NITROGEN LOSSES FROM LAYING HEN MANURE IN COMMERCIAL HIGH-RISE LAYER FACILITIES

Abstract

Nitrogen (N) losses from four high-rise laying hen houses, representing four commercial layer farms in Iowa,were determined from measured performance data of Hy-Line W-36 White Leghorn layers (i.e., manure production, eggproduction, feed intake, body weight, and mortality). Nitrogen loss was 25, 33, 37, and 41% for Farms A, B, C, and D,respectively, based on the Total Kjeldahl Nitrogen (TKN) in feed. A significant factor contributing to the difference in theN losses was the moisture content (MC, percent on an as-is basis) in manure stored in the ventilated manure storage areaof the layer houses. The higher the MC, the higher the ratio of NH 3 /TKN Manure in the stored manure, and therefore, thehigher the percentage of N loss. Mathematical relationships were developed. Manure handling systems played animportant role in N loss by influencing MC of the manure which, in turn, affects rate of manure decomposition.Understanding the factors affecting decomposition and N loss mechanisms of layer manure could provide a means tosignificantly reduce ammonia emissions to the atmosphere from poultry facilities.