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Papers by jorge perez

This paper studies the effect of minimum wage changes on spatial equilibriums in local labor mark... more This paper studies the effect of minimum wage changes on spatial equilibriums in local labor markets. Using data for the U.S. and minimum wage variation across state borders, I analyze how commuting, residence, and employment locations change in response to local minimum wage changes. I find that areas where the minimum wage increases receive fewer low-wage commuters. I formulate a spatial equilibrium model and calculate counterfactuals with a higher minimum wage for U.S. cities considering an increase. For small minimum wage increases, most counties would receive higher low-wage commuting and have fewer low-wage residents. As minimum wage increases are larger, there arehigher low-wage commuting reductions driven by employment relocation.

Revista Mexicana de Ciencias Pecuarias, 2004

A study was done of the morphological behavior, specific leaf area (SLA) and leaf nitrogen concen... more A study was done of the morphological behavior, specific leaf area (SLA) and leaf nitrogen concentration (LNC) of "mulato" grass (Brachiaria ruziziensis x B. brizantha) at different phenological stages (PS). Plant morphology (PM), growth rate (GR), height (H), SLA, and LNC were measured at seven-day intervals during a 21-week experimental period. Data were analyzed using the SAS GLM procedure in a completely randomized experimental design, with four replications and a regression analysis for each variable. PM varied significantly (P<0.05) in the different PS's. The highest leaf biomass was reached on d 102 after germination (5.7 +- 1.059 g DM plant-1). The highest GR was recorded at about wk 16 (2.44 +- 0.474 g DM plant-1 day-1). LNC attained the highest level at wk 4 (6.98%) and then declined until wk 21 (0.683%). LNC was positively correlated to SLA (R2=0.86971, P<0.001), and negatively correlated to plant height (R2=0.90231, P<0.001). Results suggest that ...

Revista Mexicana de Ciencias Pecuarias, 2009

The objective of the present study was to evaluate herbage accumulation, morphological compositio... more The objective of the present study was to evaluate herbage accumulation, morphological composition, growth rate and structural characteristics in Mombasa grass swards subject to different cutting intervals (3, 5 and 7 wk) during the rainy and dry seasons of the year. Treatments were assigned to experimental units (17.5 m2) according to a complete randomised block design, with four replicates. Herbage accumulation was greater in the rainy than in the dry season (83 and 17 %, respectively). Herbage accumulation (24,300 kg DM ha-1), average growth rate (140 kg DM ha-1 d-1) and sward height (111 cm) were highest in the 7 wk cutting interval, but leaf proportion (56 %), leaf:stem (1.6) and leaf:non leaf (1.3) ratios decreased. Herbage accumulation, morphological composition and sward structure of Mombasa grass sward may be manipulated through defoliation frequency. The highest leaf proportion was recorded in the 3-wk cutting interval. Longer cutting intervals affected negatively sward st...

Revista Mexicana de Ciencias Pecuarias, 2009

The objective of the present study was to assess the effect of nitrogen fertilization on Guinea G... more The objective of the present study was to assess the effect of nitrogen fertilization on Guinea Grass (Panicum maximum Jacq.) cv. Tanzania seed yield and quality. The experiment was carried out under rainfall conditions in 2001 in Tejupilco, State of Mexico, Mexico, (18o 54' N, 100o 08' W, 1,320 m asl). Treatments were five Nitrogen doses (0, 50, 100, 150 and 200 kg ha-1), in a randomized complete block design, with four replicates. Variables evaluated were: total seed yield (TSY), pure seed yield (PSY), number of panicles per square meter, panicle length, branches per panicle, number of seeds produced and harvested per panicle, 1000-seed weight, physical purity and germination. Nitrogen fertilization increased both TSY and PSY (P 0.05). It can be concluded that the highest Guinea Grass seed yield was obtained when fertilized with 100 kg N ha-1.

