Abstract:

Evaluation of Lablab {Lablab purpureus [Sweet]) cv Rongai
supplementary forage legume for lactating dairy cows (Friesian x Zebu) fed
grass (Pennisetum purpureum), was done at Namulonge
Agricultural and Animal Production Research Institute. The effect of stage
of maturity on the herbage dry matter yield (DMY), in vitro organic matter
digestibility (IVOMD) and chemical composition of Lablab was assessed in
Experiment I. As plant age advanced, herbage biomass DMY, spread and
stem fraction increased significantly (P<0.05). Lablab biomass DMY was 6.6,
10.9 and 12.2 Mt ha'1, for the vegetative, flowering and pod-ripening stages
of growth (75, 110 and 140 days post-planting respectively). The leaf
fraction decreased (P<0.05) with increasing plant age starting from FS to
PS. Likewise, crude protein (CP) content decreased (P<0.05) with increasing
plant age. Neutral detergent fibre (NDF) and acid detergent fibre (ADF)
increased with plant age while, acid detergent lignin (ADL) remained
constant. In vitro organic matter digestility of the leaf and stem fractions
also declined over the growth period by 12 and 19.5%, respectively. Calcium
(Ca) and phosphorus (P) contents remained unchanged during the study
period.
The performance of lactating dairy cows fed elephant grass based
diets supplemented with Lablab hay was studied in Experiment II. Four
and
average live weight of 405.5 (S.D=+15kg).
cross-bred Friesian (Friesian x Zebu), were used in a 4 x 4 Switch-over
Latin square design. The animals had a mean milk yield of 9.5 kg day'1
as a
on elephant
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Addition of Lablab hay significantly increased elephant grass DMI.
The optimum supplement level was 3 kg day.'-1 (as fed), beyond which there
was a substitution effect. Sole feeding on elephant grass resulted in lower
(P<0.05) total dry matter intake (TDMI) than when lablab hay was included
as a
lablab hay supplementation: 9.1; 9.8 and 10.8kg day for levels: 0; 2 and
respectively of lablab hay but decreased to 10.7kg day at a
level of 4kg day.-I. The decrease was not significant. Milk composition was
not affected by supplementation. Animal live weight decreased with sole
elephant grass feeding. Supplementation with Lablab, however significantly
(P<0.05) increased live weight of the animals but there were no differences
among the different supplement levels. A level of 3 kg day,-1 of lablab hay
was sufficient to maintain milk yields and improve animal live weight.
Experiment III evaluated the effect of supplementing a concentrate
to elephant grass-lablab hay basal diets. The experimental design and
animal management were similar to those used in Experiment II. Mean milk
and mean liveweight was 384.5 (+15kg).
Supplementing a basal diet of elephant grass and 3 kg day,-1 of
lablab hay with a concentrate, in Experiment III impaired the intake of
elephant grass although TDMI increased significantly (P<0.05). Daily milk
of a concentrate but there was no significant (P<+0.05)
differences beyond the level of 3 kg day’1. Milk composition, on the other
hand, was not affected by concentrate supplementation. Both supplemented
and unsupplemented animals gained weight. However, the difference in live
weight gains was not significant (P<0.05).
yield was 8.5 kg day’1
3kg day’1
yield was increased (P<0.05) by supplementing: 9.8; 10.4 and 11.3 for levels
0; 1 and 2 kg day’1
supplement. Daily milk yield was significantly (P<0.05) increased by
,-l
viii
A simple cost benefit analysis showed an increase of 5% in gross
margin when lablab was further supplemented with a concentrate.
In Uganda, utilization of elephant grass accompanied by Lablab hay
with a concentrate for lactating dairy cattle is a new intervention which
has not now been documented especially. This practice certainly needs to
be encouraged in light of the results of this study.