La producción de gas in vitro para estimar la energía neta de lactancia
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2020
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artículo original
Autores
Sobalvarro Mena, Jorge Luis
Elizondo Salazar, Jorge Alberto
Rojas Bourrillón, Augusto
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Introducción. El contenido energético de los forrajes es limitante para la producción de leche en sistemas de pastoreo, y la energía neta de lactancia es el parámetro más utilizado para expresar los requerimientos energéticos de los bovinos lecheros. Objetivo. Comparar el valor de energía neta de lactancia de alimentos, obtenido a partir de ecuaciones basadas en la producción de gas in vitro, con respecto a lo estimado por el modelo del National Research Council (NRC). Materiales y métodos. El experimento se llevó a cabo de agosto a diciembre del 2017 en el Centro de Investigación en Nutrición Animal de la Universidad de Costa Rica, San José, Costa Rica. Se determinó la producción de gas in vitro en muestras de pasto estrella, ryegrass, ensilado de maíz, morera y concentrado. Se evaluaron cinco ecuaciones que incorporaron la producción acumulada de gas a las 24 horas. Resultados. La producción de gas mostró diferencias (p<0,001) entre alimentos. El mayor volumen de gas producido y contenido de la energía neta de lactancia (ENL1x) se presentaron con el concentrado. La ecuación 3 mostró la mayor precisión en la estimación de ENL que obtuvo el índice de correlación de concordancia mayor (r2=0,92). La utilización de ecuaciones por tipo de alimento mejoró la precisión en la predicción de ENL. La ecuación 1 fue más precisa en alimento balanceado, mientras que en ensilado de maíz fue la ecuación 4, y en morera, pasto estrella y ryegrass la ecuación 3. El índice de concordancia de Lin explicó mejor las diferencias en predicción de ENL que el índice de correlación de Pearson. Conclusión. La producción de gas in vitro con la aplicación de la ecuación 3, fue un método confiable para estimar el contenido de ENL1x en cinco alimentos utilizados en vacas lecheras.
Introduction. The energy content of forages is a limitation for milk production in grazing systems, and the net energy of lactation is the parameter most used to express the energy requirements of dairy cattle. Objective. To compare the net energy of lactation in feeds, obtained from equations based on in vitro gas production, with that estimated by the National Research Council (NRC) model. Materials and methods. The experiment was carried out from August to December 2017 at the Animal Nutrition Research Center of the Universidad de Costa Rica, San Jose, Costa Rica. In vitro gas production was determined in samples of star grass, ryegrass, corn silage, mulberry, and concentrate. Five equations that incorporated accumulated gas production at 24 hours were evaluated. Results. Gas production showed differences (p<0.001) between feeds. The highest volume of gas produced and content of net lactation energy (NEL) was obtained with concentrate. Equation 3 showed de highest precision for the estimation of NEL, which also reached the highest concordance correlation index (r2 =0.92). The use of equations by type of feed improved the accuracy for the NEL prediction. Equation 1 was more precise in concentrate while in corn silage it was equation 4, and in mulberry, star grass and ryegrass it was equation 3. Lin’s concordance index explained the differences in prediction of NEL1x better than the Pearson correlation index. Conclusion. The in vitro gas production technique with the application of equation 3 was a reliable method to estimate the NEL1x content in five feeds used in dairy cows
Introduction. The energy content of forages is a limitation for milk production in grazing systems, and the net energy of lactation is the parameter most used to express the energy requirements of dairy cattle. Objective. To compare the net energy of lactation in feeds, obtained from equations based on in vitro gas production, with that estimated by the National Research Council (NRC) model. Materials and methods. The experiment was carried out from August to December 2017 at the Animal Nutrition Research Center of the Universidad de Costa Rica, San Jose, Costa Rica. In vitro gas production was determined in samples of star grass, ryegrass, corn silage, mulberry, and concentrate. Five equations that incorporated accumulated gas production at 24 hours were evaluated. Results. Gas production showed differences (p<0.001) between feeds. The highest volume of gas produced and content of net lactation energy (NEL) was obtained with concentrate. Equation 3 showed de highest precision for the estimation of NEL, which also reached the highest concordance correlation index (r2 =0.92). The use of equations by type of feed improved the accuracy for the NEL prediction. Equation 1 was more precise in concentrate while in corn silage it was equation 4, and in mulberry, star grass and ryegrass it was equation 3. Lin’s concordance index explained the differences in prediction of NEL1x better than the Pearson correlation index. Conclusion. The in vitro gas production technique with the application of equation 3 was a reliable method to estimate the NEL1x content in five feeds used in dairy cows
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Palabras clave
Forrajes, NUTRICIÓN ANIMAL, Ganado de leche, Digestión ruminal, Rumen, Forage, Animal nutrition, Dairy cattle, Rumen digestion, GANADO VACUNO