El déficit de forrajes tropicales en la temporada seca requiere de estrategias de alimentación alternas que involucren trasferencia de tecnologías y la conservación de alimentos locales. El objetivo fue evaluar la respuesta animal y el costo beneficio ante raciones mixtas con diferentes niveles de inclusión de ensilado de maíz en sistemas de producción doble propósito del sur de Quintana Roo. Se utilizaron nueve vacas lactantes con 152 días en leche en un diseño experimental de cuadrado latino 3 x 3 por triplicado. Las secuencias de tratamiento fueron asignadas al azar con periodos experimentales de 12 días, el tratamiento uno (T1) estuvo conformado por la inclusión del 15% de ensilado maíz; el T2 por 31%, T3 por un 45%. Se evaluó la producción de leche, peso vivo, condición corporal, la composición química de la leche y la viabilidad económica. La producción de leche promedio fue de 4.4 kg vaca−1 día−1, con un contenido de grasa de 3.3% y proteína cruda de 3.4%. El peso vivo promedio fue de 424.6 kg y la condición corporal de 2.3, manteniéndose constante a lo largo del experimento. Solo se observaron diferencias (P < 0.05) para la condición corporal siendo favorable para T3. La incorporación del ensilado de maíz en un 15, 31 o 45% vaca−1 día−1 en las raciones mixtas de vacas doble propósito que producen 4.4 kg leche−1 día−1 no incrementó la producción de leche, pero si tienen un efecto en los costó total de alimentación.
<p><strong>Background</strong>: The use of <em>Tithonia diversifolia</em> foliage can improve the quality of animal feed because its crude protein content doubles that of tropical grasses. However, plant response regarding biomass production to frequent harvest disturbances are not known well. <strong>Objective</strong>: To evaluate the effect of different cutting heights and repeated harvests on biomass production and nutrient content of <em>T. diversifolia</em> in fodder banks under warm sub-humid climate. <strong>Methodology</strong>: We used a completely randomized design with a factorial arrangement; the treatments consisted of six harvest dates: Mar, May, July, September, November 2019 and January 2020; and three harvest heights: 40, 60 and 80 cm from the ground level. After each harvest date, the biomass was separated into different components, weighed and dried. Samples were taken to analyse the chemical composition of the forage. <strong>Results</strong>: The highest yield of leaves was found in the month of January, while tender stems in November. The Senescent material and total biomass were lower in September. The cutting height influenced leaf yield. Crude protein content was higher in September at a cutting height of 60 cm. Neutral detergent fiber was higher in the month of November for all cutting heights. Likewise, the highest contents of acid detergent fiber were in November for all cutting heights and in January for the cutting height of 60 cm. Lignin content was similar for all treatments. <strong>Implications</strong>: These results contribute to the development sustainable livestock production by providing alternatives to reduce grassland degradation from overgrazing. <strong>Conclusion</strong>: Biomass yield and chemical composition of <em>T. diversifolia</em> are affected by harvest date and heights, so it is necessary to consider it in the management strategies for optimal use of forage resources, incorporation in silvopastoral systems and the development of sustainable livestock production.</p>
<p><strong>Background:</strong> Nitrogen (N) plays an important role within milk production systems (MPS), as an indicator of environmental and economic efficiency. <strong>Objective. </strong>The objective was to determine utilisation of N offered in the ration and estimate GHG from the enteric fermentation and manure management in 12 small-scale dairy farms under two feeding strategies. <strong>Methodology.</strong> Six farms had their herds in confinement under a cut-and-carry feeding system, and six farms implemented day grazing of mixed pastures, both systems used commercial concentrates as a supplement. Cows in milk production and their replacements were considered in the study. Pasture intake was calculated by difference in dry matter intake, using 3.2 % of live weight as intake factor. The N utilisation was determined by difference between N intake and excretion at each farm during a whole year operation. The GHG emissions were estimated following Tier 2 guidelines rom IPCC. Differences in feeding strategies were analysed with a completely random block design using farms as a blocking factor. <strong>Results.</strong> Mean farm size was 5.0 ha for cut-and-carry and 16.0 ha for grazing, and dry matter feed self-sufficiency was 62 and 83% respectively, considering 12% and 22% refusals for each strategy. There were no statistically significant differences (P>0.05) for any of the N utilisation components (N in diet, N in milk, N in manure, NH<sub>3</sub> and N<sub>2</sub>O or GHG emissions. <strong>Implications.</strong> This is a novel report on assessing N fluxes and GHG emissions from small-scale dairy systems in Mexico and Latin America. <strong>Conclusions.</strong> In general, 87.6% of the N consumed is excreted in manure and urine. The feeding strategies did not diverge enough to have an impact on GHG emissions.</p>
