Lohmann Hatchery Guide

18 LOHMANN TIERZUCHT › MANAGEMENT GUIDE 18 SETTER It is important not standardise these data in different brands of incubator, but rather to test and control brand by brand (air flow, warming and cooling system and relative action is different and can cause different reactions in our embryos). Every breed has a different metabolic heat production, and for this reason our only reference to the air temperature set-point is the necropsy and the quality of the chicks, where we undertake repeated ac- curate controls. Heat production of the embryo per kg egg mass 4 3,5 3 2,5 2 1,5 1 0,5 0 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Incubation time (days) Heat production (W/ kg) Broiler LOHMANN BROWN layers LOHMANN LSL layers Adapted from Janke, Tzschenktke and Boerjan (2004) In the incubation process, water vapour moves through the pores of eggs to the setter atmosphere. This is very impor- tant because it has a great effect on our weight loss target for the eggs, which is determined by external data concerning number of pores (normally determined by age of flock, size or breeder), eggshell quality (size, health and breed), and the humidity value set in humidity set-point. In Multi-Stage incubation, this value nor- mally ranges between 52% and 55%, and is balanced by a humidifier system. In Single-Stage incubation there are different solutions possible: some brands use the same methods as at Multi-Stage incuba- tion with a little adjustment in humidity value from 60 % at the start of incubation to 45% at the end of the process, which is followed by a constant weight loss of eggs and which involves, in some cases, a strong action of the humidity system on the last day of incubation. This is needed for the essential formation of an air cell and the simultaneous evapo- ration of water, to optimise water and minerals in embryonic compartments; the movement of water from albumen to the sub-embryonic cavity guarantees the right balanced proportion of nutrients. Different philosophies exist in extreme Sin- gle-Stage brands, where there is no humid- ity system in the setter, and where the set- ter starts with a humidity value of around 80 %, and conserves the eggs’ humidity in first week with the proximity of the damp- er. This humidity value constantly decreas- es until it is 30 %–35 % in the final stages of the process. The objective is to not use external water, which can have negative effects in temperature stability in a micro- climate and in biosecurity, but all of these points are possible with a good control of an active damper. Remember, in both situations it is extreme- ly important to reach the right weight loss of eggs for the respective age, in order to have a correct fix point, for a good hatcher performance. Humidity