On a diet of rice straw sprayed with a mixture of urea and molasses, the effect of different levels of cassava leaf meal (CLM) on intake, and daily live weight gain have been studied in young cattle. Fifteen young crossbred Sindhi cattle (Red Sindhi x Yellow cattle) of 112±7.92 kg weight and 7-8 months of age, were randomly allocated to five treatments in a completely randomized design in the first experiment. The experiment lasted 120 days. The treatments were five levels of CLM of 0, 0.25, 0.5, 0.75 and 1% of live weight (LW). DM intake, live weight gain and feed conversion were improved with significant linear trends according to the level of supplementation with crude protein from CLM.
In the second experiment, five plant protein sources [Cassava
(Manihot esculenta Crantz) (CLM), Sesbania (Sesbania
grandiflora) (SG), Leucaena (Leucaena leucocephala)
(LL), Gliricidia (Gliricidia sepium) (GS) and Water hyacinth
(Eichornia crassipes) (WH)] were heated
for 2 hours at three temperatures: 60, 100 or 140oC to
determine effects on the protein fractions. The experimental
treatments were laid out in a 5x3 factorial arrangement in
Completely Randomized Design (CRD) with 3 replications. The protein
fractions of treated leaves (A, B1, B2,
B3 and C) were estimated using the Cornell Net
Carbohydrate and Protein System (CNCPS) model. The highest
estimated rumen undegraded protein value (fraction B3)
was in WH, followed by CLM, LL, SG and GS. Heating the leaves at
140oC depressed fraction B2 and increased
fraction B3.
In summary, the results confirmed the beneficial effects of supplementing low quality roughages with a source of bypass protein, in this case CLM. The usefulness of the Cornell Net Carbohydrate and Protein System (CNCPS) model appears to be questionable when applied to leaves of tropical plants as according to this system of fractionation, the leaves of water hyacinth were rated superior to those from Cassava, Sesbania, Leucaena and Gliricidia, in terms of rumen undegradable protein. Despite the abundance of water hyacinth in tropical ecosystems there appear to be no reports showing beneficial effects from feeding it to ruminant animals under either experimental or practical conditions. There is an urgent need to correlate in vitro ranking of tropical vegetative protein sources with results of practical feeding trials.