Resumo

NSA, E.E.; UKACHUKWU, S.N.; ISIKA, M.A.  e  OZUNG, P.O.. Performance of layers fed toasted, boiled or boiled and soaked castor oil seed meal (R. Communis). Arch. zootec. [online]. 2013, vol.62, n.240, pp.479-489. ISSN 1885-4494.  https://dx.doi.org/10.4321/S0004-05922013000400001.

A feeding trial was conducted to investigate the response of Isa Brown laying hens to three different methods of processing castor oil seed meals (CSM); toasting, boiling and boiling-and-soaking for using as total substitute for soybean meal. Two hundred, 75-week old laying birds were randomly assigned to four experimental diets in a completely randomized design experiment. The control diet (CD) contained 19.10 % soybean; the proportion of soybean in the CD (T₁) was replaced completely with toasted, boiled and boiled-and-soaked castor oil seed meal in diets T₂, T₃ and T₄ respectively. Chemical analysis showed that treatment methods did not have any significant (p>0.05) effect on the dry matter (DM), crude fibre (CF), ether extract (EE), ash, nitrogen free extract (NFE) and gross energy of the meal. However, the crude protein value of the toasted meal (24.55 %) decreased (p<0.05) significantly as compared to the other two treatment methods. Toasted method also retain significantly (p<0.05) higher level of ricin value (0.21 mg/100 g) when compared to boiling (0.09 mg/100 g) and boiling-and-soaking (0.03 mg/100 g). Birds on the control diet, T₃ and T₄ had numerically (p>0.05) similar values of final live weight, weight gain, feed conversion ratio and hen day production that were significantly (p<0.05) favorable than birds on T₂. Birds on T₂ also had significantly (p<0.05) depressed liver weight (2.11 %) as compared to birds on the control diet (2.87 %). Haemoglobin (Hb) values also showed a significant decrease (p<0.05) in birds on T₂ (2.23 g/dL) than that of birds on the control (10.67 g/dL), T₃ (10.11 g/dL) and T₄ (10.35 g/dL). Birds on T₂ equally had a significantly (p<0.05) decreased RBC (154.33 x10³) in relation to the control diet (288.02 x10³ ).The egg quality parameters were not significantly (p>0.05) affected by the test ingredient apart from promoting lighter egg yolk coloration. The study showed that boiled and boiled-and-soaked CSM can totally replace soybean meal in layers diet without any adverse effect on egg production, external and internal egg qualities, except encouragement of lighter yolk coloration. Boiling-and-soaking however, as a processing method had no special advantage in terms of egg production parameters and egg quality parameters, hence the additional task of soaking after boiling was unnecessary. Boiling of castor oil seed for 40 minutes is therefore preferred among the treatment methods. As an industrial waste, CSM incorporation in layer diets as a feed ingredient especially for large scale operations would results in substantial cost savings.

Palavras-chave : Egg quality; Layers; Processing; Ricin.

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