Chemical composition, digestibility and in situ degradability of dried and ensiled apple pomace and maize silage

The nutritive value of the dried and ensiled apple pomace (DAP and EAP), taken from two processing factories in Urmia city, was compared with maize silage (MS). For EAP, 1 tonnes of AP was mixed with 100 kg of wheat straw and 5 kg of urea (on fresh weight basis). The chemical composition of all feedstuffs was determined by laboratory analysis. Additionally, pH and the concentration of ammonia-N and volatile fatty acids (VFA) were measured in the EAP and MS silages. An in vivo digestibility study was undertaken with three Gezel wether sheep to determine the digestible organic matter content in the dry matter (DOMD) and to estimate the metabolisable energy (ME) content. The dry matter (DM) and protein effective degradabilities (ED) of the feedstuffs were assessed using a nylon bag method. The mean values of the DM, OM, CP, acid detergent fibre (ADF), neutral detergent fibre (NDF), lignin and acid detergent insoluble nitrogen (ADIN) were, respectively, 749 g/kg fresh weight, 929, 64, 405, 473, 10 and 5.6 g/kg DM for DAP, 284 g/kg fresh weight, 925, 72, 460, 567, 20 and 6.5 g/kg DM for EAP and 429 g/kg fresh weight, 936, 260, 463, 44 and 4.4 g/kg DM for MS. No butyric acid was found in EAP and MS, which indicate good preservation for these silages. However, ammonia-N was higher in MS than EAP. The DOMD values were 690, 654 and 580 g/kg DM for DAP, MS and EAP, respectively. The DOMD and ME values for DAP and MS were significantly higher than those of EAP. The dry matter ED of EAP was significantly lower than that of DAP and MS and there was a significant difference among all feedstuffs in the protein ED where MS was the highest and EAP the lowest. The nutritive value of AP was reduced by the addition of wheat straw. However, ensiling apple with straw is a practical method to preserve such high moisture by-product.