The Effects of Extended Water Restriction on the Hematological Cell Distribution of Beef Cattle in Confinement

Climate change is likely to limit water availability and drought intensity in the future. The objective of this study was to assess the impacts of water restriction on the health of beef cattle. Four groups of cattle (n = 461) over the course of two years were water restricted with the use of the Insentec System. Baseline water intakes were calculated over a 70-day baseline phase, which was used to step animals down by 10% increments over one week (10%/week) until animals were consuming 50% of their ad libitum intakes. Blood samples were collected every 14 d, except during the step down period when they were collected weekly, for CBC or manual hematocrit analysis. Respiration rates were collected twice daily 2 days a week during ad libitum water intake and twice daily every day starting at the step down period. Weather data was obtained from the Stillwater, OK Mesonet station. White blood cell (WBC) counts were higher during the restriction in the two winter groups in comparison to the summer groups (P < 0.05). The neutrophil: lymphocyte in the winter groups were also greater than the summer groups (P < 0.05). Hematocrit values were greater during the early restriction in all groups than during baseline (P < 0.05). Animals that had been treated at any point in the study had overall higher WBC than animals that were never treated (P < 0.05); however, there were no significant differences in hematocrit between the healthy and morbid animals. Animals that consumed higher amounts of water as percent of body weight had higher WBC than other intake categories while being stepped down (P < 0.05), but there was no difference during 50% restriction. While animals were able to handle the water restriction without increasing sickness, immunosuppression was evident at the 50% restriction and may leave animals more susceptible to increased illness.