Effects of dry-matter intake and egg production on water influx in single comb White Leghorn hens

Abstract

SummaryWater influx, i.e. total water intake from water drunk and water obtained from food, was measured using tritiated water in six groups, each containing ten single comb White Leghorn (SCWL) hens, in which each group received decreasing amounts of dry matter (D.M.) in decrements of 10%. Group 1 received 101·2 g D.M./day, an amount normally offered these hens, group 2 received 92·4 g D.M./day, group 3 received 81·0 g D.M./day, group 4 received 70·4 g D.M./day, group 5 received 61·6 g D.M./day and group 6 received 52·8 g D.M./day. In the first 4 weeks, egg production remained relatively high in the restricted fed groups compared with group 1 and body mass declined rapidly (period I); in the second 4 weeks, egg production declined to a great extent but body mass remained constant (period II). The ratio of water influx to DMI remained constant in the two periods in hens with the same DMI but with different egg production. The linear regression of DMI and/or egg production on water influx were significant within each period. DMI explained 65% of the variation in water influx, egg production explained 30/55% of the variation, and both DMI and egg production explained 66/70% of the variation. Within each period, the regressions of DMI on water influx in hens with similar egg production were generally significant, and, in contrast, the regressions of egg production on water influx within each DMI were generally not significant. It was concluded that DMI was more important than egg production in affecting water influx in laying SCWL hens.