Effect of the Weaning Period on the Development of the Chewing Function in Guinea Pigs

Abstract

Mastication is one of the main developmental functions among mammals. Several cases of children who show difficulty during mastication have been reported. Unsuitable weaning methods and periods have been suggested as being responsible for this difficulty. These assumptions have been, however, based only on questionnaires or claims by paramedical personal, but have not been sufficiently solved yet. The purpose of the present study was therefore to clarify the effect of different weaning periods on the development of the masticatory function in guinea pigs used as animal models.
A total of forty Hartley guinea pigs were used. They were divided into four groups according to the weaning period (3,7,14 and 30 days after birth) and each group was divided into two subgroups. One sub-group was fed with solid-type food (RC-4 Oriental Kobo Co. ) and the other was fed with softd-type food after they were divided with dams. Begining with 3 days after birth, body weight, behavior and intraoral pressure were recorded at an interval of 3 days in the morning for period of 60 days. A pressure transducer (Gould Stahan Co. P 231-D) connected to a specially deviced nipple was used for recording the intraoral pressure.
The results were as fellows:
There was no difference in the body weight between the solid-type food group and the soft-type food group. Chewing rhythm formation times in the solid-type food groups, and soft-type food group were 60.8±1.5 days,70.6±1.5 days in the 3 day group,50.6±1.8 days,60.4±1.9 days in the 7 day group,42.6±2.7 days,50.6±1.9 days in the 14 day group,39.6±2.1 days,42.2± 2.4 days in the 30 day group. By separation with the dam, the chewing rhythm of all of the experimental groups including the 30 day group was more confused than that of before separation. It is therefore suggested that breeding with a dam is a positive factor for making the rhythmical chewing formation. In conclusion, it is suggested that the chewing rhythm formation is eventually formed, however, the time required to form the chewing rhythm is affected by weaning period and delayed in guinea pigs.