Revista Mexicana de Ciencias Pecuarias, 2001

Velasco ZME, Hernandez-Garay A, Gonzalez- Hernandez VA, Perez PJ, Vaquera HH, Galvis SA. Tec Pecu... more Velasco ZME, Hernandez-Garay A, Gonzalez- Hernandez VA, Perez PJ, Vaquera HH, Galvis SA. Tec Pecu Mex 2001,39(1):1-14. Due to limited information about seasonal growth curve of cocksfoot grass (Dactylis glomerata) in temperate areas, a study was carried out in order to determine its optimum harvesting time. Twenty four plots 3 x 3 m were allocated in a completely randomized design with eight treatments and three replicates, treatments consisted of successive cuts at weekly intervals during a regrowth cycle (eight weeks) in each season of the year. All plots were cut to 5 cm and three samples of 0.1 m2 were taken to ground level to determine residual herbage mass, from then onwards, every week three different plots were harvested. Cumulative herbage mass, growth rate (GR), botanical and morphological composition, leaf:stem ratio, leaf:not leaf ratio and leaf-area index (LAI) were evaluated. Cumulative herbage mass and GR increased steadily after defoliation, until a maximum green lea...

Revista Mexicana de Ciencias Pecuarias, 2002

The objective of this study (which was carried out in a greenhouse) was to investigate the effect... more The objective of this study (which was carried out in a greenhouse) was to investigate the effects of cutting height on herbage production and regrowth dynamics of perennial ryegrass swards. All plots were randomly allocated to six treatments (3, 6, 9, 12, 15 cm cutting height and control) with 15 replicates (three per tray). All pots were cut twice weekly. Every four weeks from March 7 to July 15 all pots contained in one tray were withdrawn for destructive readings of tiller population density, tiller weight, leaf:stem ratio and leaf:non-leaf ratio. Treatments were analyzed in a completely randomized design with three replicates. A multiple regression analysis (stepwise) was also carried out. Cumulative herbage mass was higher at 9 and 12 cm cutting heights (P 0.05); stem, leaf and dead material and total tiller weight increased as cutting height decreased (P<0.05). The highest leaf:stem and leaf:non-leaf ratios were obtained at a 3 cm cutting height (P<0.05). Leaf growth, s...

Revista Mexicana de Ciencias Pecuarias, 2010

El objetivo fue evaluar el efecto de la distancia entre plantas en el rendimiento y calidad de se... more El objetivo fue evaluar el efecto de la distancia entre plantas en el rendimiento y calidad de semilla de Brachiaria brizantha cv. Marandu. El experimento se realizo en temporal durante 2007, en la Universidad del Papaloapan, Loma Bonita, Oaxaca. Se evaluaron seis distancias entre plantas (voleo, 25 x 25, 50 x 50, 75 x 75, 100 x 100 y 125 x 125 cm entre lineas y plantas, respectivamente), con un diseno de bloques completos al azar, con cuatro repeticiones. Se midio el rendimiento de semilla pura (RSP), rendimiento de semilla pura germinable (RSPG), numero de paniculas m-2, longitud de panicula, numero de semillas cosechadas por panicula, peso de 1,000 semillas, porcentaje de dehiscencia, semilla pura y germinacion. El RSP y RSPG vario entre tratamientos (P0.05). Se concluye que el mayor rendimiento de semilla de B. brizantha cv. Marandu, se logro con la distancia 25 x 25 cm entre lineas y plantas, respectivamente. La germinacion de la semilla no fue mejorada por ninguno de los trata...

Revista Mexicana de Ciencias Pecuarias, 2004

The aim of this research was to determine the optimum harvesting time of alfalfa during the diffe... more The aim of this research was to determine the optimum harvesting time of alfalfa during the different seasons of the year. The experiment was carried out from April 2000 to March 2001, at the Instituto Tecnologico Agropecuario research unit, in Nazareno, Xoxocotlan, Oaxaca. The varieties used were: Valenciana and Oaxaca. Thirty-two plots (2 x 2 m) per variety were allocated in a completely randomized design with eight treatments and four replicates, treatments consisted of successive cuts at weekly intervals during a regrowth cycle (eight weeks) in each season of the year. All plots were cut to 5 cm and four samples of 0.25 m2 were taken, per variety, to ground level to determine residual herbage mass, from then onwards, four different plots were harvested to ground level at weekly intervals. Cumulative herbage mass, growth rate (GR), leaf:stem ratio, leaf number per tiller and leaf area index (LAI) were evaluated. The results showed that cumulative herbage harvested had the followi...

