Ventilation rate, Balance Temperature and Supplemental Heat Need in Alternative vs. Conventional Laying-Hen Housing Systems

Abstract

An Excel-based spreadsheet model was developed to delineate ventilation rate (VR), supplemental heat requirement (Hs), balance temperature (tbal, outdoor temperature below which Hs is required), energy consumption and cost for Hs in alternative (aviary and enriched colony) versus conventional cage laying-hen housing systems. The model was then applied to the Midwestern U.S. housing characteristics at winter weather conditions (-30C to 5C temperature, 70% RH). Effects of stocking density, target house temperature and RH (ti, RHi), building insulation level, and light vs. dark period on VR, tbal and Hs were examined. For the housing characteristics considered, tbal for the alternative housing systems was found to be 2.5C to 3.7C higher than that for the conventional cage counterpart to maintain the houses at 25C ti and 60% RHi. The heater capability needs to be at least 26.6 to 28.4 kW per 10,000 birds for the aviary houses (107,000-bird capacity), and 22.7 kW per 10,000 birds for the enriched colony house (124,000-bird capacity). Annual Hs use was estimated to be 0.17 to 0.25 MJ [kg egg]-1 in the alternative houses. Among the influencing factors considered, ti and RHi setpoints have more pronounced impact on tbal and Hs than other factors. The Hs energy cost for the alternative housing systems in the Midwestern US was shown to account for less than 0.5% of the total production cost. The interactive model can be readily used for analysis of other production and climatic conditions.