Phosphorus Availability in Laying Hens Given Non-phytate Phosphorus Deficient Diets Containing Buckwheat

: To date, the effect of buckwheat phytase on laying hens has not yet been investigated. Thus, this study was conducted to compare the production performance, egg quality, and phosphorus (P) balance of laying hens given nonphytate P deficient diets supplemented with non-germinated buckwheat (BU) or germinated buckwheat (GBU). Experimental diets (17.8% CP, 2,988 kcal/kg ME) consisted of two control diets, the positive control (PC), satisfying all nutrient requirements and negative control (NC) containing 0.16% less non-phytate P than that in the PC diet, and six experimental diets (containing 10%, 15%, 20% BU or GBU), prepared by replacing maize with BU or GBU, along with the raw materials of NC diet. Fifty-six laying hens (46 week of age) were allocated to eight dietary groups (seven hens each) and experimental diets were given for a period of six weeks (week one was employed for acclimatization, and the subsequent five weeks for data collection). Deteriorated production performance (hen-day egg production, feed intake, egg weight and egg mass) and eggshell quality (shell breaking strength, shell weight and shell thickness) in laying hens given a non-phytate P deficient NC diet was restored by the addition of at least 15% BU and 10% GBU to the NC diet. Total P retention significantly increased in 20% BU, 15% GBU and 20% GBU groups as excretion decreased considerably in these groups than the NC group. Considering the hen-day egg production as an economically important parameter, we found that a 340 phytase unit (PU)/kg diet of buckwheat phytase was equivalent to 0.10% non-phytate P in laying hens. These results suggested that the addition of buckwheat in non-phytate P deficient diets can alleviate the deficiency and improve P availability in laying hens.