Effect of heat and separated calcium feeding on laying hens selected for a residual feeding consumption

This paper states the responses at heat and separated calcium feeding of two laying hens selected for the residual feed consumption. For ten variables, interactions lines x treatment revealed meaningful effects, especially for egg weight average, the percentage of broken eggs, the number of duplicate the broken eggs weight, the percentage of the shell, the albumen weight, the yellow weight, the consumption of feed without calcic source, the voluntary consumption with a calcium source. For all these interactions; the under consumer line (R-) gave the best answer to the treatment with egg production in the same level with R+ line, as a less percentage of broken eggs (14,5 % versus 20,9 %), the mean egg weight (48,6 g versus 46,2 g), better egg and shells qualities, finally a better food efficiency. The best performance of R- line is due to the specific calcium appetite, the reduction of the residual consumption (around 30 %). The observed reduction of the residual consumption of R- birds in high temperature constitutes an original characteristic in the selection of the two lines. The study suggested that the adaptation to the heat of the R- line might be improved by combining dwarf and naked genes known for their benefit effects, further in a small farming system in tropical area.