Abstract :
The objective of this experiment was to evaluate the nutritive value of two seaweeds (Ruppia
maritima and Chaetomorpha linum) and the possibility of including them in a concentrate
for partial replacement of common ingredients. Each species was incorporated in a concentrate
at 20% level with barley and soybean meal. These two concentrates were compared
to a control composed of 80% barley, 17.5% soybean meal and 2.5% mineral and vitamin
supplement (MVS). The same proportion of MVS was incorporated in the two other concentrates.
Twenty-one 5-month-old weaned Barbarine lambs (21.1±2.7 kg body weight)
were divided into three groups and housed in individual boxes then in metabolism cages.
Each lambs group received one of the above concentrate ad libitum and 300 g/day of oat
hay. The three concentrates had similar crude protein (CP) contents (18% DM) but different
proportions of ash. Seaweed-containing concentrates are higher in ash than control
concentrate (12% DM vs. 5% DM). Dry matter (DM), organic matter (OM) and CP digestibility
were similar (P > 0.05) for the control group (77%, 79% and 77%, respectively) and the
seaweed groups (74%, 76% and 72% DM, respectively). Nitrogen retention was not affected
by diet composition (12 g/day), it representing 47% of N intake. Average daily gain (ADG)
was not affected by diet composition (P > 0.05) and lambs grew at rates 183, 172 and 138 g
with control, Ruppia and Chaetomorpha diets, respectively. Feed conversion ratio was similar
for control and Ruppia diets (6.1) and slightly higher for animals fed diet including
Chaetomorpha (7.3).
It is concluded that seaweeds evaluated in this study (i.e. Ruppia maritima and Chaetomorpha
linum) could be used as alternative feed resources for growing lambs during drought
periods.
