MORPHOMETRIC CHARACTERISTICS OF DWARF RABBITS: EFFECT OF AGE AND GENDER

The aim of the study was to provide information on the morphometric evolution of dwarf rabbits from growing age until adult age, according to their gender. A total of 136 “coloured dwarf” rabbits (74 males and 62 females) were used. At 20 and 45 weeks of age, the rabbits were weighed and body measurements were taken from each rabbit at predefined anatomical points using digital Caliper (mm) or measuring tape (cm). The measurements were: three distance measurements (in cm): body length, BL; ear length, EL; head length, HL; one height measurement (in cm): head height, HH; seven width measurements (in mm): shoulders width, SW; rump width, RW; tibia width, TW; ear width, EW; forehead width, FHW; head width, HW, fold width, FW; two circumferences (in cm): thorax circumference, TC; abdomen circumference, AC. Using these body measurements, a total of 3 body indices were estimated to define the general conformation of the animals: compact index 1: rump width/body length (RW/BL); compact index 2: thorax circumference/body length (TC/BL); compact index 3: abdomen circumference/body length (AC/BL). Data collected were subjected to analysis of variance (ANOVA) studying the effect of age (20 wk, 45 wk), sex (M, F) and their interaction (age x sex). Statistical significance of differences was assessed by the t-test. Considering the main effects, all parameters were affected by age and almost all body measurements by sex with the exception of BL, EL, FHW, HL, TC/BL. At both ages, females showed higher live weights than males (1630 vs 1542 g and 1953 vs 1850 g, at 20 and 45 wk of age, respectively). Significant sex differences were found for AC at 45 wk of age: females presented higher AC value than males (29.5 vs 27.8 cm; P<0.01). As concerns the head measurements with increasing age the males showed the highest mean value of FHW and HW than females 45 wk old and males and females 20 wk old (4.25 vs 4.13 and 3.86 and 3.87 mm, P<0.05; 4.64 vs 4.29 and 4.34 and 4.18 mm, P<0.01, respectively). The FW resulted significantly higher in males at 45 wk of age than females of the same age and males and females 20 wk old (4.28 vs 3.63 and 3.76 and 3.62 mm, P<0.01, respectively). Within the considered indices only compact index 1 (RW/BL) showed significant differences (P<0.01): males 20 wk old resulted less compact than females of the same age and of adult ones. The results showed a clear sex dimorphism for quite all parameters considered, resulting in higher live weight in females than males at both age considered. The live weight and ear length at 45 wk of age exceeded the standard values of the considered dwarf breed and, considering also the high variability observed in most of the measurements used, it appears that through the selection procedures employed probably other breeds were used.