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The influence of strategic fertilization with nitrogen (150 kgN/ha) applied in the rainy season in Cenchrus purpureus varieties tolerant to drought (CT-600, CT-601, CT-602, CT-603, CT-604, CT-605, CT-608 y CT-609) compared with CT-115 as control was studied. A random block design with five replications was used. In the dry season only CT-604 had the highest (P<0.001) dry matter percentage of leaf, stem and the hole plant. The highest (P<0.001) leaves content was showed by CT-605 (60.07 and 60.17 % in the rainy and dry season, respectively). The varieties CT-605, CT-608 and CT-609 (5.0, 5.6 and 5.2 tDM/ha, respectively) exceeded (P<0.001) the yield of CT-115 (3.4 tDM/ha) in the dry season. The leaf area varied (P<0.001) between varieties, while CT-604 showed the lower population (P<0.001) in both climatic seasons (7.2 and 4.6 tillers/5min the dry and rainy season, respectively). The varieties CT-605, CT-608 and CT-609 increased their yield in the dry season with adequate leaves contents and adequate population. It is suggest expanding this information with the chemical composition and extending these varieties in the western region, always you had the nitrogenous fertilizer. [ABSTRACT FROM AUTHOR]

A three-year experiment was carried out to evaluate the agronomic performance of new varieties of Cenchrus purpureus (CT-600, CT-601, CT-602, CT-603, CT-605, CT-607, CT-608 and CT -609), tolerant to drought, obtained by in vitro tissue culture, and compared with its parent (CT-115) through a completely random design with five replications. There were significant differences between the height of the varieties and in both seasonal periods CT-605 stood out with values higher (P<0.05) at 90 cm. The leaves content (%) was only significantly different between the varieties in the dry season during the experimental stage, while the percentage of stems showed a similar response pattern. There were varieties that exceeded the DM yield of the control and especially the CT-605 with values of 21.82, 16.37 and 9.05 t DM/ha/year for the first, second and third year, respectively. With the exception of the first year, the varieties did not express their potential for biomass production under water stress conditions and future researches are suggested where rainfalls is less than 800 mm, as well as studying the effect of strategic fertilization on regimes of greater rainfall. [ABSTRACT FROM AUTHOR]

The objective of this paper deal with the analyses of the information obtained in Cuba related to the influence of climatic factors on the production and quality of grasses and forages. The results showed that: the species within the genus and varieties showed a particular and specific response to climatic factors; the same variety of grass responded differently in both seasons of the year; minimum temperatures lower than 15 ºC and maximum lower than 27 ºC, as well as the number rainy days, had a marked effect; the models between yield and quality with the elements of the climate had high complexity and when comparing Pennisetum purpureum (as an experimental model) it showed higher height and lower yield in the 2000s compared to the ´60s. The results showed the specific response of each grass against the climate indicators, like the mathematical models that relate it, as well as the change that the climate has undergone. [ABSTRACT FROM AUTHOR]

The objective of this study was to analyze the composition of some mineral nutrients of Cenchrus purpureus cv. Cuba CT-115 after grazing when used as a biomass bank. For this, a completely randomized sampling design with 15 repetitions was used. Treatments consisted on regrowth age or grass rest from the time of departure of animals from the paddock (time zero) and in accordance with the biomass bank technology. Results indicated that contents of ash, calcium, phosphorus and magnesium had a variable performance, while nitrogen was reduced with the regrowth age for all grazing cycles of this technology. Ash contents ranged between 3.89% and 15.41% (P <0.01), while calcium and phosphorus were between 0.30 and 0.83% (P <0.05) and between 0.17 and 0.43% (P <0.05), respectively. All the studied indicators had higher values in leaves than in stems for tillers and for residue with their new growth. Phosphorus and magnesium contents found in leaves and stems for some regrowth ages were lower than those required for proper growth and development of the grass, so the use of maintenance fertilization might be necessary. It is recommended to use these results to design other management options. [ABSTRACT FROM AUTHOR]

Using a randomized block design with four replications, clones of Cenchrus purpureus (CT-6, CT-9, CT-13, CT-15, CT-24 and CT-28) obtained by in vitro tissue culture were evaluated and compared with their progenitor (CT-115) in typical red Ferralitic soil, for two years without irrigation and fertilization. In both evaluation years during the seasonal periods the height differed (P<0.001) between the clones and the CT-28 surpassed the CT-115 was highlighted. There were differences (P <0.001) in the percent of DM and their values varied in narrow range (17-23% and 19-21% in the dry and rainy season, respectively). With the exception of CT-24, the rest of clones showed leaves contents higher than 50% and differed among them, but the highest value (64.88%, P <0.001) was showed by CT-28 during the rainy season. The leaves length varied (P <0.0001) between clones and CT-9 was highlighted in both years (73.73 and 84.23 cm for the dry and rainy season, respectively for the first year and 68.6 and 76.7 cm for similar stages of the second year). Similar response pattern was obtained in the leaf width. The leaf area also differed between clones and the highest values were recorded in the rainy season of both years. There were significant differences between the clones in the seasonal and annual DM yield and the clones CT-9, CT-15, CT-24 and CT-28 were highlighted. There were also significant differences in the population of the clones at the beginning and end of the experiment, but when comparing these two stages there were not variation and the values ranged between 5.43 and 9.49 bunches/5m. In general terms, the studied indicators varied when comparing the studied years. There is a group of clones with favorable characteristics for forage production, where CT-9 and CT-28 were highlighted. Future studies using strategic fertilization and irrigation of promising clones are suggested. [ABSTRACT FROM AUTHOR]

During two years the relation between some climatic factors and the chemical composition of Tithonia diversifolia was studied, using a completely randomized design and five replications, in brown soil with carbonate. The chemical composition indicators consisted of: NDF, ADF, lignin, cellulose, hemicellulose, cell content, organic matter, ashes, N, Si, P, Ca and Mg; while the climatic factors were the maximum, minimum and average temperatures, rain and number of rainy days. The results are expressed by the Pearson correlation coefficient in each seasonal period. In the rainy season, high and positive correlation coefficients were found between total rain and NDF, ADF, lignin and organic matter (0.87-0.97) and were negative for cellulose, cell content, ashes and N (between -0.88 and -0.97). The relation with the temperatures were variable and the highest value (r = 0.92) was recorded between the P and the average temperature. For the number of rainy days, there was a similar performance to that described above, but the coefficients were higher. In the dry season, there was a positive correlation between total rain and NDF, ADF, lignin, hemicellulose, ashes, P and Ca (0.52-0.88) and were negative with cellulose, cell content, organic matter and N (between - 0.55 and -0.88). For the number of rainy days there was similar performance, but the coefficients were higher and there was relation with the Si (r = -0.45). The linear multiple equations were established between the chemical composition indicators and some climatic factors, with high values of the determination coefficient, low standard error and high significance. The chemical composition indicators showed a specific response to climatic factors in each seasonal period, but the higher effect, expressed by the correlation coefficient, is related to the amount and distribution of precipitation. It is recommended to determine the mathematical model that allows to predict the performance of each indicator of the chemical composition with the climatic factors, as well as to perform this study in other plants of economic importance for animal feeding and to extend it to the secondary metabolites or antinutritional factors. [ABSTRACT FROM AUTHOR]

