Effect of restricted cooled drinking water on the performance of broiler breeder hens in a hot, dry climate

1. We tested the effect of cooled drinking water on the performance of broiler breeder hens maintained in a hot, dry climate. Hens from 24 weeks of age (mean body mass = 2–5 kg) were offered one of three treatments: cooled water (18-5°C, COLD) or tap water (27-5°C, CONR) twice a day for a total time of 2.5 h, or tap water ad libitum (CONA). Food was restricted for all hens. 2. Daily water influx in the COLD hens (120 ml/kg) was similar to that of the CONR hens (123 ml/kg), but was 36% lower than that of the CONA hens (163 ml/kg). The same pattern was found in the ratio of water drunk (ml/d) to food intake (g/d): 1.85 and 1.88 in the COLD and CONR hens, respectively, and 2•73 in the CONA hens. 3. There were no significant differences in body mass change among groups. Over the first 28 d of treatment, the COLD hens increased their body mass by 20–9 g/d, the CONR hens by 19.6 g/d and the CONA hens by 21.8 g/d. 4. When offered cooled water from 24 to 30 weeks, egg production decreased in the COLD hens. Egg production in this group was similar to controls during weeks 31 and 32, 1 to 2 weeks after treatment had stopped and at a time that all hens were receiving tap water ad libitum.