1. The effects on food intake and weight gain of offering broiler chickens (2 to 7 weeks of age) dry food, wet food, wet food containing whey, whey as drinking liquid and combinations of two of these were studied in 5 experiments. 2. Wet feed generally improved both weight gain and feed efficiencies significantly. Feeding whey also improved weight gain and feed conversion efficiency, but whey offered as a drinking fluid had an adverse effect on broiler performance. 3. When whey was offered both as drinking liquid and added to the food it had a deleterious effect. 4. When whey was offered from 4 or 6 weeks of age, it had a better effect than when offered from 2 weeks of age. 5. There was better performance when whey in the drinking water was diluted and/or offered on alternate days or half-days. 6. Broilers allowed to choose between wet and dry feed when water was freely available chose mostly dry feed; in the absence of drinking water they chose mostly wet food. Birds offered water and liquid whey avoided whey completely. 7. It is concluded that whey can be used in diets for broiler chickens by incorporating it in the food as long as drinking water is offered ad libitum. Whey may be offered as a drink if the food is mixed with 1.8 times its weight of water but it is better to dilute the whey with an equal volume of water whether it is added to food or given as drink. Good results can also be obtained when undiluted whey is offered alternately with water, either in half-day or full-day periods.

1. A 3 x 2 factorial experiment was conducted with three diets and two lines of broiler breeder females to evaluate the contribution of low-energy rations for improving the welfare of feed-restricted birds during rearing. Experimental diets were fed from 6 to 16 weeks of age and were created by diluting a conventional grower (Control) ration containing 11.0 MJ ME/kg with 200 (8.8 MJ ME/kg) or 400 (6.6 MJ ME/kg) g oat hulls/kg using Optimoist to facilitate the pelleting process. Welfare was assessed by changes in behaviour and physiological variables at 8, 12 and 16 weeks of age. Birds were fed restricted quantities of feed to meet recommended body weight targets. 2. There was a decrease in the proportion of observations of drinking and an increase of preening in birds fed on the two experimental diets compared with the control. There was a linear decrease in litter moisture and the number of litter changes with increasing diet dilution, and water intake at 12 weeks was higher in the control than in the two experimental diets. There were no changes in physiological indexes of welfare (heterophil-lymphocyte ratio, plasma corticosterone and antibody responses) associated with the dietary treatments. 3. There were no important differences in the growth, behaviour or physiological responses to dietary treatment between the two lines of broiler breeders. Changes with age were similar to those reported in other experiments. 4. It was concluded that low-energy pelleted diets would improve litter conditions but not improve indexes of welfare in feed-restricted broiler breeders.