Behavioral and physiological responses of dairy goats to food thwarting.

Eight Nubian dairy goat does in one experiment, and eight Alpine dairy goat does in a second experiment, were randomly allotted to food-thwarted or fed groups in a crossover experimental design. Food thwarting was hypothesized to produce an emotional state analogous to frustration. After a 1-week training period during which the goats of both breeds were conditioned to being simultaneously fed in adjacent feeding stalls, frustration was induced in half the goats by feeding only alternate does. Focal animal behavior was recorded for the initial five min after feeding frustration commenced. Blood samples were collected via a jugular cannula before, during and after frustration was induced for thyroxine (T4), triiodothyronine (T3), cortisol, norepinephrine (NOR), and epinephrine (EPI) determinations. Food thwarting was characterized by increased plasma concentrations of NOR, and increased incidences of pawing, head movements, mouthing of objects, behaviors directed toward neighboring does being fed, and rearing (p less than 0.01). When data were pooled across experiments, breed had a strong influence on cortisol (p less than 0.05), with Nubian does having higher concentrations regardless of treatment. Concentrations of hormones were not significantly correlated with behaviors. These findings suggest that frustration may elicit a discharge of NOR but not EPI.