Effects of Individual Cage Floor Area and Single Housing on Growth, Behaviour, Stress Responses and Health of Male Albino Rats

The laboratory rats were widely used for the scientific research without much attention for their welfare especially the cage floor area available for them during their childhood period. Therefore, the current study was conducted to evaluate the effects of cage floor area on growth, behaviour, stress responses and health of Wister albino male rats from weaning to maturity. A total of 60 rats were used from 3 to 10 weeks old. The rats were divided into 4 groups; control (630 cm2/ rat), low cage floor area (157.5 cm2 / rat), moderate cage floor area (315 cm2 / rat), and single housing (1260 cm2 / rat). Thereafter, the body weight (BW), body weight gain (BWG), feed intake, and water consumption were measured weekly. The behaviour of rats including total motor activity, locomotor and movement distance were measured by Actimeter. At the end of the experiment, all rats were slaughtered, and blood was collected for either blood smear performing or for determination of serum biochemicals and corticosterone (CORT). The results showed single housing of rats resulted in a reduced BW and BWG. Moreover, total motor activity, locomotor activity, and movement distance of rats were numerically decreased due to low cage floor area and single housing. Furthermore, crowding stress resulted in higher neutrophils to lymphocytes ratio (N / L ratio), higher level of serum CORT, and elevated serum high density lipoprotein (HDL) and alanine transaminase (ALT). In conclusion, crowding stress produced severe adverse effects for growth, behaviours, stress responses and health of rats.