The effect of confinement on motivation to exercise in young dairy calves.

The objective of this research was to determine if confinement of 8-day-old calves for varying lengths of time is associated with an increase in motivation to perform locomotor behaviors. Holstein heifer and bull calves (N=48) were used in a factorial arrangement with two crossed factors. Factor A was housing with two levels (individual confinement versus group pens) and factor B was hours in confinement with four levels (6, 12, 24, and 48h). Individual confinement was in 1.06mx1.06m pens, while group pens had a 3.68mx6.09m outside run and a 3.68mx6.09m covered area that also contained a 3.68mx2.44m area bedded with wood shavings. The calves were placed on treatment when they were 8+/-2 days of age.At the end of the treatments, a blood sample was taken for plasma cortisol determination and lymphocyte counts and the calves were open-field tested for 5min.Walk, trot, distance traveled and behaviors performed while standing during the open-field test were higher in the calves kept in group pens (P=0.0003, 0.01, 0.04 and 0.04), but were not influenced by hours in treatment. Calves confined for 48h had greater incidences of kicking and falling (P=0.014 and 0.025). Lymphocyte count (P=0.029) was lower in the calves confined for 12h, but there was not a trend across hours in confinement that indicated a consistent effect. Housing or hours in treatment did not affect canter, buck, buck-kick, rear, stumble, vocalization and cortisol concentrations. The interaction between hours in treatment and housing was not significant for any of the variables tested.This study suggests that 2 days may not have been enough time for the effects of close confinement to influence motivation in young calves, or that calves averaging 8 days of age may be too young to display increased motivation for locomotor activity. Confinement of such young calves actually inhibits locomotor activity in open-field tests.