was high and that of genus Enterobacter was low. Silages inoculated with ISO and CI showed predominance of the family Lactobacillaceae. The data support the recommendation to ensile forage peanut at both regrowth ages (40 and 80 days) associated with microbial inoculant application to promote improvements in the fermentation characteristics of the silage and a greater abundance of genus Lactiplantibacillus.

In vitro CHEMICAL AND FERMENTATIVE CHARACTERISTICS OF TROPICAL PASTURES AT DIFFERENT AGES OF REGROWTH

The low nutritive value of pastures in tropical regions represents a limitation in the productivity of grazing ruminants. The objective was to determine the in vitro chemical and fermentative characteristics of nine tropical grasses (Aruana [Panicum maximun Jacq. cv. Aruana], Bermuda [Cynodon dactylon L.], Estrella de África [Cynodon Cynodon nlemfuensis Vanderyst], Insurgente [Brachiaria brizantha Hochst. Stapf.], Llanero [Andropogon gayanus Kunth], Mombaza [Panicum maximun Jacq. cv. Mombaza], Pará [Brachiaria mutica Stapf], Pangola [Digitaria eriantha Steud.], and Tanzania [Panicum maximun Jacq. cv. Tanzania]) at three regrowth ages (30, 45, and 60 days). The chemical analysis was used to determine the concentrations of dry matter (DM), crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), and ash (Ce). The in vitro trial measured partial (24, 48, and 72 h) and cumulative biogas and methane production, fermentation kinetics estimators (A, b, and k), dry matter degradation (DMD) and detergent neutral fiber degradation (NDFD), pH, and ammonia nitrogen (N-NH3). The experimental design was completely randomized at each regrowth age. In conclusion, based on chemical analysis and fermentative characteristics, Pangola and Estrella pastures performed better at each regrowth age.

Mineral profile in Panicum maximum cv Mombaza and Tanzania pastures at two regrowth ages

This research was carried out in the Cattle Line Livestock Program, properties of the Río Suma experimental farm of the agricultural engineering career of the Laica Eloy Alfaro de Manabí University, in the El Carmen canton, Manabí province, located at Km 30 of the Santo Domingo - Chone road, right margin, between the coordinates of 0° 15' S and 79° 26' W. This study aimed to evaluate the effect of two varieties of pastures at two cut-off ages in mineral content. A completely random design with a 2 x 2 factorial arrangement was used. A total of 4 treatments were used, distributed in 12 repetitions. The statistical software INFOSTAT was used to process the information. The factors under study were varieties of pastures (Mombaza and Tanzania) and age of cutting or regrowth (20 and 25 days), and the variables under study Content of Phosphorus (P), Potassium (K), Calcium (Ca), Magnesium (Mg) and Copper (Cu). The Mombasa grass variety reaches a higher content of K and Mg, and the Tanzania grass contains a higher amount of Ca. The cut or regrowth age of 20 days obtains a more significant amount of Cu; at 25 days, it is possible to fix a more significant amount of P, Ca and Mg. The interactions between Mombaza x 25 days and Tanzania x 25 days reached a higher P content, and Tanzania x 25 days fixed a more significant amount of Ca. Keywords: content; minerals; pastures

Influencia de los intervalos de corte en la calidad del heno de Panicum maximum cv. BRS Tamani en el Cerrado brasileño

The grass Panicum maximum cv. BRS Tamani is a hybrid high-quality, small-sized forage plant with intense tillering activity. This study was carried out to examine the potential of the grass Panicum maximum cv. BRS Tamani at different regrowth ages (49, 63, 77, and 91 d) for hay production, in the rainy period. The experiment was conducted at the Farm School of the Federal University of Mato Grosso do Sul-Brazil, between October 2015 and April 2016. The treatments corresponded to four regrowth ages, with four replicates, distributed into 9 m2 plots. Regrowth ages influenced the morphogenetic characteristics of the grass, except for leaf senescence and final leaf length. Green (9.6–17.6 t ha-1) and dry-matter (2.6–5.9 t ha-1) yields, hay yield (3.4-6.9 t ha-1), and proportions of stem (91.6–455.9 g kg-1) and senescent material (34.8–98.4 g kg-1) increased with the regrowth ages, while the proportion of leaves (837.7-402.1 g kg-1) and the leaf: stem ratio (15.9–0.9) decreased (P<0.05). The dry matter (881.7–852.8 g kg-1) and protein contents (81.2–47.6 g kg-1) of the hay decreased with the higher regrowth ages; however, the neutral detergent fibre (746.5–759.2 g kg-1) acid detergent fibre (519.8–567.7 g kg-1) and lignin (74.3–86.4 g kg-1) contents rose as the regrowth ages did. Nutrient digestibility decreased with the regrowth ages (P<0.05). Panicum maximum cv. BRS Tamani has the potential to produce of hay ha-1, better nutritive value and a high proportion of leaves in the regrowth interval of 49 to 63 d.

