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Leguminosae
Common names
Jack bean (southern Africa and Zimbabwe), sword bean (Australia),
one-eye bean (West Indies), feijao de porco (Brazil), horse gram, chickasaro
lima bean, overlock.
Description
Vigorous herbaceous annual climber or woody shrub; three leaflets,
ovate or ovate-elliptic, acutely acuminate at the apex, broadly cuneate
at the base, up to 20 cm long, 10 cm broad, smooth, with six to seven pairs
of lateral nerves. Flowers rose, mauve or white with red base, about 2.5
cm long; few, on stout axis. Pod variable, sword-shaped, elongate, 30 cm
or more long, with two longitudinal ribs near the upper suture; seeds narrowly
ellipsoid, white, smooth (Andrews, 1952). Each seed has a brown hilum extending
around one quarter of it.
Distribution
Occurs in the tropics of both hemispheres, usually in cultivation.
Characteristics
Hardy, drought-resistant annual, immune to most pests; cultivated
extensively for forage and green manuring. Young pods and immature seeds
used as a vegetable for human consumption; mature seeds ground for livestock
feeding. Planted in prepared seed bed in rows about 0.6 to 1 m apart, with
two to three seeds in holes 0.4 m apart (54 kg./ha). Sown with 550 kg.
superphosphate per hectare. Addison (1957) found early planting gave higher
yields in Zimbabwe. Delaying planting one or two months reduced seed yields
by 410 and 2 134 kg./ha respectively. 22 kg. N/ha reduced yields, but some
potash deficiency occurred. Grows slowly at first, flowers three months
after planting, at which stage it is ploughed in for green manure for sugar
cane in Mauritius, where broken seeds are also boiled and fed to cattle.
In Hawaii, half-ripe seeds and sorghum are fed. Forage has low palatability
(Otero, 1952), but Krauss (1911) said that cattle acquire a taste for it.
Forage yields of 18 to 23 tonnes/ha have been reached in Hawaii (Takahashi
and Ripperton, 1949) . In Brazil and Cuba, silage has been made successfully
from the plant.
Addison (1957, 1958) advocated feeding the whole pod and seed to cattle.
In a trial, cottonseed cake fed at 0.7 kg./head/day for 115 days gave a
live weight gain of 51 kg.; C. ensiformis meal at 1.1 kg./head/day a gain
of almost 51 kg. and urea at 84 g/head/day a gain of 25 kg. This was additional
to a basic ration of 7 kg. grass silage and 3.6 kg. maize stover per head
per day. Addison (1958) found that the meal was unpalatable but cattle
would eat it if 18 litres of molasses were added to each tonne of C. ensiformis
meal.
Affleck (1961) and Shone (1961) have reported toxicity in cattle grazing
C. ensiformis aftermath and consuming too much seed meal. The beans contain
a basic amino acid, canavanine, which can be hydrolyzed to urea and catalyzed
by an enzyme contained in an extract from pigs' liver. The seed is an important
source of urease. Animals affected by eating too much of the plant or meal
reach a temperature of 30°C, have a clear nasal discharge, and exhibit
lameness and prostration. Mucus membranes become muddy in appearance and
clear urine is passed more frequently than usual. It has been shown that
28 g of seed per 0.73 kg. body weight are lethal to cattle and either the
meal should not comprise more than 30 percent of the ration or it should
be heat-treated to destroy the enzyme before feeding. The husk of the seed
is always removed before milling.
Chemical analysis of the seed revealed 91.1 percent dry matter, of
which 33.9 percent is crude protein, 2.2 percent fat, 11.2 percent crude
fibre, 49.6 percent nitrogen-free extract and 3.1 percent ash. Otero (1952)
lists several analyses. Crude protein content of the plant about 11.0 percent,
of the silage 10.67 percent, of the seeds 31.96 percent and of the ensiled
seeds 21.25 percent.
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