Impact of water deprivation on broilers divergently selected for water efficiency.

Introduction: Sustainable water use in poultry production is becoming pivotal. Extreme weather events and increased water scarcity may increase the risk of temporary disruptions in freshwater access. To address this challenge, the aim of this study was to determine how broilers selected for low (LWE) and high (HWE) water conversion efficiency responded to water deprivation. Methods: Straight-run LWE (n=90) and HWE (n=89) broilers were raised in 12 pens (6 pens per line). On D25 and D32, half of the pens were subjected to water deprivation for a minimum of 12 h (deprived), whilst the remaining pens had Results: LWE broilers consistently weighed more than HWE (p<0.05), whereas water deprivation did not affect body weight at either time point. From D14 onward, LWE broilers had higher feed and water conversion ratios than HWE (p<0.05). Water intake tended to differ between lines, with LWE broilers having the greater post-deprivation water intake (p=0.06). Water deprivation resulted in lower beak surface temperatures (p<0.001) and changes in blood chemistry consistent with dehydration, with deprived broilers having lower bicarbonate (p=0.01), base excess (p=0.02), and total carbon dioxide levels (p=0.02), and increased sodium levels (p<0.001) than controls. Water deprivation did not affect circulating glucocorticoid concentrations, but it altered central neurochemical activity, primarily through increased serotonin turnover (p<0.05). Drinking behavior did not differ between controls of either line, but HWE-deprived broilers were less likely to remain near drinker nipples immediately after water access was restored than LWE-deprived broilers (p<0.05) on D32. Discussion: Water deprivation induced physiological signs of dehydration and compensatory drinking behavior, with limited evidence of a stress response, and selection for water efficiency did not result in clear resilience to short-term water deprivation.