Influence of rare earth elements as alternative growth promoters in unconventional diets for Oreochromis niloticus [electronic resource].

Includes reference.

The present work was conducted to study the effects of corn replacement by unconventional feed stuffs (pea by products, (pbp) carrot- tops hay, CTH) and rear earth elements (REE) supplementation on growth performance, health condition and body composition of Oreochromis niloticus fingerlings. A total of 450 Oreochromis niloticus fingerlings (body weight 65.6 g) were divided into six groups, which were fed on experimental diets for 12 weeks. The control groups (1, 2) fed on diets contained 37% yellow corn without and with REE- citrate (400 mg/kg). Groups 3, 4 fed on diets replaced 50% yellow corn protein in control diets by pea by products 31.1% without and with REE supplementation. Groups 5, 6 fed on diets which replaced also 50% yellow corn protein in control diets by carrot- tops hay 13.6% without and with REE supplementation. The results showed that there were no significant difference in the final body weight and body gain between fish groups, but there was increase in final body weight of fish in group (2) by 5.6% than group (1) and group (4) by 4.4% than group (3), also group (6) by 6.3% than group (5). The condition factor value indicates the good nutritional state of all fish groups. The survival rate did not differ among the fish groups and the macropathological examination did not reveal any pathological difference in the fish fed unconventional diets. The general healthy condition of the fish was good and all tested fish able to responds positively to all tested reflexes especially escape reflex. The protein efficiency ratio, protein retention and protein productive value were better in groups fed unconventional diets and supplemented with REE. The results of this study revealed that pea- by products and carrot- tops hay can be used as corn replacer with REE supplementation in fish diets. The control diet 2 and also the inclusion of the unconventional feed stuffs (pea by products or carrot- tops hay) and supplementation of REE in diets of fish showed improvement of Productive performance and had lowest value of economical efficiency.

Summary in Arabic.

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