Composición química y características fermentativas de ensilaje de cuatro variedades comerciales de sorgo forrajero en un suelo vertisol en Puerto Rico.

Abstract

An evaluating of four different varieties of commercial Sorghum compared with the Mayorbela corn. Three of the sorghum varieties evaluated contained the bmr (triunfo, pampa verde, and centurion) gene, and one did not possess the bmr (pampa pacas) gene. All sorghum varieties and the corn were planted and were harvested after 84 days in an experimental design in randomized blocks with 5 treatments times 4 repetitions. The samples were sent to the DairyOne Laboratory in Ithaca, NY for Crude Protein (CP), Neutral Detergent Fiber (NDF), and Acid Detergent Fiber (ADF), Total digestive nutrients (TDN) and estimates lactation metabolic energy (ENL). A second sampling of whole plants was done. Experimental PVC silos were filled with approximately with 2Kg of vegetative material that was ensilaged. The vegetative material was ensilaged for 21 days. After this period the silos were opened and pH and aerobic stability tests were performed. Sorghum varieties whether they possessed the bmr gene or not showed higher values of NDF than the corn. Statistically speaking, the no bmr pacas sorghum variety had the most percentage of NDF with an average of (63.58%,P<0.05), followed by the bmr varieties both significantly similar to the pacas variety; triunfo 57.03%, and green 57.83%.The centurion variety had the lowest NDF content with an average of 54.45%.The Mayorbela corn was the one with less content of NDF when compared to all the sorghum varieties with 29.18%.The corn also showed the lowest number in terms of ADF and showed significant difference (P<0.05) when compared to all the sorghum varieties studied.||The sorghum varieties, whether they had the bmr gene or not did not showed a significant difference in the content of ADF within themselves. None of the treatments studied presented any significant difference (P>0.05) in terms of CP %. In terms of the estimated percentage of Total Digestive nutrients (TDN), the pacas variety was the only one that showed a significant difference with the lowest percentage (55.75%), the corn percentage was higher than all the sorghum varieties studied with 58.25%. Except for the pacas all varieties did not present a significant difference in TDN content. The Pacas variety also presented the less amount of estimated lactation metabolic energy (ENL) (1.08 Mcal kg-1). There was no significant difference between the AS and pH of the sorghum varieties and the corn (P>0.05). Both the ensilages of the sorghum varieties that have the BMR gene (Triunfo, Verde, and Centurion) and the sorghum varieties that don’t have the gene (Pacas) as well as the corn where stable during the first 24 hours of aerobic exposition.

Se evaluaron cuatro variedades de sorgos comerciales con el maíz mayorbela, Tres variedades de sorgo forrajero triunfo (BMR), pampa verde (BMR) y pacas y una variedad intermedia centurión (BMR).El diseño experimental evaluado fue de bloques aleatorizados (5x4). Los forrajes fueron cosechados a los 84 días post- siembra. Una muestra fue enviada al laboratorio DairyOne, en Ithaca, NY para análisis de valor nutritivo. La segunda muestra fue ensilada en silos experimentales de 2 kg. Al día 21 los silos fueron analizados para pH y estabilidad aeróbica por 72 horas. Las variedades de sorgo, independientemente de que poseyeran o no el gen BMR, mostraron mayores contenidos de FDN que el de maíz. El sorgo forrajero mostró un mayor contenido de FDN (63.58 %, P < 0.05) que los ensilados de las variedades BMR, Triunfo (57.03%) y Verde (57.83%). Entre los sorgos, la variedad BMR intermedio, Centurión tuvo el menor contenido de FDN (54.45%) y fue similar a la del maíz (52.68%).No se observaron diferencias significativas (P > 0.05) en el contenido de FDA entre las variedades de sorgo, (36.21 %). Sin embargo, el contenido de FDA del ensilaje de maíz (29.18 %) fue significativamente (P < 0.05) el más bajo. No se observaron diferencias significativas (P > 0.05) en el contenido de PB (7.8 %). El contenido de NDT de la variedad forrajera Pacas (55.50 %) fue inferior al del resto de las variedades. No hubo diferencias. El contenido de ENL siguió un patrón similar y se observó que la variedad Pacas fue el que presentó el menor valor (1.08 Mcal kg-1). Tanto los ensilajes de las variedades de sorgo que poseen el gen BMR (Triunfo,Verde y Centurión) como los de las que no lo poseen (Pacas) y el de maíz fueron estables durante las primeras 24 horas de exposición aeróbica. El sorgo intermedio BMR se comportó de manera similar al maíz en términos de su composición química y estabilidad aeróbica.