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The test was conducted at the Experimental Station of Black River from the Universidad Nacional Experimental Simón Rodríguez, located in the town of Black River County Acevedo Miranda state area for a life of tropical rain forest. The floor is open texture, pH 6,0, low-N, P and K and high in Mg, with a rainfall of 2.450 mm and average annual temperature of 26,5 ° C. With the aim of assessing the biomass and nutritional value of forage grass cultivation Megathyrsus maximus 'Gamelote', six harvest ages (21, 28, 35, 42, 49 and 56 days). The variables were Biomass Dry Matter (MSB), height (A), leaf: stem (L / T), crude protein (CP), Degradability of dry matter (DMS), content of phosphorus (P) and Calcium (Ca). Employment is a block design with three replications randomly split plot arrangement. The effect of the period of the year and the age of the plant had significant effects on the production of MSB, M and H: T. The average biomass in the dry periods of high precipitation from 42 to more than 5.000 Kg.MS / ha. The ratio L/T decreases with increasing age of plant performance was equal to the contents of the PC to be above the critical value of 7% for all ages. P content decreased with the increase in age beyond the minimum level of 0,18%, just like Ca feed. The DMS decreases with increasing age ranging from 71 to 54%. Grass Megathyrsus maximus is a good potential for biomass production and nutritional value to animal feed in the soil and climatic conditions of Black River, Acevedo Municipality. Miranda State.

In order to evaluate under cutting for four gramineous forage species, an experiment was set up at the Experimental Station of Rio Negro, belonging National Experimental University Simon Rodriguez, located nearly the town of Rio Negro, Municipality of Acevedo, State of Miranda. The ecosystem is considered as Humid Tropical Forest with 2.450 mm precipitation mean and 26,5°C of mean annual Temperature. The soil texture is a loam pH 6,0; containing low levels of N, P and K and high level of Mg. The grass species evaluated were Urochloa decumbens, Urochloa humidicola cv. Humidicola and Urochloa arrecta harvested at 21, 28, 35, 42,49 and 56 days of age, during four different periods of the rainy regime of the area. A randomized block design with three replicates arranged as a split-split plot design was used. The variables studied were dry matter standing crop(DMC), height of the plants(H), Leaf: Stem ratio (L:S), crude protein content (CP), dry matter degradability (DMD), P and Ca, D.M content. The rainy regime period and age of cutting had a significant statistical effects upon DMC, H and the L:S ratio. U. decumbens DMC out yielded (3.870 Kg./ha) the other nown species. The L:S ratio and CP content diminished as the plant aged, staging the latter variable over the critical threshold value (7%) up to 42 days of age. Similar trends occurred to P and Ca content as plant aged, except U. humidicola with values under the cited level, during the minimum rainy period. The DMD varied from 62 to 69%, being significantly effected by age and grass species.

Lozano Z.,Central University of Venezuela | Romero H.,Central University of Venezuela | Bravo C.,Simon Rodriguez National Experimental University
Agrociencia | Year: 2010

Production systems based on single crops and grazing of crop leftovers have produced grave soil degradation problems in soils of Venezuelan savannas. As alternatives to prevent degradation and improve the quality of these soils, some conservation management systems have been proposed. With the objective of evaluating changes in physical properties of a typical soil of a natural savanna, from use of cover crops (Brachiaria dictyoneura and Centrosema macrocarpum) as residues for direct corn (Zea mays L.) sowing and later grazing with cattle, a trial was set up in a soil classified as Typic Plinthustults, located in the savannas of Guárico (Venezuela). The initial physical characteristics of natural savanna soils were characterized, before establishing the trial (2002) and the following were evaluated in samples collected in each plot (in two seasons of the 2006-2007 cycle; before and after grazing): bulk density, saturated hydraulic conductivity, porosity and its distribution, resistance to mechanical penetration, and humidity volume content, in samples taken at 0 to 5 and 5 to 15 cm of depth, in each parcel. Analysis of the results indicates that there were statistical differences in the physical properties evaluated, which could be due to the cover crop and the season; especially bulk density, saturated hydraulic conductivity, total porosity and mechanical resistance. The best physical conditions were present in the superficial layer of the soil (0 to 5 cm) and in the B. dictyoneura cover.

Jedrzejewski W.,Venezuelan Institute for Scientific Research | Jedrzejewski W.,Polish Academy of Sciences | Cerda H.,Simon Rodriguez National Experimental University | Viloria A.,Venezuelan Institute for Scientific Research | And 2 more authors.
Mammalia | Year: 2014

Killing behavior and consumption rate are important components that determine the final predation rate. We studied the predatory behavior of a female jaguar with one offspring in Hato Piñero in Venezuelan Los Llanos. Seven carcasses of freshly killed calves were found over a period of 9 days. Automatic video recording was used to document the jaguar's behavior. Our study revealed a detailed, repetitive sequence of female jaguar behavior while hunting for calves. The sequence started with the female killing a calf by biting through the skull or neck, then she dragged the carcass to concealment, eviscerated it and left it concealed; then, the next evening, the female returned with its cub, fed intermittently for a total time of about 90 min while in the meantime it hunted for new prey. All this sequence seems to have a highly adaptive significance for a female jaguar rearing cubs and utilizing large prey. During the short period of our observations, the estimated kill rate of the female jaguar with one offspring was from 0.67 to 1 calf per day. Proper cattle management is necessary to avoid high losses of calves from predation by jaguars. © 2014 by Walter de Gruyter Berlin/Boston.

Brito D.,University of the East Venezuela | Brito R.,Simon Rodriguez National Experimental University | Pereira G.,Central University of Venezuela
Zootecnia Tropical | Year: 2011

In the nourishment of the zooplankton several species of microalgae have been in used selected by their size, digestibility of the cellular wall and nutritional value since they influence the survival, growth and metamorphosis of crustaceans larvae. The purpose of this research was to determine the survival of Dendrocephalus spartaenovae from 1 to 6 and from 6 of 32 days of age in different conditions of culturing and fed to a concentration of 5 *105 cells/ml. The survival of larvas was evaluated of D. spartaenovae from 1 to 6 days of life considering the age and population density. The survival of the organisms from 6 to 32 days of life, it measured up in relation to the age, population density and sexual condition. The survival of larvas of D. spartaenovae diminished with the age, reaching a survival of 78,33 % to 6 days of life. The minor mortality of larvas registered was for the population densities from 10 to 20 individuals/100 ml with percentages of 93,75% and 94,79%, respectively. In the anostraceos from 6 to 32 days of life; the survival diminished according to the age of individuals, the lowest rate of survival was found at 32 days with 46,53%. Concerning to the population density, higher values of survival in adults population was 80,79% and 83,33% obtained in densities of 4 and 10 individuals/L, respectively. Females showed higher survival rates than the males with averages of 87,5% and 72,94%, respectively.

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