Revista Mexicana de Ciencias Pecuarias, 2008

Forage production was determined for the gramineae Brachiaria dictyoneura, B. brizantha (cv. Tole... more Forage production was determined for the gramineae Brachiaria dictyoneura, B. brizantha (cv. Toledo) and B. ruziziensis x B. brizantha (cv. Mulato) as monocrops as well as in association with the legume Arachis pintoi. Experimental design was completely random blocks with four replications. Measured variables included forage dry matter production, growth rate, botanical and morphological composition, tiller density, and tiller weight. Cumulative forage production was higher (P<0.05) among the gramineae monocrop treatments (average = 15,498 kg DM ha-1) than among the gramineae + A. pintoi associations (average = 10,745 kg DM ha-1). The lowest growth rates occurred during the dry season (9 kg DM ha-1 d-1 for A. pintoi, 12 kg B. dictyoneura + A. pintoi), and the highest during the early rainy season (80 kg for cv. Toledo, 71 kg DM ha-1 d-1 for B. dictyoneura). Leaf percentage was high in all treatments with an overall average of 65 % during the northwind season, 57 % for the dry sea...

Revista Mexicana de Ciencias Pecuarias, 2002

The objective of this study was to measure Insurgente grass regrowth (total forage, forage compon... more The objective of this study was to measure Insurgente grass regrowth (total forage, forage component and shoots) grazed at different green leaf allowances, by means of a rotational grazing scheme having fixed rest periods, in the rainy season. Forage was grazed under three different allowances: 3, 5 and 7 kg dry matter (leaf) per 100 kg live weight -,1 day -,1. Experimental design was a random complete block with three replications, and the experimental unit was 0.5 ha carrying two heifers. Grazing was rotational, consisting of a 3 day occupancy period and a 30 day regrowth interval. Four grazing cycles were completed. The smallest allownce (P0.05) differences between them relative to the defoliation rate (49 %). Daily plant weight gain was smaller for the 3 % treatment in the first 15 days but higher in the last 15 days of the regrowth period, compared to the other two treatments. This different growth pattern was determinant in producing a non significant difference (P>0.05) be...

Revista Mexicana de Ciencias Pecuarias, 2001

Joaquin TBM, Hernandez GA, Perez PJ, Herrera HJG, Garcia SG, Trejo LC. Tec Pecu Mex 2001,39(3)245... more Joaquin TBM, Hernandez GA, Perez PJ, Herrera HJG, Garcia SG, Trejo LC. Tec Pecu Mex 2001,39(3)245-254. A study was carried out during 1999 in Tejupilco, State of Mexico (18o 54' N, 100o 08' W and 1320 masl), with the aim to evaluate the effect of nitrogen (N) application and harvest time on seed yield and quality of guinea grass (Panicum maximum Jacq.) cv. Tanzania. Treatments were three N levels (50, 100 and 150 kg ha-1) and six harvest times (6, 10, 14, 18, 22 y 26 days after anthesis, DAA), distributed in a randomized complete block design, arranged in split plots with three replicates. variables evaluated were: pure germinable seed yield (PGSY), number of panicles m-2, panicle length, number of harvested spikelets per panicle (NHSP), shedding percentage, dry matter content, and germination percentage. Results showed that N application increased PGSY, number of panicles m-2, panicle length, and NHSP (P<0.01). The highest yields of PGSY occurred with the application of ...

Revista Mexicana de Ciencias Pecuarias, 2009

The objective of the present study was to assess perennial ryegrass seasonal herbage accumulation... more The objective of the present study was to assess perennial ryegrass seasonal herbage accumulation, growth rate (GR), tiller population density (TPD) and weight (TW) at different grazing frequencies and intensities. Treatments consisted of two grazing frequencies (14 and 21 d in the rainy season and 35 and 42 d in the dry and cold seasons) and three grazing intensities: (hard 4-6 cm), medium (6-8 cm) and lax (8-10 cm) in a completely randomized block design with a factorial 2x3 arrangement and three replicates. In the rainy season herbage accumulation was 28 % greater (P<0.05) at 21 d grazing frequency than at 14 d grazing frequency (4,457 vs 3,457 kg DM ha-1). In the cold and dry seasons herbage accumulation at 35 d interval produced 27 % more herbage than at 42 d interval (2.270 vs 1,787 kg DM ha-1). Medium intensity grazing yielded more herbage than both hard and lax in the three seasons. The highest GR was recorded in the rainy season, especially in August at 21 d frequency an...

