Abstract:
I. YOSELEWITZ* and D. BALNAVE* Drinking water containing an electrolyte replacer (ER) is often given to laying hens during periods of stress. A typical ER, and one recOmmended by the.NsW Department -of Agriculture, is that derived by Gumming and Heath This treatment (1969) for use during outbreaks of Infectious Bronchitis. consists of administering 2-z g NaCl and 4 g potassium citrate/l of drinking water forup t& 7 d. We have found that drinking,water containing between 0.2 and 2 g NaCl/l causes large increases in egg shell defects which are detected within a few days of administering saline water to older hens (Balnaveet al., 1988). The present study was madetodeterminethe ----effect of the a.boveER on the incidenceof eggshell defects from hens of two ages from the same flock. In this split-plot design 20 hens consistently producing eggs with goodshell quality were selected at 48 and 72 weeks of age from the same University layer,flock. They were fed a proprietary layer mash (11.0 MJ of ME and 160 g crude protein/kg) throughout lay and given free access tofood and water at all times. Ten hens in each age group were maintained on town water while the remaining 10 hens received this water containing the ER at the recoimended dosage for 7 d. Results are shown in the Table. TABLE1 Responses to electrolyte replacer (ER) in drinking water Food intake (range 154-158 g/d) was not significantly affected by treatment or age. The use of the ER significantly increased the incidence of shell defects at both ages without affecting the other aspects of production. The response was evident within the 7 d of ER administration and the effect was significantly greater in the older hens. During the four weeks after removal of the ER egg shell defects increased to 44 and VRrespectively in the two age groups whereas increases to 5 and 7% respectively were observed in hens which received the town water only. BALNAVE., D., YOSELEWITZ, I. and DIXON, R.J. (1988). Proc. Poult. Res. Found. Symp., University of Sydney. p. 29. CU4MING, R.B. and HEATH, (1969). Proc. Aust. Poult. Sci. Conv. p. 45% *. Bepartment of Animal Husbandry, Univ&rsity of Sydney, Werombi Road, camden, Nsw 2570. IA