Irrigated agriculture requires better estimates of crop water demand. The aim of this study was to estimate the evapotranspiration (ETc) in forage corn through vegetation indices obtained in situ and estimated with remote sensing in the Comarca Lagunera, Mexico. The research was carried out in 2011 and 2012 in four 900 m2 plots irrigated with a subsurface drip irrigation system. Normalized Difference Vegetation Index (NDVI) and crop coeff icient (Kc) during crop development were determined. The initial, maximum and f inal NDVI values were 0.13, 0.79 and 0.63 for both methods and in both cycles. The maximum Kc values were obtained 54 and 48 days after sowing (DDS) with GreenSeeker, and at 61 and 59 DDS with satellite images in 2011 and 2012, respectively. The results showed a good relationship between ETc estimated in situ and ETc estimated with remote sensing (r = 0.98) for both years. Although the variation of ETc using both methods was 1.2 mm day‑1, early in the cycle and 7.4 mm day-1 to flowering start-milky grains. Water needs of forage corn were estimated with similar precision using remote sensing and in situ measurements. Therefore, both methods can be used to improve irrigation scheduling and preserve water resources in agriculture.
The objective was to evaluate the effects of two (2×) vs three (3×) times per day milking on milk production and milk composition in dairy cows. Fourteen scientific papers, containing production data from 16 trials, where dairy cows were milked 2× or 3×, were analysed using meta-analysis with fixed and random-effects with the R statistical program. The degree of heterogeneity and publication bias were measured with the I2 statistic and Begg’s test, respectively. In addition, the meta-regression analysis explored other sources of heterogeneity for the response. The estimated effect size of 2× and 3× milkings was calculated for dry matter intake (DMI), milk production, and milk composition. Dry matter intake, milk production, and milk fat and protein yields showed substantial heterogeneity (I2>50%). Whereas milk fat-percentage had moderate heterogeneity (I2<50%), and milk protein had no (I2=0%)heterogeneity. The year of publication, trial duration, and cattle breed did not influence production response parameters to milking frequency. We found no evidence of publication bias for the parameters evaluated (Begg’s test; P>.05). Cows milked 2× produced less milk (2.23 kg/d), less milk fat (0.06kg/d), and less milk protein (0.05 kg/d). In contrast, the fat percentage was lower (0.07 units) in 3×, compared with 2× milking frequency. There was no effect of milking frequency on DMI and milk protein percentage. In conclusion, milk production and milk fat and protein yields improves as milking frequency increase from 2× to 3× daily, without affecting DMI. The implementation of 3× milking frequency must consider dairy cow management, labor, and milking parlour infrastructure, particular to each dairy farm.
A batata-doce é uma cultura importante para alimentação da população, sendo rica em proteínas, fibras, nutrientes como potássio (K), fósforo (P), cálcio (Ca), magnésio (Mg), ferro (Fe), manganês (Mn), cobre (Cu), e compostos bioativos. É cultivada em geral por pequenos produtores. No Brasil, a produtividade obtida é muito inferior ao potencial produtivo da cultura. A nutrição e adubação da cultura da batata-doce é um tema bastante complexo e contraditório. O objetivo deste trabalho foi analisar os trabalhos existentes na literatura a respeito desse tema, visando melhorar a compreensão das questões relacionadas a adubação e nutrição e da batata-doce. Por meio dessa revisão, conclui-se que a batata-doce tem alta capacidade de produção, mesmo em condições de baixa fertilidade do solo. Porém novas pesquisas são necessárias, já que muitos resultados obtidos até a atualidade são ainda controversos. Nesse sentido, o presente trabalho sugere algumas práticas que podem auxiliar a obtenção de altas produtividades: evitar utilizar doses de nitrogênio (N) maiores que 150 kg ha-1; parcelar a adubação nitrogenada em 33% no plantio, 33% aos 30 dias após o plantio (DAP) e 33% aos 60 DAP; procurar equilibrar as doses de N e K, evitando aplicar doses de N muito mais altas que a de K; não utilizar doses de P maiores que 200 kg ha-1; em solos com baixo teor de B, aplicar 1 a2 kg ha-1 de boro (B). Em solos com alta fertilidade, a adubação orgânica com doses de 25-30 t ha-1 de esterco bovino é suficiente para a obtenção de boas produtividades.
El objetivo de este estudio fue evaluar el efecto del ciclo de producción sobre el potencial de rendimiento y calidad nutricional del maíz forrajero en la Comarca Lagunera. El experimento se estableció en el Campo Experimental-INIFAP. Se utilizó el híbrido de maíz SB-302 en los ciclos agrícolas de primavera y verano bajo un diseño de bloques completamente al azar con cuatro repeticiones durante 2018, 2020 y 2021. La información se analizó con el PROC MIXED de SAS usando el ciclo agrícola como un efecto fijo y el año como efecto aleatorio. Se evaluaron los rendimientos de forraje verde (RFV) y seco (RFS), materia seca (MS), proteína cruda (PC), fibra ácido detergente (FDA), fibra neutro detergente (FDN), digestibilidad in vitro de la FDN a las 30 horas de incubación (DFDN-30 h), energía neta de lactancia (ENL), almidón y lignina, producción potencial de leche por tonelada y por hectárea y rendimientos de FDN, DFDN-30 h y ENL, almidón y lignina. El RFV y RFS fueron mayores en primavera que en verano por 8.8 y 3.7 t ha-1, respectivamente. El ciclo de producción no afectó la MS, FDN, ENL, almidón y lignina. Sin embargo, para el ciclo de primavera los contenidos PC, FDA y DFDN-30 h fueron mayores que en el verano con 0.57, 1.98 y 7.87%, respectivamente. Además, la producción potencial de leche por tonelada y los rendimientos de FDN, DFDN-30 h y ENL fueron superiores en primavera que en verano. En general, el maíz sembrado en primavera presentó mayores rendimientos de forraje por hectárea y mejor digestibilidad de la fibra que el maíz sembrado en verano en la Comarca Lagunera.
El alto valor nutritivo de las brásicas puede incrementar la productividad en los sistemas de producción de forrajes tradicionales. El objetivo del estudio fue comparar el valor nutricional y el rendimiento de materia seca (MS) y nutrientes entre brásicas forrajeras y especies tradicionales de otoño-invierno. Las brásicas forrajeras fueron Winfred, Hunter y rábano Graza y los forrajes tradicionales fueron avena, triticale, cebada, trigo y el trébol Alejandrino. El estudio se realizó en Matamoros, Coahuila, México en el ciclo 2018-2019, bajo un diseño experimental de bloques completos al azar con cuatro repeticiones. Se determinó la capacidad de rebrote, la composición nutricional del forraje y los rendimientos de MS y nutrientes. Todas las especies presentaron capacidad de rebrote, con tres cortes en trébol Alejandrino en 154 días, y con dos cortes en brásicas (150-154 días) y cereales (133-144 días). Las brásicas presentaron similar composición nutricional al trébol Alejandrino y mejor al de los cereales, principalmente por su mayor contenido de energía neta para lactancia (ENL; 6.57 a 7.32 MJ kg-1 MS). Los rendimientos de MS de las brásicas fueron similares a los observados en los forrajes tradicionales; sin embargo, por su alta composición nutricional las brásicas fueron iguales o superiores en producción de proteína cruda (PC) (1,608 a 2,986 kg ha-1) y ENL (62,819 a 84,044 MJ ha-1) a los forrajes tradicionales. En general, las brásicas forrajeras pueden incrementar el rendimiento de nutrientes respecto a los cereales y al trébol Alejandrino, especialmente en la producción de ENL (27.5 a 47.3 %).
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