A quantitative analysis of the feeding behavior of suckling rabbits.

Three experiments are reported on the feeding behavior of suckling rabbits ("kittens"). In the 1st the latency with which the kittens attached to the nipple, and then left the nipple, was determined. Attachment was very rapid and wholly reliable: on the 80 tests the nipple was seized in every case in under 9 sec, and on 67 of these in less than 3 sec. The kittens also invariably left the nipple within the next minute. If the kittens were 5 or 10 days old speed of attachment was unaffected by the presence or absence of saliva on the nipple, but 15- and 20-day-old kittens seized the sucked nipples more rapidly than the unsucked nipples. In a 2nd experiment with 12-day-old kittens, washing the nipple with solvents did not affect speed of attachment; nor did saliva. The results show that suckling rabbits, in contrast to rat pups, are not heavily dependent on saliva cues. In the 3rd experiment both attachment latency and milk intake were shown to be affected by an internal stimulus, a gastric load of.9% saline, 5 g/25 g body weight: attachment latency was significantly increased and milk intake reduced by 75%.

The milk ejection of the rat, as a stimulus and a response to the litter.

A finding that the milk ejection of the rat is stimulated effectively only if at least half the pups are suckled is confirmed. This relationship, however, is found if the mother is anaesthetized but not if the mother is conscious. If the mother is conscious, the milk obtained by individual hungry pups is unaffected by the number of other hungry pups suckled. This is true whether the other pups of the litter are removed, or whether they are present but satiated. After the milk ejection, pups tend to leave the mother's nipple. Milk yield decreases with each milk ejection of a series, but getting less milk does not make the pups more likely to leave the nipple in search of another.