Revista Mexicana de Ciencias Pecuarias, 2003

The aim of this study was to investigate the effects of herbage allowance (HA) on herbage product... more The aim of this study was to investigate the effects of herbage allowance (HA) on herbage production and utilization in stargrass (Cynodon plectostachyus) clitoria (Clitoria ternatea) mixture. Four treatments (3.0, 4.5, 6.0 and 7.5 kg de DM 100 kg-1 PV d-¹) were allocated in a randomized block design with five repetitions. The experimental unit was a paddock of 250 m2. Treatments were rotationally grazed every 30 d. Herbage mass on offer, botanical and morphological composition, leaf:non-leaf ratio and pasture utilization percentage were measured. The highest herbage mass on offer (5077 kg DM ha-1), herbage yield (2588), and leaf (826), stem (1210) and dead matter quantity (666) was observed in stargrass with HA of 6.0 and 7.5. For clitoria, treatments with HA of 4.5 and 6.0 (P£0.05) presented the highest herbage mass on offer (1240 kg DM ha-1), leaf (558) and stem quantity (649). The leaf:non-leaf ratio (0.58) and pasture utilization percentage (53 %) increased as HA decreased (P£0...

Revista Fitotecnia Mexicana, 2011

El objetivo del estudio fue determinar la densidad, tasa de rebrotación o recambio y estabilidad ... more El objetivo del estudio fue determinar la densidad, tasa de rebrotación o recambio y estabilidad de la población de tallos del pasto Panicum maximum Jacq. cv. ‘Mombaza’, cosechado a intervalos de cortes (IC) de 3, 5 y 7 semanas, durante un año, en las épocas de sequía (10-nov-2006 a 09-jun-2007) y lluvias (10-jun a 06-nov-2007). Los IC (tratamientos) se distribuyeron en 12 parcelas de 17.5 m2, mediante un diseño de bloques completos al azar con cuatro repeticiones. Las mayores densidades de tallos se registraron en el IC de 3 semanas durante la sequía (428 tallos m-2), y en los IC de 3 y 7 semanas durante las lluvias (413 y 394 tallos m-2, respectivamente). Hubo mayor dinámica de recambio de tallos durante la época de lluvias que en la de sequía, con mayores tasas de aparición (38.0 vs. 4.6 tallos/100 tallos x mes, respectivamente) y muerte de tallos (32.9 vs. 6.4 tallos/100 tallos x mes, respectivamente) y menores tasas de supervivencia (67.1 vs. 93.6 tallos/100 tallos x mes, respe...

El Agora Usb, 2010

El presente estudio consiste en una descripción del uso de los juegos de azar y vídeo juegos en l... more El presente estudio consiste en una descripción del uso de los juegos de azar y vídeo juegos en los estudiantes, docentes y empleados de la Universidad de San Buenaventura, seccional de Medellín, y su relación con las dimensiones médica y psicológica con variables como son: dificultades de concentración, cambio del estado de ánimo, las molestias físicas, preferir el juego a las prácticas deportivas, y la distensión que produce el juego; en este segundo momento se presentan los resultados con docentes. La asesoría metodológica Epi-Info: a cargo de Federico Burgos Acevedo del Centro de Investigaciones Roger Bacon de la USB. El presente estudio está avalado por el Grupo Interdisciplinario de Estudios Psicosociales en Adicciones, GIEPSA (coordinado por Víctor Hugo Cano B. y como investigador principal Jorge Arturo Pérez P.