Pearson correlation coefficients were established among secondary metabolites of Leucaena leucocephala and some climatic factors (maximum, minimum and mean temperature, rainfall and number of rainy days), primary metabolites and digestibility (organic matter, dry matter, protein and NDF). The metabolites were A) secondary: total tannins, total phenols, total condensed tannins, free condensed tannins, alkaloids, saponins, triterpenes, steroids and flavonoids and B) primary: glucose, fructose, sucrose and N. Secondary metabolites were correlated with the maximum temperature and the highest coefficient (r = 0.78) was for steroids. Similar result was obtained for condensed tannins bound to the fiber, but with the minimum temperature (r = -0.90). The highest coefficient for the number of rainy days was presented in flavonoids (r = 0.99), while for total rainfall coefficient, it was for total phenols (r = -0.90). Correlation coefficients between the secondary metabolites and OMD ranged from -0.57 to -0.74. For the in vitro of dry matter digestibility, they ranged between -0.65 and -0.94 and for NDF between -0.91 and -0.98. For PBD, the values were the lowest (-0.39 and 0.55). Considering the phenolic compounds as independent variables and related to alkaloids, saponins, triterpenes, steroids and flavonoids, the highest coefficients (=0.80) were recorded by total tannins, total phenols, total condensed tannins and condensed tannins bound to fiber. When the secondary metabolites were related to the primary metabolites (glucose, fructose, sucrose and N), coefficients were negative and varied between -0.41 and -0.98. It can be concluded that the elements of the climate influenced the studied metabolites. All digestibility expressions were negatively affected by the presence of the secondary metabolites. Phenolic compounds were positively correlated with flavonoids, alkaloids, saponins, triterpenes and steroids, while primary metabolites correlated negatively with secondary metabolites. It is recommended to consider the results of this study in Leucaena leucocephala to assess the effect of climate change on the secondary metabolites, counteract the negative effect of these compounds on ruminant feeding systems, conduct future research to establish its maximum allowable value in the diet and apply the simulatio n and mathematical modeling to predict the performance of these substances in this and other plants. [ABSTRACT FROM AUTHOR]

With the new clones of Pennisetum purpureum drought tolerant, obtained from the progenitor Cuba CT-115, agronomic and biomass quality studies were carried out in an ecosystem of intense seasonal drought in Valle del Cauto. With these results, a multivariate analysis was performed to determine the weight variables in the agronomic performance and its relative contribution to the classification of the promising clones for drought conditions. In the analysis for the rainy season, two components that explained 71.04 % of the total variance were extracted. The weight variables were height, length and wide of leaf, stem thickness, yield of total DM and leaves , absolute growth rate and leaf area. For the dry season, two components that explained 76.63 % of the total variance were extracted, the weight variables coincided, except the stem thickness, and the number of green leaves / plant and the number of branches was also significant. In the grouping dendograms, three groups at each time of the year were formed. In rainy season, one group showed a promising performance (CT-600, CT-601, CT-603, CT-605, CT-608 and CT-609). With the exception of leaf wide, this group achieved the highest expression of the weight variables; another group achieved an intermediate performance including Control Cuba CT-115, CT-602 and CT-607. The group formed by CT-604 and CT-606 had lower height, lower absolute growth rate and lower yields of dry matter. In the dry season, a poor performance group appeared, with CT-604, CT-606 and CT-602. The remaining groups showed some similarity. It is concluded that the performance of these clones is very marked by the season of the year. The CT-606, CT-604 and CT-602 are highlighted for their low biomass production. [ABSTRACT FROM AUTHOR]

The productive performance of growing females of the Cuban Charolais breed under a silvopastoral system with Leucaena leucocephala cv. Peru, in a 3 x 5 sowing frame, associated with an improved grass (Cynodon nlemfuensis) was studied compared to a monoculture. The experiment was conducted at the Empresa de Genética y Cría ?Manuel Fajardo?, Granma province, Cuba. Thirty animals per cycle were used and the experiment lasted three years. Data were processed through a multivariate analysis and measurement of the impact index. The best live weights gains with 0.55 kg.animal.d-1 and age at incorporation to reproduction of the females of 19 months of age were obtained in the leucaena silvopastoral system. The best gain and the lowest cost per animals were recorded in the silvopastoral system. It is recommended using this leucaena sowing density for maintaining favorable total pasture productions, live weight gains and adequate weight for age relationship at the incorporation in rearing systems of replacement Cuban Charolais growing females. [ABSTRACT FROM AUTHOR]

This research was carried out with the objective of studying the performance of some morphophysiological indicators after grazing P. purpureum cv. Cuba CT-115 used as biomass bank. A completely randomized sampling was used and a total of 15 tufts were collected (experimental unit) immediately after grazing and every 15 days until to complete each growth cycle. The treatments consisted on the age of the grass regrowth from the moment the animals exit the paddock (zero time) and according to the biomass bank technology. During the first year and for each resting cycle the regrowth age influenced (P<0.001) on the plant height. For more of the cycles the length and width of leaves, and the leaf area increased (P<0.001) with the age and the higher values were in the cycles with more favorable climatic conditions for growth and leaf expansion, reaching the leaf area values of 246 cm2 for the fourth cycle of the first year and 204 cm2 for the fifth cycle of the second year. It was also determined the total yield performance with the regrowth age and growth indexes as Culture Growth Rate (CGR) and Net Assimilation Rate (NAR).The results showed that the growth cycles of the studied crop have an specific response pattern in function of the regrowth age and climatic characteristics. The CGR and the NAR have specific response for each cycle and are appropriate indicators for the analysis and characterization of grass growth. It was also proven that the increase of dry matter yield is done with low efficiency (NAR) from the high Culture Growth Rate is reached. It is recommended to incorporate the growth indexes studied in this research as novel tool for the management of other grasses and forage species. [ABSTRACT FROM AUTHOR]

This study reports the results of four experiments, with a minimum duration of two years, carried out in typical red ferrallitic soils and using random blocks design with five replications, in order to establish the influence of strategic fertilization with N on Pennisetum purpureum clones, tolerant to drought, and determine the differences among others that could be used forage production or grazing. Several drought tolerant clones showed their superiority during dry period (CT-601, CT-602, CT-604, CT-605, CT-608 and CT-609) regarding CT-115, when they were fertilized during rainy period. Other clones (14, 18, 19, 20 and 21) showed ability to produce forage during the dry season, while 41 and 43 showed characteristics for grazing. Basic and chemical composition studies are recommended, which will allow to explain the differences among clones, as well as experiments in grazing with promising clones. It is also suggested the introduction of the best clones, which are drought tolerant and strategically fertilized with N during rainy season, to social practices. [ABSTRACT FROM AUTHOR]

The plant Páramo grasslands ecosystem characterization was carried out by means of field expeditions to eight protected areas that Ecuador maintains through the Ministry of Environment. The expeditions were carried out every two months during three years, to evaluate in situ the botanical composition, frequency, density, height, basal cover and aerial cover. The observations were registered during two periods per year, at 60, 90, 120, 150 and 180 d, for a total of 36 evaluations in each study place. The soil pH varied between 5.0 and 8.5, it is volcanic, with sandy and loamy characteristics. The identified species in the Ecuadorians heathlands were: 169 plants with forage importance, 90 grasses, 14 legumes, 28 compounds and 37 belonging to Equitaceas, Oxalidaceas, Liliaceas, Scrophulariaceas, Rosaceas, Ciperaceas, Poligonaceas, Plantaginaceas, Arbustivas, Orchideaceas, Ranunculaceas and Gentianaceas. A total of eighteen species showed good performance, when locating, at least, in a place. Those of great persistence and adaptation were Agrostis breviculmis, Agrostis exigua, Arrhenatherum pratensis, Arrhenatherum elatius, Bromus lanatus, Bouteloua curtipendula, Calamagrostis bolanderi, Calamagrostis tarmensis, Digitaria floridona, Eragrostis curvula, Euchlaena mexicana, Festuca weberbaueri, Holcus lanatus, Paspalum plicatulum, Paspalum bomplandianum, Poa pratensis, Stipa plumeris and Stipa plumosa. For the production of green and dry forage, respectively, the best were Euchlaena mexicana, with 25.9 and 6.7 t/ha/cut, and Arrhenatherum elatius, with 24.4 and 6.9 t/ha/cut; also Arrhenatherum pratense, with 23.0 and 6.1 t/ha/cut and Stipa plumeris, with 21.9 and 6.8 t/ha/cut. There was great plants biodiversity that can be use for animal feeding, which is observed from other studies of chemical composition and management. [ABSTRACT FROM AUTHOR]

