Effect of age of regrowth, chemical composition and secondary metabolites on the digestibility of Leucaena leucocephala in the Cauto Valley, Cuba

Finding alternatives to deal with the lack of feed during the dry period is a challenge for animal research in tropical areas. The effect of age of regrowth (60, 120 or 180 days), chemical composition and secondary metabolites on Leucaena leucocephala digestibility was evaluated. A randomized block design with six replicates was used. The statistical procedures included analysis of variance and correlation and regression analysis. Multiple linear equations between in vitro and in situ digestibility, as dependent variables, and the age of regrowth, NDF, ADF, lignin, Ca, Si, NDF/N, ADF/N, tannins, condensed tannins and saponins, as explanatory variables, were established. An increase in cell wall content and its components with age of regrowth, and a variable response in mineral concentrations were observed. The linear equations relating digestibility with the age of regrowth, NDF, ADF and Si (R2 > 0.78) or with the secondary metabolites tannins, condensed tannins and saponins (R2 > 0.79) were statistically significant (p < 0.05) explaining a high proportion of variance. The regrowth age, cell wall components, polyphenol compounds, saponins contents determined the forage digestibility and these aspects must be taken into consideration to estimate the nutritional value of Leucaena roughage to be used as feedstuff for animals.