Revista Mexicana De Ciencias Pecuarias, Jun 1, 2013

Revista Del Instituto De Estudios Economicos, 2008

This paper studies the effect of minimum wage changes on spatial equilibriums in local labor mark... more This paper studies the effect of minimum wage changes on spatial equilibriums in local labor markets. Using data for the U.S. and minimum wage variation across state borders, I analyze how commuting, residence, and employment locations change in response to local minimum wage changes. I find that areas where the minimum wage increases receive fewer low-wage commuters. I formulate a spatial equilibrium model and calculate counterfactuals with a higher minimum wage for U.S. cities considering an increase. For small minimum wage increases, most counties would receive higher low-wage commuting and have fewer low-wage residents. As minimum wage increases are larger, there arehigher low-wage commuting reductions driven by employment relocation.

Revista Mexicana de Ciencias Pecuarias, 2004

A study was done of the morphological behavior, specific leaf area (SLA) and leaf nitrogen concen... more A study was done of the morphological behavior, specific leaf area (SLA) and leaf nitrogen concentration (LNC) of "mulato" grass (Brachiaria ruziziensis x B. brizantha) at different phenological stages (PS). Plant morphology (PM), growth rate (GR), height (H), SLA, and LNC were measured at seven-day intervals during a 21-week experimental period. Data were analyzed using the SAS GLM procedure in a completely randomized experimental design, with four replications and a regression analysis for each variable. PM varied significantly (P<0.05) in the different PS's. The highest leaf biomass was reached on d 102 after germination (5.7 +- 1.059 g DM plant-1). The highest GR was recorded at about wk 16 (2.44 +- 0.474 g DM plant-1 day-1). LNC attained the highest level at wk 4 (6.98%) and then declined until wk 21 (0.683%). LNC was positively correlated to SLA (R2=0.86971, P<0.001), and negatively correlated to plant height (R2=0.90231, P<0.001). Results suggest that ...

Revista Mexicana de Ciencias Pecuarias, 2009

The objective of the present study was to evaluate herbage accumulation, morphological compositio... more The objective of the present study was to evaluate herbage accumulation, morphological composition, growth rate and structural characteristics in Mombasa grass swards subject to different cutting intervals (3, 5 and 7 wk) during the rainy and dry seasons of the year. Treatments were assigned to experimental units (17.5 m2) according to a complete randomised block design, with four replicates. Herbage accumulation was greater in the rainy than in the dry season (83 and 17 %, respectively). Herbage accumulation (24,300 kg DM ha-1), average growth rate (140 kg DM ha-1 d-1) and sward height (111 cm) were highest in the 7 wk cutting interval, but leaf proportion (56 %), leaf:stem (1.6) and leaf:non leaf (1.3) ratios decreased. Herbage accumulation, morphological composition and sward structure of Mombasa grass sward may be manipulated through defoliation frequency. The highest leaf proportion was recorded in the 3-wk cutting interval. Longer cutting intervals affected negatively sward st...

Revista Mexicana de Ciencias Pecuarias, 2009

The objective of the present study was to assess the effect of nitrogen fertilization on Guinea G... more The objective of the present study was to assess the effect of nitrogen fertilization on Guinea Grass (Panicum maximum Jacq.) cv. Tanzania seed yield and quality. The experiment was carried out under rainfall conditions in 2001 in Tejupilco, State of Mexico, Mexico, (18o 54' N, 100o 08' W, 1,320 m asl). Treatments were five Nitrogen doses (0, 50, 100, 150 and 200 kg ha-1), in a randomized complete block design, with four replicates. Variables evaluated were: total seed yield (TSY), pure seed yield (PSY), number of panicles per square meter, panicle length, branches per panicle, number of seeds produced and harvested per panicle, 1000-seed weight, physical purity and germination. Nitrogen fertilization increased both TSY and PSY (P 0.05). It can be concluded that the highest Guinea Grass seed yield was obtained when fertilized with 100 kg N ha-1.

