Nutritional uniformity of neutral detergent solubles in some tropical browse leaf and pod diets

An experiment was conducted to study the nutritional uniformity of neutral detergent solubles (NDS) in tropical browse species comprising Faidherbia albida, Acacia tortilis, Delonix elata and Mulberry (Morus alba) leaves and F. albida, A. tortilis, A. nilotica and Dichrostachys cinerea pods. The browse supplements were fed together with maize bran to individually caged goats at increasing levels in hay-based diets. Each diet had five levels of the browse feeds in duplicate which were randomly allocated to the goats in five periods of 14 days each. Chemical composition of the feeds consumed and faeces voided were determined. Nutritional uniformity (Lucas test) of NDS was determined for individual browse by regressing the digestible amount upon its content in the dry matter, in which the regression slope represents true digestibility and the y-intercept, endogenous excretions. otica pods and A. tortilis and D. elata leaves were not well accepted by the animals, due to the high levels of phenolic compounds and mould. There was no significant (p > 0.05) relationship between the estimated amount of digested NDS and content of phenolic compounds in the browses. True digestibilities of NDS were significantly (p < 0.05) different between the species. The y-intercepts were not significantly (p > 0.05) different from zero for all species except F. albida leaves (−7.89). The true digestibility (±SD) of NDS for all the species combined in the Lucas test was 91.9 ± 0.03% and the metabolic matter was estimated at 3.38 ± 1.13 g/100 g of dry matter intake. The variable true NDS digestibility among the species was an indication of non-uniformity of this fraction, implying that the digestibility of the NDS fraction of tropical browse species may not be predicted from its content. Further studies to include more species are necessary to determine if this is a general phenomenon with tropical browse species.