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Medina M.G.,University of Los Andes, Venezuela | Garcia D.E.,University of Los Andes, Venezuela | Moratinos P.,Instituto Nacional Of Investigaciones Agricolas Inia | Iglesias J.M.,Estacion Experimental de Pastos y Forrajes | Clavero Y.T.,University of Zulia
Revista de la Facultad de Agronomia | Year: 2012

An experiment was carried out in order to evaluate the effects of fertilization level (0, 132 and 264 g N.plant.year-1), grazing frequency (60, 90 and 120 days), association modality (mulberry-grasses and mulberry-leucena-grasses), pruning strategies (with pruning and without pruning), the year and the season in the total (BT), edible (BC) biomass, (leaves and edible stem) and woody stem (TL), relationship BC/BT and chemical composition (proximal and secondary metabolites) using a randomized blocks design with split plot arrangement and measures repeated and 4 replicates by sub-plots. The interaction grazing frequency x pruning strategy x fertilization for the BT and BC availability was significant (P<0.05). The BT and BC were superior in the plants without pruning, fertilized with 132 and 264 g of N.plant.year-1 and grazed each 90 and 120 days (P<0.05). The year only affected the BT and TL values (P<0.05). The BT and BC availability oscillated between 193-210 and 156-159 g of DM.plant-1, respectively. The highest biomass value was observed in the rainy period (BT: 214.66; BC: 187.33 gDM/ plant) (P<0.01) and in the multi associated system (BT: 254.33; BC: 224.06 gDM/ plant). Marginal influence of year, the season, the modality and the fertilization in the chemical composition was observed. However the pruning strategy and the grazing frequency caused significant variations (P<0.05). The biggest nutritional value was observed when pruning and with the most intense grazing frequencies (60 and 90 days). Considering the values of biomass availability and the chemical composition, Mulberry can be used as grazing plant in multi associated systems when its managed agronomically with organic fertilization and only with strategic pruning.


Gonzalez Garduno R.,National Autonomous University of Mexico | Ortega J.C.C.,National Autonomous University of Mexico | Hernandez G.T.,Colegio de Mexico | Garcia J.A.,Estacion Experimental de Pastos y Forrajes | de Gives P.M.,Instituto Nacional de Investigaciones Nucleares
Tecnica Pecuaria en Mexico | Year: 2010

The study included two experiments. The objective of experiment one was to learn about the in vitro effect of different sodium hypochlorite concentrations and a commercially-available citric extract on the survival of infestant larvae of gastrointestinal nematodes by observation at different time points. With >0.05% sodium hypochlorite concentrations, larvae lost their sheaths in two minutes, while at 1.3% concentration larvae died within one hour. Larval mortality also occurred as late as 12 h after exposure to the concentrations tested of citric extract. The second study was performed to evaluate the effect of applying both compounds directly on the grasslands on the re-infestation of grazing sheep. Eleven (11) lambs per treatment group were used, i.e.: treatment TI, untreated control; TII, application of one (1) liter 0.5% sodium hypochlorite/20 m2; TIII, application of 5% citric extract on the grass also at the rate of 1 L/20m2. Data on live weight, packed cell volume (pcv), and nematode egg counts per gram (epg) of feces was analyzed using the GLM (SAS) procedure. The highest effect on epg and pcv was obtained in the group of lambs grazing the paddock treated with sodium hypochlorite, with the lowest epg and the highest pcv values as compared to both the controls and the group treated with citric extract (1,088 vs 1,997 and 2,891 epg; 25.6 vs 23.1 and 23.5%, respectively; P<0.05).


Torres-Vazquez J.A.,National Autonomous University of Mexico | Pech C.I.V.M.,Colegio de Mexico | Zepeda A.B.,Estacion Experimental de Pastos y Forrajes | Rios-Utrera A.,Instituto Nacional de Investigaciones Nucleares | And 4 more authors.
Revista Mexicana De Ciencias Pecuarias | Year: 2012

The objective of the present study was to estimate (co)variance components, heritabilities and genetic and phenotypic correlations for yearling weight (YW), scrotal circumference (SC) and frame score (FS) of Simmental and Simbrah young bulls from Mexico. All traits were adjusted to 365-d according to the Beef Improvement Federation (BIF). Final data file included 1,949 Simmental and 1,259 Simbrah records. A three-trait animal model was used to estimate (co)variance components and genetic parameters. For each trait, the model included fixed effects of herd-year-season, and the age of dam, gene proportion of Simmental breed, heterozygosity and recombination losses effects as covariates; animal and residual were included as random effects. Additive variances were 376.3±130.9 kg2, 2.89±0.69 cm 2 and 0.37±0.08 units2; and heritabilities were 0.33±0.11, 0.35±0.08 y 0.42±0.08, for Y W, SC and FS, respectively. Genetic correlations were 0.36±0.19, 0.47±0.17 and 0.59±0.12, for YW-SC, YW-FS and SC-FS, respectively. Heritability estimates show that a favorable response would exist to selection for the studied traits. Genetic correlations indicate that no genetic antagonisms exist, suggesting that would be a positive correlated response to selection of any trait. It would be necessary the use of selection indices in order to avoid greater FS as correlated response due to direct selection of YW and SC.


Becquer C.J.,Estacion Experimental de Pastos y Forrajes | Salas B.,Estacion Experimental de Pastos y Forrajes | Avila U.,Estacion Experimental de Pastos y Forrajes | Palmero L.,Estacion Experimental de Pastos y Forrajes | And 4 more authors.
Cuban Journal of Agricultural Science | Year: 2011

In order to select rhizobia inoculated in corn, a field trial was performed in the environmental conditions of Sancti Spiritus, Cuba. Ten native strains belonging to Bradyrhizobium sp. were applied, as well as three commercial ones of Sinorhizobium fredii, B. lupini, and Bradyrhizobium sp. The T-66 corn hybrid variety (Zea mays, L) was evaluated. A complete random block design was used, with 15 treatments and four replicates. The analysis of variance and the differences between means were applied, according to LSD of Fisher (P < 0.05). In aerial dried weight, all the inoculated treatments had values statistically higher than the non-inoculated control. The treatments inoculated with the JJ4, JJ2, SP6, HA1, HG2, SP20, and TE4 native strains, as well as the inoculated, with the 25B6 and ATCC 10317 commercial strains, showed similar superscripts in respect to the fertilized control as to the aerial dried weight. For the stalk length, the 10 inoculated treatments were statistically superior to the absolute control. Except the treatments inoculated with the SP21 native strain and the 61B7commercial strain, the other inoculated treatments were statistically superior to the absolute control as to the corncob weight. It was concluded that the inoculation with rhizobia equaled the effects of the chemical fertilization, although the result was not the same for all the variables and for the two genera of rhizobia applied either. It was proved that the inoculation favored the production of seeds in respect to other agro-productive variables of the plant. The JJ4, JJ2, SP6, HA1, and SP20 strains are recommended, as well as the 25B6 commercial strains for corn crops, in edaphic and climatic conditions similar to those of this trial, with chemical fertilization of 80 kgN/ha.

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