Effect of Short-term Water Restriction on Body Weight, Egg Production, and Immune Response of Local and Commercial Layers in the Late Phase of Production

Forty-five Hisex commercial layers and forty-five local Saudi breed layers were used to determine the acceptable limit of short-term water restriction in the late phase of production, when the problem of high feed and water consumption is expected. The experiment was performed under hot and arid environmental conditions when the layers were at fifty weeks of age. Layers from each breed were randomly assigned in groups of five into nine floor pens. The average environmental temperature was 37.2-$38.6^{\circ}C$, and the relative humidity was between 20 to 37%. The trial was divided into 3 periods; control (1 week), water restriction (2 weeks) and rehydration (1 week). During the restriction period, layers from each breed were divided into three groups that received 20, 40, and 0% restriction of drinking water relative to their consumed water during the control period. During the study, feed and water consumption, body weight, changes in body weight, egg production, primary antibody response to SRBC, and rectal temperature were evaluated. Water restriction did not result in any clear effect on feed intake in either breed, however, commercial layers tended to consume less feed compared to the local breed. Body weight declined with water restriction during the first week of restriction in the commercial breed regardless of rate of restriction, but it was delayed until the second week in the local breed. Water restriction of 40% decreased egg production in both breeds but with a delay of 1 week in the local breed. Antibody level to SRBC was not affected by water restriction in the commercial line while it was highly affected in the local breed. A water restriction of 20% is considered to be an acceptable limit under the current experimental conditions without a negative effect on egg production in both breeds and considering the immune status of the local breed. Whereas, 40% restriction had a negative effect on egg production, and varied effects in the other traits in both breeds.