This research was carried out in the Ecuadorian Páramo grasslands, between 2900 and 4200 m o.s.l, in Loja, Zamora Chinchipe, Azuay, Cañar, Chimborazo, Bolívar, Tungurahua, Cotopaxi, Pichincha, Imbabura and Carchi provinces. For the identification and taxonomical classification of species there were taken herborized samples and identified by agrostologists. The Hitchcock, Gould, Lombardo and Tovar taxonomic keys were used for the identification. From the grasses family, in the eight study places, 90 species were identified, including 37 genus, being the mains, with higher number of species: Festuca (14), Paspalum (10), Agrostis (7), Calamagrostis (7), Bromus (6), Stipa (5), Poa (5), Agropirum (3), Arrhenatherum (2), Brisa (2) and Andropogon (2).The species that prevailed in the study places were: Agrostis breviculmis, Agrostis exigua, Bromus lanatus, Calamagrostis tarmensis, Festuca humilior, Festuca ortophylla, Festuca weberbaueri and Paspalum bomplandianum. The diversity indexes of the existent meadow species showed values from mean (0.72) to high (0.90), as for their uniformity. This allowed determining that the biodiversity is variable, according to the environmental conditions of the studied Páramo grassland ecosystems. Similar performance was obtained for trees grasses species. [ABSTRACT FROM AUTHOR]

This study deals with the main results of the evaluation of grasses in the Instituto de Ciencia Animal from 1965 to 2014. Evaluations took into consideration aspects related to species and varieties, soil preparation, sown and establishment, intercropping, rehabilitation, nutrition, production of biomass and seeds, plagues and their control, physiological aspects, chemical composition and quality. In addition, the study refers to the effect of these grasses on biomass production and some guidelines are suggested for further researches. [ABSTRACT FROM AUTHOR]

The performance of the edaphic macrofauna was evaluated in a Leucaena leucocephala-Cynodon nlemfuensis silvopastoral system at the Cattle Breeding Enterprise "Manuel Fajardo", located in the municipality of Jiguaní, Granma province. An area of 6.71 ha distributed in six paddocks was used in a completely randomized design with six replications in a carbonated brown soil. The study was conducted in the litter strata, 0-10, 10-20 and 20-30 cm depth. The taxonomical composition, density and biomass of the macrofauna organisms were determined. The taxonomic composition consisted of 216 individuals, represented by three types, five classes and seven orders. From them, the most represented was the class Insecta. In the density of individuals there were differences (P < 0.05), from the litter of 8.08 individuals/m<>2 to 1.83 individuals/m<>2, at the 20-30 cm depth. For the biomass, there were differences (P < 0.05) and varied from 0.16 to 0.03 g/m<>2 for the litter at 20-30 cm, respectively. Also, in total density there was growth, following tree incorporation (6.07 ind./m<>2) and after total biomass grew by 0.18 g/m<>2, thus proportional abundance increased with the appearance of Hymenopterous, Diplopodous and Lepidopterous. The silvopastoral system improved the macrofauna with advantages for their exploitation as time went by. [ABSTRACT FROM AUTHOR]

To study the performance of some growth indexes of Pennisetum purpureum cv. Cuba CT - 115, when it is used as biomass bank, it was applied a completely randomized sampling design, with 15 repetitions, (bunches as experimental unit) .The treatments consisted on the regrowth age or grass rest . The culture growth rate (CGR), the net assimilation rate (NAR) and the specific foliar area (SFA) were determined to describe the growing of this cultivar. The culture growth rate was characterized, generally, by its gradual increase from 15 days, to get the maximum growth rate that was specific for each cycle and, from that moment on, began to decrease. The maximum productivity during the first year was reached at 71, 57 and 61 days of re-growth for cycles one, two and four, respectively. In the second year, it was obtained at 86, 46, 45, and 69 days of re-growth for cycles one, two, three and five, respectively. The specific foliar area did not vary in the first rest cycle with age in the first year, and decreased in the remaining cycles. The net assimilation rate shows specificity in its response pattern to the re-growth age in each rest cycle. It is concluded that CGR, SFA and NAR had specific response for each cycle, regarding the re-growth age and the climatic characteristics, and showed to be adequate indicators for the analysis of the growing of Cuba CT-115 cultivar. It is recommended the use of growth indexes of this grass as a tool for the management of biomass banks, as well as its utilization in the studies of other species of Pennisetum genre and in the design of other management options. [ABSTRACT FROM AUTHOR]

The effect of regrowth age (30, 45, 60, 75 and 90 d) in the content of secondary metabolites from Neonotonia wightii was evaluated through a random blocks design, with six replications. The experiment took place from January to March (dry season) and from May to July (rainy season), in a carbonated brown soil, without irrigation and fertilization. Total tannins, total phenols, total condensed tannins, total mixed condensed tannins, free condensed tannins, flavonoids, saponins, alkaloids, triterpenes and steroids increased (P < 0.05) with age and the highest values were obtained at 90 d (5.24; 10.07; 77.67; 76.72; 0.95; 3.29; 0.53; 0.30; 8.58 and 0.63 g/kg DM during May-June-July and 3.12; 8.24; 96.64; 94.68; 1.96; 3.99; 0.52; 0.30; 8.51 and 0.69 g/kg DM during January-February-March, respectively). It can be concluded that regrowth age and climatic factors had a marked effect on the concentration of secondary metabolites. It was demonstrated that while the plant was maturing, the tenors of secondary metabolites increased. Only total condensed tannins and total mixed condensed tannins surpassed the limits in which the ruminant fermentation could be affected. It is recommended not to use this plant with an regrowth age higher than 75 d old. A similar study is suggested to be conducted with this and other legumes, in different environmental conditions, and to determine the relation between these metabolites and the digestibility and intake of these plants. [ABSTRACT FROM AUTHOR]

A random block design with five replications and thirteen treatments was applied. Treatments consisted of three varieties of Pennisetum purpureum (king grass, Cuba CT-115 and Cuba CT-169) cut two (August and February), four (May, July, September and February) and five times a year (November, February, May, July and September) and two of Saccharum officinarum (Jaronú 60-5 and Villa Clara 21), cut one (February) and two (February and August) times a year for determining their influence on some forage quality indicators. The experiment was conducted in a red ferrallitic soil for four years with fertilization (100-60-80 kg/ha/year of N, P2O5 and K2O, respectively) and irrigation during the dry period. There were differences (P < 0.001) in the CP content of the varieties according to the cutting frequency. The highest values were registered in leaves, stems and the whole plant of the Pennisetum varieties with ranging values of 7.6-10, 4.2-5.9 and 5.1-7.3 %, respectively when cut five times a year. Crude fiber differed (P < 0.001) and the lowest values were recorded in the Pennisetum varieties with the highest cutting frequency. For in vitro organic matter digestibility there were differences (P < 0.001) favorable to the highest cutting frequency. Best results were attained when the Pennisetum varieties were cut five times per year. Cutting Saccharum two times per year propitiated the disappearance of Jaronú 60-5 at the end of the second year of study. The best balance of the studied indicators was obtained when Pennisetum and Saccharum varieties were cut five and once per year, respectively. There is available information that will allow improving the management of these varieties, for using them efficiently and attaining greater longevity of the plantation. [ABSTRACT FROM AUTHOR]