Revista Mexicana de Ciencias Pecuarias, 2001

Velasco ZME, Hernandez-Garay A, Gonzalez- Hernandez VA, Perez PJ, Vaquera HH, Galvis SA. Tec Pecu... more Velasco ZME, Hernandez-Garay A, Gonzalez- Hernandez VA, Perez PJ, Vaquera HH, Galvis SA. Tec Pecu Mex 2001,39(1):1-14. Due to limited information about seasonal growth curve of cocksfoot grass (Dactylis glomerata) in temperate areas, a study was carried out in order to determine its optimum harvesting time. Twenty four plots 3 x 3 m were allocated in a completely randomized design with eight treatments and three replicates, treatments consisted of successive cuts at weekly intervals during a regrowth cycle (eight weeks) in each season of the year. All plots were cut to 5 cm and three samples of 0.1 m2 were taken to ground level to determine residual herbage mass, from then onwards, every week three different plots were harvested. Cumulative herbage mass, growth rate (GR), botanical and morphological composition, leaf:stem ratio, leaf:not leaf ratio and leaf-area index (LAI) were evaluated. Cumulative herbage mass and GR increased steadily after defoliation, until a maximum green lea...

Revista Mexicana de Ciencias Pecuarias, 2002

The objective of this study (which was carried out in a greenhouse) was to investigate the effect... more The objective of this study (which was carried out in a greenhouse) was to investigate the effects of cutting height on herbage production and regrowth dynamics of perennial ryegrass swards. All plots were randomly allocated to six treatments (3, 6, 9, 12, 15 cm cutting height and control) with 15 replicates (three per tray). All pots were cut twice weekly. Every four weeks from March 7 to July 15 all pots contained in one tray were withdrawn for destructive readings of tiller population density, tiller weight, leaf:stem ratio and leaf:non-leaf ratio. Treatments were analyzed in a completely randomized design with three replicates. A multiple regression analysis (stepwise) was also carried out. Cumulative herbage mass was higher at 9 and 12 cm cutting heights (P 0.05); stem, leaf and dead material and total tiller weight increased as cutting height decreased (P<0.05). The highest leaf:stem and leaf:non-leaf ratios were obtained at a 3 cm cutting height (P<0.05). Leaf growth, s...

Revista Mexicana de Ciencias Pecuarias, 2010

El objetivo fue evaluar el efecto de la distancia entre plantas en el rendimiento y calidad de se... more El objetivo fue evaluar el efecto de la distancia entre plantas en el rendimiento y calidad de semilla de Brachiaria brizantha cv. Marandu. El experimento se realizo en temporal durante 2007, en la Universidad del Papaloapan, Loma Bonita, Oaxaca. Se evaluaron seis distancias entre plantas (voleo, 25 x 25, 50 x 50, 75 x 75, 100 x 100 y 125 x 125 cm entre lineas y plantas, respectivamente), con un diseno de bloques completos al azar, con cuatro repeticiones. Se midio el rendimiento de semilla pura (RSP), rendimiento de semilla pura germinable (RSPG), numero de paniculas m-2, longitud de panicula, numero de semillas cosechadas por panicula, peso de 1,000 semillas, porcentaje de dehiscencia, semilla pura y germinacion. El RSP y RSPG vario entre tratamientos (P0.05). Se concluye que el mayor rendimiento de semilla de B. brizantha cv. Marandu, se logro con la distancia 25 x 25 cm entre lineas y plantas, respectivamente. La germinacion de la semilla no fue mejorada por ninguno de los trata...

Revista Mexicana de Ciencias Pecuarias, 2004

The aim of this research was to determine the optimum harvesting time of alfalfa during the diffe... more The aim of this research was to determine the optimum harvesting time of alfalfa during the different seasons of the year. The experiment was carried out from April 2000 to March 2001, at the Instituto Tecnologico Agropecuario research unit, in Nazareno, Xoxocotlan, Oaxaca. The varieties used were: Valenciana and Oaxaca. Thirty-two plots (2 x 2 m) per variety were allocated in a completely randomized design with eight treatments and four replicates, treatments consisted of successive cuts at weekly intervals during a regrowth cycle (eight weeks) in each season of the year. All plots were cut to 5 cm and four samples of 0.25 m2 were taken, per variety, to ground level to determine residual herbage mass, from then onwards, four different plots were harvested to ground level at weekly intervals. Cumulative herbage mass, growth rate (GR), leaf:stem ratio, leaf number per tiller and leaf area index (LAI) were evaluated. The results showed that cumulative herbage harvested had the followi...

