Revue internationale d'écologie méditerranéenne International ...
Revue internationale d'écologie méditerranéenne International ...
Revue internationale d'écologie méditerranéenne International ...
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KAMAL H. SHALTOUT, TAREK M. GALAL, THANAA M. EL-KOMI<br />
Figure 1 – Map of the Nile Delta region of Egypt.<br />
*: indicating the study locations (after El-Komy 2002).<br />
80<br />
Digestible crude protein (DCP) was calculated<br />
according to the equation of Demarquilly<br />
and Weiss (1970):<br />
DCP (in % DM) = 0.929 CP (in % DM) –3.52<br />
where, DM = dry matter<br />
Carbohydrates (NFE) were calculated from<br />
the following equation (Le Houérou 1980):<br />
NFE (in % DM) = 100 – (CP + CF + EE + MINS)<br />
where, CF = crude fibre, EE = ether extract<br />
and MINS = total minerals.<br />
Total digestible nutrients (TDN) were estimated<br />
according to the equation applied by<br />
Naga and El- Shazly (1971):<br />
TDN (in % DM) = 0.62 (100 + 1.25 EE) – PK<br />
where, P = percentage of crude protein, and<br />
K = coefficient depends on the protein and<br />
fiber contents (0.7).<br />
Digestibile energy (DE) was estimated following<br />
this equation (NRC 1984):<br />
DE (Mcal kg-1 ) = 0.0504 CP (%) + 0.077 EE (%)<br />
+ 0.02 CF (%) + 0.000377 NFE 2 (%)<br />
+ 0.011 NFE (%) – 0.152.<br />
Metabolized energy (ME) = 0.82 DE (Garrett<br />
1980), net energy (NE) = 1/2 ME<br />
Gross energy (GE) was calculated following<br />
this equation (NRC 1984):<br />
GE (Kcal 100g-1 ) = 5.72 CP + 9.5 EE<br />
+ 4.79 CF + 4.03 NFE.<br />
One-way ANOVA was applied to assess the<br />
significance of variations in standing crop<br />
phytomass, elements, organic components<br />
and nutritive variables in relation to the type<br />
of water course and the season (SAS 1985).<br />
ecologia mediterranea – Vol. 36 (1) – 2010