Biomass production performance of nine Pennisetum purpureum clones was evaluated in function of air temperature, rainfall and number of rainy days. The research was based on an experimental study developed at the Institute of Animal Science during the period 2009-2010 in a typical red ferrallitic soil without applying fertilization or irrigation. A completely randomized design was used and nine cuttings with four replications were practiced. Average yields of the two years of evaluation were 2.32 - 4.08 t/ha in the rainy period which were higher to those obtained in the dry period (0.75 - 1.36 t/ha). Yield had a decreasing tendency in time The highest significant correlations were achieved with the temperature (0.33-0.70) besides the number of rainy days. The coefficients of determination ranged between 58 and 80 %. It is concluded that forage production of P. purpureum was connected with the performance of the rainfall and temperature, and constitute a viable alternative for biomass production. [ABSTRACT FROM AUTHOR]

Biomass production performance of nine Pennisetum purpureum clones was evaluated in function of air temperature, rainfall and number of rainy days. The research was based on an experimental study developed at the Institute of Animal Science during the period 2009-2010 in a typical red ferrallitic soil without applying fertilization or irrigation. A completely randomized design was used and nine cuttings with four replications were practiced. Average yields of the two years of evaluation were 2.32 - 4.08 t/ha in the rainy period which were higher to those obtained in the dry period (0.75 - 1.36 t/ha). Yield had a decreasing tendency in time The highest significant correlations were achieved with the temperature (0.33-0.70) besides the number of rainy days. The coefficients of determination ranged between 58 and 80 %. It is concluded that forage production of P. purpureum was connected with the performance of the rainfall and temperature, and constitute a viable alternative for biomass production. [ABSTRACT FROM AUTHOR]

An experiment was conducted during two years to establish the variability of the agronomic indicators of Pennisetum purpureum cv. Cuba CT-115. Samples were taken at different sampling distances (1, 2, 3, 4 and 5 m length). The data of an experiment with random block design and four replicates were used. The lowest variance, standard deviation and coefficient of variation were obtained with sampling distance of five meters for the height (4.3, 2.1 and 1.88, and 1.1, 1.0 and 0.99 for the rainy and dry season, respectively). Similar performance had the per cent of leaves and dry matter of the whole plant. The sampling distance of five meters propitiated lower yield variability (18.04 and 12.35% in the rainy season and dry season, respectively). Similar performance had the number of bunches/m (8.34 and 12.27, in that same order). In all the indicators, the lowest width of the values range was obtained, in general, in the distance of five meters. When sampling the population, five bunches/m recorded the lowest variability compared with 11 bunches/m. It is concluded that for the best estimation of the agronomic indicators, the samplings should be conducted in five linear meters. No less than five bunches as sample units should be taken. Similar studies in grasslands with different growing habits are recommended. [ABSTRACT FROM AUTHOR]

An experiment was carried out to determine the agronomical indicators, expressed in humid basis, most contributing to account for the variability in 49 clones of Pennisetum purpureum, obtained by in vitro tissue culture from the apical tissue of P. purpureum cv Cuba CT-115. A completely random design with five replications was applied. The experiment lasted one year. The analysis of the main components indicated that in the rainy period two components accounted for 81.65% of the variability among clones integrated by height, leaf and stem contents and length of the fourth leaf completely opened, internode length and fresh matter yield. In the dry period two main components accounted for 84.68% of the variability between clones integrated by the same indicators than in the rainy period. It is concluded that the above mentioned indicators, expressed in humid basis, can be used for establishing the variability among Pennisetum clones. This determines savings in time and resources, without losing the quality and scientific rigor in the research. Similar studies are recommended under different environmental conditions and with other pasture varieties including other indicators. [ABSTRACT FROM AUTHOR]

The influence of sampling distance (1, 2, 3, 4 and 5 meters) on the agronomical indicators of Pennisetum purpureum cv. Cuba CT-115, cultivated in a typical red ferrallitic soil without irrigation or fertilization was studied using a random block design with four replications. The experiment was developed during two years and samplings were practiced every 90 d. In both seasonal periods, plant height differed (P < 0.001) between sampling distances, the same as the dry matter percentages of leaves, stems and the whole plant. Similar performance showed the leaf and stem contents. The highest (P < 0.001) DM yields were obtained in the highest sampling distances and varied between 0.39 - 2.01 and 0.13 - 1.48 kg for five and one meter, respectively. The number of sprouts/m showed the same performance ranging between 8.0 and 9.8 for the distance of five meters regarding to 2.25 - 2.59 for the distance of one meter. The best sampling distance was five meters, due to lower variability of the agronomical indicators and high representativeness. Similar studies with grasses of different growing habits as well as with legumes are recommended. [ABSTRACT FROM AUTHOR]

Through a completely randomized design with six replicates, the effect of the re-growth age (30, 45, 60, 75 and 90 d) on the nutritive quality of Neonotonia wightii was assessed, as well as the relation between its digestibility, ME and tannins. The experiment was conducted during the trimesters January-February-March (dry season) and May-June-July (rainy season), on a brown soil with carbonate, without irrigation or fertilization. The DM, silica (Si), NDF, ADF and lignin increased (P < 0.05) with age and the highest values were obtained at 180 d, while the CP, DM in vitro digestibility and ME diminished (P < 0.05). The highest values were reached at 30 d. The total phenols, total tannins and total condensed tannins increased (P < 0.05) with the re-growth age in both seasons and reached the maximum concentrations at 90 d (10.7, 5.24 and 77.66 g/kg DM in May-June-July and 8.24, 3.12 and 96.64 g/kg DM in January-February-March, respectively). In both seasons, high negative correlations (between -0.82 and -0.99) were obtained between the total phenols, total tannins and total condensed tannins and the DM in vitro digestibility, OMD, DM in situ digestibility, true digestibility (TD) and ME. It is concluded that age had a marked effect on the indicators assessed, more highlighted in the rainy season, when the nutritive quality diminished due to the increase of the fiber fraction, diminishing of the protein, digestibility and ME, and due to the inverse relation between the two last indicators and the phenolic compounds. Studies on other legumes under different edafoclimatic and management conditions are suggested. [ABSTRACT FROM AUTHOR]

The performance of some agronomic indicators of 12 new Pennisetum purpureum clones (14,18,19,20,21,24, 30, 36, 39,41,42 and 43) obtained by in vitro tissue culture was assessed during a year and they were compared to their progenitor (P. purpuereum vc. Cuba CT-115) through a completely random design with four repetitions. Plots of 25m2, without irrigation and fertilization, were used. The samplings were conducted every 60 and 90 d in the rainy and dry seasons, respectively. There were differences (P < 0.001) in the clones' height, but none of them surpassed the control (67.9 cm) in the rainy season, while the 14, 18, 20, 30 and 36 highlighted in dry season (P < 0.001). Similar performance was recorded for the leaves' length during the rainy season. The highest (P < 0.001) width was for the clones 39 (3.7cm) and 43 (3.1cm) in the rainy and dry seasons, respectively. The highest (P < 0.001) leaves percentages were reached by the clones 41 and 43 (65.8 and 66.1 %, respectively) in the rainy season and the 39, 41 and 43 (53.5; 53.1 and 54.8 % respectively) in the dry season. The clone 20 recorded the highest (P < 0.001) total yield (14.9 tDM/ha/year), but only produced the 28.2 % in the dry season. This clone also had the highest population (17.6 bunch/5m) at the end of the experiment. There are new clones of P. purpureum with favorable productive characteristics increasing the available gene-fund of this species, mainly the clone 20 that surpassed the control in the yield, content of leaves and population. Basic studies to explain the differences found between clones are necessary, as well as the study of their responses when using maintenance fertilization. [ABSTRACT FROM AUTHOR]