Revista Mexicana de Ciencias Pecuarias, 2008

Forage production was determined for the gramineae Brachiaria dictyoneura, B. brizantha (cv. Tole... more Forage production was determined for the gramineae Brachiaria dictyoneura, B. brizantha (cv. Toledo) and B. ruziziensis x B. brizantha (cv. Mulato) as monocrops as well as in association with the legume Arachis pintoi. Experimental design was completely random blocks with four replications. Measured variables included forage dry matter production, growth rate, botanical and morphological composition, tiller density, and tiller weight. Cumulative forage production was higher (P<0.05) among the gramineae monocrop treatments (average = 15,498 kg DM ha-1) than among the gramineae + A. pintoi associations (average = 10,745 kg DM ha-1). The lowest growth rates occurred during the dry season (9 kg DM ha-1 d-1 for A. pintoi, 12 kg B. dictyoneura + A. pintoi), and the highest during the early rainy season (80 kg for cv. Toledo, 71 kg DM ha-1 d-1 for B. dictyoneura). Leaf percentage was high in all treatments with an overall average of 65 % during the northwind season, 57 % for the dry sea...

Revista Mexicana de Ciencias Pecuarias, 2002

The objective of this study was to measure Insurgente grass regrowth (total forage, forage compon... more The objective of this study was to measure Insurgente grass regrowth (total forage, forage component and shoots) grazed at different green leaf allowances, by means of a rotational grazing scheme having fixed rest periods, in the rainy season. Forage was grazed under three different allowances: 3, 5 and 7 kg dry matter (leaf) per 100 kg live weight -,1 day -,1. Experimental design was a random complete block with three replications, and the experimental unit was 0.5 ha carrying two heifers. Grazing was rotational, consisting of a 3 day occupancy period and a 30 day regrowth interval. Four grazing cycles were completed. The smallest allownce (P0.05) differences between them relative to the defoliation rate (49 %). Daily plant weight gain was smaller for the 3 % treatment in the first 15 days but higher in the last 15 days of the regrowth period, compared to the other two treatments. This different growth pattern was determinant in producing a non significant difference (P>0.05) be...

Revista Mexicana de Ciencias Pecuarias, 2001

Joaquin TBM, Hernandez GA, Perez PJ, Herrera HJG, Garcia SG, Trejo LC. Tec Pecu Mex 2001,39(3)245... more Joaquin TBM, Hernandez GA, Perez PJ, Herrera HJG, Garcia SG, Trejo LC. Tec Pecu Mex 2001,39(3)245-254. A study was carried out during 1999 in Tejupilco, State of Mexico (18o 54' N, 100o 08' W and 1320 masl), with the aim to evaluate the effect of nitrogen (N) application and harvest time on seed yield and quality of guinea grass (Panicum maximum Jacq.) cv. Tanzania. Treatments were three N levels (50, 100 and 150 kg ha-1) and six harvest times (6, 10, 14, 18, 22 y 26 days after anthesis, DAA), distributed in a randomized complete block design, arranged in split plots with three replicates. variables evaluated were: pure germinable seed yield (PGSY), number of panicles m-2, panicle length, number of harvested spikelets per panicle (NHSP), shedding percentage, dry matter content, and germination percentage. Results showed that N application increased PGSY, number of panicles m-2, panicle length, and NHSP (P<0.01). The highest yields of PGSY occurred with the application of ...

Revista Mexicana de Ciencias Pecuarias, 2009

The objective of the present study was to assess perennial ryegrass seasonal herbage accumulation... more The objective of the present study was to assess perennial ryegrass seasonal herbage accumulation, growth rate (GR), tiller population density (TPD) and weight (TW) at different grazing frequencies and intensities. Treatments consisted of two grazing frequencies (14 and 21 d in the rainy season and 35 and 42 d in the dry and cold seasons) and three grazing intensities: (hard 4-6 cm), medium (6-8 cm) and lax (8-10 cm) in a completely randomized block design with a factorial 2x3 arrangement and three replicates. In the rainy season herbage accumulation was 28 % greater (P<0.05) at 21 d grazing frequency than at 14 d grazing frequency (4,457 vs 3,457 kg DM ha-1). In the cold and dry seasons herbage accumulation at 35 d interval produced 27 % more herbage than at 42 d interval (2.270 vs 1,787 kg DM ha-1). Medium intensity grazing yielded more herbage than both hard and lax in the three seasons. The highest GR was recorded in the rainy season, especially in August at 21 d frequency an...

