Use of Carmine as a Balance Study Marker in Rats

Abstract

The use of carmine as a balance study marker was evaluated. Twenty-four male Fischer rats were preliminarily maintained for one week on an AIN-93G diet and then divided into four groups. Two kinds of experimental diet were administered: a AIN-93G (M) diet (Con) and a sucrose diet (Suc), in which the source of carbohydrate was sucrose alone. Also, two kinds of balance study method were employed: a marker-use group (M) and a non-marker group (NM). The first balance study was carried out just after preliminary maintenance (I), and the second to fifth balance studies (II, III, IV, and V) were conducted in the third week, fifth week, fifth month and seventh month of the experiment. The M groups were given a 0.1% carmine diet (red diet) on the first and last days of the balance study, and red feces and white feces were collected separately on the following day. All feces during the balance study in the NM groups were collected. It was found that the feces on each day of the balance study included feces derived from the diet admininstered two days before, and the proportion of these feces increased with advancing age. In balance study I, the dry fecal weight per unit food intake in the SucNM group was significantly lower than that in the SucM group, and high calcium absorption was observed in the SucNM group. In the other balance studies, there was no difference between the M and NM groups. These results show that a marker is needed when a balance study is conducted immediately after a diet regime has been started, or for comparing a diet among animals of different ages. When the same diet is supplied continuously under conditions such as constant feeding and constant fecal excretion, it is possible to conduct a balance study without a marker.