A comparison of methods of inducing a pause in egg production in crossbred layers

Abstract

Three methods of inducing a pause in egg production in 84-week-old crossbred layers were compared with the conventional method (i) of feed and water restriction. The alternative methods were the feeding of: (ii) a nutritionally balanced diet high in zinc, (iii) a nutritionally balanced diet low in calcium, and (iv) a nutritionally imbalanced diet low in calcium in the form of wheat alone. Birds on the low-calcium diet and birds fed only on wheat were slow to reduce their rates of lay, and their subsequent rates of egg production were significantly lower than those of birds from the other treatments. Leg weakness was a major problem in birds on the nutritionally balanced, low-calcium diet but not in birds fed on wheat only. In a second experiment, graded levels of supplementary zinc were used to determine the optimum concentration required to induce a pause in egg production. Compared with birds rested by the conventional method, the birds given a diet high in zinc (18.7 g/kg diet) took approximately the same time to cease laying and to return to 50% production, and there were no significant differences in any of the production parameters examined. When graded levels of dietary zinc were used, only the two highest levels (7.5 and 18.7 g/kg) were effective in producing a pause in egg production. Feed intake was related to dietary zinc levels: high dietary zinc supplementation suppressed appetite and reduced daily feed intake to extremely low levels.