BEHAVIOURAL, PHYSIOLOGICAL AND PRODUCTIVE EFFECTS OF WATER UNAVAILABILITY AS A FORM OF UNPREDICTABLE MANAGEMENT STRESSOR IN DAIRY COWS

Introduction - The efficient management of drinking water is an important issue in the dairy farm industry. Lactating dairy cows metabolize large amounts of water, and water deprivation can affect feed intake and milk production. Although accidents which could cause a temporary water unavailability are not unlikely to occur in the dairy cows industry, the effect of such a situation has seldom been scientifically investigated in temperate climates. Aim - The aim of this study was to assess whether there were behavioural, productive and hormonal effects in dairy cows subjected to 3.5-hour water withdrawal (between 06:00 a.m. and 09:30 a.m.) during winter months in a temperate climate. Materials and methods - Twelve healthy lactating Holstein dairy cows were studied. During the “changed management” periods, the 3.5-hour water withdrawal was applied either for one (Tuesday, “one-day change condition”) or for three consecutive (Tuesday to Thursday, “repeated change”) days. The cows were observed by instantaneous scan sampling every 2 minutes for 4.5 hours on Tuesday, Thursday and Saturday. Blood samples were taken at 11.00 on Tuesday and Thursday and cortisol levels analysed by RIA. Data on activity and production were automatically recorded. GLMs, Wilcoxon tests, and ANOVAs were used for analyses. Results and discussion - Cows moved more and interacted more with structures (p<0.05) during water withdrawal, suggesting they were experiencing a certain degree of unfulfilled expectations. However, their overall behaviour was not suggestive of them experiencing a significant stress. No significant differences due to water withdrawal were detected in automatically recorded general activity, which presented marked circadian variations with three peaks (the first between 08:00 and 12:00; the second between 14:00 and 16:00, and the third between 18:00 and 20:00). No significant differences due to water withdrawal were detected in milking parameters and plasma cortisol concentrations. Conclusions - The 3.5 hour water unavailability during winter months, investigated in the present study, did not alter the behavioural, endocrine and productive parameters in a way suggestive of the cows experiencing significant stress.