A completely random sampling design was used to study the chemical composition of CT-115 used as biomass bank. The treatments corresponded with the re-growth ages of the pasture from the moment the animals went out to the paddock (zero time) to completing each growth cycle, according to the technology of biomass bank. In all the cycles, the re-growth age diminished the CP value (P < 0.001) and the cell content (P < 0.01) in the basal tillers as in the residue. The higher protein values were found in the leaves of the basal tillers and the residue (P < 0.001), with 14.3 %and 11.9 % respectively, at 15 d in cycle one. The cell wall increased (P < 0.01) with age in all cycles. The leaves had lower values than the stems. The highest values were, generally, in the residue stems (84.07 %), at 105 d of re-growth for cycle four. The cellulose and lignin contents increased with age in most of the cycles, with maximum values in the leaves of 38.8 % and 7.9 %, respectively. The lignin values were inferior in leaves and stems of the basal tillers. The results of this study allow concluding that the cell wall, cellulose and lignin increased with the re-growth age. The CP and the cell content reduced similarly in the rest of the pastures. However, these indicators in the leaves of CT-115 get to the 105 d with an acceptable quality for cattle. Due to the leaves quality in this variety of Pennisetum, grazing with a high defoliation index up to the height desired by the animal is recommended and, therefore, a higher productivity would be achieved. [ABSTRACT FROM AUTHOR]

In a random block design with four replications, quality indicators related to the climate and age of Pennisetum purpureum cv. Cuba CT-169 were determined in both seasonal periods. The experiment was carried out in a fluvisol soil, under non-irrigation conditions and without fertilization. A multivariate analysis of main components was made, considering the climatic factors and the quality indicators. The preponderance value, equal or higher than 0.75 was considered as the selection factor. Linear multiple equations and the values of the coefficient of determination were above 0.88. The highest R2 were obtained for DMD and OMD (equation II = a + b*CF + d* Age, P < 0.001). Pennisetum purpureum cv. Cuba CT-169 can be characterized by rainfall, temperature (minimum, mean, maximum) and relative humidity, also through CP, CF, ADF, L, CW, DMD, OMD, ME, FNE, CC and cellulose. Linear multiple regression equations were established between DMD, OMD, ME and FNE considering: a) CP, CC and age; b) CF, CW and age; c) CP, L and age, with high R2 and low standard errors of estimation and square mean of the error. Further studies on regrowth physiology in other varieties and types of soil are recommended. More studies mainly on the performance of the chemical composition indicators are suggested to collect more information about the climatic conditions of Cauto Valley so as to validate results in other regions of the country. [ABSTRACT FROM AUTHOR]

Rainfall performance in the farm of the Institute of Animal Science (ICA) in Cuba during the period 1970-2009 was studied with data recorded at the agro-meteorological station. The methodology of analysis of seasonal series was applied and the performance of its components: seasonal variations, trend, cyclicity and random component of the time series were studied. It was confirmed that the seasonal character of rainfall was maintained each year, but showed stability during the last decade, as well as decrease of the minimum and maximum values. There was a very high variability and it was confirmed by the analysis of the coefficients of variation, which reached values above 41% in all months, particularly, in the poor rainy period, with average fluctuations of 200 mm. Also in this stage there was a decrease in the amount of rainfall of 324 mm in the period 1970-1980 to 225 mm presently. It is foreseen that this decrease will continue and that the difference between periods will increase, with a probability of 1105.7 mm for 95%. In general, rainy days also showed a decreasing trend. Regarding rainfall cyclicity at ICA, the duration was variable. It can be concluded that the high rainfall inter-annual variability, the inequality of its distribution throughout the year and the decrease of the rainy days favor the instability of these events at ICA's farm. [ABSTRACT FROM AUTHOR]

In a random block design with six replicates, the influence of the regrowth age (30 to 75 d) and the climatic factors were evaluated in the nutritive quality of the pasture Panicum maximum cv Mombasa. The experiment was conducted in the trimesters January-February-March (dry season) and May-June-July (rainy season), on soil of the brown type with carbonate, without irrigation or fertilization. The highest correlations were between the indicators quality and age, mean temperature, maximum relative humidity and rainfall. The equations of linear regression during the rainy season had R² that varied between 0.97 and 0.99. DM, NDF, cellulose, hemicellulose, and in situ digestibility were outstanding. The lowest standard errors of estimation were obtained in NDF, cellulose, and hemicellulose. It is concluded that the regrowth age and the climatic conditions had marked effect on the nutritive value. Further studies on these indicators are recommended in different types of soils, in the edaphoclimatic conditions of the Cauto Valley, with the aim of having more information available. [ABSTRACT FROM AUTHOR]

Quality and yield data of Pennisetum purpureum cv. Cuba CT-169 were used. The data were from an experiment using a random block design with four replicates, connecting them with climate factors. The experiment was carried out on soil of the fluvisol type, and without fertilization and irrigation. An analysis of linear correlation was performed between the indicators of yield, quality, and climate elements in each period. Besides, multiple linear equations were determined between them. High correlations were obtained (coefficients higher than 0.80) with the rainfall and the average temperature (except for the yield, the percentage of leaves and stems, CP, hemicellulose, ash, and OM). With the relative humidity, ADF, lignin, phosphorus, cellulose, ash, and OM were oustanding in the rainy season. In the rainy season, the yield, CP, CF, cell wall, phosphorus, cell content, hemicellulose, ME and NFE were outstanding. Multiple linear equations were determined and the values of the coefficient of determination were above 0.92. In the rainy season, the highest R2 were obtained for CP, and, in the dry season, for DMD, ME and NFE (P < 0.001). It was established the degree of relation between some climatic factors, the yield, and the quality of the CT-169 in the Cauto Valley. Equation sof multiple linear regression were established relating the yield, CP, CF, lignin, DMD, OMD, ME, and NFE with the rainfall, maximum temperature and humidity. This allows to make an approximate calculation of the indicators, out of the knowledge of the climatic factors. This type of study should be continued with other species and environmental conditions, in a way that the results could be further spread. [ABSTRACT FROM AUTHOR]

In order to study the performance of some morpho-agronomic indicators in strata of Pennisetum purpureum cv. Cuba CT-115, a completely randomized design was used with 15 repetitions. The treatments consisted of five strata: 0-30 cm, 30-60 cm, 60-90 cm, 90-120 cm and more than 120 cm. The results indicated that in the rejected material (immediately after grazing) the residue yield was stabilized up to the upper strata (P < 0.05), whereas there were no differences at 30 and 60 d of regrowth. At 90 d of regrowth it appeared plant material in the stratum of more than120 cm, with values of 0.64 kg DM/tuft, differing from the rest of the strata (P < 0.001), except the basal stratum (0-30 cm). The percentages of leaves from the residue for all regrowth ages were increased up to the upper strata, with maximum values of 18.67, 19.45, 21.66, and 46.51 % for the rejected material, 30, 60, and 90 d of regrowth, respectively. However, the percentages of stems and dead material were reduced. The basal tillers emerged since 60 d of regrowth, not showing differences so as to their yield between strata. The percentage of leaves in the basal tillers was increased (P < 0.001) up to the stratum of 30-60 cm, with values of 60.37 and 63.33 %, for 60 y 90 d, respectively. The stems had an inverse performance. It was concluded that the upper strata had the highest percent-ages of leaves, the lowest of stems and dead material, in the basal tillers as in the residue, for all the regrowth ages, favoring the nutritive value of the forage. Using this information for designing other management choices is recommended. [ABSTRACT FROM AUTHOR]

