The aim of this study was to evaluate the effect of dietary inclusion of microalga Spirulina platensis (SP) and Chlorella vulgaris (CV) as feed additives in balanced diets formulated for growing rabbits on digestibility, growth performance, carcass traits, some blood parameters of rabbits. Sixty New Zealand White (NZW) rabbits (five weeks old with an average initial live body weight (626.85 g) were divided into five experimental groups (12 in each) for the feeding trail where rabbits in control group was fed 100% complete feed diet without algae supplements (T1), while both kinds of algae were added at 0.75 or 1.5g/Kg diets as T2 and T3 for spirulina diets and at the same two levels T4 and T5 for chlorella supplement, respectively. Rabbits fed the experimental diets till twelve weeks old and then digestibility trail was carried out using three animals for each group. Slaughtered test for carcass characteristics evaluation was done in addition some blood parameters were determined as well.
Results indicated that the final LBW was significantly higher with both levels of SP supplement (T2&T3) than that of control (T1), but the other two levels of CV supplement (T4 &T5) were insignificantly higher than of control, with the highest value being occurred with T3. Similarly , total body weight gain was significantly higher with both levels of SP during the whole experimental period than that of control group , while the value of the two levels of CV were insignificant higher than that of control one . The highest value was associated with T3 followed in descending order by T2, T4, T5 and lastly the lowest value with control (T1). Only feed intake was significant affected by the addition of high level of SP, while the other tested dietary treatments did not significantly influenced, over the whole experimental period , compared with control . Feed conversion was improved significantly due to all algae treatments except that of the high level of CV supplement (T5) which nearly equal to that of control group. Non significant differences among treatments were found in respect of digestion coefficients of DM, OM, CP, CF, EE and NFE nutrients. Concerning the results of slaughter test , slaughter weight for the two levels of SP- diets had significant higher values than those of CV-diets and control one.
Similar trend was observed respecting hot carcass weight among experimental treatments. However, both weights and percentages of liver, kidney, heart and total giblet, didn't significant affected by dietary treatments. Also no significant differences among treatments respecting the dressing percentage was found. The lowest significant (P≤0.05) cholesterol value (37.64 mg/dl) was obtained by rabbits fed diet with high level of SP compared with the control (52.74 mg/dl). Rabbit fed diets supplemented with both levels of SP and also the low CV- diet had performed more economically than the other treatments.
Conclusively, results indicated that both levels of Spirulina – diets markedly improved growth performance of growing rabbits and in addition reduced liver enzyme activities, cholesterol and total lipids concentration in blood compared with control and the chlorella algae supplement