Behavior in situ and during open-field testing of calves in stall, pen, hutch and yard housing systems

Abstract

Holstein bull calves (N = 46) were blocked by birth order and randomly assigned to be raised in one of four treatments: stall, pen, hutch and yard. Treatments were representative of commonly-used methods of neonatal calf housing. They differed by the degree of restraint and social isolation imposed on the calves, with stalls being the most restrictive and yard the least. Calves were housed as a group in the yard; in all other treatments they were housed individually. Calves were placed on treatment within 24 h of birth and remained on treatment 6 wk. Behavior was monitored for 24 h in situ during the fifth week on treatment. Behavior was also monitored during weekly 5 min individual open-field tests and a 20 min open-field test at 6 wk in the presence of alien calves. Total time standing or lying per 24 h in situ was not affected by treatment (P (LESSTHEQ) .05). Hutch calves got up and down more often than others (P (LESSTHEQ) .05) in order to remain in sun or shade. During open-field testing, stall and pen calves spent more time performing actions utilized in locomotion, defense and social behavior (P (LESSTHEQ) .05). Hutch calves commenced grazing sooner and were grazing more than others by wk 5. Treatment effects were found for vocalizations during open-field testing: yard calves emitted more "moos" and stall and pen calves emitted more "baaocks" (P (LESSTHEQ) .05). Stall and pen calves engaged in more social encounters (P (LESSTHEQ) .05) during the longer open-field test at 6 wk. Stall calves stumbled and fell more (P (LESSTHEQ) .05) than others during open-field testing. Specific action potential for locomotor activity increased with increasing degree and duration of confinement. Comparison of results based on timed data with those based on count data indicated count data can be utilized to estimate behavioral characters. Results of a physiological study also conducted on the calves showed the more restrictive treatments induced stress, as indicated by an adrenal response test. Treatment effects on other physiological characters were also found. The congruity of the behavioral and physiological data indicates that the intensification of drives induced by their chronic suppression is accompanied by physiological responses indicative of chronic stress.