Growing male rats in individually ventilated and open-top cages.

During the past few decades, the development and use of individually ventilated cages (IVC), which are now commercially available for housing laboratory mice and rats, have increased. Because limited information is available regarding the influence of caging systems on the growth of rats, the present study assessed body weight and food and water consumption in growing male rats that were housed in IVC and open-top cages (OTC). We allocated 21-d-old male Wistar outbred rats (HsdOla:WI; n = 24) into 2 groups, which then were housed in pairs in IVC (n = 12) and OTC (n = 12). After an 8-d acclimatization period, body weight and food and water consumption were assessed every 3 d until the rats were 94 d old. There were no significant differences between the body weights of rats housed in IVC compared with OTC over the 65-d observation period. Food and water consumption were greater in rats housed in OTC compared with IVC, becoming significantly different when the rats were 50 and 53 d old, respectively. In conclusion, IVC and OTC housing conditions influenced food and water intakes but not body weight in growing male rats. Further research is needed to clarify the exact basis for these changes in food and water consumption.