In vitro biogas production and degradations of sheep diets containing Crotalaria or Chipile at two different regrowth ages

Objective: To determine the in vitro biogas production and fermentative characteristics of diets for fattening lambs containing 20% chipile or crotalaria at 30 or 40 d of regrowth.Methodology: The treatments were whole diets containing 20% crotalaria with 30 d (T1) or 40 d of regrowth (T2), as well as 20% chipile with 30 d (T3) or 40 d of regrowth (T4). In vitro gas production was measured at 2, 4, 6, 8, 10, 12, 24, 48, and 72 h and the following elements were determined: kinetic estimators (A, b, k), dry matter (DMD), organic matter (OMD), neutral detergent fiber (NDFD), and acid detergent fiber (ADFD) degradation, metabolizable energy (ME), and short-chain fatty acids (SCFA). The experimental design was completely randomized.Results: Regarding the accumulated biogas production, T4 presented higher production from 2 to 24 h, T3 and T4 higher at 48 h, and T1 higher at 72 h. Kinetic estimators showed that T1 was higher in A and k and T4 was higher in b. T2 presented the lowest DMD, OMD, NDFD, ADFD, ME, and SCFA.Study Limitations: Scale production of chipile, aimed to obtain a greater biomass volume, is limited since it has not been domesticated yet. Conclusions: Sheep diets containing 20% chipile or crotalaria with 30 d of regrowth have proven to be an alternative for the manufacturing of whole diets for the intensive fattening of lambs in the tropics.

Productive characteristics, chemical composition, in vitro digestibility, and degradation kinetics of two Brachiaria grasses at different regrowth ages.

The study aimed at the effect of different regrowth ages on chemical, productive, and morphological characteristics, in addition to the kinetics of gas production and in vitro digestibility of grasses of the genus Brachiaria. The treatments consisted of two regrowth ages (21 and 35days) and two grass species (Brachiaria brizantha and B. ruziziensis), in plat with a dimension of 10 × 10 with four replications, totaling 16 plats in a completely randomized design. The regrowth age did not change the leaf:stem ratio of the grasses. Ruziziensis-grass had higher crude protein (CP) content in leaves than Marandu-grass (14.0% versus 10.9% respectively). Marandu-grass leaf had higher NDF content than Ruziziensis-grass (65.0 and 58.3%, respectively) and ADF content (39.6 and 33.2%, respectively). The accumulation rate is high in Marandu-grass regardless of the age of regrowth; however, the in vitro digestibility of dry matter of Ruziziensis-grass is better both in the leaf and in the stem. The regrowth age did not influence the dry matter (DM) and neutral detergent fiber (NDF) in vitro digestibility (ivD) of the leaves. The ivDNDF of leaves of both types of grass were similar. There was an increase in the ivDDM of stem when the regrowth age was 21days. The DM degradation rate was higher in Marandu-grass at both regrowth ages, and the total gas production was higher at 21days. The parameters evaluated in the dual-pool logistic model showed interaction for age and cultivar, except for fractions λ (lag time) and total gas production. Marandu-grass presented a greater volume of gas for the rapidly degradable fraction and a lower degradation rate. There was a significant interaction for the parameters evaluated in the models between ages and grasses. The exponential model showed interaction in all fractions. Grasses had reduced CP content and increased fibrous fraction as a function of age, with no reduction in leaf DM and NDF digestibility. The Ruziziensis-grass has higher digestibility at the regrowth ages evaluated, while Marandu-grass has higher yields. We recommend adjusting the in vitro degradation kinetics by the dual-pool logistic model.