At the middle of the 80's in the Institute of Animal Science, it started a program of improvement of Pennisetum purpureum through the use of biotechnology (in vitro tissue culture) and mutagenesis (radiation with 60 Co). This responded to, at that time, the most spread and used Pennisetum varaiety was King grass, which occupied 85 % of the forage areas in the country. The object of this program was the obtainment of new varieties with superior traits and that responded favorably to adverse conditions such as salinity and drought. Several clones were obtained through in vitro tissue culture. Out of them, two were selected: Cuba CT-115 and Cuba CT-169. The former was used to developed the biomass bank technology for grazing and to fulfill the feed deficit in the dry season, whereas the latter is purely for forage. Through mutagenesis, two new clones were obtained Cuba MF-24 and Cuba MQ-1 which by being exploited in dry conditions and with moderate doses of nitrogenous fertilizer, surpass the yields of king grass. Also, others were obtained having better agronomic and quality indicators. Special care was paid to drought and salinity, and the clones managed to surpass the yields of their predecessors. It was concluded that plants were obtained having favorable traits for forage production, grazing, drought and salinity resistance, as well as with better agronomic and quality indicators. Further studies are suggested using fertilization strategically and introducing new plants in commercial production, having wide variety of germplasm for further studies. [ABSTRACT FROM AUTHOR]

An experiment was developed to characterize the monomeric composition of the lignin from Pennisetum purpureum cv. Cuba CT-115 and its variation with the regrowth age, according to random block design, with three replicates and five treatments (28, 56, 84, 112, and 140 d of regrowth). It was proved that the incorporation of monolignoles to the lignin molecule from Cuba CT-1115 occurred in increasing order of their complexity. With the regrowth age, the concentrations of all the phenolic monomers were increased (P < 0.01). The contents of vanillin and siringilaldehide up to 84 d were minimum and showed drastic increment (P < 0.01) at 140 d of regrowth, when there was higher value (4.567 and 0.913 mg mL-1 for vanillin and siringilaldehide, respectively). An equation of multiple regression between lignin, phenolic monomers and age was adjusted: lignin= 2.12 + 0.050 (± 0.004) age - 0.285 (±0.178) p-hydroxybenzaldehide -1.530 (±0.780) siringilaldehide + 0.359 (±0.125) vanillin (R²=0.99, P < 0.001, standard error of estimation = ±0.115). There was high correlation between the IVDMD and the monomeric components of the lignin. The best equation that accounted for the performance of the in vitro dry matter digestibility (IVDMD) was established: IVDMD=72.83-1.61 (±0.89) p hydroxibenzaldehide-0.97 (±0.24) lignin (R²=0.90, P < 0.001. error of estimation=±0.88). The results permit to establish the basis for programs of genetic improvement or biotechnological manipulation of Pennisetum purpureum cv. Cuba CT-115 that permit to use at maximum its potential as biomass source. Further studies are suggested with the use of irrigation and fertilization. [ABSTRACT FROM AUTHOR]

Through a completely randomized sample design with fifteen repetitions, the effect of the regrowth age (30, 45, 60, 75, and 90 d) on the content of green pigments and carotenoids was studied after the grazing on Pennisetum purpureum cv. Cuba CT-115 in the dry season. Also, chlorophyll a (Chla) and crude protein (CP) ratios were explored. The lowest contents (P < 0.001) of chlorophyll a (2.43 mg/dm²) and chlorophyll b (Chlb) (1.07 mg/dm²) were observed at 90 d of the regrowth, whereas the highest (P < 0.001) was obtained at 30 d. There were no significant differences in the content of carotenoids. In an independent form, the sum of chlorophylls had the same pattern of response as that of the chlorophylls, but the ratio (Chla/Chlb) was higher (P < 0.01) at 90 d, whereas for the chlorophyll/carotenoid ratios, the highest value was obtained at 30 d of regrowth. The Chla and CP ratio was direct and highly significant (P < 0.001), with coefficients of correlation between 0.94 and 0.99. It was concluded that in the conditions of the study, the contents of chlorophyll diminished with the age. There was no variation of the carotenoids and the Chla was related in appositive form to crude protein. Further similar studies are recommended in the rainy season. [ABSTRACT FROM AUTHOR]

Three experiments were undertaken to study in Pennisetum purpureum varieties: I) the light absorption spectra of the green pigments from three varieties (King grass, Cuba CT-115, and Cuba CT-169) with three regrowth ages (28, 56, and 84 d), II) the contents of green pigments and carotenoids of four varieties (King grass, Taiwan A-146, Cuba CT-115, and Cuba CT-169) at different times of the year, and III) the contents of green pigments with the regrowth age (30, 60, and 90 d). The light absorption spectra of the varieties showed little differences and maximums were obtained in the wave lengths of 430 and 660 nm, which were more marked at 28 d of regrowth. There were significant differences in the content of green pigments between the varieties in the different seasons. In general, the highest values were recorded in the dry season (up to 4.50 mg/dm² of chlorophyll a) respective to the rainy season (up to 3.03 mg/dm² of chlorophyll a). Similar performance was 2 obtained in the carotenoids, with contents that varied between 0.10 and 1.44 and between 0.61 and 0.93 mg/dm², for the rainy and dry seasons, respectively. There was interaction between the varieties and the regrowth age (P < 0.001) for the green pigments in both seasons. The highest values of light absorption at 28 d after regrowth in the varieties seem to indicate the need for higher energy to keep the cell metabolism, although they may also suggest lower photosynthetic efficiency. This is confirmed by marked variation of green pigments and carotenoids at the different times of the year, with particular values for each variety. Also, further research is recommended to complete the results herein. [ABSTRACT FROM AUTHOR]

An introduction is presented to the articles published in this issue on cattle breeding and environmental aspects of cattle breeding.

In order to find methodologies with enough sensitivity to determine more precisely the degree of deterioration of seeds, several procedures have been developed under the conventional name of "vigor tests". There are profound debates and suppositions with regard to the concept and processes related to vigor. One idea is that vigor tests were developed in order to provide only additional information to that obtained with the germination test and they also allow to estimate the potential of emergency in the field in a wide range of environmental conditions. In this article, the authors offer a review on vigor, its concept and the most commonly used tests to evaluate it. At the same time, these researchers try to highlight that vigor is not a simple and isolated characteristic from the general performance of a seed feature, but it is the interaction of those biotic and abiotic properties, which influence on seeds and determine the activity level and their performance in time, such as the expressions of viability, dormancy, germination and emergence. Therefore, the term vigor is an integrated and dynamic concept, which cannot be separated because it is an essential part of seed quality. [ABSTRACT FROM AUTHOR]

The yield and content of nutrients was assessed in leaves, stems and dead material of Pennisetum purpureum cv. Cuba CT-115 sown at two densities (D1=17850 and D2=11350 plants/ha) and on two sowing seasons (late and early) in the northeast of Mexico. The sowing was conducted considering a completely random design, with factorial arrangement 2 x 2 x 3 and on July-August (early season) and September-October (late season) of 2009. Sixteen experimental plots in a total area of 900 m² were used. Seven sprouts per experimental unit were randomly sampled, 45 d after the regrowth during May of 2010. The variables were yield (t/ha), cell content, CP, NDF, ADF, hemicellulose and in vitro organic matter digestibility. The production of leaf, stem and dead material (t/ha) had significant differences (P < 0.01) and the values were 2.65, 1.84 and 0.74, respectively. The CP content was higher (P < 0.05) in leaf and stem (11.3 and 10.04 %) compared with the dead material (6.01 %). The ash content was higher (P < 0.05) in both sowing seasons, with range between 14.5-20.9 % for the different morphological components. The digestibility was of 63.6 %. It is concluded that the pasture CT-115 (Pennisetum purpureum) had good quality and may be considered an alternative for cattle feeding in the northeast of Mexico. [ABSTRACT FROM AUTHOR]

