Effects of Acacia nilotica, A. polyacantha and Leucaena leucocephala leaf meal supplementation on performance of Small East African goats fed native pasture hay basal forages

Optimal utilisation of tannin-rich browse tree fodders including Acacia spp. foliages as crude protein (CP) supplements to ruminants in the tropics is limited by less available information on their feed nutritive potential. Two studies were conducted to: (1) determine rate and extent of ruminal dry matter (DM) degradability (DMD) and (2) investigate effect of sun-dried Acacia nilotica (NLM), A. polyacantha (PLM) and Leucaena leucocephala leaf meal (LLM) supplementation on growth performance of 20 growing (7–9 months old) Small East African male goats (14.6 ± 0.68 kg) fed on native pasture hay (NPH) basal diet for 84 days in a completely randomised design experiment in north-western Tanzania. The goats were randomised into four treatment groups consisting of five animals each. Three supplement diets: 115.3 g NLM (T2), 125.9 g PLM (T3) and 124.1 g LLM (T4), which was used as a positive control, were supplemented at 20% of the expected DM intake (DMI; i.e., 3% body weight) to the three animal groups fed on NPH (basal diet) compared to the animals in a control group that were fed on NPH without browse supplementation (T1).NPH had significantly the lowest (P < 0.05) CP of 45.5 g kg−1 DM compared to NLM, PLM and LLM (159, 195 and 187 g kg−1 DM, respectively). NPH had higher (P < 0.05) fibre fractions; lower ruminal DM degradability characteristics and ME than NLM, PLM and LLM. Supplementation of the animals with browse resulted to (P < 0.05) higher average daily weight gains (ADG) of 157.1 g day−1 in T4 than the animals fed on T2 (114.3 g day−1) and T3 (42.9 g day−1), and even to those fed on T1 (control), which lost weight (−71.4 g day−1). Improved weight gains were mainly due to corrected feed nitrogen (N) or CP due to supplementation of the animals with browse fodder. Too low CP of the NPH would not meet the normal requirements of CP (80 g CP kg−1 DM) for optimal rumen microbial function in ruminants. Higher ADG due to LLM (T4) and NLM (T2) supplementation suggest optimised weight gains due to browse supplementation (20% of expected DMI); while lower weight gains from supplementation with PLM (T3) indicate the possible utilisation of A. polyacantha leaves to overcome weight losses especially during dry seasons.