The motivatin of non-nutritive
sucking in calves (Bos taurus)
A.M de Passille and J. Rushen
Agriculture and Agri-Food
Canada, Lennoxville, Canada
Although non-nutritive
sucking is common, the motivation is poorly understood. The motivation
of non-nutritive sucking in dairy calves was examined by independently
varying milk intake and prior opportunities for non-nutritive sucking and
observing calves sucking at a non-functional teat. Small amounts of milk
elicited non-nutritive sucking, suggesting a relatively inflexible response
to the taste of milk. Reinforcement from milk was not needed to maintain
sucking. When calves were given less than the normal volume of milk, their
subsequent non-nutritive sucking was not affected, but calves on a low
feed level sucked more, and those that missed a meal increased sucking
after a subsequent meal. When calves sucked after ingesting milk they sucked
less after immediately ingesting further milk. Thus, sucking motivation
is reduced more by sucking behaviour than by milk intake, although it is
not completely independent of hunger. Deprivation of non-nutritive sucking
after one meal did not increase sucking 40 min later or sucking after subsequent
meals. Thus, sucking motivation does not continue to accumulate across
bouts. Non-nutritive sucking
by precocial calves has
some, but not all of the properties of Lorenzian processes.