The effect of broom millet (Sorghum bicolor var. Technicum, jav), entire or ground was studied in the carcass characteristics and primary cuts in 40 pelibuey ovines (Dorper x Pelibuey), of 31.55 ± 6.02 kg of live weight during 42 d. Seventy five percent of broom millet entire was substituted by that ground. A completely random design with two treatments and four replicates was used. A feeding test with 40 animals receiving integral diets was conducted. The inclusion of entire broom millet did not influence significantly on the final live weight, weight of the hot carcass, rib eye area, width of the dorsal and renal-pelvic fat, weight of the digestive viscera and weight of the primary cuts. However, the carcass yield decreased (P < 0.05) (56.01 vs. 52.94 %) as well as the percentage of empty body (84.74 vs. 81.62 %) and increased (P < 0.05) the percentage of filled viscera (26.39 vs. 23.94 %), weight of the gastrointestinal content (6.84 vs. 5.71 kg) and percentage of the gastrointestinal content (18.38 vs. 15.26 %). It is concluded that the inclusion of entire broom millet in the feeding of lambs diminishes the carcass yield, without affecting its characteristics, weight of the primary cuts and their relation. [ABSTRACT FROM AUTHOR]

This work was developed with the object of evaluating the anti-insect effect of powder from different parts of the plant 49-1-XIV, as natural alternative to control the corn borer (Sitophilus zeamais Motschulsky). Therefore, a complete random design was used with four repetitions and a negative control. The treatments were the structural organs of the plants separately: seeds, pod, leaf, stalk, and root. Mortality, adult emergence, and repellent effect of the insect were evaluated. Besides, weight loss and percentage of germination of the seed of Zea mays, used as substrate by the insects, were determined. The results showed, for powders from the stalk, seed, and leaves of the plant, evaluated at a concentration of 1 %, values of mortality of 69.93, 64.93, and 46.81 %, respectively, for the adults of S. zeamais. The treatments having higher mortality, had the lowest emergence with values of 30.56 % for the stalk, followed by the seed (40.48 %) and the leaves (43.75 %). The lowest weight losses were obtained with the powders from the stalks and seeds. As to the percentage of germination, there were not significant differences between treatments. It is concluded that the powders from the stalks, the seeds, and the leaves of the plant 49-1 -XIV, applied as powders at 1 % have anti-insect effect in presence of S. zeamais by their positive effect on mortality, decrease of the emergence of adults, effect on insect repellence, lower weight loss of the grain, and by not affecting the germination of the seeds. [ABSTRACT FROM AUTHOR]

An experiment was developed with Pennisetum purpureum cv. CUBA CT-115, previously established without irrigation or fertilization in an experimental area of the Institute of Animal Science, to determine the effect of the regrowth age on the chemical composition of this cultivar. The experiment was developed according to random block design, with three replicates and five treatments (28, 56, 84, 112, and 140 d of regrowth). After the homogeneity cut, 100 plants were randomly collected per treatment and replicate to determine the chemical composition. It was proved that the advance of age was associated with the decline CP content and the increase (P < 0.001) of the DM concentration and of all the cell wall components of CUBA CT-115, except hemicelluloses. For CP and DM, linear regression equations were adjusted between these indicators and the age. For NDF, ADF, cellolose and lignin, quadratic regression equations were adjusted. The range of values of NDF varied from 60.42 to 80.80 %, that of cellulose from 29.36 to 39.85 %; whereas that of lignin from 3.22 % at 28 d up to 8.55 % at 140 d of regrowth. The lowest value (P < 0.001) of hemicelluloses (27.84 %) was obtained at 28 d of regrowth. There was no increasing trend, but a variable one in all the ages under study. There was increase (P < 0.001) in the ash content with the regrowth age, regardless the lack of differences in Ca and P. The silica content was increased (P < 0.001) since 0.33 % at 28 d up to 1.22 % at 140 d of regrowth. It was noteworthy the lack of variation in the contents of Ca and P with the regrowth age. The information from this study should be considered to have adequate management strategies of Pennisetum purpureum cv. CUBA CT-115 in animal feeding in a way that its maximum potential may be used as biomass source to obtain productive benefits and higher sustainability in our ecosystems. [ABSTRACT FROM AUTHOR]

An experiment was carried out with Pennisetum purpureum cv CUBA CT-115, already established without irrigation or fertilization, in an experimental area of the Institute of Animal Science to determine the effect of regrowth age on the in vitro dry matter digestibility (IVDMD). A random block design was applied with three replicates and five treatments (28, 56, 84, 112, and 140 d of regrowth). After the homogenous cut, 100 plants were randomly collected per treatment, being replicated for determining the indicators of chemical composition and the IVDMD through NIRS. It was proved that as the regrowth age increased, the IVDMD of the CUBA CT-115 declined (P < 0.001). A quadratic regression equation was fit between both and the range of values varied from 67.94 at 28 d up to 59.93 % at 140 d of regrowth. There was high correlation of the IVDMD with the cell wall components of this clone, except with hemicellulose, and the regression equation was established. It accounts for the close relation between the content of silica and the IVDMD, with high R² and homogenous spread of the residues. It was concluded that there was marked regrowth age effect on the in vitro dry matter digestibility of this clone, being the increase in the silica content the one that accounted the best for the decline in the IVDMD with the regrowth age of the clone. The use of this regression equation is recommended as useful tool to have more efficient management strategies in animal feeding. [ABSTRACT FROM AUTHOR]

Six simultaneous experiments were carried out to determine the content of primary and secondary metabolites of six species of trees, shrubs and forage herbaceous legumes under the edaphoclimatic conditions of Valle del Cauto, Cuba. A randomized block design with six replications was used and the treatments were the regrowth ages of 60, 120 and 180 days for trees and shrubs (Leucaena leucocephala, Tithonia diversifolia, Gliricidia sepium and Eritrina variegata) and 30, 45, 60, 75 and 90 days for creeping legumes (Neonotonia wightii and Teramnus labialis), in the rainy and dry seasons. There were determined N, glucose, fructose and sucrose (primary); total phenols, total tannins, total condensed tannins, total bound condensed tannins, free condensed tannins, alkaloids, flavonoids, saponins, triterpenes, total steroids, stachyose, verbascose and raffinose. Cluster analyzes to group species with similar characteristics were performed. During the rainy season seven groups were found and in the dry season eight; with the best results, comprehensively, for Gliricidia sepium and Tithonia diversifolia in both seasonal periods. The age had a marked effect on the content of primary and secondary metabolites by decreasing the former and increasing the latter as maturity advanced. This performance was evidenced by verifying, through cluster analysis, that the groups where the highest contents of secondary compounds were found were composed of the most advanced ages of the Neonotonia wightii, Teramnus labialis, Erythrina variegata and Leucaena leucocephala species, in both seasonal periods. Aspects of vital importance for future studies where the associative effects of species with lower content of these compounds (Tithonia diversifolia and Gliricidia sepium) were are analyzed, both in the ecosystem and in the animal response. [ABSTRACT FROM AUTHOR]

