Mathematical curves for the description of input and output variables of the daily production process in aviary housing systems for laying hens.

The objectives of this study were 1) to compute appropriate mathematical curves that describe the daily production process by the input variables daily feed consumption, water consumption, ambient temperature, and output variables hen-day egg production, egg weight, second grade eggs, floor eggs, cumulative mortality, body weight, and flock uniformity; and 2) to obtain insights into the daily variations in these variables, in order to support the poultry farmer with an aviary housing system in his daily management. Literature and research data attained from six unmolted flocks that were housed in aviary systems were used to formulate the mathematical curves. The curves were a function of the number of days in the laying period. Curves for cumulative mortality, hen-day egg production, egg weight, body weight, and percentage of floor eggs described individual flock results well (0.72 < R2adj < 1.00). The coefficients of determination for feed consumption, water consumption, flock uniformity, and percentage of second grade eggs were in general low (0.33 < R2adj < 0.54), which implies that the form of the curve differs between flocks. Egg weight, body weight, cumulative mortality, and hen-day egg production had the lowest minimum coefficients of variation (0.8 to 1.9), followed by feed consumption, water consumption, and flock uniformity (2.8 to 3.6). Ambient temperature, percentage floor eggs, and percentage of second grade eggs had the highest minimum coefficients of variation (4.8 to 9.1).