The influence of experimentally manipulating a component of weaning on the development of play in domestic cats
Abstract Two previous studies found that simulating aspects of early weaning, starting 5 weeks after birth, increased the frequency of object play and, to a lesser extent, social play in kittens. The present study further investigated this finding, using the lactation-suppressing drug bromocriptine to simulate a component of early weaning (a reduction in maternal milk production). The experimental manipulation was started a week earlier in ontogeny than in the previous studies. The subjects were 14 litters of domestic kittens ( Felis catus ), living with their mothers in large indoor pens. Each litter consisted of two kittens. Seven Experimental (E) mothers were injected with bromocriptine on the 28th, 30th and 33rd days after their kittens were born. Seven Control (C) mothers were injected with saline. Observations of the kittens' social play, object play and locomotor play were carried out in each 3-day period from 36 to 60 days after birth. The E kittens showed significantly higher frequencies of a social play measure (Cat Contact) than the C kittens. However, object play was not significantly affected by the manipulation, in contrast to the previous studies. The E kittens also scored higher on a measure of locomotor play and fell off a climbing frame more often than the C kittens. E mothers played less than C mothers. Absolute frequencies of Cat Contacts and Object Contacts were higher in the present study than those previously reported.