Estimation of in vitro digestibility and fermentation of elephant grass by near infrared spectroscopy

AbstractThe methods used to evaluate kinetic parameters of ruminant feeds can be in situ and in vitro. For both methods, it is necessary to maintain cannulated animals in order to collect the inoculum from the rumen, which has been under strong pressure from society, in terms of animal welfare policies, to avoid this type of practices. This work aimed to evaluate the estimation of in vitro digestibility and fermentation of elephant grass forage by near infrared reflectance spectroscopy (NIRS), as a fast and noninvasive alternative to the in vitro method. The experimental design was in randomized blocks with three repetitions. The treatments were arranged in a split‐plot scheme, with 13 genotypes in the plot and 15 regrowth ages in the subplot. Crude protein (CP) and neutral detergent fiber (NDF) contents; in vitro dry matter (IVDMD) and NDF (IVNDFD) digestibilities; and total volume (Vt), gas production rate (μ) and half‐life conventional analyses were determined for pre‐dried elephant grass forage samples. For the evaluation of NIRS models performance, coefficient of determination (R2cv) and standard error of cross validation (SECV) were used. As the regrowth age advanced, there was a linear increase in the NDF content and a linear reduction in the IVDMD, IVNDFD and Vt values. The NIRS estimates proved to be adequate for IVDMD (R2cv = .95), IVNDFD (R2cv = .85), Vt (R2cv = .81) and gas production at 48 (R2cv = .82), 72 (R2cv = .85) and 96 h (R2cv = .84), confirming as an alternative to the in vitro methods that dispense with the use of cannulated animals.

EFECTO DE LA EDAD Y ALTURA DE CORTE DE HÍBRIDOS DE Urochloa sp. SOBRE LA PRODUCCIÓN DE GAS In vitro

<p><strong>Background</strong>. The production of ruminants in the tropics is based on the grazing of grasses, which present variations in their nutrient content depending on the intensity and frequency of cutting. <strong>Objective.</strong> To determine the effect of cutting intensity and regrowth age of the morphological composition of three hybrids of the genus <em>Urochloa sp</em> on gas production and <em>in vitro</em> gas production kinetics. <strong>Methodology</strong>. The samples were formed by the interaction of three morphological-hybrids (Cobra, Cayman and Mulato II-leaf and stem), two cutting intensities (10 and 15 cm) and 5 regrowth ages (7, 21, 35, 49 and 63 d). Partial and accumulated gas production, maximum volume (V), gas production rate (S) and Lag time (λ) were determined for the samples. The statistical design was a 6 x 2 x 5 factorial arrangement within a completely randomized design. <strong>Results</strong>. The leaves and stems of Cobra and Cayman showed the highest partial and cumulative <em>in vitro</em> gas production (p<0.05). The evaluated variables were not affected by the cutting intensity and the behavior in the <em>in vitro</em> tests was greater at 21 and 35 days of regrowth of the pastures. <strong>Implications</strong>. The cut intensity variable did not modify the mean values of the variables evaluated in this research work, while age negatively affects it. <strong>Conclusions</strong>. The leaves and stems of Cobra and Cayman grasses showed the highest partial and cumulative <em>in vitro</em> gas production.</p>

Ruminal kinetics and nutritive value of Zuri grass silage harvested at different ages and added with powder molasses.

This study aimed to evaluate the effect of regrowth ages and the use of powdered molasses on nutritional characteristics of Zuri grass (Megathyrsus maximus) silages. A completely randomized design was used, in a 3 × 3 factorial scheme: three regrowth ages (65, 80, and 95days) and three inclusion levels of powdered molasses of sugarcane (0, 20, and 40g), with four replications. The chemical composition, fermentation parameters, in vitro digestibility, and in vitro degradation kinetics of the silages were evaluated. Greater dry matter (DM) contents were observed in silages with 95days with 40g of molasses. The 65days of regrowth silages with 40g of molasses had greater in vitro digestibility of dry matter compared to other treatments. However, lower pH values, N-NH3, DM losses, gas losses, and density were observed in silages with 95days of regrowth with 40g of molasses. It is recommended to cut the Zuri grass in the range of 80 to 95days of regrowth with the addition of 40g/kg of molasses in powders for the production of silages.

