Gabriela Maria Cornescu

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Gabriela Maria Cornescu, Rodica Diana Criste, Arabela Elena Untea, Tatiana Dumitra Panaite, Margareta Olteanu

This experimental study evaluated the supplementation effects of Zn and Mn from laying hens diets on the physical parameters of egg quality. The experiment was conducted for 42 days, on 120 Lohmann Brown laying hens, aged 22 weeks. Birds, accommodated in cages (3 birds/cage), were divided in 4 batches (C, E1, E2, E3). The basal diet (corn, rice, rape meal and soybean meal), identical for all four batches, was characterized by 17.96% protein and 2724.31 kcal/kg metabolisable energy. Diets of the 4 batches differentiated among them by Mn (source MnO) and Zn (source ZnO) levels (mg/kg). Conventional diet of batch C had 71,9 mg Mn/kg NC and 60 mg Zn/kg CF(compound feed). In batch E1 dietary levels of Mn and Zn (85 mg Mn, respectively 145 mg Zn /kg CF) were 5 times higher than NRC requirements, 1994. Batch E2 diet had 100 mg Mn/kg CF and 80 mg Zn/kg CF (according to Lohmann Brown Guide Manual), and batch E3 used double levels in regard to Lohmann Brown Guide Manual (200 mg Mn, respectively 160 mg Zn/kg CF). The results showed that eggshell breaking strength was significantly (P≤0.05) higher for E3 batch (4,68±0.16 kgF) compared to all other batches. Similarly, E3 batch had a significantly (P≤0,05) higher Zn concentration in eggshell compared to C and E2 batches. Eggshell thickness was not different between batches.

Key words: laying hen, Mn, Zn, egg, eggshell quality