Blood electrolyte status over the daily laying cycle and the effect of saline drinking water on the availability of calcium in the blood for egg-shell formation in the laying hen

Nutrition, feeding and laying hen welfare

The relationship between nutrition and welfare is usually considered to be a direct result of supplying the hen with adequate quantities of feed and water. This simple notion of freedom from hunger and thirst belies the fact that nutrients play a pivotal role in the body’s response to challenges whether they relate to ambient temperature, gastrointestinal health, pathogen exposure, metabolic disorders, or social and mental stress. In all instances, maintaining homeostasis and allowing for physiologic response is dependent on an adequate and balanced nutrient supply. It is accepted that most laying hens are fed a complete diet, formulated commercially to provide the required nutrients for optimal health, egg production and welfare. In other words, the laying hen, irrespective of her housing, does not experience hunger or thirst. However, despite adequate nutrient and water supply, certain senarios can significantly affect and alter the nutrient requirements of the hen. Furthermore, the chemical composition and also the physical form of feed can significantly contribute to prevent or treat welfare and health conditions and is, therefore, a highly relevant tool to ensure and maintain an adequate welfare status. Therefore, this review takes a broader perspective of nutritional welfare and considers the nutrition of hens managed in different production systems in relation to nutritional physiology, gut microbiota, stress, metabolic disorders and feeding management.

The influence of drinking water containing sodium chloride on performance and eggshell quality of a modern, colored layer strain

Hubbard ISA IsaBrown pullets were purchased from a commercial supplier at 16 wk of age and kept at a constant 18 C or a constant 30 C in temperature-controlled rooms. The purpose of our experiment was to determine the effect of ambient temperature on the eggshell quality responses of laying hens receiving saline drinking water with or without simultaneous supplementation of the diet with ascorbic acid or Zn methionine. Four treatments were investigated: 1) a basal layer diet (C) and local drinking water, 2) diet C and local drinking water containing 2 g NaCl/L, 3) diet C containing 200 mg ascorbic acid/kg and local drinking water containing 2 g NaCl/L, and 4) diet C with 360 mg Zinpro 100 (Zn methionine)/kg and local drinking water containing 2 g NaCl/L. The local drinking water contained <1 mmol Cl/ L. The pullets received a continuous daily photoperiod of 16 h from fluorescent lighting, and production measures were made between 20 and 60 wk of age. Production and eggshell quality were significantly reduced at 30 C compared with 18 C but were not significantly affected by the dietary and water treatments. The results indicated that the IsaBrown hens were relatively insensitive to intakes of NaCl from the drinking water at concentrations of 2 g/L. This lack of sensitivity in eggshell quality contrasts with the majority of published reports, including earlier work with local Australian layer strains. It is suggested that this contrasting sensitivity may relate to the concentration of dietary NaCl used during the selection of layer genotypes.