Revista Mexicana de Ciencias Pecuarias, 2003

The aim of this study was to investigate the effects of herbage allowance (HA) on herbage product... more The aim of this study was to investigate the effects of herbage allowance (HA) on herbage production and utilization in stargrass (Cynodon plectostachyus) clitoria (Clitoria ternatea) mixture. Four treatments (3.0, 4.5, 6.0 and 7.5 kg de DM 100 kg-1 PV d-¹) were allocated in a randomized block design with five repetitions. The experimental unit was a paddock of 250 m2. Treatments were rotationally grazed every 30 d. Herbage mass on offer, botanical and morphological composition, leaf:non-leaf ratio and pasture utilization percentage were measured. The highest herbage mass on offer (5077 kg DM ha-1), herbage yield (2588), and leaf (826), stem (1210) and dead matter quantity (666) was observed in stargrass with HA of 6.0 and 7.5. For clitoria, treatments with HA of 4.5 and 6.0 (P£0.05) presented the highest herbage mass on offer (1240 kg DM ha-1), leaf (558) and stem quantity (649). The leaf:non-leaf ratio (0.58) and pasture utilization percentage (53 %) increased as HA decreased (P£0...

Revista Fitotecnia Mexicana, 2011

El objetivo del estudio fue determinar la densidad, tasa de rebrotación o recambio y estabilidad ... more El objetivo del estudio fue determinar la densidad, tasa de rebrotación o recambio y estabilidad de la población de tallos del pasto Panicum maximum Jacq. cv. ‘Mombaza’, cosechado a intervalos de cortes (IC) de 3, 5 y 7 semanas, durante un año, en las épocas de sequía (10-nov-2006 a 09-jun-2007) y lluvias (10-jun a 06-nov-2007). Los IC (tratamientos) se distribuyeron en 12 parcelas de 17.5 m2, mediante un diseño de bloques completos al azar con cuatro repeticiones. Las mayores densidades de tallos se registraron en el IC de 3 semanas durante la sequía (428 tallos m-2), y en los IC de 3 y 7 semanas durante las lluvias (413 y 394 tallos m-2, respectivamente). Hubo mayor dinámica de recambio de tallos durante la época de lluvias que en la de sequía, con mayores tasas de aparición (38.0 vs. 4.6 tallos/100 tallos x mes, respectivamente) y muerte de tallos (32.9 vs. 6.4 tallos/100 tallos x mes, respectivamente) y menores tasas de supervivencia (67.1 vs. 93.6 tallos/100 tallos x mes, respe...

El Agora Usb, 2010

El presente estudio consiste en una descripción del uso de los juegos de azar y vídeo juegos en l... more El presente estudio consiste en una descripción del uso de los juegos de azar y vídeo juegos en los estudiantes, docentes y empleados de la Universidad de San Buenaventura, seccional de Medellín, y su relación con las dimensiones médica y psicológica con variables como son: dificultades de concentración, cambio del estado de ánimo, las molestias físicas, preferir el juego a las prácticas deportivas, y la distensión que produce el juego; en este segundo momento se presentan los resultados con docentes. La asesoría metodológica Epi-Info: a cargo de Federico Burgos Acevedo del Centro de Investigaciones Roger Bacon de la USB. El presente estudio está avalado por el Grupo Interdisciplinario de Estudios Psicosociales en Adicciones, GIEPSA (coordinado por Víctor Hugo Cano B. y como investigador principal Jorge Arturo Pérez P.

Revista Mexicana De Ciencias Pecuarias, Jun 1, 2013

Revista Del Instituto De Estudios Economicos, 2008