The objective of this research was to evaluate and compare the yieldperformance and quality of Tithonia diversifolia forage under different harvesting heights, during the dry and rainy seasons in tropical Mexico. The treatments consisted of three harvest heights 40, 60 and 80 cm from the ground level, cut every60 days, during two seasons of the year. In each period, the biomass was harvested and separated into edible and non-edible components. We determined the biomass yield, and the concentration of crude protein (CP), neutral detergent fibre (NDF), acid detergent fibre (ADF), lignin, ash and organic matter (OM) of the forage. Cutting at 80 cm height yielded the highest forage biomass per harvest (2 008 kg DM ha−1) while there were no significant differences in forage yield between 40 and 60 cm heights. The differences in cutting heights also affected the nutrient qualityof the animal edible forage because the concentrations of CP, ADF and NDF varied significantly. There was a significant interaction between cutting heights and the season on forage production and quality. In the dry season, the content of NDF, FDA, lignin and ash were higher, while the PC and OM were lower. The use of T. diversifolia as a forage plant and cutting it to a height of 80 cm is recommended to maintain the best production and the quality of the forage throughout the year for livestock production.
The objective of this study was to develop and evaluate linear, quadratic, and allometric models to predict live weight (LW) using the body volume formula (BV) in crossbred heifers raised in southeastern Mexico. The LW (426.25±117.49kg) and BV (338.05±95.38 dm3) were measured in 360 heifers aged between 3 and 30 months. Linear and non-linear regression were used to construct prediction models. The goodness-of-fit of the models was evaluated using the Akaike Information Criterion (AIC), Bayesian Information Criterion (BIC), coefficient of determination (R2), mean squared error (MSE), and root MSE (RMSE). In addition, the developed models were evaluated through cross-validation (k-folds). The ability of the fitted models to predict the observed values was evaluated based on the RMSEP, R2, and mean absolute error (MAE). The quadratic model had the lowest values of AIC (2688.39) and BIC (2700.05). On the other hand, the linear model showed the lowest values of MSE (7954.74) and RMSE (89.19), and the highest values of AIC (2709.70) and BIC (2717.51). Despite this, all models presented the same R2 value (0.87). The cross-validation (k-folds) evaluation of fit showed that the quadratic model had better values of MSEP (41.49), R2 (0.85), and MAE (31.95). We recommend the quadratic model to predictive of the crossbred beef heifers' live weight using the body volume as the predictor.
In dairy production systems, the efficient use of resources is required to guarantee its sustainability. Worldwide, the efficiency of feed utilization and its effects have been widely studied. However, few studies have quantified animal nitrogen use and its corresponding soil contribution in small-scale production systems. Therefore, this study aimed to determine the efficiency of feed utilization and quantify the soil chemical composition in small-scale production systems using two different feeding strategies. Twelve dairy farms were evaluated from May 2016 to April 2017. Data analysis was performed using an ANOVA following a completely randomized model and using feeding strategies as treatment. Regarding the feeding systems' characteristics, significant differences (P < 0.05) were only observed in land surface and land used to produce mixed-grass and corn. Nitrogen (N) input and output in dairy cattle were significantly different (P < 0.05) for crude protein intake. The highest results were observed in grazing feeding systems. The cut and carry strategies excreted 71% of the consumed N in the manure; grazing strategies excreted 72%. The efficiency of feed utilization (EFU) is low; only 19% of the consumed N is recovered during milk production. As for the soil chemical composition, significant differences (P < 0.05) were observed in the percentage of total N and the carbon to nitrogen (C:N) ratio. The remaining components behaved similarly in both feeding systems. Systems that include crops and livestock can positively change the biophysical and socioeconomic dynamics of agricultural systems.
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