Chemical composition and fatty acid profile of a seedpropagated elephant grass genotype, ensiled at different regrowth ages

This study aimed to evaluate the chemical composition and fatty acid (FA) profile of forage and silage of a seed-propagated elephant grass genotype called “PCEA” harvested at 75, 90, 105 and 120 days of regrowth. A randomized block design with five replications was used. The results were analyzed by mixed models (P < 0.05) that included treatment (regrowth age) as a fixed effect and block as a random effect. Linear and quadratic effects of the treatments were analyzed using orthogonal contrasts. There was linear increase on total dry matter (DM) forage production and linear decrease on leaf:stem ratio as a function of the increase in regrowth age (P < 0.05). In response to the advance of regrowth age, “PCEA” forage and silage showed linear decreases on crude protein (CP) content (g kg-1 DM) and in vitro DM digestibility (g kg-1); and linear increases on DM (g kg-1), lignin (g kg-1 DM), and acid detergent insoluble protein (%CP) contents (P < 0.05). All “PCEA” silages had DM content < 200 g kg-1, pH > 4.0, and ammonia N content > 10% total N. In response to the advance of regrowth age, linear decreases (P < 0.05) were observed on forage and silage linoleic, α-linolenic, and total FA contents (g kg-1 DM). From 75 to 120 days of regrowth, the seed-propagated elephant grass genotype “PCEA” presents forage and silage with low nutritional quality for feeding dairy cattle, moderate to high linoleic acid contents, and moderate to low α-linolenic acid contents. The “PCEA” forage and silage obtained from 75 to 120 days of regrowth presents low potential for production of milk naturally enriched with bioactive FAs beneficial to human health.

Digestibilidad in vitro de gramíneas Brachiaria con líquido ruminal bovino y ovino como inóculo

It was hypothesized that it is possible that inoculum from different ruminant species with different digestive abilities feeding from a certain forage may show different feed utilizations comparing to other ruminant species. Five Brachiaria grasses were evaluated: B. decumbens cv. Basilisk, B. decumbens access D70, B. humidicola cv. Tupi, B. humidicola cv. Common, and B. ruziziensis access R124, at two regrowth ages (21 and 42 d). Production, bromatological content, in vitro dry matter digestibility (ivDMD) and in vitro neutral detergent fiber digestibility (ivNDFD) were analyzed using bovine or ovine inoculums. The experiment used a 5 × 2 × 2 factorial design and found significant effects for grass variety and regrowth age. In addition, significant interactions from grass × age on dry matter, crude protein, neutral detergent fiber and acid detergent fiber of total sample and leaf blade were found. There were significant effect of grass variety and grass age on forage mass, leaf blade/stem ratio, leaf blade, stem, senescent material and growth. In vitro digestibility assays of inoculum source showed significant effect in some varieties. Due to differences in in vitro assays, it was recommended the use of species-specific inoculums for feed evaluations according to the animal it is intended for. Also, B. decumbens cv. Basilisk presented the best in vitro digestibility (ivDMD and ivNDFD) in bovine inoculum, whereas B. humidicola cv. Tupi had better in vitro digestibility (ivDMD and ivNDFD) in ovine inoculum.

Response of central Amazon rainforest soil seed banks to climate change - Simulation of global warming

The most severe global warming is predicted to occur in the Amazon region of Brazil, with an estimated temperature increase of 4 to 8 °C between 2071 and 2100. Our study evaluated the effects of increased temperatures on germination success of seeds in the soil seed bank of secondary forests in Central Amazonia. Soil samples (3-cm depth) were collected in six secondary forests with different land-use histories and ages of regrowth. Soils from all sites were sieved and mixed, and germination and seedling development were assessed during 4 months of incubation in germination chambers at (1) a constant temperature of 25 °C and a 12:12 h alternating temperature regime of 20:30 °C, considered as controls; (2) a simulated 5 °C temperature increase to 30 °C and 25:35 °C and (3) a 10 °C temperature increase to 35 °C and 30:40 °C. To determine the effect of light vs. dark on germination, germination was compared for samples in light (12 h daily photoperiod) vs. continuously dark for 1 month, followed by 3 months in light. Six temperature conditions were tested with 30 subsamples each. In the mixed soil seed bank, 3640 seeds germinated, of which 18 families, 28 genera and 41 species (grouped in 20 trees, 11 shrubs, eight herbs and two lianas) could be identified. A light requirement for germination was detected for 94–97% of the species. Alternating temperatures did not stimulate germination in the dark. Seedling density m−2 was 1.7 to 2.3 times higher at alternating (20:30 °C and 25:35 °C) than at constant temperatures (25 °C and 30 °C); but an increase of 10 °C decreased seedling density to 47% at 35 °C and 26% at 30:40 °C compared to control (100% at 25 °C and 20:30 °C); and furthermore increased seedling mortality. Thus, the secondary forest at the study area may maintain its integrity with a 5 °C but not with a 10 °C temperature increase. Species-specific sensitivities to temperature were detected. Temperature may function to fine-tune germination at a specific microsite, and the variety of germination requirements may enhance coexistence and maintenance of species diversity within the pioneer species subset. In general, seeds of tree species were more sensitive to increased temperatures than those of shrubs and herbs, supporting the hypothesis of replacement of the tropical forest by savanna-like vegetation in the Amazon region. Our results show that natural regeneration may be significantly affected by global warming and with potential to alter floristic composition.

