Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Objective: To evaluate the effect of the harvesting interval on the quality of Taiwan grass (Pennisetum purpureum Schum.). Design/Methodology/Approximation: Crude protein (CP), in vitro dry matter digestibility (IVDMD), crude fiber (CF), neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin, ether extract, and ashes were determined. Samples were collected from the Papaloapan experimental site of the Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Isla, State of Veracruz (18° 01’ 45’’ N, 95° 31’ 35’’ W). Treatments consisted of five harvesting intervals (30, 60, 90, 120, and 150 days). Data were analyzed under the general linear model and means were separated using Tukey’s test (P<0.05). Results: The nutritional value decreased (P<0.05) as the harvesting interval increased from 30 to 150 days. The following elements decreased: CP (leaves, from 12.3 to 3.7%; stems, from 8.9 to 2.1%), IVDMD (leaves, from 66.5 to 43.5%; stems, from 62.7 to 32.5%), ether extract (leaves, from 2.4 to 1.4%; stems, from 1.4 to 0.6%), and ashes (leaves, from 10.3 to 6.1%; stems, from 10.9 to 2.9%). On the contrary, the following elements increased: CF (leaves, from 28.4 to 41.1%; stems, from 33.4 to 44.5%), NDF (leaves, from 60.4 to 72.5%; stems, from 63.8 to 74.3%), ADF (leaves, from 36.7 to 46.8%; stems, from 34.6 to 50.7%), and lignin (leaves, from 9.7 to 15.3%; stems, from 11.0 to 18.3%). Study Limitations/Implications: Neither ˂30 days harvesting intervals nor yields (tons) per hectare were taken into account. Findings/Conclusions: Taiwan grass should be harvested at 60 days, when its nutritional value has not decreased too much.

Objetive: To evaluate the growth rate, leaf:stem ratio and height of crotalaria plants (Crotalaria juncea L.), cultivated at different densities, in the dry tropics of the state of Guerrero, Mexico. Desing / Methodology / Approach: The treatments were: four planting densities at 400,000, 200,000, 100,000 plants ha-1 and trickling. A growth analysis was also evaluated at 30, 38, 45, 52, 60, 68 and 75 days of growth, including that the pod was fully developed. The variables evaluated were: growth rate, leaf:stem ratio and plant height. Results: The best growth rate was found at a density of 400,000 plants ha-1, at 75 days of development, with 577 kg DM ha-1 d-1; similar to plant height, which at this density presented 281 cm. Contrary to the leaf:stem ratio, which was greater than 30 days. Regardless of age, a descending behavior was found in the following order: 100,000 ˃ chorrillo ˃ 200,000 ˃ 400,000 plants ha-1 with 0.65, 0.60, 0.59 and 0.55 (p < 0.05). Study Limitations / Implications: This study is essential for future research because these variables have not been evaluated in this crop; being important for forage production. Findings / Conclusions: It is recommended to sow at a density of 400,000 plants ha-1, finding a higher leaf:stem ratio at 30 days of development and a plant height at day 75, when pod production also begins

Objective: To evaluate the chemical quality and in vitro fermentative characteristics to find the optimum cutting point of Panicum maximum cv. tanzania grass under four fertilization schemes. Methodology: The grass was tanzania, which received chemical (F1), vermicompost (F2), compost (F3) and compost+lixiviate (F4) fertilizations. The grass was cut at 20, 35, 50, 50, 65, 80 and 105 days. Neutral detergent fiber (NDF), acid detergent fiber (ADF), crude protein (CP), dry matter (DMD), NDF (NDFD) and ADF (ADFD) degradations and in vitro gas production were determined. The experimental design was a 4x6 factorial arrangement in a completely randomized system with fertilization and days of cutting as factors. Results: F3-65, F1-65, F4-80 and F1-8 d higher NDF content; F1-65 d higher ADF; F1-20 d higher CP (p≤0.05). F4-50 and F2-50 d higher gas production; F4-20, F4-35, F4-50, F2-20, F2-35, F1-20 d higher DMD, F2-20 and F4-20 d higher NDFD; F4-20, F4-35, F4-65 and F2-20 d higher ADFN (p≤0.05). Limitations/implications: Lack of previous research studies on organic fertilization of tanzania. Conclusions: Fertilization with vermicompost or compost+lixiviate improve chemical content, in vitro gas production and degradations of tanzania grass

