ADVERSE RESPONSES IN EGG-SHELL QUALITY IN LATE-LAY RESULTING FROM SHORT-TERM USE OF SALINE DRINKING-WATER IN EARLY-LAY OR MID-LAY

Three experiments were carried out to determine the long-term response s in egg shell quality when hens were given saline drinking water for only a few weeks either at the start of lay or in mid-lay. Shell quali ty of eggs from hens given town water containing an additional 2 g sod ium chloride (NaCl)/L as drinking water for periods of 5 or 6 weeks pr ior to 30 weeks of age or between 48 and 53 weeks of age was significa ntly poorer at the end of lay than shell quality of eggs from hens giv en town water throughout lay. Apart from these short periods of saline water supply the NaCl-treated hens received town water throughout lay . Shell defects were increased significantly after 55 weeks of age eve n when no apparent detrimental effects of saline drinking water on she ll quality were observed during the period of saline water intake or w hen the incidence of shell defects returned to normal after the replac ement of saline water with town water. The results indicate that the a dverse effects of saline drinking water on egg shell quality is of lon g-term significance, being especially noticeable towards the end of la y.