Using a random block design with factorial arrangement (3x2) the effect of the climatic area (Guayas and El Empalme) in the yield components and bromatological composition of three Brachiaria varieties (Decumbens, Brizantha and Mulato I) was studied. The yields of total dry matter, biomass, leaves and stems, the plant height, length and width of leaves, the contents of DM, CP, NDF, ADF, ADL, cellulose (Cel), hemicellulose (Hcel), cellular content (CC), P, Ca, ash, OM, DMD, OMD, ME, NFE and relations leaf/stem, NDF/N and ADF/N were determined. Analysis of variance was performed according to experimental design. There was significant interaction (P <0.0001) between the varieties and the area for some of the studied indicators. The highest yields of total DM, leaves, stems and biomass were obtained in Mulato I in El Empalme (1.32, 0.79, 0.53 and 5.08 t/ha, respectively P<0.001). The CP was better in Mulato I in Guayas (13.08 %, P<0.001), the cell wall components did not showed variety x area interaction, with significant differences in terms of the varieties for NDF, CEL and CC with the highest results for cv. Decumbens and Mulato I (38.21, 17.26 and 64.22 %, respectively P< 0.05). While for the area the highest percentages of ADF and ADL (20.12 and 3.47 %, respectively P< 0.02) were for Guayas. In this research was showed the effect of the climate factors and the variety on the yields and some quality indicators were the best productive and morphological performance in the higher rains area (El Empalme) was obtained, while for the content of protein, minerals, ash, the relations leaf/stem and NDF/N was better for the one of lower rains (Guayas). It is important to highlight that there were not differences between the varieties for the cell wall components, ADF/N, digestibility and energy contribution that is why their adaptability and potentialities in different ecosystems is confirmed. [ABSTRACT FROM AUTHOR]

With the objective of evaluating the yield components and bromatological composition of three Megathyrsus maximus cultivars in Guayas area, Ecuador at different regrowth ages, the research was carried out, following a random block design with factorial arrangement (3x3) with five replications. The productivity (yields of total dry matter, leaves, stem and biomass), morphological components (plant height, length and width of leaves, number of leaves and stems) were studied; as well as the contents of DM, CP, NDF, ADF, ADL, cellulose (Cel), hemicellulose (Hcel), cellular content (CC), P, Ca, ash, OM, DMD, OMD, ME, LNE and the relations NDF-N and ADF-N at the ages of 21, 42 and 63 days. Analysis of variance was performed according to experimental design. The highest yields of DM and biomass were obtained in Tanzania at 63 days of regrowth (2.74 and 8.25 t/ha, respectively). The highest DM and biomass yields were obtained in Tanzania at 63 days of regrowth (4.18 and 12 t/ha, respectively). The CP and CC decreased with the maturity of the plant and the best values were obtained in Tanzania at 21 days of regrowth (15.67 and 62.16 %, respectively), while the components of the cell wall increased with age and Tanzania showed the best values. There was significant interaction between varieties and maturity (P <0.0001) for all indicators. It is concluded that the studied varieties show adequate productive performance under conditions of low rainfalls. The Tanzania and Tobiata cultivars are a good option to replace the food deficit during the dry period due to its higher proportion of leaves, better relations NDF-N and ADF-N that give it higher quality. [ABSTRACT FROM AUTHOR]

Using a random block design and four replications with six treatments consisting on regrowth ages (30, 45, 60, 75, 90 and 105 days), their biomass production, dry matter, chemical composition and In situ ruminal degradation kinetics of Morus alba, was evaluated in la María, Los Ríos, Ecuador. It was sampled in plots of 1,200 m2, in which a uniformity cut was applied at 0.5 m high over the soil level, without using irrigation or fertilization. Edible biomass, DMY, DM, CP, NDF, ADF and OM were determined, as well as In situ ruminal degradation kinetics (DM, NDF and OM). There were increases of dry matter and edible biomass production of 1.77 and 0.45 t/ha-1, respectively, as well as 7.5, 11.21 and 18.28 percent units for DM, NDF and ADF, while there was a decrease for CP and OM of 4.99 and 8.44 percent units, respectively up to 105 days. For degradation kinetics of dry matter, the best results were obtained at 30 days with 81.24%, 7.08%, 0.41%/h, 88.32%, 66.06%, 63.78%, and 61.5 1% for soluble fraction (a), potentially degradable (b), degradation rate (c), potential degradability (a+b) and effective degradability at ruminal passage rate of 2, 5 and 8%, respectively. This same performance was maintained for OM and NDF. It can be concluded that regression equations were established, which explain the close relation among age, edible biomass production and dry matter. Dry matter and crude protein values were lower than those reported for this species in the international literature for production systems in tropical areas. These differences could be attributed to the zero use of irrigation and fertilization during the research. It is important to highlight that soluble fraction, potential and effective degradation of DM, OM and NDF were maintained with values superior to 50%. Further studies are suggested in other periods of the year, cut height, phytochemical composition, intake tests and animal response. [ABSTRACT FROM AUTHOR]

Using a random block design with factorial arrangement (3x3) with five replications, the quality of Brachiaria decumbens, Brachiaria brizantha and Brachiaria decumbens x Brachiaria ruziziensis cv. Mulato I at different regrowth ages (21, 42 and 63 days) were evaluated in Guayas area, Ecuador. The yields of total dry matter, biomass, leaves and stems were determined; as well as the plant height, length and width of leaves, the contents of DM, CP, NDF, ADF, ADL, cellulose (Cel), hemicellulose (Hcel), cellular content (CC), P, Ca, ash, OM, DMD, OMD, ME, LNE and relations leaf-stem, NDF-N and ADF-N. There was significant interaction (P <0.0001) between the varieties and the regrowth age for all the studied indicators. The highest DM and biomass yields were obtained in Mulato I at 63 days of regrowth (1.59 and 5.23 t/ha, respectively).The CP and CC decreased with the maturity of the plant and the best values were obtained in Mulato I at 21 days of regrowth (15.74 and 73.45%, respectively), while the components of the cell wall increased with age and Brachiaria decumbens showed the highest values. There was variability in terms of the varieties in the studied indicators, with the best general performance for Mulato I. In this study the variability of the nutritional quality was showed by the interaction between the variety and the forage maturity, determined, among other aspects, by the decrease of digestibilities and the energy contribution, as well as increases of the relations NDF/N, ADF/N, it is important to highlight that the biomass production, total yields of leaves and stems, in addition to the morphological indicators height, number of leaves, length and width showed the best results in Mulato I at 63 days. [ABSTRACT FROM AUTHOR]

Using a random block design with factorial arrangement (3x3) with five replications, the components of the yield and bromatological composition of three Brachiaria varieties (Decumbens, Brizantha and Mulato l) and three regrowth ages (21, 42 and 63 days) were studied in El Empalme area, Ecuador. The yields of total dry matter, biomass, leaves and stems were determined, as well as the plant height, length and width of leaves, the contents of DM, CP, NDF, ADF, ADL, cellulose (Cel), hemicellulose ( Hcel), cellular content (CC), P, Ca, ash, OM, DMD, OMD, ME, FNE and relations leaf-stem, NDF-N and ADF-N. Analysis of variance was performed according to experimental design. There was significant interaction (P<0.0001) between the varieties and the regrowth age for all the studied indicators. The highest DM and biomass yields were obtained in Mulato 1 at 63 days of regrowth (2.49 and 8.64 t/ha, respectively). The CP and CC decreased with the maturity of the plant and the best values were obtained in Mulato 1 and Brizantha at 21 days of regrowth (14.23 and 74.77 %, respectively), while the components of the cell wall increased with age and Decumbens showed the highest values. There was variability in the studied indicators in the varieties, with the best general performance for Mulato 1. It was demonstrated that as the maturity of the plant advanced, there was a decrease in its nutritional quality, determined among other aspects, by the lower digestibilities and energy, as well as increases in the relations NDF/N, ADF/N. However, although leaf/stem ratio decreased with age, leaf production in all studied cultivars was above 50 % with respect to stems, aspects to be taken into account in the management of these plants in ruminants production systems. [ABSTRACT FROM AUTHOR]