Objective: to evaluate the forage production performance of hybrid grasses of the genus Urochloa at different mowing intervals and intensity. Design/methodology/approach: Camello I (GPB025) and Camello II (GPB07) hybrids were evaluated at different intervals (5 and 7 weeks) and cutting intensities (10 and 20 cm). The study was carried out under temporary conditions, from 2020 to 2021, in a randomized complete block experimental. The variables evaluated were: yield of total dry matter (DMT) and by morphological component, leaf (DMl), stem (DMs) and inflorescence (DMi) and senescent matter (DMsm), plant height, basal cover, specific leaf area and leaf area index (LAI). Results: on average, when harvesting the forage at an interval of 7 weeks and intensity of 20 cm, higher DMT, DMl and DMs (66, 46 and 85 %, respectively) were obtained, than that obtained when harvesting at an interval of 5 weeks and intensities 20 cm. Limitations of study/implications: Agronomic management in pastures is a factor that affects forage yield and meadow persistence. Making cuts at different intervals and intensities in grasses allows generating adequate management strategies to increase yields and the persistence of the meadow. Findings/conclusions: The highest yield of total dry matter in both cultivars, by morphological component, plant height and leaf area index, was obtained when harvesting at an interval of 7 weeks and at a height of 20 cm of residual forage

Objetive: The objective of this study was to evaluate the yield, intercepted radiation and morphology of crotalaria (Crotalaria juncea L.) at different planting densities, in the dry tropics of the state of Guerrero, Mexico. Desing / Methodology / Approach: The treatments were: four planting densities at 400,000, 200,000, 100,000 plants ha-1 and a stream. A growth analysis was also evaluated at 30, 38, 45, 52, 60, 68 and 75 days of growth, understanding that the pod was fully developed. The variables evaluated were: dry matter yield, intercepted radiation and morphological composition. Results: The dry matter yield, regardless of the cutting age, was obtained in descending order at the planting densities of: 400,000 ˃ chorrillo ˃ 200,000 ˃ 100,000 plants ha-1 with 19,837, 17,918, 8,786 and 4,074 kg DM ha-1, Study Limitations / Implications: In the tropics it is necessary to broaden the panorama with the producers, in the use of forage legumes to improve the feeding of cattle. Findings / Conclusions: It is recommended to sow at a sowing density of 400,000 plants ha-1 and to cut after 45 days of growth in crotalaria since it is when the best structural characteristics of the meadow and 95% of intercepted radiation are found

Objective: to evaluate the effect of breed, reproductive season, dose and time of application of equine chorionic gonadotropin (eCG) on the estrous cycle and ovarian activity in hair ewe lambs. Design/methodology/approach: 216 Hair lambs were used (62 Dorper, 69 Katahdin y 85 Pelibuey), 91 in the high reproductive season and 125 in the low reproductive season, they were synchronized with intravaginal sponges containing 20 mg of fluorogestone acetate (FGA) and equine chorionic gonadotropin (eCG; 200 and 300 IU) intramuscularly. The treatments are the breed, reproductive season, dose and time of application of eCG. The presence of estrus was analyzed under a logistic regression model, the interval to estrus and ovulation rate were analyzed by analysis of variance using a completely randomized design with a 2x2x2x3 factorial arrangement with the PROC LOGISTIC and PROC GLM procedures. Results: the breed influenced (P<0.01) the presence of estrus, Dorper ewe lambs presented 9.74 times more possibilities than the Pelibuey. The interval to estrus was shorter in duration (P<0.05) in Dorper (29.5±0.9 h) and Katahdin (29.1±0.9 h) compared to Pelibuey (34.8±0.9 h). The interval to estrus was lower (P<0.05) with the application of 200 or 300 IU of eCG 24 h before the end of the protocol, compared to the application of 200 IU of eCG at the time of progestogen withdrawal. Ovulation rate was only affected by breed (P<0.05), being higher in Pelibuey (2.4±0.1) compared to Dorper (2.0±0.1) and Katahdin (1.9±0.1). Study limitations/implications: To complement the study, it would be convenient to take the research to a second phase where the gestation part of the females is included to relate it to the ovulation rate, and also to make measurements of ovarian structures by means ultrasound. Findings/conclusions: Estrus and ovarian activity in hair ewe lambs synchronized with progestogens is mainly influenced by breed.