Chemical composition and fatty acid profile of BRS Capiaçu ensiled at different regrowth ages

This study aimed to evaluate the chemical composition and fatty acid (FA) profile of chopped forage and silage of BRS Capiaçu elephant grass at four regrowth ages: 50, 70, 90 and 110 days. A randomized block design with five replications was used. The ensiling was carried out manually in experimental silos without wilting using no additives or bacterial inoculants. The results were analyzed using mixed models (P < 0.05). The model included treatment (regrowth age) as a fixed effect and block as a random effect. Linear and quadratic effects of the treatments were analyzed using orthogonal contrasts. There were linear increases in the dry matter (DM, g kg-1) and lignin (g kg-1 DM) contents and linear reductions in the in vitro DM digestibility (g kg-1) of chopped grass and silage as a function of regrowth age (P < 0.001). Quadratic effects (P ≤ 0.01) were observed for the chopped grass contents (g kg-1 DM) of crude protein (CP), ether extract (EE) and neutral detergent fiber (NDF) as a function of regrowth age. There were linear decreases (P < 0.0001) in the CP content (g kg-1 DM) and pH and linear increases (P < 0.001) in the EE and NDF contents (g kg-1 DM) in the silage as a function of regrowth age. There were linear decreases (P < 0.01) in the chopped grass contents and linear increases (P < 0.05) in the silage contents of total FAs, linoleic and α-linolenic acids (g kg-1 DM) asa function of regrowth age. BRS Capiaçu elephant grass must be harvested at up to 70 days of regrowth to obtain forage with good nutritional value and the highest levels of linoleic and α-linolenic acids (g kg-1 DM). To produce silages with adequate pH values and the highest levels of linoleic and α-linolenic acids (g kg-1 DM), BRS Capiaçu must be harvested between 90 and 110 days of regrowth.

COMPOSICIÓN QUÍMICA-NUTRICIONAL DE REBROTES DE Cenchrus purpureus (Schumach.) Morrone DURANTE LA ESTACIÓN LLUVIOSA

<p><strong>Background:</strong> The rainfall regime and its distribution define the productivity and quality of the pastures for use as forage. <strong>Objective:</strong> Evaluate changes in the chemical-mineral composition and nutritional value of <em>Cenchrus purpureus</em> sprouts in the rainy season. <strong>Methodology:</strong> A study was developed in a completely randomized design in factorial arrangement, with varieties of <em>C. purpureus</em> (CT-601; 603 and 115 as control) at different regrowth ages (60, 80, 100 and 120 days) and their interaction 4 x 3, for a total of twelve treatments with four repetitions. <strong>Results:</strong> The second degree interaction affected the structural composition of the cell wall in leaves, increasing (P≤0.001) the fiber concentration in acid detergent (FAD) as the age of the plant advanced, while lignin (LAD), cellulose (Cel) and hemicellulose (Hcel) showed erratic behaviors at different ages in the three varieties (P≤0.001). In the whole plant (WP), the FAD and FND decreased (P≤0.001) as a function of the increase in age, LAD, Cel and Hcel showed the same pattern as in leaves, differing (P≤0.001) between varieties with respect to the control in the different ages. The highest <em>in vitro</em> degradability’s of dry matter (IDDM) and organic (IDOM) in leaves were centered at the age of 60 days in the varieties CT-603 and 115, respectively, in WP at 100 days in CT-601 and 603 (P≤0.001) compared to CT-115. <strong>Implications:</strong> The varieties CT-601 and CT-603 do not show affectations in the structure of the cell wall that affect the nutritional value with respect to the control treatment (variety CT-115). <strong>Conclusions:</strong> Varieties, depending on DR, modify the structure of the cell wall, without affecting their nutritional value.</p>

