Sun-drying as an effective strategy to reduce total oxalate and phytate contents of plant leaves commonly used in quail feeding in Uganda
Keywords:Chemical composition, Oxalate, Phytate, Quail feeding, Sun-drying
Plant leaves are increasingly being integrated into poultry production systems in developing countries because leaves can reduce the proportion of the expensive conventional protein ingredients. Plant leaves are also good sources of minerals and carotenoid pigments for colouring broiler skins and egg yolks. In Uganda, leaves from plants including Colocasia esculenta (cocoyam), Manihot esculenta (cassava), Amaranthus dubius (amaranthus), Brassica oleracea (sukuma wiki) and Ipomoea batatas (sweet potato) are largely fed to quails in their fresh forms. However, minerals, particularly calcium and phosphorus of fresh plant leaves are biologically less available for absorption because of the presence of oxalates and phytates, which bind these minerals. Therefore, in this study, the effect of sun-drying on total oxalate and phytate contents of plant leaves commonly used in quail feeding in Uganda was determined. Samples of five most commonly used plant leaves in quail feeding were collected during the dry and wet seasons, and analysed for total oxalate and phytate compositions after sun-drying or oven-drying. Total oxalate and phytate contents were significantly lower (P ≤ 0.05) in the sun-dried samples compared with the oven-dried samples. Overall mean oxalate contents were 71, 67, 64, 62, and 58% lower for sun-dried Colocasia esculenta, Manihot esculenta, Ipomoea batatas, Brassica oleracea and Amaranthus dubius leaves, respectively. For total phytate, the contents were 66, 19 and 9 % lower for sun-dried Colocasia esculenta, Amaranthus dubius and Amaranthus dubius leaves, respectively. Total oxalate and phytate contents were highest in Brassica oleracea, followed by Colocasia esculenta leaves, and lowest in Amaranthus dubius and Ipomoea batatas leaves. The contents ranged from 2.3 - 5.4 g/100g DM (total oxalates), and 12 - 68 mg/100g DM (total phytates). It was concluded that oxalate and phytate contents varied with plant type and that sun-drying is an effective processing technique for reducing total oxalates and phytates in plant leaves used to feed quails in Uganda.