Objective: To determine the thermal sum requirements in degrees days of development (GDD) of the varieties of Avena sativa, Cuauhtémoc and Chihuahua by phenological stage and its effect on the accumulation of total forage and by morphological component in Güémez, Tamaulipas. Design/methodology/approach: The sowing was carried out in plots of 6×6 m and four repetitions of the Cuauhtémoc and Chihuahua varieties through the mechanized preparation of the land, with doses of 120 kg ha-1 of seed and, subsequently, irrigation and fertilization work was carried out. The treatments were made up of the two varieties and six phenological stages (Zadoks scale: Z2, Z3, Z4, Z7, Z8, Z9) in a random complete block design. Results: It was found that, the months of November to March allow to obtain 1923.5 and 1831.5 GDD as a requirement of the crop to complete the biological cycle of the Chihuahua and Cuauhtémoc varieties. Yields by morphological component depended on the observed phenological stage and the highest leaf yield was obtained with 2.7 and 3.6 t ha-1 in Cuauhtémoc and Chihuahua, respectively (P<0.05) in stage Z3, with an accumulation of 1032 and 980 GDD in the stem elongation stage. Limitations on study/implications: These results are applicable only for the evaluation area, because they are physiological responses where the environment intervenes. Findings/conclusions: In Güémez, Tamaulipas, the Chihuahua oat variety requires 1923.5 GDD to complete the biological cycle, while Cuauhtémoc 1831.5 GDD. The difference between the thermal accumulation of the varieties and the phenological stages has an impact on the total forage yield and by morphological component.

Objective: To evaluate the effect of two concentrates and corn stover on the productive performance and economic impact of finished hair sheep lambs. Design/methodology/approach: Twenty hair lambs (Dorper × Katahdin) with initial live weight of 33.3 ± 2.9 kg, were grouped into ten blocks where each block had two lambs of similar live weight that were randomly assigned to two treatments: T1) commercial concentrate + corn stover and T2) experimental concentrate + corn stover, in proportion 80 - 20%. Total weight gain (GPT), daily weight gain (GDP), dry matter intake (DMI), feed conversion (FC), feeding costs, gross value of GPT, gross profit margin and economic efficiency (EE). An analysis of variance was performed under a completely randomized block design. The means were compared with the Tukey test at α = 0.05. Results: There were no differences in GPT, GDP, CA and CMS (P>0.05). The T1 has higher costs (US$41.91) per ton of feed. The production costs of diets and feeding costs were lower for T2, and it also showed the best economic efficiency (EE = 26.6 %). Limitations on study/implications: The advantage of using agro-industrial and agricultural by-products such as corn stover in integral diets for finishing sheep is their availability throughout the year. Findings/conclusions: The finishing of lambs is profitable when the producer formulates and elaborates his own diet, reducing production costs for feeding without affecting the productive variables.

Objective: To determine the dry matter yield of Guinea grass (M. maximus Jacq.) in response to mineral fertilization with N-P-K in a tropical humid climate. Design/Methodology/Approach: We conducted an experiment with Guinea grass in Loma Bonita, Oaxaca, Mexico, during the cold front season (November 2018 to February 2019) and the dry season (March to May 2019). The following N-P-K fertilization formulations were used: 00-00-00, 100-00-00, 140-20-00, 180-40-20, 200-00-00, 240-40-20, 260-60-40, and 300-00-00. The response variables were: plant height (cm), chlorophyll content, and dry matter yield (kg ha-1). Results: The fertilization with the highest nitrogen, phosphorus, and potassium levels (p£0.05) increased the dry matter yield, the chlorophyll content, and the height of the Guinea grass above the control. Study Limitations/Implications: Mineral fertilization improved the productive performance of Guinea grass. However, studying more seasons is necessary to validate the results obtained. Findings/Conclusions: The fertilizer formulas with 260-60-40 and 240-40-20 N-P-K units improved the productive performance of Guinea grass. Consequently, the season of the year had a considerable influence on grass yield in a humid tropical climate

Objective: To determine the effect of cutting height, season, and year on the forage yield of African Star grass (Cynodon nlemfuensis Vanderyst) in Loma Bonita, Oaxaca, México. Design/Methodology/Approach: A randomized block design was used in plots divided using a factorial arrangement and three replications. The treatments consisted of the combination of cutting heights, seasons, and years of evaluation with four repetitions. The following variables were taken into consideration: fresh and dry forage yield (kg ha-1), leaf weight (kg FM ha-1), stem weight (kg FM ha-1), dead material (kg ha-1), leaf-steam ratio, and total yield per hectare (kg ha-1). An analysis of variance was carried out and the means were compared using Tukey's test. Results: The cutting heights did not have an effect on the DM yield. The uniformity cut can be made between 7 and 10 cm. DM performance for the 6 characters evaluated was better in 2018 than in 2016. Study limitations/Implications: Applying dolomite calcium to increase soil pH, N, P, and K levels under irrigated conditions could improve growth rates and DM production. Findings/Conclusions: Cutting heights did not have an impact on forage yield. The uniformity cut could be made at a 7-10 cm height. The rainy season had a higher dry matter yield (3,310 kg ha-1) than the dry season (1,902 kg DM ha-1) and the cold front season (1,914 kg DM ha-1).