EVALUACIÓN DE LA FERTILIZACIÓN EN RESPUESTAS MORFO AGRONÓMICAS DE VARIEDADES DE Cenchrus purpureus EN DIFERENTES EDADES DE REBROTE

<p><strong>Background:</strong> It was noted in 2012 that the Cenchrus genus absorbed the Pennisetum genus, within which grass varieties that accumulate a large amount of standing dry matter (DM) are currently included, which is favored by the rainfall regime and assistance with fertilizers. <strong>Objective:</strong> To evaluate the effect of different fertilization variants (NPK, ferti-forage and without fertilization (control)) on the agronomic morpho response in varieties of <em>Cenchrus purpureus</em> (King grass verde, Elefante, Morado, Maralfalfa and Cuba CT-115) in different regrowth ages (45 and 60 days) in the conditions of the Santo Domingo Canton, Ecuador. <strong>Methodology:</strong> A study was carried out in a randomized block design with factorial arrangement, and its interaction (5x3x2) with five replicates. Yield of green biomass (t YG ha<sup>-1</sup>), total dry matter, leaves and stems (t DM ha<sup>-1</sup>) and morphological variables were considered. <strong>Results:</strong> The interaction of the second degree affected (P≤0.001) the performance of YG in favor of the Maralfalfa variety at 60 days of regrowth with the application of complete formula (83.60 t YG ha<sup>-1</sup>), also this variety in this same age and fertilizer, provided the highest (P≤0.001) values in the total DM and stem yield (20.90 and 11.71 t DM ha<sup>-1</sup>, respectively), the highest (P≤0.001) dry leaf yield was provided by the Cuba CT-115 at 60 days with application of ferti-forage (9.49 t DM ha<sup>-1</sup>). <strong>Implications:</strong> The use of fertility provides greater accumulation of DM at the leaf level, where, under the conditions in which the study was carried out, it was the CT-115 that showed the best response to this alternative. All the varieties showed at the age of 60 days the greater accumulation of DM. <strong>Conclusion:</strong> The varieties Maralfalfa, Morado and CT-115 stood out in the productive response and morphology during growth under the combination of the factors of interest in this investigation.</p>

Efecto de la edad del rebrote y el clima en la composición química de Cenchrus purpureus en ecosistemas degradados de Cuba

The objective of this work was to determine the effect of age and climate on the chemical composition of Cenchrus purpureus in degraded ecosystems of Cuba. An experiment was carried out in two well-defined periods: slightly rainy (January to April) and rainy (July to October). The treatments (regrowth ages: 30, 45, 60, 75, 90 105 days) were distributed in a randomized block design with four replicas. The structural constituents of the cell wall, minerals (calcium and phosphorus), and digestibility of dry and organic matter were determined. The neutral detergent fiber showed a behavior defined by the climatic season (72.37%) in rains and 69.67% in few rains). The elements of the climate showed a high relationship with the chemical composition and linear regression models were adjusted with high coefficients of determination, greater than 0.71 in the two periods evaluated; the rainfall and maximum temperature variables were the ones that provided the greatest adjustments. With the increase in age, the quality of the plant decreased, and of climatic factors, rainfall and maximum temperature are those that most affect the nutritional quality of the plant.

Forage yield and quality of buffel ‘H‐17’ and Urochloa hybrids at different regrowth ages under semi‐arid conditions

AbstractUrochloa hybrids produce large amounts of biomass and have drought tolerance; however, there are few reports on the forage yield and quality of these forage grasses in semi‐arid environments. We evaluated the forage yield and nutritional value of Urochloa hybrids (‘Mulato II’, ‘Cayman’ and ‘Cobra’) and Pennisetum ciliare ‘H‐17’ (control) at three regrowth ages (RA: 4, 6 and 8 weeks), at maximum (MAR) and minimum (MIR) rainfall periods in semi‐arid climate. The variables evaluated were as follows: dry matter of leaves (DMl), stems (DMs), and total (DMT), crude protein (CP), in vitro dry matter digestibility (IVDMD) and detergent fibers (neutral: NDF, and acid: ADF). The hybrids showed higher DMl, CP and IVDMD with values of 423 g/m2, 11% and 70%, respectively. ‘H‐17’ presented higher DMs, NDF and ADF, with values of 110 g/m2, 69% and 35%, respectively. Urochloa hybrids showed higher forage yield and nutritional value compared to Pennisetum ciliare ‘H‐17’ and could be an alternative for semi‐arid zones.