Condensed tannins in Leucaena and their effects on forage quality and psyllid resistance
Abstract
This study evaluates the presence of condensed tannins in species and hybrids of the genus Leucaena. Following the outbreak of the Leucaena psyllid in Hawaii several new varieties and hybrids of Leucaena were evaluated for psyllid resistance. Favorable results particularly with varieties and hybrids related to L. diversifolia and L. pallida led to the establishment of the Mealani Forage Trial on the island of Hawaii. Four six month harvests were collected from the trial and leaf material were oven-dried and stored for forage analysis. The Near Infrared Reflectance Spectrophotometer was used at Purdue University to examine the spectrum of Leucaena leaf samples and to develop a calibrated program to accurately predict forage components (NDF, ADF, crude protein, IVDMD, and condensed tannins) in Leucaena leaf samples. A procedure was developed to estimate relative condensed tannin levels in Leucaena leaf material based on a similar technique used for Sorghum tannin research. An evaluation of KX2 (L. leucocephala x L. pallida) leaf samples for ruminal dry matter and crude protein digestibility was conducted using nylon bag incubation with four cannulated domestic sheep. Digestibility results indicate that considerable variation occurs within the KX2 population for both dry matter and crude protein digestibility and indicates that tree selection for improved forage value could be successful and facilitated though application of near infrared spectroscopy. An additional study of rumen and post-rumen dry matter and crude protein digestibility was conducted using two Holstein steers with rumen and duodenal cannulas. Rumen nylon bag incubation was followed with mobile nylon bag insertion in the proximal duodenum. Results indicate that by-pass protein can be substantial in Leucaena and varies considerably between L. leucocephala, KX2, and L. pallida.
Degree
Ph.D.
Advisors
Chaney, Purdue University.
Subject Area
Botany|Forestry|Agricultural chemicals
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